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Acidified CO2 fracturing is a viable method for increasing production in deep, tight sandstone reservoirs. However, the potential mechanism of changes in pore structure and mechanical properties of sandstone under acidified CO2 supercritical composite is not clear. Understanding this mechanism is important for the study of crack initiation and extension in tight sandstone reservoirs. This study utilizes sandstone samples from the Xujiahe Formation reservoir in Rongchang District as experimental specimens. The primary focus is to analyze the changes in pore structure and mechanical properties of these samples after acidification–supercritical CO2 composite action. Nuclear magnetic resonance (NMR) and uniaxial compression tests are employed as the main investigative techniques. The results show that there was a physicochemical synergy between the acidification–supercritical CO2 composite effect; the crack initial stress, damage stress, and peak stress of the sandstone after 16 MPa supercritical CO2 acidification treatment were reduced by 20%, 49.5%, and 49.8%, respectively; the crack volumetric strain accelerated and the sandstone evolved from brittle to ductile damage; and the larger pore space and microcracks of the sandstone increased significantly after the treatment, which can be attributed to the gradual dissolution of intergranular cement leading to the formation of new pores connected to the existing pore network. The change mechanism of sandstone after acidification–supercritical CO2 compound treatment is also proposed. [ABSTRACT FROM AUTHOR]

The re-mobilization risks of potentially toxic elements (PTEs) during stabilization deserve to be considered. In this study, artificial simulation evaluation methods based on the environmental stress of freeze–thaw (F-T), acidification and variable pH were conducted to assess the long-term effectiveness of PTEs stabilized by MgO in Pb/Zn smelter contaminated soils. Among common stabilizing materials, MgO was considered as the best remediation material, since PTEs bioavailability reduced by 55.48% for As, 19.58% for Cd, 10.57% for Cu, and 26.33% for Mn, respectively. The stabilization effects of PTEs by MgO were best at the dosage of 5 wt%, but these studied PTEs would re-mobilize after 30 times F-T cycles. Acid and base buffering capacity results indicated that the basicity of contaminated soils with MgO treatment reduced under F-T action, and the leached PTEs concentrations would exceed the safety limits of surface water quality standard in China (GB3838–2002) after acidification of 2325 years. No significant changes were found in the pH-dependent patterns of PTEs before and after F-T cycles. However, after F-T cycles, the leaching concentrations of PTEs increased due to the destruction of soil microstructure and the functionality of hydration products formed by MgO, as indicated by scanning electron microscopy (SEM) coupled with energydispersive Xray spectroscopy (EDS) results. Hence, these findings would provide beneficial references for soil remediation assessments of contaminated soils under multi-environmental stress. [ABSTRACT FROM AUTHOR]

China currently has the highest acid deposition globally, yet research on its status, impacts, causes and controls is lacking. Here, we compiled data and calculated critical loads regarding acid deposition. The results showed that the abatement measures in China have achieved a sharp decline in the emissions of acidifying pollutants and a continuous recovery of precipitation pH, despite the drastic growth in the economy and energy consumption. However, the risk of ecological acidification and eutrophication showed no significant decrease. With similar emission reductions, the decline in areas at risk of acidification in China (7.0%) lags behind those in Europe (20%) or the USA (15%). This was because, unlike Europe and the USA, China's abatement strategies primarily target air quality improvement rather than mitigating ecological impacts. Given that the area with the risk of eutrophication induced by nitrogen deposition remained at 13% of the country even under the scenario of achieving the dual targets of air quality and carbon dioxide mitigation in 2035, we explored an enhanced ammonia abatement pathway. With a further 27% reduction in ammonia by 2035, China could largely eliminate the impacts of acid deposition. This research serves as a valuable reference for China's future acid deposition control and for other nations facing similar challenges. [ABSTRACT FROM AUTHOR]

Steam-assisted gravity oil drainage (SAGD flooding) is a cutting-edge technology for the development of oils which is gradually replacing steam huff and puff and is being used more and more widely. Low-permeability interlayers are generally developed in oil reservoirs in China, which may shield the migration of steam, oil and gas. Targeted acidizing fracturing was proposed to break through the low-permeability interlayers, and hence, the problem that the hindrance to the expansion of the steam chamber led to heat loss and seriously affected the development effect could be solved. A typical kind of well with SAGD flooding actually applied in China, Shuyi District of Liaohe Oilfield, was taken as the example for studying the optimization of crack parameters. Based on the study of reservoir sensitivity characteristics in this well, the formulations of working fluids for targeted acidizing fracturing were developed by optimizing the weight percentages of main acid solution and additives. The formula of '4% hydrochloric acid + 2% polyphosphoric acid + 5% fluoroboric acid + 4% acetic acid' could be used as the acidizing fracturing working fluid for typical blocks of the Shuyi District of Liaohe Oilfield, which can increase the permeability of the natural core by 40.19–57.06%. Studies on targeted acidizing fracturing are beneficial for enhancing the oil recovery of oil reservoirs. [ABSTRACT FROM AUTHOR]

Copyright of Shipin Kexue/ Food Science is the property of Food Science Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Acidic pollution from gangue oxidation has become a primary environmental problem in coal mining areas in China. The use of microorganisms to remediate acidic pollution in coal gangue piles has been indicated to be effective, but environmental differences and carbon sources in different mining areas have become important factors restricting microbial activity. Instead of the addition of new functional bacteria to gangue piles, carbon sources and nutrient salts were added to recently discharged gangue to enhance the activity of beneficial bacteria in the indigenous microbial community. The changes in pH and electrical conductivity (EC) of the gangue leachate as well as the composition and abundance of the functional microbial community on the surface of the gangue were analyzed by leaching simulation experiments and 16S rRNA sequencing. The results showed that the addition of a carbon source maintained the pH of the gangue leachate at 6.31~6.65 in 14 d, which was significantly higher than that of the control group, but the pH of the leachate decreased significantly after the addition of the carbon source was stopped. The most effective treatment is adding a low concentration of nutrient salt (20% concentration) and sodium lactate (0.02 g/L) to the gangue first, and then adding sodium lactate (0.1 mg/L) every 7 days. The addition of carbon sources and nutrient salts changed the microbial community composition on the surface of the gangue, and the species diversity index decreased. The dominant genera in the experimental group were Listeria, Arthrobacter, and Enterococcus. The functional gene types in the experimental and control groups were almost the same, but their relative abundance changed. The abundance of functional genes related to the sulfur cycle increased substantially in the experimental group, and the abundance of genes involved in the nitrogen and carbon cycles also increased, albeit to different degrees. [ABSTRACT FROM AUTHOR]

Although Taihu watershed is an "acid-insensitive" region, anthropogenic acidification has greatly changed the water chemistry in Taihu Lake. However, how soil carbonates responded to the long-term human-induced acidification received less attention. In this work, we investigated soil carbonate concentrations from different land uses in the upstream of the lake and sediment carbonate profiles in the lake, to explore the linkage of carbonates dissolution in the land and sedimentation in the lake. The result showed that the wheat-rice surface soil, the most acidification-impacted by fertilization and acid deposition, had significantly lower pH than vegetable and wetland soils (p < 0.05). Meanwhile, the carbonate concentration in wetland soils, only impacted by acid deposition, was significantly higher than that in wheat-rice and vegetable soils (p < 0.05). The pH profile of fertilized soils, with an increasing trend from the surface to bottom, further indicated the acidifying effect of fertilization. Although the average soil pH across all land uses was 6.6 in the upstream of the lake, remaining carbonate buffering system, the significant carbonate decrease especially in surface soils evidenced the definite carbonate dissolution by acidification, which is cumulative and irreversible. Contrary to the topsoils, the sediment carbonate concentration presented an increasing trend from the depth of 15 cm (denoting around the early 1980s) to the surface, indicating that lake sediment is a major sink of carbonate Ca and Mg from the watershed, particular under an alkaline lake environment caused by frequent algae blooms in the past decades. In addition, Ca/Mg ratio in the sediment, having higher values in a higher pH environment, was quite different from the watershed soil pattern, suggesting different biogeochemical processes Ca and Mg underwent during their transportation and sedimentation. The effects of acidification-altered re-distribution of carbonate Ca and Mg and Ca/Mg ratio in the terrestrial and aquatic environments deserve wider considerations of ecosystem consequence. [ABSTRACT FROM AUTHOR]

