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Regional differences in socio鄄economic development, land use, vegetation cover, and relative location of water body within a watershed bring about significant effects on the water environment quality of the watershed. Concerning about the core demands of water body protection, it is important and necessary to carry out zoning water environment protection for whole watershed. With a view to the spatial differences in regional characteristics of eco鄄environment and water body pressure鄄respond features, this paper studied the zoning of water environment protection in the Three Gorges Reservoir watershed, based on the methods of ecological factors overlay and ecological sensitivity analysis. The factors considered included hydrothermal conditions, terrain topography, administrative unit, and ecological sensitivity. Three regions in the watershed were zoned, i. e. , 1) red region, namely strictly protected region, with an area of 2924 km2 and occupying 5郾1% of the total; 2) yellow region, namely first class protection region, with an area of 10477 km2 and occupying 18. 4%; and 3) blue region, namely second class protection region, with an area of 43599 km2 and occupying 76郾5%. The key environmental problems of the regions were identified, and the strategies for the regions爷development and water environment protection were proposed. [ABSTRACT FROM AUTHOR]

Organophosphates （OPEs） are widely used as flame retardants and additives and thus are commonly detected in the environment. In order to explore their environmental behavior, the concentrations of 13 OPEs in the surface water and sediment of Dongting Lake were analyzed using UPLC-MS/MS. The results showed that 11 OPEs were detected, with detection frequencies of 5.26%-100% and 58.3%-100%, and the concentrations of OPEs were 2.06-2 028 ng·L -1 and 19.6-2 232 ng·g -1 in water and sediment, respectively. Overall, contamination concentrations were ranked in descending order as follows： inflowing rivers, lake area, and outlet, whereas the spatial distribution of concentrations in sediment was inversely proportional to hydrodynamics. The concentration of OPEs in Dongting Lake was at a high level compared with that of domestic and foreign lakes. Among the detected 11 OPEs, tri-iso-butyl phosphate （TnBP） and （TiBP） were dominant in water, accounting for 52.3% and 22.4% of ∑OPEs, respectively. TPhP was the dominant OPEs in sediment, accounting for 31.2% of ∑OPEs. The correlation and principal component analysis indicated that OPEs pollution in Dongting Lake was mainly affected by industrial production emissions, fishery aquaculture, and atmospheric deposition. The assessment results of the risk entropy showed that most of the detected OPEs in water had relatively low ecological risks, whereas the ecological risk of 2-ethylhexyl diphenyl phosphate （EHDPP） at some sampling points requires further attention.

In order to fully understand the pollution of polychlorinated biphenyls (PCBs) in Dongting Lake, 209 PCB congeners were quantitatively detected and analyzed by isotope-dilution high-resolution mass spectrometry in 21 surface water sampling sites of Dongting Lake and the inflow rivers of the lake. The results showed that a total of 50 PCB congeners were detected in the study area. The ρ (ΣPCBs) ranged from 0.077 to 10 ng·L -1 , with an average concentration of 2.7 ng·L -1 and a median concentration of 1.9 ng·L -1 . The order of contamination concentrations were as follows:the inflow rivers of the lake > lake region > outlet. Compared with the reports of domestic and foreign studies, PCB pollution in Dongting Lake is at a low level. The main pollutants in the surface water were dichlorobiphenyls and tri- and tetrachlorobiphenyls, with relative abundances of 67%, 14%, and 16%, respectively. PCB11, PCB17, PCB18, PCB20+33, PCB28, PCB47+75, PCB52, and PCB68 were the most widely distributed and detected in more than 80% of samples. Among them, ρ (PCB11) was the highest, with an average concentration of 1.6 ng·L -1 , accounting for 59% of ρ (ΣPCBs), from the domestic organic pigment production process of unintentional emissions. Atmospheric transport deposition and historical residue were the main sources of PCBs in water. According to the toxicity equivalent factor method, the ecological toxicity risk of the study area was evaluated, and the results showed that the TEQ in the water was far lower than the relevant standard limit, indicating that the pollution of PCBs in the surface water of Dongting Lake and the inflow rivers would not cause harm to exposed organisms.

