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Glyphosate is one of the most widely used pesticides globally. The environmental micro-molar hydrogen peroxide (H 2 O 2)-driven Fenton reaction has been reported to degrade herbicides in natural water. However, the impact of micro-molar H 2 O 2 (50 μM) on the degradation of glyphosate in soil and glyphosate-degrading bacteria remains unclear. In this study, degradation of glyphosate in the sterilized and unsterilized soil system and MSM medium under micro-molar H 2 O 2 was investigated; bacterial diversity, enzyme activity and gene abundance in the soil following micro-molar H 2 O 2 addition were also investigated. The results indicated that the addition of micro-molar H 2 O 2 facilitated the degradation of glyphosate in a sterilized environment, resulting in a 76.30% decrease in glyphosate within 30 days. The degradation of glyphosate increased by 52.32% compared to the control treatment. However, in an unsterilized environment, the addition of micro-molar H 2 O 2 leads to a reduction in the biodegradation efficiency of glyphosate. Bacteria, enzymes and specific genes were found to be affected to varying degrees. Firstly, micro-molar H 2 O 2 affects the relative abundance of functional bacteria related to glyphosate degradation, such as Afipia, Microcoleus and Pseudomonas. Secondly, micro-molar H 2 O 2 resulted in a decrease in soil phosphatase activity. Thirdly, the expression of resistance genes was affected, particularly the glyphosate resistance gene aroA. The findings presented a novel research perspective on the degradation of soil glyphosate by micro-molar H 2 O 2. [Display omitted] • The degradation of glyphosate was investigated in sterilized and unsterilized soil environments. • Micro-molar H 2 O 2 reduced the efficiency of glyphosate biodegradation in soil. • Micro-molar H 2 O 2 affected bacteria activity and glyphosate resistance gene aroA. • Potential role of environmental micro-molar H 2 O 2 in the degradation of soil organic contaminants. [ABSTRACT FROM AUTHOR]

Arsenic is one of the most toxic heavy metals in water and soil pollution. Biochar, as a high-quality remediation material, has been widely used as an adsorbent for remediation of arsenic-polluted water and soil. However, the adsorption capacity of biochar has certain limitations, so modifications have been made to enhance its adsorption ability for arsenic. Selenium is an essential trace element for plants, promoting plant growth and also competing with arsenic, making it an excellent modification material. We studied the selenium-modified rich biochar and original selenium-rich biochar, including their production, physicochemical properties, and arsenic adsorption mechanism. Selenium-rich biochar and selenium-modified biochar showed no significant differences in properties, arsenic adsorption efficiency, promotion of plant growth, and selenium enrichment effects, both being excellent materials for arsenic remediation. The theoretical maximum adsorption capacities (qm) for As(III) on raw biochar, selenium-modified biochar, and selenium-enriched biochar were 49.87 mg/g, 55.89 mg/g, and 59.00 mg/g, respectively, with the selenium-enriched biochar exhibiting the highest adsorption capacity. The results of planting experiments indicate that, compared to the original biochar, both selenium-enriched biochar and selenium-modified biochar significantly enhanced growth promotion and adsorption efficiency by 24.68 %, 24.35 %, 59.50 %, and 64.64 % respectively. However, the preparation cost of selenium-modified biochar is high, making it challenging to promote, with a total cost price 84.31 % and 83.40 % higher than selenium-rich biochar. It is evident that selenium-rich biochar not only possesses the efficacy of selenium-modified biochar but also has the advantage of low cost, making it a material with significant potential for arsenic remediation. [Display omitted] • Modified biochar enhances arsenic adsorption effectiveness. • Modified biochar alleviates the toxic effects of arsenic on water spinach. • The effects of selenium-rich biochar and selenium-modified biochar are similar. • Selenium-rich biochar is lower in cost than selenium-modified biochar. [ABSTRACT FROM AUTHOR]

Glyphosate is one of the most widely used pesticides globally. However, glyphosate and its residual metabolite, aminomethyl phosphonic acid (AMPA), are persistent and mobile chemicals. Large amounts of glyphosate residue can accumulate in the environment, causing adverse effects in organisms. Urea hydrogen peroxide (UHP) in soil slow-release H 2 O 2 undergoes a Fenton-like reaction with Fe2+, and the resulting hydroxyl radical (·OH) degrades glyphosate. This experiment investigated the effects of three fertilisers (UHP, ferrous sulphate, and urea) on the degradation of glyphosate in agricultural soils and their effects on soil ammonia nitrogen effectiveness and enzyme activity. Among all treatments, the half-life of glyphosate in the mixed application of UHP and ferrous sulphate was the shortest (11.9 d), and its degradation rate was the highest (70.64%), degrading within 28 d. Throughout the experimental cycle, in 1–7 d, the application of UHP reduced the effect on indigenous microorganisms and maintained nitrogen availability and enzyme activity in the soil; in 7–14 d, the mixed application of UHP and ferrous sulphate alleviated the nitrification of soil nitrogen and reduced the loss of ammonia from the soil; in 14–28 d, the mixed or single application of UHP and ferrous sulphate and the low dose of glyphosate remaining in the soil had a catalytic effect on enzyme activity, promoting the secretion of catalase and nitratase, which participate in soil glyphosate degradation and nitrogen cycling. Therefore, this study provides a scientific basis for the in-situ remediation of herbicide-contaminated soil in agricultural fields using chemical fertilisers. [Display omitted] • Potential role of urea hydrogen peroxide in degradation of glyphosate in soil. • A method for in-situ remediation of glyphosate contaminated soil. • Urea hydrogen peroxide slowly releases H 2 O 2 and produces Fenton-like reaction with Fe2+. • Glyphosate degradation affects soil nitrogen and enzyme activity. • Urea hydrogen peroxide can increase the content of ammonium nitrogen in soil. [ABSTRACT FROM AUTHOR]