Soil acidification has occurred and accelerated in Jiaodong Peninsula, China, causing serious problems, such as manganese (Mn) toxicity and soil organic carbon (SOC) losses. However, the relationships between SOC and soil Mn are still unclear. This study aimed to explore the changes of Mn fractions and SOC under soaking conditions and the acidification‐induced positive coupled relationship between them. A sequential extraction for Mn species after acid soaking of a Cambisol was conducted, and the soil (pre‐ and post‐soaking) was characterised by X‐ray diffraction (XRD) and scanning electron microscope (SEM). The results showed that acidification of a Cambisol (from pH 6.48 to pH 2.79) induced SOC losses (15.8% of initial SOC). Meanwhile, lower mobile or immobile Mn (especially oxide‐Mn) significantly decreased, accompanied by an increase in readily soluble Mn. It was further shown that the amount of decrease in free Mn reached 268.7 mg kg−1, accounting for 93.8% of the total loss of soil Mn, indicating that the reductive dissolution of amorphous Mn (III/IV) oxides is the dominant reaction in acidified Cambisols. This result was also supported by XRD and SEM. Correlation analysis showed that under soil acidification, the reductive dissolution of amorphous Mn (III/IV) oxides drove losses of both SOC and soil Mn. Therefore, a possible reaction mechanism was proposed: at neutral and alkaline pH, immobile complexes of Mn (III/IV) and particulate organic carbon (POC) formed; and, at acidic pH, readily mobile complexes of Mn (II) and dissolved organic carbon (DOC) formed. Our research suggested that Mn‐organic carbon complexes regulated the transport, transformation, and leaching of soil Mn and SOC, and future research should focus on the soil acidification‐driven Mn reduction‐carbon oxidation processes. Highlights: Acidification accelerated soil organic carbon losses.Acidification induced reductive dissolution of amorphous Mn (III/IV) oxides.A positive couple relationship between SOC and soil Mn existed in acidified soils. [ABSTRACT FROM AUTHOR]

Cropland reactive nitrogen losses (Nr) are of the greatest challenges facing sustainable agricultural intensification to meet the increases in food demand. The environmental impacts of Nr losses and their yield responses to the mitigation strategies were not completely evaluated. We assessed the environmental impacts of Nr losses in China and coupled the efficiency of mitigation actions with yield responses. Datasets about Nr losses in China were collected, converted into potentials of acidification (AP), global warming (GWP), and aquatic eutrophication (AEP), and analyzed by a meta-analysis program. Results showed that producing 1 Mg of rice grains had the highest AP (153 kg acid equiv.), while wheat had the highest GWP and AEP (74 kg CO2 equiv. and 0.37 kg PO4 equiv., respectively). Using the conventional rates (averagely, 200, 230, and 215 kg N ha−1) of urea as a surface application to produce 131.4, 257.2, and 212.1 Tg of wheat, maize, and rice resulted in 17–33 Tg, 7–10 Tg, and 6–87 Gg of AP, GWP, and AEP, respectively. For their balanced effect on reducing AP, GWP, and AEP while maximizing yields, inhibitors, and subsurface application could be set as the best mitigation strategies in wheat production. Inhibitors usage and biochar are strongly recommended strategies for sustainable production of maize. None of the investigated strategies had a balanced effect on rice yield and the environment, thus new mitigation technologies should be developed. [ABSTRACT FROM AUTHOR]

The acidification of the marginal seawater was a more intricate process than the ocean. Although some studies have been done on seasonal acidification in the bottom water of Chinese marginal seas, research on surface water acidification has still been insufficient. We analyzed the acidification properties and controlling factors in the Bohai Sea (BS) and Yellow Sea (YS) surface water during April 2023. The observation showed that the average surface water pH of the BS, North Yellow Sea (NYS), and South Yellow Sea (SYS) were 8.09 ± 0.06, 8.13 ± 0.05, and 8.15 ± 0.05. Phytoplankton significantly impacted pH and Ω arag , while riverine inputs and biological activity played a vital role in controlling DIC and TA. The Yellow River significantly impacted the BS. The North Yellow Sea Cold Water Mass had a limited impact on acidification, while the South Yellow Sea Cold Water Mass significantly affected the SYS. Regarding seasonal fluctuations, Ω arag was significantly higher in summer than in other seasons. DIC and TA showed different patterns in both the BS and YS, with a minimal fluctuation in pH. Over the last two decades, the pH in the BS showed a slight annual decline, and the rate of change was (-1.45 ± 2.19) × 10 -5 yr -1 . In contrast, the NYS and SYS have slightly risen, with rates of change of (2.39 ± 1.24) × 10 -5 and (1.23 ± 0.76) × 10 -5 yr -1 . We believed that surface water acidification in the BS and YS did not follow the expected trend of significant acidification observed in open oceanic regions. Instead, the acidification process in these marginal seas was dominated by local factors such as riverine inputs, biological activity, and cold water masses, resulting in minimal pH changes over the last two decades., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Hypoxia and acidification are universal environmental issues in coastal seas, especially in large river dominated shelves, and the East China Sea shelf is a typical case among them. However, the responses of status of hypoxia and acidification in coastal seas to the extremes of river discharges are still to be revealed. This study surveyed the influences of a summer drought on the status of hypoxia and acidification on the inner East China Sea shelf off the Changjiang estuary. In August of 2023 during a summer drought, carbonate system parameters and dissolved oxygen (DO) were surveyed on the East China Sea shelf off the Changjiang estuary. As expected, dissolved inorganic carbon (DIC) removal (up to >40 μmol kg -1 ) and DO over-saturation (up to >110 %) accompanied by high pH (up to >8.15) in the surface water were observed. However, low DO (32-172 μmol kg -1 ), low pH (7.63-8.04) and low saturation state index of aragonite (Ω Ar ) (1.34-3.06) in the bottom water were observed. Relationships of Excess DIC with DO consumption, and pH and Ω Ar with Excess DIC indicated that the hypoxia and acidification in the bottom water was due mainly to the remineralization of the marine-sourced organic matter. Nevertheless, both hypoxia and acidification were mitigated, i.e. the hypoxic area was smaller, the minimum DO concentration, pH and saturation state index of aragonite were higher in August of 2023 than under the general summer condition. The lower Changjiang discharge (∼60 % of the long-term monthly average) mitigated eutrophication of the East China Sea shelf and decreased the phytoplankton biomass in the surface water and subsequently the hypoxia and acidification in the bottom water. However, acidification of the bottom water on the East China Sea shelf was still severe even during the summer drought. Regulating the anthropogenic impact on the coastal marginal seas is still urgently needed to mitigate the acidification status., Competing Interests: Declaration of competing interest The authors declare that the study was conducted in the absence of any commercial or financial relationships that could be construed as potential conflicts of interest., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Seawater calcium ion (Ca 2+ ) concentration was investigated based on the potentiometric titration method during the summer of 2018 in the Bohai Sea, China. The measured Ca 2+ concentration ranged from 7760 to 9739 μmol kg -1 and deviated from the theoretical Ca 2+ values, which were estimated from the calcium/salinity ratio. The excess calcium (Ca 2+ excess ) ranged from 186 to 1229 μmol kg -1 , showing a decreasing trend from the estuary to the nearshore, and then the offshore areas. Riverine input was an important source of seawater Ca 2+ excess in the Bohai Sea. Biological activity was another factor in regulating seawater Ca 2+ excess concentrations, especially in the estuarine area with a maximum difference of 18.5%. Therefore, the disregard of the calcium addition would lead to an underestimation of the calcium carbonate saturation state and a deviation in the assessment of ocean acidification in marginal seas.arag ) values calculated from the measured Ca 2+ concentrations showed a significant deviation from the values calculated from the theoretical Ca 2+ concentrations, especially in the estuarine area with a maximum difference of 18.5%. Therefore, the disregard of the calcium addition would lead to an underestimation of the calcium carbonate saturation state and a deviation in the assessment of ocean acidification in marginal seas., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Copyright of Petroleum Geology & Recovery Efficiency is the property of Petroleum Geology & Recovery Efficiency and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Carbonate reservoirs in Western China are characterized by deep burial, high temperature, and strong heterogeneity. In this paper, based on the physical properties of high-temperature carbonate reservoirs, the authors have developed an autogenic acidic fracturing fluid suitable for high-temperature carbonate reservoirs. The performance of the new acidic fluid has been experimentally evaluated. The results show that the fluid demonstrates satisfactory viscosity-temperature performance, and after continuous shear tests at 140°C for 2 h the viscosity of the fluid remains about 100 mPa∙s. At room temperature (RT), the pH value of the fluid is neutral, and the titratable acid concentration could reach 15.49% at 90°C. When subjected to high temperatures, the fluid is characterized by a high acid concentration, low acid generation rate, and moderate corrosion inhibition rate. The static rock corrosion rates of the fluid at room temperature and 140°C are 0.00009125 and 0.009575 g/min, respectively. The corrosion rate is slow, and the effective action distance of the fluid can be five times higher than that of a thickened acid and three times higher than that of a cross-linked acid. The experimental results verify the acid's ability to transform high-temperature carbonate reservoirs and good applicability in high-temperature carbonate reservoirs. The proposed autogenic acidic fracturing fluid system provides essential technical support for the efficient development of high-temperature carbonate reservoirs. [ABSTRACT FROM AUTHOR]