To reasonably evaluate the eco-environmental health of the Tangwang River, which is a tributary of the Songhua River in China, community structures of periphyton and cleanliness of the benthic diatom at 24 sampling sites were investigated using McNaughton's dominance index, clustering, and ecotype analysis, while the relationship between the environmental factors and the diatom communities were studied by principal component analysis, Spearman correlation test, and redundancy analysis, in August 2018 (flood season). A total of 99 species or variants of benthic diatoms have been identified, indicating that there were abundant diatoms in the Tangwang River. Achnanthidium minutissimum and other diatoms that can be used as clean water indicators were dominant species in the Tangwang River, which indicates that the eco-environmental quality of the Tangwang River was relatively healthy in the flood season. Of these, the dominant degree of A. minutissimum was 0.32, making it the absolute dominant species in Tangwang River. Sampling sites can be divided into three groups based on clustering analysis. The dominant species of group 1 and group 2 were mainly clean species, indicating that the two groups were in a relatively healthy state. Nitzschia palea, Ulnaria ulna , and other diatoms that can be used as eutrophication indicators were the dominant species of group 3, indicating that group 3 was less healthy than the other two groups. From groups 1 and 2, the results from ecotype analysis showed a decrease in the proportion of polyoxybiontic diatoms and an increase in the proportion of α-mesosaphrobe diatoms, polysaprobe diatoms, oligo-mesotrophic diatoms, mesotrophic diatoms, meso-eutrophic diatoms, and eutrophic diatoms. Compared to the other two groups, the results from ecotype analysis showed a significant increase in the proportion of α -mesosaphrobe diatoms, polysaprobe diatoms, eutrophic diatoms and hypereutrophic diatoms in group 3. The predominant aquatic influencing factors of diatom community structures for the Tangwang River were permanganate index, total nitrogen (TN), and ammonia nitrogen (NH 4 + -N), of which permanganate index was the main factor for group 2, while TN and NH 4 + -N were the main factors for group 3. As a result, the eco-environmental quality of the Tangwang River was good, and the benthic diatom was found to be an effective indicator of the nutritional conditions and saprophytic status.

To understand the difference between transport coefficients of water runoff, sand discharge, and phosphorus flux in each subsection of a river, a judgement method for analyzing the characteristics of phosphorus transport and transformation in water of rivers was established in this study. Based on the measured data of water runoff, sand discharge, and phosphorus fraction concentrations in the water of the Three Gorges Reservoir (TGR) in January and July 2015, characteristics of phosphorus transport and transformation in the water were analyzed by using the conceptual method. The results showed that the predominant phosphorus fraction in water of the TGR was total dissolved phosphorus (TDP), which accounted for 51%-96% of total phosphorus in water. The TDP flux relative to runoff in the TGR decreased in January 2015 That was caused by the adsorption of TDP by suspended particles in the dry season. In contrast, TDP flux showed additive effect relative to water runoff in July 2015 due to exogenous water inputs with high TDP concentrations in the wet season. Both sand and total particulate phosphorus (TPP) presence in the water showed obvious sediment and retention characteristics during the two periods. The TPP flux presented an additive effect relative to sand discharge, meaning that the major transformation direction of phosphorus fractions was from TDP to TPP. The subsection between Qingxichang and Wanzhou was the main retention area of water, sand, and phosphorus in the TGR, which can be associated with the enhancement of phosphorus adsorption capacity caused by particle size reduction of suspended particles in the subsection.