The Arsenic (As) accumulation problem of plants has to be solved when exploring scattered As micro-polluted water as a new irrigation water source for food production. Herein, efficient As immobilization (1 mg-As/L) was realized by simply adding TiOSO 4 (TOS) solution in the irrigation water during rice seedling cultivation. The free soluble As in the rice culture was reduced by 99.4%. Most of the As was enriched in hydrous titanium oxide (HTO) formed from in situ TOS hydrolysis (HTO-TOS), which possessed a very high specific surface area (347.6 m2/g) and the most abundant adsorption-active hydroxyl group. Adding TOS (100 mg/L) is tens of times better than adding TiO 2 nanoparticles and is even better than commercial HTO at a dosage up to 1000 mg/L in As-immobilization ability. On the one hand, TOS treatment transformed soluble As to insoluble forms by the strong complexation between freshly formed active HTO and As. On the other hand, a barrier of titanium and iron plaque was formed on root surface. Benefiting from these two aspects, the As contents in rice roots and shoots were reduced by 74.6% and 95.6%, respectively. The TOS treatment strategy had no adverse influence on rice growth while promoted the root growth by 39.4% and alleviated the oxidative stress of rice seedlings. Considering its simple application manner and good As control performance, TOS treatment has great potential on in situ remediation of As-contaminated water and soil during cultivating diverse agricultural plants. [Display omitted] • TiOSO 4 was used for in situ remediation of As-contaminated rice-irrigating water. • Hydrous titanium oxide was formed from TiOSO 4 hydrolysis. • TiOSO 4 treatment significantly decreased the As content in rice seedlings. • TiOSO 4 treatment had no negative effect on rice seedling growth. • TiOSO 4 treatment alleviated the oxidative stress and promoted the root growth. [ABSTRACT FROM AUTHOR]

In-situ immobilization is a fast soil remediation method that can recover the value of As-contaminated land quickly. Hydrous zirconium oxide was reported for its efficient arsenic adsorption properties in wastewater treatment, but has not been reported in soil remediation with As contamination. Herein, hydrous zirconium oxide modified biochar (BC-Zr) was synthesized along with hydrous ferric oxide modified biochar (BC-Fe) and hydrous titanium oxide modified biochar (BC-Ti). After comparing their As(III)/As(V) adsorption performance under diverse conditions, BC-Zr showed superior As-immobilization potential in both simulated water and real soil leachate environment. To evaluate its performance in soil remediation, pot experiments were conducted in real As-contaminated agricultural soil using cowpea (Vigna unguiculata L.) as an indicator plant. Although all these modified BC could improve the growth of cowpea, the shoot biomass treated by BC-Zr increased by 115.8% than CK, while the As concentration in the stem and leaves decreased by 30.8% and 42.6%, respectively. Interestingly, BC-Zr promoted the root nodule system of cowpea in real As-contaminated soil while BC-Fe and BC-Ti failed. The observation of improved root nodule symbiotic system is significant for further development of soil remediation using in-situ remediation technology. This first successful trial of Zr-based soil amendment indicates the superior As-immobilization property of hydrous zirconium oxide in in-situ remediation of As-contaminated soil, implying the great potential applications of BC-Zr in soil remediation. [Display omitted] • BC-Zr outstands BC-Fe and BC-Ti in As-immobilization in soil environment. • The shoot biomass treated by BC-Zr increased by 115.8% compared with control. • BC-Zr addition in soil significantly decreased the As content in the shoot of cowpea. [ABSTRACT FROM AUTHOR]

Highlights: [•] The ingredients (Fe2 + and H2O2) for Fenton reaction are naturally present in many open waters. [•] Fenton-driven degradation is likely to affect herbicide behavior and fate in natural waters. [•] Microcosm experiments using three common herbicides were conducted to test the hypothesis. [•] Rapid degradation occurred under Fe2+–H2O2 combinations likely to be encountered in the field. [•] The findings shed some light on an overlooked natural process of environmental significance. [Copyright &y& Elsevier]