Biochar is considered as a universal conditioner to improve soil quality, but its effects of different addition rates on soil properties, bacterial community structure and plant growth are still unclear, particularly in the typical acid purple soil in the southwest of China. In this study, 110 days of rape growth pot experiment under the application rate of 0.0% rice husk biochar (CK), 0.8% (CT1), 2.0% (CT2) and 4.0% (CT3) to the acid purple soil. Results showed that all biochar additions improved soil pH, soil organic carbon (SOC), total phosphorus, available phosphorus, available potassium concentrations in the acid purple soil. The activity of both invertase and catalase, not urease, was significantly increased with the increasing of biochar addition rates. The 16s-gene sequencing results showed that the Chao1 index was increased only under CT3, and the Shannon index was increased after all biochar applications. Furthermore, biochar increased the relative abundance of bacteria that play important roles in soil carbon and nitrogen cycles, SOC decomposition, plant diseases control and growth. The plant height and biomass production of rapes were increased under the low biochar level (CT1), but not under the higher rates of CT2 and CT3. These results demonstrated that biochar, as a soil conditioner to the acid purple soil, could increase soil pH value, SOC, available phosphorus and potassium and affect carbon and nitrogen cycles related to bacterial communities for promoting plant performance under low application rate. [ABSTRACT FROM AUTHOR]

Flowering Chinese cabbages are widely planted in the south of China and often exposed to acid rain. However, the effect of acid rain on the growth of flowering Chinese cabbage is unclear. In this study, we investigated the influence of simulated acid rain (SAR) on plant height, soil-plant analysis development (SPAD) value (an index for chlorophyll content), proline, malondialdehyde (MDA), antioxidant enzyme activities, nitrogen (N), phosphorus (P), or potassium (K) uptake and variation of soil nutrients. Our results showed that SAR at pH 5.5 did not damage plant development because growth characteristics, photosynthesis, and superoxide dismutase and peroxidase activities did not change obviously at this pH compared to those at pH 7.0. However, 2- to 7-time of SAR exposure at pH 4.5 and pH 3.5 led to the increases of antioxidant enzyme activities, MDA and proline contents, and the decreases of leaf SPAD value and root activity. Nutrient analysis indicated that spraying 4 to 7 times of SAR at pH 3.5 reduced the uptake of N, P and K of flowering Chinese cabbage significantly. In addition, treatment with SAR at pH 3.5 decreased the pH value of the surface soil and the contents of alkaline-hydrolytic N and readily available K but increased that of readily available P in the surface soil by 8.5% to 14.9%. Taken together, our results indicated that SAR at pH 3.5 influenced the antioxidant enzyme system and the contents of soil nutrients, caused metabolic disorders and ultimately restricted the development and growth of flowering Chinese cabbages. [ABSTRACT FROM AUTHOR]

Soil bacterial communities are pivotal in regulating terrestrial biogeochemical cycles and ecosystem functions. The increase in global nitrogen (N) deposition has impacted various aspects of terrestrial ecosystems, but we still have a rudimentary understanding of whether there is a threshold for N input level beyond which soil bacterial communities will experience critical transitions. Using high‐throughput sequencing of the 16S rRNA gene, we examined soil bacterial responses to a long‐term (13 yr), multi‐level, N addition experiment in a temperate steppe of northern China. We found that plant diversity decreased in a linear fashion with increasing N addition. However, bacterial diversity responded nonlinearly to N addition, such that it was unaffected by N input below 16 g N·m−2·yr−1, but decreased substantially when N input exceeded 32 g N·m−2·yr−1. A meta‐analysis across four N addition experiments in the same study region further confirmed this nonlinear response of bacterial diversity to N inputs. Substantial changes in soil bacterial community structure also occurred between N input levels of 16 to 32 g N·m−2·yr−1. Further analysis revealed that the loss of soil bacterial diversity was primarily attributed to the reduction in soil pH, whereas changes in soil bacterial community were driven by the combination of increased N availability, reduced soil pH, and changes in plant community structure. In addition, we found that N addition shifted bacterial communities toward more putatively copiotrophic taxa. Overall, our study identified a threshold of N input level for bacterial diversity and community composition. The nonlinear response of bacterial diversity to N input observed in our study indicates that although bacterial communities are resistant to low levels of N input, further increase in N input could trigger a critical transition, shifting bacterial communities to a low‐diversity state. [ABSTRACT FROM AUTHOR]

In recently years, China's livestock and poultry breeding industry has gradually developed in the direction of large-scale and centralization. With the continuous expansion of the scale of breeding, the problem of rapid increase of animal slurry emissions is becoming more and more seriously. Animal slurry were applicated reasonably can not only solve the problem of pollution, but also improving soil nutrients. There is a large amount of ammonium nitrogen in animal slurry. Unreasonable application will lead to the emission of a large amount of ammonia gas from animal slurry into the soil. In generally, the animal slurry should be stored for a period of time and then returned to the field. During the storage period, methane (CH4) emission was reduced, and the fertilizer efficiency of stored manure may improve. Acidification is a way to improve storage quality. At present, there are more studies abroad on the effect of treating animal slurry return to the field. However, the effect of the acidification storage of animal slurry on soil nutrients has been rarely reported in China. In order to explore the application effect about fresh (MS), acidification (HMS), storage (SMS), and acidification storage (SHSM) of animal slurry to field. The pot experiments were conducted to study the effect of animal slurry on soil nutrients and crop yield by using concentrated sulfuric acid and long-term storage of animal slurry. Two control groups were set up for the experiment: Animal slurry before and after storage, and animal slurry before and after acidification of H2SO4. Four different levels (5%, 25%, 50% and 100%) were set for each treatment. The results indicated that the concentration of animal slurry to the field should be strictly controlled (the level at 25%-50%). Animal slurry stored was benefit to the total nitrogen (TN) and total phosphorus (TP) of soil nutrients. After storage, the total nutrients (TN, TP, and total potassium (TK)) increased by 11.32%-73.16%, and the crop yield of SMS(100%) increased by 21.22%. However, after the acidification with H2SO4, the effect of animal slurry on the total soil nutrients changed significantly. Compared with MS, the TP content of HMS increased by 20.21%, 3.45%, 14.10% and 12.82%, and the content of available phosphorus increased by 64.59%, 0.48%, 2.66% and 19.69% at the level of 5%-100%, respectively. The crop yield of HMS(25%) increased by 27.94%. On the basis of the H2SO4 acidized and stored, the TN content of soil increased very significantly (P<0.05), the TN content increased by 20.65%, 25.14%, 46.99% and 82.98% at four different level. Acidification and storage processing to reduce the loss of TN have promoting effect to the increase of soil available nutrients, especially for the effect of available nitrogen significantly (P<0.05), and the crop yield of SHMS(25%) increased by 13.63%. Reasonable application of stored manure slurry and low concentration of animal slurry acidified by H2SO4 can increase crop yield. In generally, the application of stored animal slurry can promote the total nutrients content of soil, promoting the accumulation of phosphorus, and increasing the crop production. However, it is not suitable to apply too high concentration of animal slurry, which will inhibit the yield of crops. The application amount should be controlled within the range of 25% as far as possible. [ABSTRACT FROM AUTHOR]

The current poor understanding of soluble iron (Fe) yield in atmospheric aerosols leaves two observational facts having not yet been correctly simulated in numerical models: the high Fe solubility in aerosols with low Fe content and, hence, the wide range of observed Fe solubility. Our observation at Qingdao, a coastal city of China, revealed that soluble Fe was produced along with aerosol acidification much more efficiently in fog than under other weather conditions. The median Fe solubility in fog aerosols, 5.81%, was 3.3 times of that in haze aerosols, 5.2 times of that in clear days, and 21.5 times of that in dust aerosols. Involving fog processing in models may reduce the discrepancy in the atmospheric flux of soluble Fe to the ocean between numerical simulations and field observations. Plain Language Summary: Aerosol soluble Fe depositing into seawater promotes marine primary productivity, alters global ocean carbon storage, and ultimately affects global climate. Current models largely underestimate the concentration of soluble Fe in aerosols, but the reason is not clear. Our present results revealed the high efficiency of fog to drive the conversion of Fe from insoluble form to soluble form in the atmosphere, a process that has been overlooked in models. To increase the simulation accuracy, proper inclusion of fog processing in models is necessary. Key Points: Conversion of aerosol Fe from insoluble form to soluble form in fog was much more efficient than in haze and dustUnderestimation of aerosol soluble Fe in latest models was largely caused by inaccurate simulation under fog conditionsProper description of processing of aerosol Fe in fog in models is essential to improve simulations [ABSTRACT FROM AUTHOR]