To elucidate succession pattern of phytoplankton in the Daning River and its driving factors, multivariate statistical analysis was conducted. By using the monitoring data in different seasons of Daning river during April 2012 to January 2013, this paper analyzed the succession pattern of phytoplankton in the Daning River and its driving factors in typical tributaries of river-style reservoirs. According to the characteristics of water level, the operational period of the TGR was classified into following four stages:stage Ⅰ (pre-November-April), stage Ⅱ (May-July), stage Ⅲ (July-September) and stage Ⅳ (September-November). ① The results indicated that the values of Chlorophyll-a concentrations and algal density showed similar seasonal variations, with the highest values occurring in stage Ⅲ, followed by stages Ⅳ, Ⅱ and Ⅰ. Succession of C-R-S growth strategies was the same generally:CR-R type dominated in stage Ⅰ, CS, CR/CS and R-CR dominated in stage Ⅱ, Ⅲ and Ⅳ, respectively. ② The mean values of Margalef index and Pielou index in stage Ⅳ and Ⅲ were significantly greater than those in stage Ⅱ and Ⅰ; the value of Shannon-waver index showed that the highest value in stage Ⅲ, followed in a descending order by stage Ⅰ,Ⅱ and Ⅳ; the successional rate had the highest value in stage Ⅳ, followed in descending order by stage Ⅲ, Ⅰ and Ⅱ. ③ The results of Correlation analysis suggested that no significant relationships were observed between the environmental parameters and phytoplankton abundance in stage Ⅰ. The results indicated that relative water column stability(RWCS), index of feasible energy for phytoplankton ( E t ) and index of feasible energy (Ef * ) were key regulatory factors for phytoplankton community in stage Ⅰ. The results indicated that E t , Ef * and total phosphorus (TP) were key regulatory factors for phytoplankton abundance in stage Ⅱ. The results of the redundancy analysis (RDA) suggested that RWCS, TP and the ratio of euphotic depth[ D eu ( λ PAR )] to mixing depth ( D mix )[ D eu ( λ PAR )/ D mix ] were key regulatory factors for phytoplankton community composition in stage Ⅱ. The results indicated that Ef * and TP were key regulatory factors for phytoplankton abundance in stage Ⅲ. The results of the RDA suggested that[ D eu ( λ PAR )/ D mix ], E t , Ef * and TP were key regulatory factors for phytoplankton community composition in stage Ⅲ. The results indicated that TP was key regulatory factor for phytoplankton abundance in stage Ⅳ. The results of the RDA suggested that[ D eu ( λ PAR )/ D mix ] was key regulatory factor for phytoplankton community composition in stage Ⅳ.

In China, trace metals (such as dissolved Cu, Zn, Pb, Cd, and Cr) are the routine mandatory monitoring indicators in existing Freshwater Quality Standard (FWQS, 2002) and Seawater Quality Standard (SWQS, 1997). Using Daliao River estuary as an example, we tried to research the general response patterns of these metals in estuarine system. Firstly, we determined the location of FSI (freshwater-seawater interface) and TCI (tidal currents interface), which were based on biological, chemical and geographic similarities by descriptive and quantitative methods, respectively. Secondly, two hypotheses were proposed to explain the difference based on distribution coefficient K d along salinity and SS (suspended solids) gradient, these results revealed that the indicators for As, Cd and Cr may be prone to be affected by salinity, and the ones in the second pattern may be more sensitive to SS. Finally, we classified the response behaviors into two patterns based on the changing trends along the distance and magnitudes affected by the FSI and TCI: 1the obvious boundary break point from FSI for As, Cd and Cr; 2 the boundary zones from TCI for Zn, Cu, Pb and Ni. The partitioning behaviors showed similar changing trends at particle and sediment phases, especially for particle phase, depending on the concentration of SS along the salinity. The difference between general behaviors for the two patterns mainly existed at water phase. In general, this paper highlighted the need to consider the background difference of trace metals and identified the sensitive indicators controlled by different environment factors (such as salinity and SS) based on the native estuarine characteristics. Our work will assist the implementation of updating the current water quality standards in China.

The water samples of the Tien Lake were collected for the three-dimensional fluorescence spectrum detected. And parallel factor analysis (PARAFAC) and principal component analysis (PCA) were used for the spectra analyzing to know the main factor and relative contribution of the chromophoric dissolved organic matter (CDOM). PARAFAC decomposed CDOM into four components, the humic-like: C1 (240, 415), C3 (265, 525), C4 (255, 505) and the protein-like: C2(230/280, 330). The fluorescence intensity of CDOM components was high in north and estuary of the lake, but low in the other region. All the four components show significant positive correlations (p < 0.01), this result means they may have the same sources. Principal component analysis shows that these four components of the Tien Lake are all from terrestrial organic matter, meanwhile its DTN, DTP, DON may also come with the terrestrial substance. These components of Tien Lake can well be connected with dissolved nutrient salts by nonlinear multiple regression, which means we can use the three-dimensional fluorescence spectrum results of CDOM to indicate the eutrophication degree of Tien Lake.