Abstract: Both sheath blight and blast are important rice diseases worldwide. The exploration of environmentally sound practices to control these diseases will help to reduce fungicide application. Effects of rice (Oryza sativa) intercropping with water chestnut (Eleocharis dulcis) on rice sheath blight and rice blast disease as well as the extracts of different plant parts and root exudates from water chestnut on pathogens of rice sheath blight (Rhizoctonia solani) and rice blast disease (Magnaporthe oryzae) were investigated using pot experiments and bioassay tests. The results from pot tests showed that rice-water chestnut intercropping system suppressed sheath blight and blast and improved land equivalent ratio (LER). The results from bioassay tests indicated that extracts and root exudates from water chestnut had significant effects to inhibit the expansion of these pathogens. The scales of these inhibitions were time and concentration dependent. The antifungal activities of the extracts from aboveground parts and pulp of water chestnut were significantly higher than the extracts from other parts and root exudates. The water extracts of aboveground parts showed the highest antifungal activity on both pathogens according to EC50 values. The antifungal activities of the same extracts from water chestnut on R. solani were significantly higher than on M. oryzae. The result suggests that water chestnut possesses bioactive substances to suppress rice sheath blight disease and rice blast disease. The rice-water chestnut intercropping system can be used as an environment-friendly method for diseases control in rice field. [Copyright &y& Elsevier]

Abstract: A 60-d greenhouse experiment was conducted to investigate the uptake and in-soil degradation of PCB-5 under single cropping and intercropping conditions involving three crop plant species: pumpkin, soybean and corn. Volatilization of PCB-5 from the soil surface was also tested. The results show that while uptake of PCB-5 by the test plant species is possible and the root concentration of PCB-5 had a control on the upward transport of PCB-5 to the above-ground portion of the plants, the PCB-5 extracted by the plants mainly accumulated in the root materials. Phytoextraction contributed insignificantly toward the loss of the soil-borne PCB-5. Volatilization of PCB-5 from the soil was recorded but it appeared that this did not result in a marked loss of PCB-5 in the bulk soil though it might cause remarkable removal of PCB-5 in a thin layer of the topsoil (1mm). It is likely that the in-soil biodegradation contributed markedly to the observed reduction in soil-borne PCB-5. The in-soil biodegradation of PCB-5 was significantly enhanced under intercropping conditions, which appeared to be related to increased microbial activities, particularly bacterial activities. The soil residual PCB-5 was correlated with the activity of the following enzymes: catalase (CAT), polyphenol oxidase (PPO) and peroxidase (POD). [Copyright &y& Elsevier]

Incubation experiments were conducted to examine the effects of activated sludge on degradation of chlorate in soils. The results show that application of activated sludge could significantly promote the decomposition of soil chlorate though the degradation rate of chlorate did not necessarily increase with increasing application rate of the sludge. The effectiveness of activated sludge on soil chlorate degradation was significantly affected by temperature, moisture content and pH. There is a tendency that the rate of chlorate decomposition increased with increasing temperature and moisture content until optimal values of temperature and moisture content were reached. This can be attributed to the enhanced activity of chlorate-reducing microorganisms in hot and more reducing soil conditions. Soil pH also had important controls on the decomposition of chlorate. The experimental results demonstrate that neutral pH more favoured the degradation of soil chlorate, compared to either acidic or alkaline pH. While soil organic matter content could affect chlorate decomposition, its impact on the effectiveness of activated sludge on chlorate degradation was minor. This study has implications for developing cost-effective techniques for remediating chlorate-contaminated soils, particularly in the longan-producing countries. [Copyright &y& Elsevier]

Rainwater contains multiple oxidants, such as hydrogen peroxide (H 2 O 2) and perchlorate (ClO 4 −). The aim of the study was to investigate the rainwater of trace H 2 O 2 and ClO 4 − affected on the arsenic (As) methylation and volatilization in the rice paddy of As contamination (arsenite (As(III)) and roxarsone (Rox)). Heavy rainfall monitoring and simulation experiments were applied in this study. The result showed that the H 2 O 2 and ClO 4 − of heavy rainfall in 2017 was 5.3–51.6 μmol/L and ND - 6.1 μg/L respectively. Because of the differences in chemical properties, H 2 O 2 and ClO 4 − affected As methylation and volatilization of paddy soil in different ways. H 2 O 2 performed a temporary effect on As volatilization, which was mainly in the 1st-hour and restored to the controls condition finally. However, ClO 4 − showed a persistent inhibition on As volatilization which decreased 32 %–69 % in the whole test. In general, the trend of volatilization was following the order: CK ≈ H 2 O 2 > ClO 4 −. The oxidants (H 2 O 2 and ClO 4 −) also could decrease As(III) in 37 %–44 % and increased As(V) in 24 %–272 %. In addition, planting rice in As contamination soil could enhance As volatilization by 36 %–334 %. These suggested that planting wetland plants on As-contaminated soil probably become a potential way to increase As volatilization. [Display omitted] • H 2 O 2 could temporarily effect on As volatilization in soil. • ClO 4 − could persistently inhibit on As volatilization in soil. • Planting rice could enhance As volatilization in soil. [ABSTRACT FROM AUTHOR]