In this study, we tested whether larvae brooded by the reef coral Pocillopora damicornis from a naturally extreme and highly variable environment are preadapted to cope with predicted increases in temperature and pCO2. We exposed larvae to two temperatures (29 vs. 30.8 °C) crossed with two pCO2 levels (~ 500 vs. ~ 1000 μatm) in a full-factorial experiment for 5 d. Larval performance was assessed as dark respiration (RD), net and gross photosynthesis (PN and PG, respectively), survival, settlement, and the activity of carbonic anhydrase (CA), the central enzyme involved in photosynthesis. The results showed that RD was unaffected by either elevated temperature or pCO2, while elevated temperature and/or pCO2 stimulated PN and PG and increased the ratios of PN to RD, indicating a relatively higher autotrophic capacity. Consequently, larval survivorship under elevated temperature and/or pCO2 was consistently 14% higher than that under the control treatment. Furthermore, elevated temperature and pCO2 did not affect host CA activity, but synergistically enhanced symbiont CA activity, contributing greatly to the stimulated photosynthetic capacity. These results suggest that brooded larvae of P. damicornis larvae from Luhuitou may be preadapted to cope with projected warming and ocean acidification. More generally, it appears that corals from highly variable environments may have increased resilience to the widespread climate change. [ABSTRACT FROM AUTHOR]

• Nutrient absorption and consumption in the mangrove forest exhibited a significantly higher nitrogen-to-phosphorus ratio compared to utilized nutrients. • The mangrove forest demonstrated a concerning trend of hypoxia and acidification, with dissolved oxygen saturation reaching a mere 57.0% and pH measuring 7.58 during ebb tides. • The enrichment factors of oils, organic carbon, and sulfide were 4.37, 2.04, and 2.06, respectively, fostering the accumulation of total Hg, Zn, and Cu in the sediments of the mangrove forest. Mangrove forests are crucial in absorbing, storing, and purifying pollutants while maintaining ecological balance. A study was conducted in 2020 to investigate the biogeochemical processes of seawater and sedimentary environmental factors in the Qi'ao Island mangrove wetland. The study comprised two survey sections and ten survey stations within the mangrove forest and 16 large-scale survey stations in the adjacent sea area. During ebb tides, the mean concentrations of inorganic nitrogen and phosphate in Section D1 of the mangrove forest were 0.63 mg/L and 0.003 mg/L, respectively. These levels were significantly lower than the results observed in the adjacent sea area and Section D2 of the mangrove forest during flood tides. The mangrove forest efficiently absorbed and consumed nutrients, with the nitrogen-to-phosphorus ratio of consumed nutrients being notably higher than that typically utilized by plants during growth. We identified various biogeochemical processes, including nitrogen fixation, mineralization, nitrification, and denitrification, occurring within the mangrove forest. Seawater measurements in Section D1 during ebb tides showed the mean pH of 7.58 and dissolved oxygen levels of 4.52 mg/L, resulting in a dissolved oxygen saturation level of only 57.0 %. The low dissolved oxygen levels were attributed to organic matter degradation in the forest. Consequently, the longer the water retention time, the more obvious the trend of hypoxia and acidification was observed. In the adjacent sea area, the sedimentary environment was deemed healthy, with pollutants primarily originating from runoff and ship discharge from waterways and ports. However, within the mangrove forest, the sediments exhibited higher enrichment factors for organic carbon and sulfide, indicating significant pollution compared to the adjacent sea area. The sediments were conducive to the accumulation and burial of total Hg, Zn, and Cu, while other heavy metals did not show prominent deposition and enrichment. Notably, the enrichment factor of oils was as high as 4.37, leading to the formation of an oil pollution zone at the forest edge, and the enrichment of pollutants in sediment may inhibit the growth and expansion of mangroves. Overall, this study shed light on the occurrence of seawater acidification, hypoxia, and the behavior of sediment pollutants within the mangrove forest. The findings provide valuable insights to support efforts aimed at promoting and maintaining the ecosystem health of mangrove forests. [ABSTRACT FROM AUTHOR]

The synthesis process of loess-based 4A molecular sieve and its performance characterization in its application to washing powder. [Display omitted] • Prepared a loess-based 4A molecular sieve using activated loess. • Studied the effect of raw materials and reaction conditions on the prepared sieve. • Studied and compared various characteristics and properties of loess and the sieve. • Sieve microstructure varied with varying crystallinity and impurity content. • Sieve showed promise as a detergent additive. Herein, activated loess was obtained via acidification and alkalisation and was mixed with sodium hydroxide, water and aluminium sulphate to prepare a loess-based 4A molecular sieve using the hydrothermal conversion method. The sieve performance was characterised, and the effect of raw materials and reaction conditions on the sieve was investigated. Results showed that it exhibits different microstructures according to its crystallinity and impurity content. Moreover, the amount of sodium hydroxide and the reaction temperature had a substantial influence on its synthesis, while water and the reaction time exhibited less influence. The synthesis method was optimal when the reaction temperature was 90 °C, reaction time was 4 h, pH was ∼ 13 and the mixture ratio was SiO 2 :Al 2 O 3 :H 2 O:NaOH = 1.9:1:213:12. Finally, the application performance of the molecular sieve in detergents was studied. The sieve showed complete adherence to the National Standard of Detergent in China (GB/T 1767–2003). [ABSTRACT FROM AUTHOR]

Based on observations in China's east coastal oceans, we conducted a preliminary assessment of 16 sets of carbonic acid dissociation constants (K 1 * and K 2 *) by comparing spectrophotometrically measured pH values at 25 °C with those calculated from total alkalinity and dissolved inorganic carbon. We obtained that K 1 * and K 2 * often performed differently within different salinity ranges, and that the constants of Millero et al. (2002) (M02) demonstrated the best performance for the salinity range of 24–35. In contrast, the often recommended constants of Mehrbach et al. (1973) refit by Dickson and Millero (1987) (DM87-M) and Lucker et al. (2000) (L00) would underestimate pH at salinities of 24–30. This was mainly associated with the higher product of K 1 * and K 2 * by DM87-M and L00 than by M02 at this salinity range. Also, we found almost no differences between pH values calculated with DM87-M and L00. • Compared to pH measured at 25 °C, M02 exhibited the best internal consistency. • Recommended constants of DM87-M and L00 underestimated pH at low salinities. • There were almost no differences between pH values calculated with DM87-M and L00. • PH can be divided into two components associated with K 1 * × K 2 * and [CO 2 *]/[CO 3 2−]. [ABSTRACT FROM AUTHOR]

We report high-resolution, high-precision δ44/40Ca, δ88/86Sr, and 87Sr/86Sr records spanning the Permian-Triassic boundary (PTB) from the Meishan and Dajiang carbonate successions in south China. The goal of the study was to understand the behavior of Ca and Sr isotopes during a time period in Earth history characterized by severe biological and environmental perturbations, including a major mass extinction, flood basalt volcanism, ocean acidification, and sea level fluctuations. Dajiang displays negative δ44/40Ca and δ88/86Sr excursions and invariant 87Sr/86Sr ratios in the <60 kyr timeframe between the main extinction horizon and the PTB. The Meishan δ44/40Ca and δ88/86Sr records are generally shifted to higher values and display both synchronous and asynchronous trends relative to Dajiang. In addition, 87Sr/86Sr ratios at Meishan are significantly elevated and do not define a clear secular pattern. We reconcile diverse conceptual models for the dataset with the aid of supporting elemental and isotope measurements (e.g., Sr/Ca, δ13C, and δ18O), as well as sequential leaching experiments. The combined body of evidence indicates that Dajiang sediments experienced recrystallization and neomorphism under rock-buffered conditions that preserved primary signals. In contrast, the Meishan records display influences from both primary and secondary processes, including local differences in fractionation, fluid-buffered early marine diagenesis, and late stage diagenetic overprinting. The three isotopic records for Dajiang, and to some extent, the δ44/40Ca and δ88/86Sr records for Meishan, preserve information about the geochemistry of end-Permian seawater. We find that enhanced weathering of shelf carbonates during sea level fall provides the best explanation for rapidly decreasing seawater δ44/40Ca and δ88/86Sr values without affecting 87Sr/86Sr ratios. [ABSTRACT FROM AUTHOR]