The aim of this article is to explore the pollution level and contamination degree of heavy metals in the upper reaches of Hunhe River (Qingyuan Section). The contents and temporal-spatial distribution of Fe, Mn, Cu, Zn, Cd and As in surface water and surface sediments from the upper reaches of Hunhe River were analyzed respectively. The integrated pollution index and geoaccumulation index were used to evaluate the contamination degree of Cu, Zn, Cd and As. The results indicated that the contents of Mn, Cu, Zn, Cd and As in surface water from the upper reaches of Hunhe River during the wet season were higher than those during normal and dry season. Similar patterns of spatial distribution of Fe, Mn, Cu, Zn and Cd in surface water were observed, which showed that the highest content appeared at H7 station. The influence of pH, DO and hardness in the upper reaches of Hunhe River during the wet, normal and dry season on the distribution of heavy metal contents in surface water varied. Significant positive correlations were found among these elements in surface water, which implied that these elements probably had common pollution sources. The contents of Cu, Zn, Cd and Fe in surface sediments from the upper reaches of Hunhe River during the dry season were higher than those during the wet and normal season. Similar patterns of spatial distribution of Mn, Cu, Zn, As and Cd in surface sediments were also observed, which showed that the highest metal contents appeared in the midway of Hunhe River. The integrated pollution index assessment showed that the water quality in the upper reaches of Hunhe River was good except for individual stations, and that Cu, Cd and As were the main pollution elements in surface sediments in the upper reaches of Hunhe River.

Twenty-six surface soil samples collected in Danjiangkou Reservoir were analyzed for organochlorine pesticides (OCPs) residues by GC-MS. The distribution characteristics, compositions and origin of OCPs were discussed. Pollution level and potential ecological risks of OCPs were also evaluated. The results showed that the concentration rang of total OCPs in soil was nd-249.37 ng x g(-1) (with a mean of 24.82 ng x g(-1)). The recent occurrence levels in soil were nd-69.68 ng x g(-1) for HCHs and nd-104.53 ng x g for DDTs. DDTs concentrations in soil were higher than those of HCHs. The OCPs residues in soil were mainly originated from the early residues, atmospheric deposition and recent input of OCPs components. The correlation between OCPs contents and organic matter contents in soil was not significant, indicating that the contents of OCPs in soil were also affected by other factors. Compared with other soil samples from different regions, the contents of OCPs in soil of relocation areas of the Danjiangkou Reservoir were at medium-low level. The study suggested that the OCPs in soil of relocation areas of the Danjiangkou Reservoir are in a state of low danger, whereas OCPs still display risks locally in some places.

In order to provide basic data for algal bloom warning system, the study on temporal-spatial distribution of algal cells was carried out in Daning River of Three Gorges form April to September, 2011. The results of temporal distribution were as follows: the dominant algal species were blue algal, green algal and diatom. During the test, the density proportion of blue algae increased continuously, the density proportion of diatom decreased, while the density proportion of green algae did not change significantly. The results of spatial distribution were as follows: algal density was extremely significantly correlated with water temperature and chlorophyll a (Chl a), the correlation coefficient were 0.97 and 0.95, respectively; algal density was significantly correlated with light intensity (LI), dissolved oxygen (DO), pH and dissoluble total phosphorus (DTP), the correlation coefficient were 0.87, 0.83, 082 and 0.82, respectively; the algal density in 0 m of Caziba was higher than those in other water depths, and in Baishuihe the highest algal density occurred at 2.0 m water depth in June and July, in Shuanglong most algal cells were found in 0 m and 2.0 m in July, August and September, in Dachang algal density in different water depth did not change significantly during the test; the proportion of different algal species in vertical direction was different in the test, probably because different algal species fitted different environments.

Twenty-nine surface sediment samples were collected from Hengyang sections of Xiangjiang River to detect concentrations and speciation percentage of heavy metals (Cu, Pb, Zn and Cd) in sediment and pore water. According to the Equilibrium Partitioning (EqP) approach, the sediment-water partition coefficients (Kp) of heavy metals in Hengyang section of Xiang River were revised by the bioavailable fraction, and the USEPA Criterion Continuous Concentration(CCC) which was based on aquatic toxicity of the final chronic level and GB3838-2002 I ,water quality standard were introduced to establish two types of sediment quality criteria (SQC) for heavy metals (Cu, Pb, Zn and Cd) in Hengyang section of Xiangjiang River for comparison. The better SQCs (base on CCC) of Cu, Pb, Zn and Cd were 64.62, 55.57, 1 360.40 and 2.34 microg x g(-1), and they can protect benthic organism from being poisoned by heavy metal chronic aquatic toxicity. The ratio of heavy metal concentration and SQC was used to assess sediment quality in Hengyang section of Xiangjiang River, the result showed that concentration levels of Cd, Pb in sediment in Hengyang section of Xiangjiang River had strong chronic toxic effects, Cd pollution could not be ignored.