• Positive interactions between Cd and Na were presented in sea rice. • Salt addition triggered the defensive ability of sea rice to enhance the Cd tolerance. • The co-existence of Cd and salinity significantly affect rice growth and yield. • Cd concentration in rice grain of sea rice met the national food safety limits under co-stress of Cd and salinity. Salt-tolerant rice (sea rice) is a key cultivar for increasing rice yields in salinity soil. The co-existence of salinity and cadmium (Cd) toxicities in the plant-soil system has become a great challenge for sustainable agriculture, especially in some estuaries and coastal areas. However, little information is available on the Cd accumulating features of sea rice under the co-stress of Cd and salinity. In this work, a hydroponic experiment with combined Cd (0, 0.2, 0.8 mg/L Cd2+) and saline (0, 0.6%, and 1.2% NaCl, W/V) levels and a pot experiment were set to evaluate the Cd toxic risks of sea rice. The hydroponic results showed that more Cd accumulated in sea rice than that in the reported high-Cd-accumulating rice, Chang Xianggu. It indicated an interesting synergistic effect between Cd and Na levels in sea rice, and the Cd level rose significantly with a concomitant increase in Na level in both shoot (r = 0.54, p < 0.01) and root (r = 0.66, p < 0.01) of sea rice. Lower MDA content was found in sea rice, implying that the salt addition probably triggered the defensive ability against oxidative stress. The pot experiment indicated that the coexistent Cd and salinity stress further inhibited the rice growth and rice yield, and the Cd concentration in rice grain was below 0.2 mg/kg. Collectively, this work provides a general understanding of the co-stress of Cd and salinity on the growth and Cd accumulation of sea rice. Additional work is required to precisely identify the phytoremediation potential of sea rice in Cd-polluted saline soil. [Display omitted] [ABSTRACT FROM AUTHOR]

Frequent detection and joint toxicity of sulfonamides (SAs) and phthalate acid esters (PAEs) in water environment have caused serious health and safety problems that can be reduced by vertical flow constructed wetland (VFCW). However, it remains unclear what kind of substrate used in VFCW can synergistically remove SAs and PAEs. In this study, it was determined if biochar, zeolite, vermiculite, peat and sand synergistically removed sulfamethoxazole (SMX) and dimethyl phthalate (DMP) as representatives of SAs and PAEs by using batch and column experiments. The batch experiments showed that pseudo-second-order and intraparticle diffusion kinetics and Freundlich isotherm could better describe the synergistic adsorption of SMX and DMP on each substrate. SMX promoted hydrophobic interaction between DMP and each substrate so that low concentration DMP almost was adsorbed completely at neutral pH. Both neutral and alkaline pH conditions were favorable for synergistic adsorption of SMX and DMP on each substrate. The column experiments showed that removal of SMX or DMP in VFCW by substrate adsorption alone was limited with run time increasing, but SMX and DMP were effectively removed with run time increasing when loaded with simulated wastewater, SMX and DMP. The VFCW not only removed 94.7% SMX and 91.8% DMP after running 50 d, but also improved total nitrogen removal. In conclusion, these results strongly suggest that biochar, zeolite, vermiculite, peat and sand filled in VFCW can synergistically remove SMX and DMP. [Display omitted] • Sulfamethoxazole and dimethyl phthalate can be adsorbed synergistically by each substrate. • Sulfamethoxazole promotes dimethyl phthalate adsorption by hydrophobic interaction. • Adsorption kinetics, isotherms, and pH influence were systematically studied. • Sulfamethoxazole and dimethyl phthalate can promote total nitrogen removal in vertical flow constructed wetland. [ABSTRACT FROM AUTHOR]

The exploitation of mineral resources is very important for economic development, but disorderly exploitation poses a serious threat to the ecological environment. However, investigations on the advantages of plant species and environmental pollution in polluted mining areas are limited. Thus, a survey was conducted to evaluate the impacts of abandoned mines on the surrounding ecological environment along rivers in polluted areas and to determine the Arsenic (As) pollution status in soil and plants. The results showed that the soil and vegetation along the river in the survey area were seriously polluted by As. The total As content of the 15 samples was significantly greater than the national soil background value (GB 15618-2018), and degree of pollution was nonlinearly related to the distance from the mine source, R2 = 0.9844. B. bipinnata, P. vittata and B. nivea were predominant with degrees of dominance of 0.01–0.33, 0.05–0.11, and 0.06–0.14 respectively. The As enrichment capacities of Juncus and P. vittata were significantly greater than those of the other plants, while the bioaccumulation factors (BCFs) were 21.81 and 7.04, respectively. [Display omitted] • The As pollution status of plants and soil in mine polluted area was evaluated by comprehensive investigation. • The degree of soil pollution was found to have a non-linear relationship with the distance from the mine source, with a high correlation (R2 = 0.9844). • B. bipinnata, P. vittata and B. nivea are dominant species in As-contaminated soils. • Juncus and P. vittata were found to have significantly higher Arsenic (As) enrichment capacity compared to other plant species. [ABSTRACT FROM AUTHOR]