Purpose: Acid rain is a primary environmental problem in Southern China. However, the effect of acid rain on soil respiration rarely received attention, especially in ecosystems with different buffering capacities to acid rain. Thus, we explored how the response of soil respiration to simulated acid rain (SAR) in Cunninghamia lanceolata and Michelia macclurei plantations, which had great difference in the buffering capacities of their litter layers to acid rain.Materials and methods: The field experiment was subjected to a split-block experiment, with four main blocks in each plantation. Each block was split into A1 (SAR treatment, pH = 3) and A0 (deionized water, pH = 6.6) plots. Each plot was separated into subplots with (L0) and without (L1) litter treatments. SAR and deionized water were applied twice a month to A1 and A0 plots, respectively. From June 2016 to June 2017, soil respiration was measured twice per month using Li-8100 infrared gas analyzer. Soil temperature and moisture at a 5-cm depth were monitored using temperature and moisture sensors connected to Li-8100 during the measurement of soil respiration.Results and discussion: The result showed that SAR did not significantly influence soil respiration neither in C. lanceolate nor in M. macclurei plantations. However, the reasons for this result were probably different in the two plantations. The unchanged soil respiration in C. lanceolata plantation was mainly attributed to the negligible effect of SAR on fine root biomass and microbial biomass carbon (MBC) in C. lanceolata plantation because of the acclimation of fine root and microorganism to acid soil environment. In addition, the increase in fine root biomass and decrease in MBC may have resulted in the absence of the influence of SAR on soil respiration in M. macclurei plantation, because the variation of soil respiration derived from fine root under SAR may have offset that derived from microorganism.Conclusions: Although C. lanceolata and M. macclurei plantations had different buffering capacities to SAR, SAR did not significantly affect soil respiration in both plantations after 1 year of SAR treatment. Therefore, the long-term effect of SAR on soil respiration should be considered, particularly in forest types with different buffering capacities to acid rain. [ABSTRACT FROM AUTHOR]

Abstract In the context of China's severe energy and environmental problems, as an alternative vehicle fuel bioethanol is a promising choice because its theoretically renewable and carbon neutral. To guarantee grain security, China is developing non-grain fuel ethanol. Based on a life cycle assessment (LCA), this paper assesses the uncertainty of energy efficiency and environmental performance in the development of cassava ethanol of 1.5-generation bioethanol whose raw materials are non-staple crops. The results show that cassava ethanol is a good alternative vehicle fuel from the view of energy efficiency. From an environment perspective, global warming potential and photochemical ozone formation potential of cassava ethanol are better than gasoline, but acidification potential and respiratory inorganics inferior. The Monte Carlo simulation reveals cassava ethanol is feasible compared with gasoline in the case of uncertain variables. Among these uncertain variables, cassava yield, nitrogen fertilizer use, and steam use are the most important variables for energy efficiency and environmental performance of cassava ethanol. Furthermore, this study calculates the potentials for energy savings and emissions reduction with improving key aspects, and gives the suggestions of enhancing the performance of key indicators to promote the development of bioethanol vehicle fuel. Highlights • Cassava ethanol is a good alternative vehicle fuel from the view of energy efficiency. • Cassava ethanol decreases GWP and POFP, but increases AP and RI compared with gasoline. • Cassava yield, nitrogen fertilizer usage and steam usage have the greatest impact on cassava ethanol. • The potentials of energy-saving and emission-reduction are calculated with improving key aspects. [ABSTRACT FROM AUTHOR]

Manganese (Mn) is a critical element in soils, essential to plant growth. Long-term and intensively managed Lei bamboo (Phyllostachys violascens) stands are usually subjected to severe soil acidification and Mn activation. However, Mn migration from topsoil to deep soil induced by severe soil acidification was poorly recognized and studied. The distribution and changes of the total and the operationally defined Mn forms in soil profiles and its potential stress and environmental effect were investigated in a chronosequence of Lei bamboo stands (0, 2, 6, 11, and 16 years of stand age). The results showed that the Mn amount was significantly decreased in topsoil and accumulated in subsoil with the long-term and intensive fertilizer application. Soil exchangeable Mn and superphosphate extractable Mn demonstrated large different variation to total Mn, whereas their sum was largely higher than and highly correlated with 8-hydroxyquinoline (HQN) extractable Mn. Soil organic carbon, pH value, exchangeable bases, and soil redox simultaneously controlled soil Mn depletion. In conclusion, long-term and intensive fertilizer application leads to soil acidification and accelerated soil Mn depletion in bamboo stand soil, promoting Mn accumulation in bamboo shoots. [Display omitted] • Intensive fertilizer application caused bamboo stands acidification seriously. • Soil acidification accelerated Mn leaching and enriching in subsoil. • Severe acidification enlarged the risk of Mn enrichment in bamboo shoot. • Soil organic carbon, pH, and exchangeable bases and soil redox controlled soil Mn's leaching. [ABSTRACT FROM AUTHOR]

Nitrate accumulation in the deep vadose zone poses direct or potential threat of environment and agriculture due to the long hydraulic retention time, especially in areas with limited rainfall. This study explored the primary causes and associated environmental problems of deep soil nitrate accumulation in apple orchards on the Loess Plateau by investigating nutrient (N, P, and K) surplus, deep soil nitrate accumulation and acidification, fertilization habits, and farmer awareness, through a combination of questionnaire and experiment. The results revealed much larger nutrient inputs than outputs, with N, P, and K surpluses 1.8–4.0-fold higher than required for apple tree growth. The huge N surplus caused nitrate accumulation and acidification in deep soil under apple orchards (up to 6 m). Soil nitrate storage in 25-year-old apple orchards within 6 m depth ranged from 5039–14,693 kg ha–1, 4.7–11.7-fold higher than under cropland. In addition, soil pH in 25-year-old apple orchards was 0.31–0.40 lower at 2–4 m depth than that of cropland. Overfertilization was the main contributor to the high cost of apple production, with most farmers unaware that they had overfertilized; the farmers also lacked an environmental conscious. We recommend multiple fertilizations, reasonable ratios of chemical and organic fertilizer, and scientific fertilization guidance to balance the economic benefits and environmental protection of apple orchards. In addition, farmers should be educated on environmental protection to sustainably develop the apple industry on the Loess Plateau. [Display omitted] • There was a significant nutrient surplus after cropland conversion to apple orchards on the Loess Plateau. • The huge N surplus leading to deep soil nitrate accumulation and acidification, which was no more than 6 m deep. • There was a significant exponential negative correlation between pH and NO3–-N content in the 0–10 m soil layer. [ABSTRACT FROM AUTHOR]

Life cycle assessment methodology was used to quantify the environmental impacts and resource use of milk production on the North China Plain, the largest milk production area in China. Variation in environmental burden caused by cow productivity was evaluated, as well as scenario analysis of the effects of improvement practices. The results indicated that the average environmental impact potential and resource use for producing 1 kg of fat and protein corrected milk was 1.34 kg CO 2 eq., 9.27 g PO 4 3 − eq., 19.5 g SO 2 eq., 4.91 MJ, 1.83 m 2 and 266 L for global warming potential (GWP), eutrophication potential (EP), acidification potential (AP), non-renewable energy use (NREU), land use (LU) and blue water use (BWU; i.e. water withdrawal), respectively. Feed production was a significant determinant of GWP, NREU, LU and BWU, while AP and EP were mainly affected by manure management. Scenario analysis showed that reducing use of concentrates and substituting with alfalfa hay decreased GWP, EP, AP, NREU and LU (by 1.0%–5.5%), but caused a significant increase of BWU (by 17.2%). Using imported soybean instead of locally-grown soybean decreased LU by 2.6%, but significantly increased GWP and NREU by 20% and 6.9%, respectively. There was no single perfect manure management system, with variable effects from different management practices. The environmental burden shifting observed in this study illustrates the importance of assessing a wide range of impact categories instead of single or limited indicators for formulating environmental policies, and the necessity of combining multiple measures to decrease the environmental burden. For the North China Plain, improving milking cow productivity and herd structure (i.e. increased proportion of milking cows), combining various manure management systems, and encouraging dairy farmers to return manure to nearby crop lands are promising measures to decrease multiple environmental impacts. [ABSTRACT FROM AUTHOR]

