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Ecological water replenishment is considered to be an important project to adjust river ecosystems with water shortages and degradation, and its impact on the water quality of the target river section deserves attention. By investigating the characteristics of inorganic ions and organic components of the Beijing section of the Yongding River (YDR) from upstream to downstream, the sources of inorganic ions and dissolved organic matter (DOM) during an ecological water replenishment event were analysed and discussed. This study illustrated the hydrochemical response to different supplemental water sources in three sections of the YDR (mountain gorge section (MGS), urban plain section (UPS), and suburb plain section (SPS)). The results showed that the total dissolved solids (TDS) and ion concentrations were significantly different (p < 0.001) in the three river sections due to different supplemental water sources. The highest concentration of TDS was found in the UPS (870.92 mg/L) replenished by reclaimed water, while the lowest concentration of TDS was found in the SPS (306.95 mg/L) replenished by the water of the South-to-North Water Diversion Project (SNWD). Despite the differences in the water sources of replenishment, the optical parameters of DOM and fluorescent components showed similar protein-like dominated endogenous source characteristics in the three river sections of the YDR, which was due to the influence of reservoir water (MGS and SPS) and reclaimed water (UPS). Our study emphasizes the importance of understanding the impact of different water sources on the water replenishment process, which provides a scientific reference for the management of ecological water replenishment., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

The present study investigated the chemical composition of summer precipitation at different altitudes in Yulong Snow Mountain, hoping to obtain some basic information about the chemical characteristics of precipitation. A couple of precipitation samples at different altitudes in the Yulong Snow Mountain area in southeastern China were collected from July 26 to July 31, 2005 for chemical analyses. Sea-salt tracer analysis showed that Cl and Na had high proportion from marine sources, while the other ions mainly were from non-marine sources. Statistics showed that the cation concentrations ranged from 0.51 to 5.26 mg L and anion concentrations ranged from 0.99 to 4.90 mg L. Further analysis showed that terrestrial ions, especially from the proximal terrestrial sources, largely affected the ion concentrations in precipitation. Ion concentrations of precipitation were correlated significantly with local atmospheric circulation at altitude 2,950-4,800 m, and also correlated closely with human activities at altitude 2,400-2,950 m. Limestone, the majority of local rocks, caused high cation concentrations in precipitation, such as Ca and Mg. The majority of vapors in the region came from the Indian Ocean whereas parts came from the eastern Pacific. The inorganic ions in precipitation increased significantly in the Yulong Snow Mountain area during this century. Compared with most of the high altitude Mountains in China, the precipitations in the Yulong Snow Mountain area had higher concentrations of inorganic ions and low acidic ion concentrations. The conclusions can provide a basis for study of regional climate characteristics, environment and ecological characteristics of Yulong Snow Mountain area. [ABSTRACT FROM AUTHOR]

This study presented a study of seasonal variations of major ion concentrations in fresh snow on Baishui Glacier No. 1, the largest glacier on Yulong Mountain, China. Fresh snow samples at Baishui Glacier No. 1 were collected from November 2008 to October 2009 for chemical data analysis. The results showed that the neutralizing effect of terrestrial source aerosols raised the pH value of fresh snow. The conductivity of fresh snow was much higher in dry season than that in rainy season. It was evident that the concentration of inorganic ions was generally higher in the dry season than that in rainy season, and the highest values occurred in the pre-monsoon period (April-May). The ions of fresh snow mainly came from terrestrial under the influence of west wind circulation and the Plateau monsoon in dry seasons, and had much complex sources in rainy season under the control of southeast and southwest monsoons. Both wind speed and precipitation had potential effects on ion concentration and composition of fresh snow as well. Moreover, principal component analysis showed that fresh snow ions were mainly from local lithology in dry season and from oceans in rainy season. [ABSTRACT FROM AUTHOR]

Abstract: Daily PM2.5 samples were collected in Chengdu, a megacity in southwest China, for a period of one month in every season during 2009–2010. Mass concentrations of water-soluble inorganic ions, organic carbon (OC), elemental carbon (EC), levoglucosan (LG), water soluble organic carbon (WSOC), and elements were determined to identify the chemical characteristics and potential sources of PM2.5. The data obtained in spring were discussed in detail to explore the impacts of dust storms and biomass burning on the chemical aerosol properties. The daily PM2.5 mass concentrations ranged from 49.2 to 425.0μgm−3 with an annual average of 165.1±85.1μgm−3. The highest seasonal average of PM2.5 concentrations was observed in the winter (225.5±73.2μgm−3) and the lowest in the summer (113.5±39.3μgm−3). Dust storm influence was observed only during the spring, while biomass burning activities occurred frequently in late spring and early summer. In the spring season, water-soluble ions, total carbonaceous aerosols, and the sum of the dominant elements (Al, Si, Ca, Ti, Fe, Mn, Zn, Pb, and Cu) accounted for 30.0±9.3%, 38.6±11.4%, and 6.2±5.3%, respectively, of the total PM2.5 mass. Crustal element levels evidently increased during the dust storm episode and LG, OC, WSOC, Cl− and K+ concentrations increased by a factor of 2-7 during biomass burning episodes. Using the Positive Matrix Factorization (PMF) receptor model, four sources for spring aerosols were identified, including secondary sulfate and nitrate, motor vehicle emissions, soil dust, and biomass burning. The four sources were estimated to contribute 24.6%, 18.8%, 23.6% and 33.0%, respectively, to the total PM2.5 mass. [Copyright &y& Elsevier]

