Metal wet deposition in the Three Gorges Reservoir (TGR) region of Southwest China.

Metal wet deposition has become an environmental concern because of its threats to soil or water quality and human health. This study was to collect rainfall waters in 2016 from seven sites, representing urban, town, rural, and wetland, within the Three Gorges Reservoir (TGR) region of Southwest China, determine the metal concentration and flux (Zn, Mn, Cu, As, Cd, Pb), and identify their possible sources. Results indicated that Zn was the most abundant metal with a concentration of 16.92 µg L-1 in fall and 19.91 µg L-1 in winter and flux of 4.71 mg m-2 in fall, while Cd was the least with a monthly mean concentration of 0.02-0.37 µg L-1. Among the seven sites, urban (FL) had the highest values of both concentrations of metals (Zn, Cu, Pb) and fluxes of metals (Mn, As), which significantly differed from the other sites. Component and redundancy analysis suggested that fossil fuel and biomass combustion be a potential metal source. Enrichment factors, box model, and potential ecological risk index showed that the TGR water quality could face a high risk due to wet metal deposition, especially Cd. Data could provide a valuable aid in mitigating metal pollution, developing the best watershed management practices, as well as safeguarding water quality and human health in the TGR region or other reservoir regions.

Spatiotemporal distribution and potential risk assessment of microcystins in the Yulin River, a tributary of the Three Gorges Reservoir, China.

Microcystins (MCs) pose potential threat for both aquatic organisms and humans, whereas their occurrence in response to hydrodynamic alterations are not clearly understood. Here, spatiotemporal variations of dissolved MC-RR and MC-LR were evaluated monthly in 2016 in the Yulin River, a tributary of the Three Gorges Reservoir (TGR). The environmental factors that linked to MCs concentration were discussed. The results revealed that MC-RR maximumly reached 3.55 µg/L, and the maximum MC-LR concentration exceeded the threshold value of 1.0 µg/L recommended by the WHO. MCs concentrations were higher during the flood season and decreased from the estuary to the upstream reach of the Yulin River. Ecological risk assessment confirmed that MC-LR had significant adverse effects on the benthonic invertebrates Potamopyrgus antipodarum. MCs content in the sediment was 1.70- to 20-fold higher than that in suspended particulate matter (SPM). The impacts of environmental factors on the MCs profile differed between flood and dry seasons and the longitudinal differences of MCs were determined by the longitudinal profile of water velocity and SPM content, which were affected by TGR operations. This study suggested that the occurrence of MCs in the Yulin River were influenced by hydrologic regime in TGR.

Time-varying sensitivity analysis of hydrologic and sediment parameters at multiple timescales: Implications for conservation practices.

Environmental models can be used to better understand the hydrologic and sediment behavior in a watershed system. However, different processes may dominate at different time periods and timescales, which highly complicate the model interpretation. The related parameter uncertainty may be significant and needs to be addressed to avoid bias in the watershed management. In this study, we used the time-varying and multi-timescale (TVMT) method to characterize the temporal dynamics of parameter sensitivity at different timescales in hydrologic and sediment modeling. As a case study, the first order sensitivity indices were estimated with the Fourier amplitude sensitivity test (FAST) method for the Hydrological Simulation Program - Fortran (HSPF) model in the Zhangjiachong catchment in the Three Gorge Reservoir Region (TGRR) in China. The results were compared to those of the traditional aggregate method to demonstrate the merits of the TVMT method. The time-varying nature of the hydrologic and sediment parameters was revealed and explained mainly by the variation of hydro-climatic conditions. The baseflow recession parameter, evapotranspiration (ET) parameter for the soil storage, and sediment washoff parameter showed high sensitivities almost across the whole period. However, parameters related to canopy interception and channel sediment scour varied notably over time due to changes in the climate forcing. The timescale-dependent characteristics was observed and was most evident for the baseflow recession parameter and ET parameter. At last, the parameters affecting the sediment export and transport were discussed together with the inferred conservation practices. Reasonable controls for sediment must be storm-dependent. Compared to management practices on the land surface, practices affecting channel process would be more effective during storm events. Our results present one of the first investigations for sediment modeling in terms of the importance of parameter sensitivity in both time periods and evaluation timescales for the model calibration, diagnostic evaluation, and prioritizing efforts for conservation practices.