Modified bentonite granulars (MBGs) were prepared by acidification, natrification, calcination, and combined modification methods, and evaluated as effective in-situ adsorption materials to remove sediment phosphorus (P) in all fractions. The morphology and microstructure of MBG were characterized by scanning electron microscope (SEM), X-ray fluorescence (XRF), fourier transform infrared (FTIR) and X-ray diffraction (XRD). Results showed that the P removal capacity of CMBG-Na10-450 treated with 10% (g/g) Na 2 CO 3 and calcined at 450 °C exhibited the highest P removal capacity. Under the optimal conditions of stirring tests, the removal rates of sediment TP, OP, IP, Fe/Al-P and Ca-P by CMBG-Na10-450 were 35.5%, 29.1%, 54.5%, 44.6% and 10.7%, respectively. The adsorption mechanism analysis found that MBG adsorbed sediment P mainly by anionic coordination exchange adsorption. These results indicated that modification enhanced the P adsorption capacity of bentonite, and the MBG can be further applied to control and reduce sediment P in eutrophication remediation. [ABSTRACT FROM AUTHOR]

In order to protect quality of Balyangdian surface water and Gaoyang groundwater, the project is applied to process printing and dyeing wastewater that contains complicated compositions, high concentrations of organlcs and SS, and lots of pollutants difficult to degrade by microorganism. The process and operating parameters of project are optimized and debugged, and its economic and environmental benefits are analyzed. The results show that the process of coagulation sedimentation - hydrolytic acidification with aeration tank - biological aerated filter - active sand filter Is applied In Gaoyang Sewage Treatment Plant. The design scale of sewage treatment plant is 120 000 m³/d. The Influent Is as following: COD is 669 mg/L; SS Is 424 mg/L; NH3-N Is 8.83 mg/L; TP is 6.03 mg/L. After the process, the best removal rates of COD, SS, NH3-N and TP are 93.5%, 98.8%, 97.1% and 96.2%, respectively. The various Indexes of effluent water complied with standard A of the first order in Pollutants Emission Standard of Urban Wastewater Treatment Plant (GB18918-2002). The processing cost is only 0.807 yuan/m³. As a result, the project construction and operation not only improve the environment, but also promote regional economic development. Process design and operating parameters provide an Important reference value for the printing and dyeing wastewater treatment industry. [ABSTRACT FROM AUTHOR]

Acidic deposition used to cause severe surface water acidification in Europe and the North America, but no damage of surface water acidification was reported under continuous heavy acid deposition in China. We present the first detailed study on regional surface water acidification in southern and northeastern China based on a survey of 255 forested headwater streams, which were investigated during 2010–2015 to explore the status and mechanism of surface water acidification. South China has a subtropical climate with high acid deposition, whereas northeast China is located in a cold temperature zone with relatively low acid deposition. High pH and acid neutralizing capacity (ANC) were observed for almost all of the streams, indicating that surface water acidification may not be a serious regional issue in China both at present and in the future. In northeast China, where soil types are similar in low weathering rate to those in Northern Europe and North America, the ANC of surface waters was lower than that in South China, indicating a higher acid-sensitivity of the surface water. In comparison, the high pH and ANC of streams in southwest China resulted from high soil weathering and atmospheric calcium (Ca) deposition, despite elevated atmospheric acid inputs due to the high sulfur (S) and nitrogen (N) deposition. Comparison of stream nitrate (NO 3 − ) and sulfate (SO 4 2 − ) concentrations with modeled N and S deposition showed significant N and possible S sinks in the catchments in south China, probably due to denitrification of NO 3 − in groundwater discharge zone and SO 4 2 − adsorption by acid soils respectively, which may also buffer the acidifying effect of S and N depositions. It seems that considerable NO 3 − leaching to stream waters does not occur in China unless N deposition is higher than 1.8 keq·ha − 1 ·yr − 1 (2.50 g N·m − 2 ·yr − 1 ) (or greater values in certain regions). [ABSTRACT FROM AUTHOR]

Based on literature data and shipboard observations, this study investigated the main environmental characteristics of the seafloor topography, current field, front, and upwelling that are closely related to hypoxia occurrence off the Changjiang estuary. The physical processes of the plume front and upwelling off the Changjiang estuary in summer were coupled. The vertical distribution pattern of the plume front was closely related to the upwelling. By reviewing and analyzing the historical summer hypoxia events off the Changjiang estuary, we statistically demonstrated the spatial structure of the horizontal distribution of the hypoxic zone and investigated the location of occurrence zone of the hypoxia. We found that the dissolved oxygen (DO) concentration on the inner continental shelf off the estuary showed a 'V' shape in relation to station depth. Therefore, we noted that the hypoxic water on the inner continental shelf mostly occurred on the slopes with steep seafloor topography. Base on the current understanding of the hypoxic mechanisms off the Changjiang estuary, we analyzed the biogeochemical mechanisms that could cause the steep terrain off the Changjiang estuary to become the main areas prone to summer hypoxia and explained the internal relations between the location of the hypoxic zone on the slopes and the plume front and upwelling. The plume front and upwelling off the Changjiang estuary and their coupling were important driving forces of summer hypoxia. The continuous supply of nutrients affected by the interaction of the plume front extension of the Changjiang Diluted Water (CDW) and upwelling and the favorable light conditions were important mechanisms causing the phytoplankton blooms and benthic hypoxia off the Changjiang estuary in summer. By analyzing oxygen utilization, organic carbon mineralization, and nutrient regeneration in the hypoxic zone, we observed that the significant oxygen utilization process off the Changjiang estuary in summer also mainly occurred near the steep slopes with front and upwelling features and confirmed the apparent nutrient loss in the benthic hypoxic zone. Meanwhile, our analysis revealed that the sediment resuspension in the benthic boundary layer in the mud areas off the Changjiang estuary could also affect the oxygen utilization and mineralization of organic carbon and nutrient recycling and regeneration. This study also demonstrated that the steep terrain off the Changjiang estuary was the main location for summer acidification, and the coupling between the plume front and upwelling on the steep slopes was an important physical driving force inducing summer benthic acidification. Finally, we discussed issues to address in future studies of the hypoxic zone and water acidification off the Changjiang estuary. [ABSTRACT FROM AUTHOR]

Intensive cultivation in greenhouses of China has degraded the soil through acidification, salinization, and has caused an increase in soil-borne pathogens accumulation that negatively impacts vegetable production. In this study, six treatments, i.e. CK, degraded soil collected from greenhouse was irrigated to maximum field capacity and covered with plastic film; Al-RSD-F, flooding soil incorporated with alfalfa; Al-RSD, soil was incorporated with alfalfa, irrigated to maximum field capacity and covered with plastic film; Al-RSD + T37, inoculating Trichoderma harzianium T37 into soil at the end of the Al-RSD; Et-RSD, soil was incorporated with ethanol, irrigated to maximum field capacity and covered with plastic film; AW, soil was incorporated with ammonia and covered with plastic film, were conducted to investigate their effects on the physicochemical properties of degraded soil and disinfestations of Rhizoctonia solani , to control the damping-off disease in the two consecutive plantings of cucumber seedlings after the treatments. Treatments with Al-RSD-F, Al-RSD, Al-RSD + T37 and Et-RSD increased the pH and reduced the electrical conductivity of the soils, reduced population of R. solani and damping off of cucumber seedlings. These treatments with exception of Et-RSD, increased the populations of bacteria and fungi and showed higher diversity of bacteria after the second season of cucumber seedlings. Treatment AW was toxic and did not allow the survival of the cucumber seedlings. The treatments Al-RSD + T37 and Et-RSD showed the higher control of damping off, probably because the antagonist was favored by the previous treatment and could efficiently colonize the cucumber seedlings roots, and the Et-RSD was favored by the highest accumulation of toxic acetic acid in the soil. Alfalfa-amended soil disinfestations with or without Trichoderma , as well as an ethanol soil disinfestation could be used to recover degraded greenhouse soils. [ABSTRACT FROM AUTHOR]

In China, incineration is essential for reducing the volume of municipal solid waste arising in its numerous megacities. The evolution of incinerator capacity has been huge, yet it creates strong opposition from a small, but vocal part of the population. The characteristics of Chinese municipal solid waste are analysed and data presented on its calorific value and composition. These are not so favourable for incineration, since the sustained use of auxiliary fuel is necessary for ensuring adequate combustion temperatures. Also, the emission standard for acid gases is more lenient in China than in the European Union, so special attention should be paid to the issue of acidification arising from flue gas. Next, the techniques used in flue gas cleaning in China are reviewed and the acidification potential by cleaned flue gas is estimated. Still, acidification induced by municipal solid waste incinerators remains marginal compared with the effects of coal-fired power plants. [ABSTRACT FROM AUTHOR]