Abstract: Effects of iron (Fe) on growth, biochemical composition and paralytic shellfish poisoning (PSP) toxins production of Alexandrium tamarense were studied. Under Fe-limited conditions (1nmolL−1 Fe), the alga exhibited a low specific growth rate (0.076±0.017d−1, n =3) that was nearly a half of that under Fe-replete conditions (1μmolL−1 Fe, 0.137±0.00752d−1, n =4), and the cell density on day 21 (8210cellsmL−1) was also less than a half of that under Fe-replete conditions (2×104 cellsmL−1). At the same time, total pigment, chlorophyll a (Chla), protein, carbohydrate contents per cell and Chla/carotenoid ratio decreased. In contrast, the PSP toxins content and the PSP toxicity per cell of the alga increased remarkably. Under Fe-limited conditions, total PSP toxins content and relative toxicity of alga were 2.55- and 2.54-fold of those under Fe-replete conditions, respectively. In addition, the profiles of PSP toxins also changed notably. The cellular content of gonyautoxin 1+4 (GTX1+4) increased for 5.6-fold along with the decrease of saxitoxin (STX) and gonyautoxin 2+3 (GTX2+3) contents contrasting to that under Fe-replete conditions. It suggested that the availability of Fe might effectively control the growth and toxic production of the alga and thereby influence the toxic effect of these harmful bloom events. [Copyright &y& Elsevier]

The apple snail (Pomacea canaliculata Lamarck) is among the 100 worst invasive alien species worldwide. Apple snail residues discarded during daily management are potential raw materials for biochar production. This study optimized the factors for producing apple snail biochar (ASB) using response surface methodology (RSM) and analyzed the As removal capacity and soil remediation effects of the optimal ASB. The optimal ASB occurred for 348.63 °C pyrolysis temperature, 2.19 h pyrolysis time, and 2.53 Fe3+/Fe2+ molar ratio. For the optimal ASB, the maximum experimental As(III) removal ratio was 98.72%. Temperature and the Fe3+/Fe2+ molar ratio were essential factors affecting the As removal ratio of ASB. The ASB had a rough surface, and As (1.09%) was evident on its surface after adsorption. The As(III) adsorption capacity on ASB was 10.59 mg/g at 288 K, 9.75 mg/g at 298 K, and 11.82 mg/g at 308 K. The As immobilization efficiency in the 3% and 5% ASB treatments exceeded 50% after 15 d. The 5% ASB treatment increased the soil organic matter, total N, available N, total P, and available P content by 120%, 245%, 47%, 62%, and 154%, respectively. Within 15 d, the soil methane oxidation potential peaked at 4.05 μg/g/h in the 5% ASB treatment. The maximum methane oxidation rate occurred after 10 d in the 5% ASB treatment. ASB has multiple benefits for As immobilization, quality improvement, and methane oxidation in soil. This study provides a reference for optimized production and application of invasive animal biochar in contaminated soil. [Display omitted] • Invasive snail residues can be produced into As adsorbent using RSM. • Apple snail biochar effectively reduces the availability of As in soil. • Snail biochar improves the physicochemical properties of As-contaminated soil. • Methane oxidation potential of As-contaminated soil is enhanced by snail biochar. [ABSTRACT FROM AUTHOR]

• Yield advantage and Cd decrease of most rice cultivars in multi-cropping systems. • Grain Cd of Changliangyou 772 was negatively correlated with that of neighboring rice. • Increasing soil pH reduced more Cd uptake by roots than increasing iron plaque (Ip). • Too much Ip and Cd in Ip weakened the ability of Ip to block the Cd uptake by roots. Ecological theories can be applied to improve agricultural sustainability. In our study, a core hypothesis behind this claim is that "selfish behaviour" of rice cultivars results in "aversion" to a toxic substance in a multi-cropping system. We studied Changliangyou 772, a low-cadmium rice cultivar, cultivated with 11 different rice cultivars in intercropping and mixed systems. Rice cultivars with medium grain yield, ranging from 25 to 45 g plant-1, had distinctly higher yields in mixtures. Rice varieties with lower grain cadmium concentrations in monocultures had greater reductions in grain cadmium in the mixtures. In the intercropping systems, the yields of Changliangyou 772 were positively correlated with those of the neighbouring rice cultivars, while the grain cadmium showed a negative correlation with the grain cadmium of intercrops in the monocultures. The neighbouring cultivars with low grain cadmium concentrations in the intercropping showed higher cadmium concentrations in the monocultures. The intercropping and mixtures reduced the grain cadmium in two ways: 1) they increased the soil pH, resulting in lower cadmium bioavailability; and 2) they enhanced the iron plaque (Ip). However, a high Ip or cadmium concentration that was too high in the Ip weakened the Ip to block cadmium uptake by the roots. [ABSTRACT FROM AUTHOR]