[Nitrification and Denitrification Rates in a Small Tributary, Nanhe River, of Three Gorge Dam Reservoir During Water Collection and Release Events].

Three Gorge Dam Reservoir (TGDR) is a new forming ecosystem and its sediments dynamics remains unknown. Investigation on the nitrification and denitrification dynamics of sediments of TGDR during water collection and release events-anti-seasonal actions-is critical for nitrogen management in TGDR. In this study, we sampled sediments in three locations (upstream, center, and downstream along water flow) of South River, located in a typical small tributary, Nanhe, in TGDR during 2015 water collection and release events to characterize its physiochemical property and determine its nitrification and denitrification rates using acetylene inhabitation method. The results showed that the concentrations of physiochemical parameters of sediments (total carbon, total nitrogen, nitrate, and ammonia) were significantly higher (P<0.05) in water collection event than those in water release event, suggesting there were external materials (e. g., soil) entering into TGDR. Furthermore, the nitrification rate of sediments in water collection event[194.06 µmol·(m2·h)-1] was significantly higher than that in water release event[16.52 µmol·(m2·h)-1]. Sediments nitrification rate was positively correlated to the physiochemical parameters. In contract, the denitrification rate of sediments was higher in water release event[647.20 µmol·(m2·h)-1] than that in water collection event[24.04 µmol·(m2·h)-1). Accordingly, the denitrification rate of sediments was negatively correlated to the physiochemical parameters.

Impact of land use changes on water quality in headwaters of the Three Gorges Reservoir.

The assessment of spatial and temporal variation of water quality influenced by land use is necessary to manage the environment sustainably in basin scales. Understanding the correlations between land use and different formats of nonpoint source nutrients pollutants is a priority in order to assess pollutants loading and predicting the impact on surface water quality. Forest, upland, paddy field, and pasture are the dominant land use in the study area, and their land use pattern status has direct connection with nonpoint source (NPS) pollutant loading. In this study, two land use scenarios (1995 and 2010) were used to evaluate the impact of land use changes on NPS pollutants loading in basins upstream of Three Gorges Reservoir (TGR), using a calibrated and validated version of the soil and water assessment tool (SWAT) model. The Pengxi River is one of the largest tributaries of the Yangtze River upstream of the TGR, and the study area included the basins of the Dong and Puli Rivers, two major tributaries of the Pengxi River. The results indicated that the calibrated SWAT model could successfully reproduce the loading of NPS pollutants in the basins of the Dong and Puli Rivers. During the 16-year study period, the land use changed markedly with obvious increase of water body and construction. Average distance was used to measure relative distribution patterns of land use types to basin outlets. Forest was mainly distributed in upstream areas whereas other land use types, in particular, water bodies and construction areas were mainly distributed in downstream areas. The precipitation showed a non-significant influence on NPS pollutants loading; to the contrary, interaction between precipitation and land use were significant sources of variation. The different types of land use change were sensitive to NPS pollutants as well as land use pattern. The influence of background value of soil nutrient on NPS pollutants loading was evaluated in upland and paddy field. It was found that total nitrogen (TN) and total phosphorous (TP) in upland were more sensitive to NPS pollutants loading than in paddy fields. The results of this study have implications for management of the TGR to reduce the loading of NPS pollutants into downstream water bodies.

[Identification of a Facultative Bacterium Strain with the Ability to Methylate Mercury Under Both Aerobic and Anaerobic Conditions].