The present study evaluated the potential ecological risk of organotin compounds (OTs) to wild veined rapa whelk (Rapana Venosa) population in Bohai Bay. The results showed that the imposex rate was 12.5% and 6.48% in Dashentang and Nanpaihe coastal areas, with relative penis size index of 9.61 and 12.45, respectively. The concentrations of butyltin compounds and phenyltin compounds were 39.04 ng x g(-1) dw and 46.48 ng x g(-1) dw in muscle tissues, and 32.09 ng x g(-1) dw and 109.03 ng x g(-1) dw in digest gland, respectively. Based on TBT levels in the muscles of all samples, a risk quotient of 0.024 was derived, indicating certain risk of OTs at current levels to wild veined rapa whelk populations in Bohai Bay.

The aim of this article is to explore the pollution level and potential ecological risk of heavy metals in soil of the relocation areas from the Danjiangkou Reservoir. The contents and spatial distribution of Cd, Pb, Cu, Zn, Cr and As in soil of the relocation areas from the Danjiangkou Reservoir were analyzed. The integrated pollution index and potential ecological risk index were used to evaluate the contamination degree and potential ecological risk of these elements. The results indicated that the average contents of Cd, Pb, Cu, Zn, Cr and As in the samples were 0.61, 23.11, 58.25, 22.65, 58.99 and 16.95 mg x kg(-1), respectively. Compared with the background value of soils from Henan province, all these 6 elements except Zn were enriched to some extent, especially Cd. Similar patterns were observed for the spatial distribution of Cu, Zn, and Pb. Compared with the contents of heavy metals in surface sediments of the typical domestic reservoirs, Cd and As in soil of the relocation areas from the Danjiangkou Reservoir were heavily accumulated. The correlation analysis showed that there were significant positive correlations among Pb, Cu, and Zn. And there was also significant positive correlation between Cr and Pb. In contrast, negative correlation was found between Cr and As. To sum up, the comprehensive assessment results showed that Cd was the primary element with high ecological risk.

To explore the condition of heavy metal pollution of Taihu Lake, the contents and spatial distribution of Cd, Pb, Cu and Zn in surface sediments of Taihu Lake were studied respectively. BCR three stages sequential extraction procedure was applied to investigate the speciation and contents of four heavy metals (Cd, Pb, Cu, Zn) in the surface sediments of Taihu Lake. And the bioavailability of these four heavy metals was also determined preliminarily. At last the contamination and potential ecological risk of these elements were evaluated by potential ecological risk index. The results indicated that all 4 elements in surface sediments of Taihu Lake were enriched to some extent, especially Cd. All of these four metals existed mainly in extractable fractions which included weak soluble fraction, reducible fraction and oxidisable fraction, and the bioavailability of four metals varied with a descending order of Cd > Pb > Zn > Cu. The comprehensive assessment results showed that Cd was the primary element with high ecological risk while Pb, Cu, Zn were slight, and the order of ecological risk was Cd > Pb > Cu > Zn.

To support the basic data for forecast of algal blooms, circadian vertical migration experiment was carried out in the Daning River Bay of the Three Gorges Reservoir in July, 2011. The results were as follows: in this period, different algal species were found in the Daning River Bay, including cyanobacteria, green algae, dinoflagellates and diatoms etc; the distribution of algal cells was uneven, 72.5%-76.2% of algal cells aggregated at 0.5-4.0 m water depths from 10:00 AM to 10:00 AM next day, but 7.5%-16.3% of algal cells aggregated at 0-0.5 m. Morisita's indexes (MI) of algal cells were from 1.41 to 1.97 in day time, and from 1.17 to 1.55 at night. Morisita's indexes of chlorophyll a(Chla)were from 1.31 to 1.59 in day time, and from 1.17 to 1.39 at night. The vertical migration also occurred at 0.5-4.0 m water depths. The algal density was not significantly related with the concentrations of nutrient except that of dissolved total phosphorus (DTP) (r = 0.89). The algal density was also influenced by water temperature (WT), pH and specific conductance (SPC), and the correlation coefficients were 0.96, 0.97 and -0.99, respectively.