Introduction: Two hundred twenty-five precipitation samples were collected at high- (summit, 1,534 m ASL) and low-elevation (base, 218 m ASL) sites between 2005 and 2008 in eastern China. The present work focused on the roles of long-range transport and under-cloud/boundary layer scavenging on chemical composition of precipitation collected at the two sites. Methods: Ionic and trace species were analyzed in 225 precipitation samples. A total of 72 precipitation events occurring simultaneously at the summit and base sites were further examined. Positive matrix factorization (PMF) and backward air mass trajectories were used to identify the sources of precipitation pollutants. Results: Low pH and high concentrations of ionic and trace species were measured at both sites. Inter-correlations for the simultaneous samples at the two sites were poor for trace elements (−0.07~0.47). A several fold increase in major ion (122~546%) and trace element (261~3,302%) concentrations occurred as the rain fell. Approximately 89% of the air masses responsible for the summit precipitation events were of distance origin. Marine salt, crustal material, fossil fuel burning plus secondary products, and metallic-industry-related factors were identified by PMF, contributing 9.7%, 22.8%, 41.8%, and 25.6%, respectively, to the precipitation pollutants at the summit and 13.3%, 31.9%, 39.6%, and 15.2%, respectively, at the base. Conclusions: Long-range atmospheric transport primarily influenced the high and the low site precipitation was strongly influenced by the under-cloud scavenging process of local boundary layer pollutants. Crustal material and fossil fuel burning plus secondary products were the predominant pollution sources in this region. [ABSTRACT FROM AUTHOR]

Abstract: TSP, PM10 and size-segregated aerosols were collected at the summit (2060 m, a.s.l.) of Mt. Hua in central China during the winter of 2009, and determined for organic (OC) and elemental carbon (EC), pH of water-extracts and inorganic ions. OC in TSP and PM10 are 6.9 ± 2.9 and 5.9 ± 2.5 μg m−3, while EC in TSP and PM10 are 0.9 ± 0.6 and 0.9 ± 0.5 μg m−3, respectively. SO4 2−, NO3 −, NH4 + and Ca2+ are major ions in PM10 with concentrations of 5.8 ± 3.7, 2.7 ± 1.6, 1.6 ± 0.9 and 1.5 ± 0.7 μg m−3, respectively. OC/EC ratios (8.2 ± 3.1 in TSP and 6.6 ± 1.8 in PM10) at the mountaintop are 2–4 times higher than those in lowland surface, suggesting an enhanced transformation of organics from gas- to solid- phase because of an increased photochemical oxidation and/or an increased condensation due to lower temperature, as well as an increased organic input from mountain plant emission. Air mass backward trajectories showed that compared with those derived from north/northwest China aerosols transported from the south contained higher concentrations of SO4 2− and NH4 + and lower concentrations of Ca2+. Size distributions of NH4 + and K+ presented as an accumulation mode with a peak at 0.7–1.1 μm, in contrast to Ca2+ and Mg2+, which maximized at the size 4.7–5.8 μm as a coarse mode. SO4 2− and NO3 − showed a bimodal pattern with a large peak at the range ... [Copyright &y& Elsevier]

The article presents a study which analyses the major ion chemistry and nutrient behaviour in the Changjiang (Yangtze) River and the Three Gorges Reservoir (TGR) in China. It examines the behavours of nutrients in the mixing zone of TGR. It says that ion water chemistry was controlled by carbonate weathering mechanism. Results show that major ions including Ca2+, Mg2+, and Na+ can be used as tracers to explore the behaviour of non-conservative elements.

As the major constituents of PM 2.5 , carbonaceous constituents and inorganic ions have attracted emerging attentions on their health risks, particularly on cardiorespiratory diseases. However, evidences on the risks of PM 2.5 constituents on other diseases (eg. nervous disease, genitourinary disease, neoplasms and endocrine disease) remain scarce. In our study, we firstly calculated residuals of PM 2.5 constituents regressed on PM 2.5 to remove the confounding effect of PM 2.5. Then, generalized additive model (GAM) was used to assess impacts of residuals of PM 2.5 constituents on mortality from 36 diseases (10 broad categories and 26 subcategories) during 2011–2015 in Guangzhou, China. Results of constituent-residual models showed that only EC, OC and NO 3 - were significantly associated with all-cause mortality, with per IQR change in corresponding constituent residuals related to percentage changes of 1.69% (95% CI: 0.42, 2.97), 1.94% (95% CI: 0.37, 3.54) and 2.59% (95% CI: 1.02, 4.18) at lag 03 days. All these pollutants were significantly associated with elevated mortality risk of cardiovascular disease, but only EC was significantly associated with respiratory mortality, and NO 3 - with endocrine disease and neoplasm. For more specific causes, the highest effect estimates of EC and NO 3 - were both observed on mortality from other form of heart disease, and OC on intentional self-harm, with estimates of 11.45% (95% CI: 2.74, 20.91), 12.59% (95% CI: 1.41, 25.02) and 18.01% (95% CI: 2.14, 36.36), respectively. Our findings highlighted that stricter emission control measures are still warranted to reduce air pollution level and protect the public health. The association between PM 2.5 and its constituents and cause-specific mortality. [Display omitted] • We explored independent effects of PM 2.5 constituents on mortality from 36 diseases. • EC, OC and NO 3 - were significantly associated with cardiovascular mortality. • EC was significantly associated with respiratory mortality. • NO 3 - was significantly associated with deaths of endocrine disease and neoplasm. [ABSTRACT FROM AUTHOR]