Excessive Cd in crop grains is toxic to humans. We conducted a field experiment to investigate the effects of intercropping on rice yield and grain Cd content as well as a pot experiment to compare the rhizosphere redox potentials of low-Cd 'Zhuliangyou 189' and the neighboring high-Cd 'Changxianggu' that mediated Cd uptake in a flooded or a ridge–furrow system. In the field experiment, Cd removal from contaminated soil in intercropping was 1.44 times higher than that in monoculture of Zhuliangyou 189. In both Zhuliangyou 189 and Changxianggu, intercropping improved the grain yield and decreased grain Cd content. In the pot experiment, Fe plaque amount was strongly and positively correlated with bulk soil Fe(II) content, root H 2 O 2 concentration, and Fe(II)-oxidizing ability of root bacteria but negatively correlated with Fe(II)-oxidizing ability of bulk soil bacteria and root Cd content. In Zhuliangyou 189, intercropping increased root H 2 O 2 concentration, rhizosphere redox potential, iron plaque amount but decreased Cd bioavailability, Fe(II)-oxidizing ability of bulk soil bacteria, and organ Cd content. In the flooded system, Zhuliangyou 189 showed higher bulk soil Fe(II) content than Changxianggu. In the ridge–furrow system, ridges decreased the Fe(II)-oxidizing ability of root and bulk soil bacteria, thereby decreasing Fe plaque amount and increasing organ Cd content of rice. In both monoculture and intercropping systems, rice cultivars planted on ridges showed higher Cd bioavailability and lower bulk boil Fe(II) content than those planted in furrows. Unlabelled Image • Intercropping increased yield and decreased organs Cd concentration of rice Z189 • H 2 O 2 in roots enhances iron plaque (Ip) formation. • Intercropping under flooding increased root H 2 O 2 , rhizosphere Eh and bulk soil Fe(II). • Cultivation on ridges decreased root surface FeOB and bulk soil Fe(II) to decrease Ip. • The ridges shared the low Fe(II) and high Cd in soil with neighboring furrow. [ABSTRACT FROM AUTHOR]

To explore the purifying effect of vertical subsurface flow constructed wetlands (CWs) on arsenic-containing biogas slurry in pig farms under natural conditions in the field, vertical subsurface flow CWs with water spinach- Pennisetum sinese as the core was constructed in this study. Under the condition of biogas slurry with different dilution ratios (2, 4, 6; v/v) was fed to the wetlands and different substrates (biochar and zeolite) were added to the wetlands, respectively, the removal efficiency of the pollutants in biogas slurry by CWs were investigated. The enrichment of arsenic (As) in wetland substrates and three wetland plants (water spinach, green Pennisetum sinese and purple Pennisetum sinese) was analyzed. The results showed that, the removal rate of ammonia nitrogen (NH 4 +-N) in biogas slurry at low dilution ratio was always higher in the CWs, while that of total phosphorus (TP), chemical oxygen demand (COD) and As was higher in biogas slurry at high dilution ratio at first and then was just the opposite. The addition of zeolite and biochar could enhance the decontamination effect of CWs. Zeolite had better removal effect on NH 4 +-N, TP and COD, while biochar showed better removal effect on As. At low dilution ratio, the enrichment of As was high in the wetland sediments and three wetland plants. Adding biochar and zeolite increased the enrichment and absorption of As by sediments, water spinach and purple Pennisetum sinese , which was more significant by adding zeolite than biochar. However, they slightly reduced the absorption of As by green Pennisetum sinese. The detailed effluent quality assessment showed TP and NH 4 +-N to be significant pollution factors. The CWs treated with zeolite showed a higher purifying effect, while the CWs added without the two substrates had a lower purifying effect. This study provides a theoretical basis for the practical application of CWs in livestock and poultry wastewater treatment. • Biogas slurry at lower dilution ratio was beneficial to increase the removal efficiency of NH 4 +-N. • Wetland sediments and plants had higher arsenic concentration at the low dilution ratio. • The removal rate of arsenic with biochar could be increased to at least 53.56%. • Zeolite increased the TP, NH 4 +-N and COD removal rate to more than 76.31%, 51.57% and 81.33% respectively. • Tackling the pollution of high concentration biogas slurry cannot rely on constructed wetlands alone. [ABSTRACT FROM AUTHOR]

