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991.
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对"十一五"江苏省地面水域水质状况及时空分布特征进行了全面分析,结果表明,"十一五"期间,江苏省地表水水质总体处于轻度污染状态,河流水质呈现较为明显的有机污染特征,影响水质的主要污染物为石油类、氨氮、五日生化需氧量等;主要湖库氮、磷污染较为突出,湖库富营养化问题尚未得到有效控制。水质污染总体表现为枯水期>平水期>丰水期。受社会经济发展影响,地表水质呈现一定的区域流域差异,经济较发达地区水质污染也相对较重。总体来看,"十一五"期间由于加大了产业结构调整与污染防治力度,江苏省地面水域水质污染状况有所改善。 相似文献
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Modeling the Effects of Extreme Drought on Pollutant Transport Processes in the Yangtze River Estuary 下载免费PDF全文
Ye Yang Xiaofeng Chen Yangyang Li Ming Xiong Zhenyao Shen 《Journal of the American Water Resources Association》2015,51(3):624-636
Water resources in the Yangtze River Estuary (YRE), which is the vital water supply for Shanghai, decreased by approximately 2.45 Gm3 in 2006, the second‐worst recorded drought year. A numerical model was developed to investigate the effects of this extreme drought on pollutant transport processes in the YRE. The model was calibrated against observations and displayed good agreement. Residence time, a critical hydrodynamic indicator, was implemented to indicate pollutant transport processes. Numerical experiments were conducted to examine the possibly drought‐induced influences. The model results demonstrated that the influences on pollutant transport processes varied spatially and temporally, and these influences could partly explain the observed temporal and spatial variations of total nitrate in 2006. The area most susceptible to drought is in the north branch with 2‐11 days' extension of residence time. As the drought occurred in both the high and normal water periods, its influences were more significant during the normal water period with saltwater intrusion into the north branch. The drought also introduced a pollutant transport lag in timescale of approximately five days by diminishing the seaward advection flux with freshwater discharge. In 2006, the magnified tidal influence during the drought contributed more than usual to structuring pollutant transport, as the pollutant transport processes were intensely associated with tidal flow and tidal cycle. 相似文献
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Shen S.Yang C.Cheng S. 《应用与环境生物学报》2015,(1):80-87
Microbes play an important role in material circulation and pollutant release in urban sediments, and its community structure can provide an important basis for evaluating the pollution load and ecosystem health of an urban river. In this study, bacterial communities in sediments from different locations of Tangxi River in Anhui Province were analyzed and compared, with an objective of evaluating the effects of aquatic environment on spatial characteristics of bacterial communities and the feasibility of using bacterial community composition as an indicator of urban river health. PCR-DGGE was applied to analyze the bacterial communities; fifteen major bands of 16S rDNA genes fragments from DGGE profiles of sediment samples were further eluted from gel, reamplified and sequenced. The sequences of these fragments were compared with the database in GenBank (NCBI). The collected samples were clustered based on UPGM Aanalysis. In addition, relationships between bacterial communities and environmental factors were analyzed by Monte Carlo test and redundancy analysis (RDA). The DGGE profiles indicated that upstream surface sediments had about 30 bands, but the differences in brightness were not significant. Although midstream surface sediments had only 18 bands on average, the brightness of some bands was relatively high, indicating that some dominant species of bacteria existed in these sediments. The amounts of bands in downstream sediments were between those of upstream and midstream, with some bands of high brightness. The NCBI comparison results showed that ten sequences shared 98-100% homology with known sequences, one with 97%, and the other four with uncultured bacteria. Shannon index (H) of bacterial diversity from upstream surface sediments was 3.31 on average, which was significantly (P < 0.05) higher than that of midstream surface sediments, and slightly higher than that of downstream surface sediments. UPGMA results showed both the distribution of bacteria communities and the diversity were strongly related with the sampling locations (Eigenvalue = 0.188, P = 0.134). Monte Carlo test and RDA analysis showed that the ion exchangeable form of nitrogen (IEF-N) was the main factor influencing the spatial characteristics of bacterial communities in the sediments. The aquatic plants had a significant effect on the richness of bacterial communities in the sediments, and the effectiveness of plant species was more notable than that of the vegetation coverage. The above results indicated that bacterial community structure and diversity in the surface sediments can well reflect the degree of urbanization development and effectiveness of ecological restoration in Tangxi River region. 相似文献
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Pot and field experiments were conducted to investigate the effects of water regimes on the speciation and accumulation of arsenic (As) and cadmium (Cd) in Brazilian upland rice growing in soils polluted with both As and Cd. In the pot experiment constant and intermittent flooding treatments gave 3-16 times higher As concentrations in soil solution than did aerobic conditions but Cd showed the opposite trend. Compared to arsenate, there were more marked changes in the arsenite concentrations in the soil solution as water management shifted, and therefore arsenite concentrations dominated the As speciation and bioavailability in the soil. In the field experiment As concentrations in the rice grains increased from0.14 to 0.21 mg/kg while Cd concentrations decreased from 0.21 to 0.02 mg/kg with increasing irrigation ranging from aerobic to constantly flooding conditions. Among the various water regimes the conventional irrigation treatment produced the highest rice grain yield of 6.29 tons/ha. The As speciation analysis reveals that the accumulation of dimethylarsinic acid (from 11.3% to 61.7%) made a greater contribution to the increase in total As in brown rice in the intermittent and constant flooding treatments compared to the intermittent-aerobic treatment. Thus, water management exerted opposite effects on Cd and As speciation and bioavailability in the soil and consequently on their accumulation in the upland rice. Special care is required when irrigation regime methods are employed to mitigate the accumulation of metal(loid)s in the grain of rice grown in soils polluted with both As and Cd. 相似文献