Severe haze occurrence in the north of the North China Plain (NCP) is recognized as a consequence of the regional transport of pollutants initially from the south and then the rapid formation of secondary pollutants in the local air. However, the origin of pollutants causing haze in the southern NCP has not yet been elucidated even through careful data observation. Based on the contents of water-soluble inorganic ions in PM 2.5 samples collected during two severe haze episodes in Zhengzhou, a mega city located on the southern edge of the NCP, we estimated the contributions of local primary emissions and secondary pollutants to haze occurrence. On average, Na + , K + , and Ca 2+ mainly originated from anthropogenic sources, and their anthropogenic fractions had proportions of 97.5%, 93.9%, and 76.5% in their respective total mass. Anions Cl - and SO 4 2- substantially originated from not only produced substantially via secondary formation but also from primary emissions, and their primary proportions in their respective total mass were 51.1% and 30.8%. In contrast, NH 4 + and NO 3 - were dominated by secondary formation. The increase in PM 2.5 was mainly caused by the formation of secondary inorganic (29.1%) and organic species (57.2%) and the primary anthropogenic emissions (12.5%). These results indicated that the haze at the southern edge of the NCP was mainly caused by pollutants in the local areas. Compared to the haze in the northern NCP, the haze in the southern NCP edge had a higher PM 2.5 mass concentration and a higher proportion of secondary species, but a lower proportion of primary species, indicating the high heterogeneity of winter haze over the NCP., 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 © 2021 Elsevier B.V. All rights reserved.)

As the major constituents of PM 2.5 , carbonaceous constituents and inorganic ions have attracted emerging attentions on their health risks, particularly on cardiorespiratory diseases. However, evidences on the risks of PM 2.5 constituents on other diseases (eg. nervous disease, genitourinary disease, neoplasms and endocrine disease) remain scarce. In our study, we firstly calculated residuals of PM 2.5 constituents regressed on PM 2.5 to remove the confounding effect of PM 2.5 . Then, generalized additive model (GAM) was used to assess impacts of residuals of PM 2.5 constituents on mortality from 36 diseases (10 broad categories and 26 subcategories) during 2011-2015 in Guangzhou, China. Results of constituent-residual models showed that only EC, OC and NO 3 - were significantly associated with all-cause mortality, with per IQR change in corresponding constituent residuals related to percentage changes of 1.69% (95% CI: 0.42, 2.97), 1.94% (95% CI: 0.37, 3.54) and 2.59% (95% CI: 1.02, 4.18) at lag 03 days. All these pollutants were significantly associated with elevated mortality risk of cardiovascular disease, but only EC was significantly associated with respiratory mortality, and NO 3 - with endocrine disease and neoplasm. For more specific causes, the highest effect estimates of EC and NO 3 - were both observed on mortality from other form of heart disease, and OC on intentional self-harm, with estimates of 11.45% (95% CI: 2.74, 20.91), 12.59% (95% CI: 1.41, 25.02) and 18.01% (95% CI: 2.14, 36.36), respectively. Our findings highlighted that stricter emission control measures are still warranted to reduce air pollution level and protect the public health., (Copyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved.)

The process of phytoplankton succession and change in primary productivity are directly determined by the seasonal variations in nutrients in tributary bays of channel reservoirs. This study aimed at analyzing the effects of the main nutrient sources on seasonal distribution of nutrients in Xiangxi Bay based on the field data collected in 2010 and 2011. The tracing inorganic ions were Cl - and Na + that showed significant differences ( P <0.01) between the mainstream and the tributary. The nutrient contribution rates of different sources were calculated by the binary linear model. The results showed that the nutrient contribution rate of the mainstream was more than 75% during the dry season and the impoundment period. The intrusion of the mainstream was the main source of nutrients in Xiangxi Bay. The difference in the contribution rates between the mainstream and the upstream decreased during the pre-flood drawdown period and the flood season. The concentration of total phosphorus was higher in the upstream, while the concentration of total nitrogen was higher in the mainstream. The patterns of density currents were different and the nutrient contribution rates of different sources changed accordingly. Therefore, the nutrients of Xiangxi Bay changed regularly in different operation periods of the Three Gorges Reservoir.