• Fillers combined with biosorbents enhanced nutrients removal rates in constructed wetland. • The removal rates : As (35.38%–83.89%), Zn (8.15%–23.69%) and Cu (0.32%–0.88%). • Biochar is effective in reducing As uptake by wetland plants. • The treated wetland plant water spinach could be used as soilages. The performance of fillers (biochar and zeolite) and their combinations with biosorbents (compound microbial agent and chlorella) in nutrients and heavy metals removal from biogas slurry in constructed wetlands (CWs) planted water spinach (Ipomoea aquatica) and plant uptake of heavy metals was investigated. The results demonstrated that the removal rate of nutrients in CWs was all above 60%. COD removal efficiencies were not significantly affected by fillers and biosorbents, all above 80%. The removal rates of TN and NH 4 +-N were the highest when the two fillers and two biosorbents were added, and the combination of biochar and chlorella presented the optimal removal effect on TP. The efficiency of removing heavy metals from biogas slurry in CWs was As > Zn > Cu, and their removal rates were 35.38%–83.89%, 8.15%–23.69% and 0.32%–0.88%, respectively. The removal efficiency of As by the combination of biochar and composite microbial agent was high. The combination of the two fillers and two biosorbents had the best effect on reducing Cu and Zn enrichment in the aboveground part of water spinach in each treatment, while biochar alone had the best effect on reducing As enrichment in the aboveground and underground parts of water spinach. This study can provide a basis for the application of fillers and biosorbents in the treatment of biogas slurry in livestock and poultry farms in wetlands. [ABSTRACT FROM AUTHOR]

This study tests the hypotheses that whether environmental relevance of glyphosate would help control spread of the invasive snail Pomacea canaliculata , or benefit its population growth worldwide. Our results showed that glyphosate induced acute toxicity to the snail only at high concentrations (96 h LC50 at 175 mg/L) unlikely to occur in the environment. Long-term exposures to glyphosate at sublethal levels (20 and 120 mg/L) caused inhibition of food intake, limitation of growth performance and alterations in metabolic profiles of the snail. It is worth noting that glyphosate at 2 mg/L benefited growth performance in P. canaliculata . Chronic exposures of glyphosate significantly enhanced overall metabolic rate and altered catabolism from protein to carbohydrate/lipid mode. Cellular responses in enzyme activities showed that the exposed snails could increase tolerance by their defense system against glyphosate-induced oxidative stress, and adjustment of metabolism to mitigate energy crisis. Our study displayed that sublethal concentrations of glyphosate might be helpful in control of the invasive species by food intake, growth performance and metabolic interruption; whether environmental relevance of glyphosate (≤2 mg/L) benefits population growth of P. canaliculata is still inconclusive, which requires further field study. [ABSTRACT FROM AUTHOR]

During 2015, we studied the temporal patterns of nutrient concentrations and turbidity in water bodies with different degrees of agricultural and urban pressures across Guangzhou and Foshan (China). Data and observations were made by trained citizen scientists and professional researchers. Our study shows that all monitored water bodies, with the exception of Qiandeng Lake and Fengjiang River, had elevated NO 3 − -N concentrations, which ranged from 0.10 to 6.83 mg/L and peaked in late winter and early spring and reached a minimum in summer and mid-autumn. PO43-P concentrations ranged from 0.01 to 0.25 mg/L and peaked during the winter, late-summer and late autumn. Turbidity values were highest at sites with agricultural activities, with maximums in the late winter and autumn, and the highest frequency (16% and 25%) of algae presence occurred in the spring and autumn. To better understand the characteristics and drivers of the algae occurrences, measurements of phytoplankton composition and physicochemical characteristics were conducted in three key seasons in the agricultural process, fallow, sowing and rainy season in 2016. Our focused study found that the occurrence of Bacillariophyta , Euglenophyta , Xanthophyta , Cryptophyta , Chrysophyta were positively correlated with dissolved oxygen and phosphorus concentrations, while Chlorophyta and Cyanophyta had positive correlations with turbidity, oxygen demand and nitrogen concentrations. Bacillariophyceae counted for the highest proportion of phytoplankton during the fallow season, comprising up to 60 +% of the phytoplankton among the sites. During the rainy season, Chlorophyceae species were the majority, comprising up to 90 +% of phytoplankton among the sampled sites. Our results pointed to the complexity of nutrient and phytoplankton dynamics in water bodies under multiple pressures, and to the value of using citizen scientists to determine contextual information to benefit more focused studies. [ABSTRACT FROM AUTHOR]

Streams in urban areas are prone to degradation. While urbanization-induced poor water quality is a widely observed and well documented phenomenon, the mechanism to pinpoint local drivers of urban stream degradation, and their relative influence on water quality, is still lacking. Utilizing data from the citizen science project FreshWater Watch, we use a machine learning approach to identify key indicators, potential drivers, and potential controls to water quality across the metropolitan areas of Shanghai, Guangzhou and Hong Kong. Partial dependencies were examined to establish the direction of relationships between predictors and water quality. A random forest classification model indicated that predictors of stream water colour (drivers related to artificial land coverage and agricultural land use coverage) and potential controls related to the presence of bankside vegetation were found to be important in identifying basins with degraded water quality conditions, based on individual measurements of turbidity and nutrient (N-NO 3 and P-PO 4 ) concentrations. [ABSTRACT FROM AUTHOR]