The combination of hydrolytic acidification and biological aerated filter (BAF) fiiled with mussel shells was used to treat domestic wastewater, and the removal rates of chemical oxygen demand (COD), ammonia nitrogen (NH3-N) and total phosphorus (TP) by the system were analyzed under different TP concentrations. When TP concentration ranged from 12. 39 to 14. 69 mg/L, the removal rate of COD was the best, over 90.92% ; as TP concentration varied from 2.26 to 2.61 mg/L, the removal rates of NH3-N and TP were the best, up to 100.00% and 76.38% respectively. The results show that it is feasible to use mussel shells as the media of BAF, and TP concentration has certain influence on the performance of the system dealing with domestic wastewater. [ABSTRACT FROM AUTHOR]

Alterations in pH have significant effects on nitrification and denitrification processes in aquatic systems. The Jiyun River in northern China experiences significant acid precipitation, and as such was selected to investigate the effects of decreasing pH (river pH at 8.2, pH at 6 and 5) on N dynamics via incubation experiments (35 and 10°C). Statistical results indicated that the NO concentrations of the control (pH at 8.2) were either significantly lower (at 35°C) or significantly higher (at 10°C) than the treatments of pH at 6 and 5 at the alpha level of 0.05 in the incubation. However, the NO concentrations of the two pH treatments showed significant difference during part of the reaction stage at 35°C and no difference at 10°C. Analysis indicated that nitrification and coupled nitrification-aerobic denitrification occurred for all treatments, which resulted in NO being either accumulated or removed at the end of the incubation. [ABSTRACT FROM AUTHOR]

• AME pretreatment can improve both the extent and rate of sludge dewatering. • AME pretreatment can increase organic content of sludge cake. • AME pretreatment can remove heavy metals from sludge. • Removal of EPS and promotion of sludge flocculation contribute to the improvements. • Sludge after AME can meet requirements of subsequent disposal processes better. In China, sewage sludge has the characteristics of poor dewatering performance, low organic content, and high heavy metal content. This would seriously hamper subsequent disposal processes of the sludge. In this study, a novel sludge pretreatment technology, Acidification combined Multistage Elutriation" (AME), was proposed to reduce sludge volume and improve sludge quality simultaneously. The results showed that AME pretreatment could reduce moisture content of sludge cake to 67.3%, increase dewatering rate of sludge by 84.5%, increase organic content of sludge by 10.3%, remove a considerable proportion of heavy metals from sludge, and recycle 40% of phosphorus from sludge. The main mechanism of the improvements is that AME removed 97% of EPS from sludge and promoted flocculation of tiny sludge particles. In conclusion, AME pretreatment can increase the dewatering efficiency of sewage sludge and improve the dewatered sludge cake qualities to meet the requirements of composting and incineration. [Display omitted] [ABSTRACT FROM AUTHOR]

Rates of seawater acidification and rise of partial pressure of CO 2 (pCO 2 ) at ocean margins are highly uncertain. In this study, nine years of time-series data sampled during 2010-2018 along Kuroshio Current near the East China Sea (ECS) were investigated. We found trends of surface seawater pCO 2 at 3.70 ± 0.57 μatm year -1 and pH at -0.0033 ± 0.0009 unityear -1 , increase and acidification under sustained DIC increase. The faster pCO 2 increase and acidification under sustained DIC increase. The faster pCO 2 growth relative to the atmosphere resulted in the CO 2 uptake through the air-sea exchange declining by ~50 % (~-0.8 to -0.4 mol C m -2  year -1 ) over the study period. Our results imply that rapidly warming boundary currents could potentially present an elevated pCO 2 trend, leading to a gradual reduction and eventual loss of oceanic CO 2 uptake under climate change., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Soil pH buffering capacity (pHBC) plays a crucial role in predicting acidification rates, yet its large-scale patterns and controls are poorly understood, especially for neutral-alkaline soils. Here, we evaluated the spatial patterns and drivers of pHBC along a 3600 km long transect (1900 km sub-transect with carbonate containing soils and 1700 km sub-transect with non-carbonate containing soils) across northern China. Soil pHBC was greater in the carbonate containing soils than in the non-carbonate containing soils. Acid addition decreased soil pH in the non-carbonate containing soils more markedly than in the carbonate containing soils. Within the carbonate soil sub-transect, soil pHBC was positively correlated with cation exchange capacity (CEC), carbonate content and exchangeable sodium (Na) concentration, but negatively correlated with initial pH and clay content, and not correlated with soil organic carbon (SOC) content. Within the non-carbonate sub-transect, soil pHBC was positively related to initial pH, clay content, CEC and exchangeable Na concentration, but not related to SOC content. Carbonate content was the primary determinant of pHBC in the carbonate containing soils and CEC was the main determinant of buffering capacity in the non-carbonate containing soils. Soil pHBC was positively related to aridity index and carbonate content across the carbonate containing soil sub-transect. Our results indicated that mechanisms controlling pHBC differ among neutral-alkaline soils of northern China, especially between carbonate and non-carbonate containing soils, leading to different rates, risks, and impacts of acidification. This understanding should be incorporated into the acidification risk assessment and landscape management in a changing world. [ABSTRACT FROM AUTHOR]

To better understand the decreases observed in pH levels downstream from the associated hydroelectric dam, the impounded Wujiang River in Southwest China was investigated. Study results indicate that the average pH decrease from upstream to downstream of the hydroelectric dam could be up to 0.47 units, and pH differences were particularly apparent during water thermal stratification. Notably, pH was controlled by [CO]/[CO] ratios in this impounded river. The decrease in [CO]/[CO] ratios and associated increases in pH at the surface of the reservoirs were mainly due to the prevalence of photosynthesis, while the reverse phenomenon was observed at the bottom due to respiration. The evidence from δC clearly demonstrated these processes. The increase in phytoplankton biomass enhanced this pH decrease, while dissolved organic carbon had limited impacts on the pH variation. The decrease in pH downstream from the hydroelectric dam resulted from the development of pH stratification in the water profile and the dam operations that release bottom waters for hydropower generation. Consequently, the cascade in hydropower development could increase the risk of river acidification. [ABSTRACT FROM AUTHOR]

Reusing industrial waste may have impressive potential environmental benefits, especially in terms of the total life cycle, and life cycle assessment (LCA) has been proved to be an effective method to evaluate industrial symbiosis (IS). Circular economy and IS have been developed for decades and have been successful in China. However, very few studies about the environmental benefit assessment of IS applied by LCA in China have been conducted. In the current article, LCA was used to evaluate the environmental benefits and costs of IS, compared with a no-IS scenario for four environmental impact categories. The results showed that four environmental benefits were avoided by the 11 symbiosis performances, namely, 41.6 thousand TJ of primary energy, 4.47 million t COe of greenhouse gasses, 19.7 thousand t SOe of acidification, and 81.1 t POe of eutrophication. Among these IS performances, the comprehensive utilization of red mud produced the most visible benefit. The results also present that energy conservation was the distinctive feature of IS in China. [ABSTRACT FROM AUTHOR]