A strain with the ability to methylate mercury under both the aerobic and anaerobic conditions was isolated from soil of the water-level-fluctuation-zone in the Three Gorge Reservoir in Shibaozhai Village, Zhongxian Country, Chongqing, China (E108°12'3″ and N30°24'36″). The soil was classified as Purple soil with a pH of 7.97 (0-20 cm depth). The isolation was performed under 1.0 mg·L-1 HgCl2 conditions. After its morphological and physiological characterization, and its phylogenetic analysis using 16S rDNA gene sequence, the strain was identified as Pseudomonas fluorescens sp., and named as Pseudomonas fluorescens XD-MeHg-B2 (GenBank accession number: KU954349). On one hand, at 30℃ under aerobic condition, the concentration of methylmercury (MeHg) in the PBS (phosphate buffer saline) solution, which was inoculated with 1×1011 cfu·mL-1 suspension of P. fluorescens XD-MeHg-B2 and an initial Hg2+ of 200 ng·L-1, was exponentially increased to 1.22 ng·L-1±0.15 ng·L-1 after 60 min incubation and then approached to the maximum of 3.85 ng·L-1±0.33 ng·L-1 160 min after incubation. The largest mercury methylation rate was 1.93%. On the other hand, at 30℃ under anaerobic condition, the concentration of MeHg in the PBS solution, which was also inoculated with 1×1011 cfu·mL-1 suspension of P. fluorescens XD-MeHg-B2 and an initial Hg2+ of 200 ng·L-1, was 2.86 ng·L-1±0.73 ng·L-1 and the largest mercury methylation rate was 1.43% 180 min after incubation. As a result, P. fluorescens XD-MeHg-B2 showed its ability to methylate mercury under both aerobic and anaerobic conditions while with a comparatively hysteretic and lower ability of mercury methylation. These results demonstrated that P. fluorescens XD-MeHg-B2 could be a promising candidate for further studies on mercury biogeochemical cycle, particularly under dry-wet alternative conditions.

[Effect of Nutrient Cycles in Tributaries on the Transport of Nutrient in the Three Gorge Reservoirs:A Case Study of Caotang River].

Backwater regions have been formed in the downstream of tributaries since the Three Gorge Reservoir (TGR) was impounded, as the most influential area to the aquatic environment within the reservoir. In order to study the effects and significance of the backwater regions on the nutrient cycling and substance fluxes, dissolved inorganic nitrogen (DIN), dissolved inorganic phosphorus (DIP), dissolved silicon (DSi) were monitored in situ in Caotang tributary backwater region, the adjacent mainstream and Caotang tributaries' upstream every month from August 2012 to July 2013. The results showed that the concentrations of DIN, DIP and DSi in Caotang tributary backwater region were similar to those in the mainstream, and the monthly variation tendency was very consistent with the mainstream Changjiang. DIN, DIP and DSi in the Caotang tributary were mainly originated from the mainstream. The influence of the mainstream water could extend to the upmost of the backwater region due to the good connection and rapid, sufficient water exchange between mainstream and tributary. Nutrients from the mainstream were retained and consumed by primary producers in the tributary during the growing seasons in spring and summer, while released back to the water during late autumn and winter. Nutrient cycling in the tributary could change the seasonal pattern of nutrient transportation. The mainstream nutrient fluxes could receive significant seasonal modification from the large numbers (more than 40) of tributaries within the TGR domain.

Study on the health related quality of life and influencing factors in emigrants with rheumatoid arthritis in Three-Gorge Reservoir area / 重庆医学

Objective To analysis the health related quality of life (HRQOL)in emigrants with rheumatoid arthritis(RA) in Three‐Gorge Reservoir area ,and to study the influencing factors on HRQOL .Methods Self‐rating depression scale(SDS) was used to assess degree of depression in emigrants with rheumatoid arthritis in Three‐Gorge Reservoir area ,and SF‐36 scalec was used to assess the HRQOL of these patients .The one‐way ANOVA and stepwise regression analysis were used to study the influence fac‐tors of HRQOL .Results SDS scores showed that there were 110 peoples with depressive symptoms (67 .5% ) ,including mild de‐pression 58 cases(35 .6% ) ,moderate depression 39 cases(23 .9% ) ,severe depression 13 cases(8 .0% ) .Stepwise regression analysis showed that :SDS score ,DAS‐28 classification ,age ,sex ,treatment ,education ,occupation ,physical exercis ,economic income ,health insurance and alcohol consumption influenced the HRQOL scores of patients with IBS .DAS‐28 classification ,economic income , health insurance ,sex ,treatment were the main influencing factors ,with the unstandardized partial coefficients of -39 .211 ,31 .512 , 25 .866 ,-42 .348 ,-51 .235 .Conclusion Most of emigrants with RA in Three‐Gorge Reservoir area suffering from depressive symptoms ,and the HRQOL scores of them is not optimistic .The results suggested that more attention must be paid to the elderly , low‐income ,women ,low education ,DAS‐28 classification and no occupation .Quiting drinking ,receiving treatment ,psychological treatment ,strengthen exercise and expanding the scope of medical insurance all can improve patients′health related quality of life .