In a previous piece of work, we reported some preliminary experimental results showing that hydrogen peroxide at a concentration range frequently encountered in rainwater could lead to degradation of three common herbicides (diuron, butachlor and glyphosate). However, the work was limited to the observation on the effects of Fenton process on the individual herbicides. In field conditions, different types of herbicides along with other organic molecules may occur concurrently. It is unclear how different herbicides and various organic molecules compete for the available hydroxyl radical. In this study, further laboratory experiments were conducted to observe the changes in the herbicides in the scenarios where multiple herbicides or humic acid are present. The results show that humic acid impeded hydroxyl radical-driven degradation of the diuron and butachlor. However, humic acid had no significant effects on reducing glyphosate removal rate. Glyphosate could compete strongly with the humic acid for the available hydroxyl radical in the reaction systems. The reactivity of glyphosate with hydroxyl radical was much higher than those of diuron and butachlor due possibly to its relatively simpler chemical structure, as compared to either diuron or butachlor, which are aromatic compounds that have higher chemical stability. Butachlor degradation was much weaker in the combined diuron and butachlor system than in the combined glyphosate and butachlor system. In the glyphosate-butachlor system, the opposite was observed. The findings have moved another step forward to understanding the potential role of rainwater-borne H 2 O 2 in degrading herbicides in open water environments. [ABSTRACT FROM AUTHOR]

[Display omitted] Bisphenol S (BPS) and its 11 emerging analogues were investigated in 325 urine samples from five occupational populations in South China. Besides BPS, ten emerging BPS analogues were newly identified and detected in the urine. It should be noted that urinary concentrations of dominant BPS analogues of 2,4′-bis(hydroxyphenyl)sulfone (2,4-BPS), bis(3-allyl-4-hydroxyphenyl)sulfone (TGSA) and diphenylsulfone (DPS) were 1.1–2.3 times higher than that of BPS, with overall detection frequencies at 74–91 %. The median sum concentrations of the target 12 bisphenols (ng/mL) were found highest in urine from cashiers (1.12), followed by water plant staffs (0.994), teachers (0.552), doctors (0.408) and power plant staffs (0.333). The composition profile of the urinary dominant bisphenols was occupational-dependent, with 2,4-BPS accounting for 45–73 % in cashiers and power plant staffs, and with DPS and TGSA for 74–82 % among doctors, teachers and water plant staffs. Significant correlations were found among the most frequently detected bisphenols in cashiers, indicating their common application and emission pathways. The median exposures based on estimated daily intakes (EDIs, ng/kg bw/day) for the 12 bisphenols in cashiers and water plant staffs (31.6–35.6) were 1.8–3.4 times higher than those of teachers, doctors and power plant staffs (10.6–17.5). This is the first study to identify multiple emerging BPS analogues in urine from occupational populations, especially cashiers and water plant staffs. [ABSTRACT FROM AUTHOR]

Water resource shortage and arsenic (As) water pollution are threatening human food security. Using As micro-polluted water for agricultural production may alleviate the water resource shortage situation after solving the As problem. In situ formed hydrous titanium oxide possesses much higher As immobilization potential than purchased TiO 2 because of its higher specific surface area and more abundant active hydroxyl group, which is proposed to reduce the As uptake of aquatic vegetables planted in As micro-polluted water. Herein, TiOSO 4 solution, which can hydrolyze into hydrous titanium oxide during dilution in water, was used as a new water amendment to realize in situ As immobilization in lake water (100 μg-As/L) during cultivation of water spinach. We found that TiOSO 4 could immobilize trace level As with its dosage as the main factor influencing the efficiency through response surface analysis. A low dosage TiOSO 4 treatment of 0.5 mg/L could reduce the As content in the edible part from 0.64 to 0.40 mg/kg, which satisfied the vegetable As standard of China (0.5 mg/kg). The shoot As content was negatively related to the used TiOSO 4 dosage and could be further reduced to 0.16 mg-As/kg at a dosage of 4 mg/L TiOSO 4 , while the health risk index of eating water spinach could be reduced by 75% (from 1.6 to 0.4). Therefore, TiOSO 4 is a useful in situ As immobilization reagent during cultivation of water spinach and may possibly be used in the production of other aquatic vegetables. In situ TiOSO 4 treatment may be an effective and facile strategy for the agricultural utilization of As micro-polluted surface water, which can alleviate the shortage on safe agricultural water resource in the context of widespread water micro-pollution. [Display omitted] • TiOSO 4 removed trace arsenic efficiently from lake water via coagulation. • TiOSO 4 -treated lake water was used for water spinach cultivation. • TiOSO 4 treatment did not affect the yield of water spinach. • 4 mg/L TiOSO 4 decreased As concentration in water spinach edible part by 75%. • In situ TiOSO 4 treatment is a facile strategy to utilize As micro-polluted water. [ABSTRACT FROM AUTHOR]