We evaluated 4-year data set to assess the trophic state and limiting factors of the Three Gorges Reservoir (TGR) during the experimental impounding period (September 2005 to September 2007) and the normal operating period (September 2008 to September 2010). The results indicated that there had been appeared new characteristics in spatial and temporal distribution of trophic state indices after impoundment. The trophic state indices (TSI(TP)) showed increased trend after the TGR impoundment during the study area, but TSI(TN) and TSI(SD) had no significant changes after the TGR impoundment. The values of TSI(CHL) showed increased trend after the TGR impoundment in S1, and the values of TSI(CHL) did not show obvious changes in S2, S3 and S4 after the TGR impoundment. The values of TSI(TN), TSI(TP) and TSI(SD) show similar spatial variances with the highest value in S4, followed in a descending order by S3, S2 and S1. TSI(CHL) in the S2 and S3 were higher than that in S1 and S4. According to the characteristics of water level, the operational period of the TGR classified into following four stages: stage I (pre-November-April), stage II (May-July), stage III (July-September) and stage IV (September-November). The values of TSI(TN) and TSI(TP) in the Daning River and the TGR mainstream showed similar seasonal variances with the highest value in the stage II and III, followed in a descending order by stage I and IV. The values of TSI(CHL) varied substantially among the four stages, with the highest value in stage III, followed by stage II, IV and I. The trophic state indices differences were getting smaller between the four stages after the TGR impoundment. Using Carlson's two-dimensional approach, deviations of the TSI(S) indicated that factors other than phosphorous and nitrogen limited algal growth and that nonalgal particles affected light attenuation. These findings were further supported by the significant correlation among the values of TSI and hydrological factors.

In order to explore the potential ecological risk of heavy metals in Three Gorges Reservoir areas, the present study analyzed the heavy metals in sediments and wild crucain carp from Daning River and Modaoxi River which are two typical tributaries, and then the potential risk was evaluated using potential ecological risk index for sediments and comprehensive pollution index for fish, respectively. The results showed that concentrations of Zn and Cr were higher (Daning River: 78.31 and 83.98 mg x kg(-1); Modaoxi River: 99.03 and 94.20 mg x kg(-1)), while Cd was the lowest (Daning River: 0.62 mg x kg(-1); Modaoxi River: 0.75 mg x kg(-1)). Moreover, an obvious increasing trend of these elements was observed in these tributaries from upstream to downstream. For the wild crucain carp, the lowest concentrations of these elements were detected in muscles, and the highest concentrations were in the intestinal. However, no obvious increasing trend of these elements was observed from upstream to downstream. The potential ecological risk in sediments showed a high risk, while no risk was observed in fish.

To explore the trend of the changes in ecological environment caused by reclamation and the situation of heavy metal pollution in Bohai Bay, the contents and spatial distribution of Cd, Pb, Cu and Zn in the surface sediments of Bohai Bay were collected in 2003 and 2011 and studied. The BCR three-stage sequential extraction procedure was applied to investigate the speciation and contents of four heavy metals (Cd, Pb, Cu and Zn) in the surface sediments of Bohai Bay in 2011. The bioavailability of these four heavy metals was also determined preliminarily. Besides, the pollution level and potential ecological risk of these elements were evaluated using the potential ecological risk index and sediment enrichment factors. The results indicated that the contents of Cu, Cd and Pb in the surface sediments of Bohai Bay in 2011 were higher than those in 2003, indicating an increased level of heavy metal pollution. The distribution of Cu, Zn and Cd showed essentially the same pattern, all with higher content in the central area of Bohai Bay. High content of Pb was found in the estuarine, the central and southern area of Bohai Bay. There were significant positive correlations among these four elements. The results indicated that these four elements probably had the same pollution source. Cu, Zn and Cd were mainly found in the residual fractions, whereas Pb was mainly found in the reducible fractions. The bioavailability of these four metals is listed here in descending order: Cd > Pb > Cu > Zn. The comprehensive assessment results showed that Cd was the primary element with high ecological risk while Cu, Zn, Pb were the minor ones with relatively low risk.