• The influence mechanism of discharge variation on NEP was explored in the PRE. • Low GPP and high ER caused lowest NEP rate at Humen with largest discharge. • Restriction of discharge increase on NEP exceeded stimulation of seasonal factors. • High discharge intensified low NEP, hypoxia and acidification at three outlets. Clarifying the influence of hydrological variations on ecological function is a topic of considerable interest in watershed ecological flow assessment and water resource management. Net ecosystem productivity (NEP) is a useful composite indicator of ecosystem function, reflecting material cycling and energy flow. However, the effects of hydrological variations on NEP, especially the influence mechanism, remain unclear due to the complex environmental characteristics in estuaries. We analysed the spatial–temporal variability of the aquatic environment and NEP through in-situ monitoring and field sampling from December 2018 to January 2020 at three outlets (Humen, Jiaomen, and Hongqimen) with different hydrological conditions in the Pearl River Estuary (PRE), China, and explored the influence mechanism of hydrological variation on NEP. The 155 groups of effective metabolism values were estimated using Odum's open-water method. The daily ecosystem respiration (ER) was higher than the gross primary production (GPP); therefore, water bodies were dominated by net heterotrophy at the three outlets. The daily NEP (–4.34 ± 1.40 mg O 2 L–1d–1), O 2 concentration (5.2 ± 1.02 mg L–1), and pH (7.53±0.24) were lowest at Humen, which also had the largest discharge and tide volume, deepest water depth, and widest channel. Seasonally, the NEP in the summer (–3.30 ± 1.39 mg O 2 L–1d–1) and autumn (–3.19 ± 1.60 mg O 2 L–1d–1) was lower than those in the spring (–1.56 ± 1.92 mg O 2 L–1d–1) and winter (–2.17 ± 1.50 mg O 2 L–1d–1). The inhibitory effect of increased discharge on the metabolic rate exceeded the stimulation provided by seasonal factors, such as increased temperature and solar radiation. The scour and dilution effect caused by discharge increase reduced chlorophyll a concentration; meanwhile, the increase in turbidity resulted in a decrease in the photosynthetic rate and GPP. ER was stimulated by heterotrophic microorganisms and high total suspended solids, resulting in a decrease in O 2 and endogenous organics, thus causing the low NEP, hypoxia, and acidification phenomenon. Our results suggest that lengthening the discharge pulse period in summer and autumn will further decrease NEP and increase the area of hypoxia and acidification at the three outlets in the PRE. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract: Liming of strongly acidified soil under a Masson pine (Pinus massoniana Lamb.) forest was studied through a seven-year field manipulation experiment at Tieshanping, Chongqing in Southwestern China. To distinguish between the individual effects of Ca2+ and Mg2+ addition, we separately applied calcite (CaCO3) and magnesite (MgCO3), rather than using dolomite [CaMg(CO3)2]. Both calcite and magnesite additions caused a significant increase in pH and a decrease in dissolved inorganic monomeric aluminium (Ali) concentration of soil water. Ecological recovery included increases of herb biomass (both treatments) and Mg content in Masson pine needles (magnesite treatment only). However, the growth rate of Masson pine did not increase under either treatment, possibly because of nutrient imbalance due to phosphorus (P) deficiency or limited observation period. In China, acid deposition in forest ecosystems commonly coincides with large inputs of atmogenic Ca2+, both enhancing Mg2+ leaching. Calcite addition may further decrease the Mg2+ availability in soil water, thereby exacerbating Mg2+ deficiency in the acidified forest soils of southern and southwestern China. The effect of anthropogenic acidification of naturally acid forest soils on P availability needs further study. [Copyright &y& Elsevier]

Highlights: [•] We established a comprehensive LCI method for landfill construction and operation. [•] We reported the consumption of materials and energy in a generic Chinese landfill. [•] The contribution of C&O to the impacts of total landfilling is not negligible. [•] Non-toxic and toxic impacts are attributed to diesel and mineral usage, respectively. [•] Replacing minerals with synthetic materials is effective in mitigating impacts. [Copyright &y& Elsevier]

Abstract: The Chinese government has established compulsory targets to reduce sulfur dioxide (SO2) and nitrogen oxide (NOx) emissions by 8% and 10%, respectively, during 2010–2015. In this study, the effect of the policy was evaluated by predicting the recovery of acidified forest soil in Chongqing, an area severely impacted by acid rain in southwest China. Since precipitation has decreased significantly in this area in recent years, the impact of drought on soil acidification was also considered. A dynamic acidification model, MAGIC, was used to predict future trends in soil chemistry under different scenarios for deposition reduction as well as drought. We found that the current regulation of SO2 emission abatement did not significantly increase soil water pH values, the Ca2+ to Al3+ molar ratio (Ca/Al), or soil base saturation to the level of 2000 before 2050. NOx emission control would have less of an effect on acidification recovery, while emission reduction of particulate matter could offset the benefits of SO2 reduction by greatly decreasing the deposition of base cations, particularly Ca2+. Continuous droughts in the future might also delay acidification recovery. Therefore, more stringent SO2 emission control should be implemented to facilitate the recovery of seriously acidified areas in China. [Copyright &y& Elsevier]

Thirty four atmospheric total suspended particulate (TSP) samples collected over the Yellow Sea between February and August, 2009 were used to study Fe solubility. Samples were classified into two groups based on calculated air mass back trajectories, i.e., one originating from a northern continental source (NCS, in which Fe solubility was 5.6 ± 3.9%) and the remaining one from other regions (non-NCS, in which Fe solubility was 3.1 ± 5.3%). The calculated enrichment factor (Al is used as a reference) indicated that Fe in the NCS samples was probably derived from natural sources dominated by mineral dust. A deep analysis of soluble Fe and Fe solubility suggested that cloud processing played an important role in the increase of both. No correlation between soluble Fe and secondary inorganic ions (sulfate and nitrate) was observed in NCS samples. However, in non-NCS samples, a good correlation between soluble Fe and secondary inorganic ions was observed, probably due to acidification reactions. Enrichment factors indicated that the Fe in the non-NCS samples was probably from anthropogenic sources. Moreover, a logarithmic curve between Fe solubility and ([SO4 2−] + [NO3 −]) together with correlations between soluble Fe and K+ obtained in the non-NCS samples further indicated that soluble Fe was more likely derived from aged ambient aerosols rather than from fresh aerosols. The lower solubility of Fe in non-NCS samples was comparable to Fe solubility in coal fly ash recently reported in the literature, while it was lower than Fe solubility in mineral dust. [ABSTRACT FROM AUTHOR]

Intensive vegetable cultivation has developed very rapidly in China, and investigation of current soil nutrient problems in vegetable fields and their potential environmental risk is important for local soil nutrient management strategies. Three hundred and sixty-six soil samples were collected from greenhouse vegetable fields, open vegetable fields and rice/wheat rotation fields in southern Jiangsu Province, the most intensive vegetable-producing areas in Yangtze River Delta, China, for the analysis of their soil fertility status. Soil acidification and P enrichment were the main problems identified in this area of vegetable production, with about 20 and 17% of the open and greenhouse vegetable field soils, respectively, being extremely acid with soil pH values below 5.0. In contrast, no soils under rice/wheat rotation fields were as acidic. Percentages of sites with Olsen- P concentrations < 90 mg/kg were 61, 85 and 0% for soils growing greenhouse vegetable, field vegetable and rice/wheat, respectively. The nitrogen ( N) surplus for vegetable fields exceeded 170 kg/ha/crop, and the phosphorus ( P) surplus exceeded 40 kg/ha/crop. Thus, current vegetable production leads to potential environmental risks of N and P pollution of nearby aquatic bodies. Insufficient supplementation with potassium fertilizers was found in some vegetable fields. Several ameliorative measures are proposed. [ABSTRACT FROM AUTHOR]

Diatoms have been regularly used as bioindicators to assess water quality of surface waters. However, diatom-based indices developed for a specific geographic region may not be appropriate elsewhere. We sampled benthic diatom assemblages in the upper Han River, a subtropical river in China, to evaluate applicability of 14 diatom-based indices used worldwide for water quality assessment. A total of 194 taxa from 31 genera were identified in the dry season and 139 taxa from 23 genera in the wet season. During the dry season, significant relationships were found for all but one of the diatom-based indices (Index Diatom Artois-Picardie) with one or more physical and chemical variables including nutrients and ion concentrations in river waters. The Biological Diatom Index (IBD) and diatom-based eutrophication/pollution index (EPI-D) were strongly related to trophic status and ionic content, while Watanabe's Index was related to organic pollution and conductivity. Yet, the diatom indices showed weak relationships with physical and chemical variables during the wet season. It suggests that diatom-based indices developed in Europe can be applied with confidence as bioindicators of water quality in subtropical rivers of China, at least during base-flow conditions. [ABSTRACT FROM AUTHOR]

Abstract: This study aims to evaluate energy, economic, and environmental performances of seven categories of biodiesel feedstocks by using the mixed-unit input–output life cycle assessment method. Various feedstocks have different environmental performances, indicating potential environmental problem-shift. Jatropha seed, castor seed, waste cooking oil, and waste extraction oil are preferred feedstocks for biodiesel production in the short term. Positive net energy yields and positive net economic benefits of biodiesel from these four feedstocks are 2.3–52.0% of their life cycle energy demands and 74.1–448.4% of their economic costs, respectively. Algae are preferred in the long term mainly due to their less arable land demands. Special attention should be paid to potential environmental problems accompanying feedstock choice: freshwater use, ecotoxicity potentials, photochemical oxidation potential, acidification potential and eutrophication potential. Moreover, key processes are identified by sensitivity analysis to direct future technology improvements. Finally, supporting measures are proposed to optimize China’s biodiesel development. [Copyright &y& Elsevier]