Assessment of runoff and sediment yields using the AnnAGNPS model in a Three-Gorge watershed of China.

Soil erosion has been recognized as one of the major threats to our environment and water quality worldwide, especially in China. To mitigate nonpoint source water quality problems caused by soil erosion, best management practices (BMPs) and/or conservation programs have been adopted. Watershed models, such as the Annualized Agricultural Non-Point Source Pollutant Loading model (AnnAGNPS), have been developed to aid in the evaluation of watershed response to watershed management practices. The model has been applied worldwide and proven to be a very effective tool in identifying the critical areas which had serious erosion, and in aiding in decision-making processes for adopting BMPs and/or conservation programs so that cost/benefit can be maximized and non-point source pollution control can be achieved in the most efficient way. The main goal of this study was to assess the characteristics of soil erosion, sediment and sediment delivery of a watershed so that effective conservation measures can be implemented. To achieve the overall objective of this study, all necessary data for the 4,184 km(2) Daning River watershed in the Three-Gorge region of the Yangtze River of China were assembled. The model was calibrated using observed monthly runoff from 1998 to 1999 (Nash-Sutcliffe coefficient of efficiency of 0.94 and R(2) of 0.94) and validated using the observed monthly runoff from 2003 to 2005 (Nash-Sutcliffe coefficient of efficiency of 0.93 and R(2) of 0.93). Additionally, the model was validated using annual average sediment of 2000-2002 (relative error of -0.34) and 2003-2004 (relative error of 0.18) at Wuxi station. Post validation simulation showed that approximately 48% of the watershed was under the soil loss tolerance released by the Ministry of Water Resources of China (500 t·km(-2)·y(-1)). However, 8% of the watershed had soil erosion of exceeding 5,000 t·km(-2)·y(-1). Sloping areas and low coverage areas are the main source of soil loss in the watershed.

Mental health,life events and coping styles of middle school students in Three-Gorges areas in Chongqing / 中华行为医学与脑科学杂志

Objective To investigate the mental health status of middle school students in Three-Gorge area in Chongqing, and to explore the relationship with their life events and coping styles. Methods The Compi-ling of mental health scales for middle school students(MSSMHS),adolescent self-rating Life events checklist and trait coping style questionnaire(TCSQ) were adopted in the study to test the randomly sampled 1 632 middle school students in Three-Gorges area in Chongqing. Results The rate of mental disorder in the samples was 27.5%. The total average scores and each factor of the mental health were positively correlated with the factors of life events(r=0. 29～0.55). Negative coping styles were positively correlated with the total average scores and each factor of the mental health (r=0.38～0.56). Positive coping styles was negatively correlated with anxiety, depression, study pressure(r=-0.07～-0.05). The factors of life events and coping styles explained 27%～49% variation of scores of the mental health total average scores and each factor of the mental health. Conclusion Both life events and the coping styles are the important factors for the mental health of middle school students in Three-Gorge area in Chongqing. Reducing negative life events and coping styles benefits the mental health of middle school students.

Study on Soil Characteristics of High_mortality Area of Esophageal Cancer in Three Gorge Dam Region / 环境与健康杂志

Objective To study soil environment characteristics of high_mortality areas of esophageal cancer in Three Gorge dam region. Methods To contrast the disparity of soil type,soil use,and basic characteristics,in particular microelement contents in high_mortality area and low_mortality area of esophageal cancer. Results Calcareous purple soils distributed dominantly in high_mortality area,and soil pH and CaCO3 content was high,and soil fertility low. While paddy soils occupyed mainly in low_mortality area,and pH and CaCO3 content was low however soil fertility high.Moreover,the microelement contents in soils in high_mortality area were lower than those in low_mortality area apparently. Conclusion Mortality of esophageal cancer was closely relative to the contents of some microelements in the soil environment.