“十一五”期间新疆湖库水质变化趋势及原因分析

通过对新疆湖库“十一五”期间水质变化趋势的分析,结合五年间地方政府采取的综合污染防治措施,分析了水质变化的原因,并提出相应对策建议,以便更好地推进新疆湖库水污染防治工作。     

Effects of seasonal climatic variability on several toxic contaminants in urban lakes: Implications for the impacts of climate change

Climate change is supposed to have influences on water quality and ecosystem. However, only few studies have assessed the effect of climate change on environmental toxic contaminants in urban lakes. In this research, response of several toxic contaminants in twelve urban lakes in Beijing, China, to the seasonal variations in climatic factors was studied. Fluorides, volatile phenols, arsenic, selenium, and other water quality parameters were analyzed monthly from2009 to 2012. Multivariate statistical methods including principle component analysis, cluster analysis, and multiple regression analysis were performed to study the relationship between contaminants and climatic factors including temperature, precipitation, wind speed, and sunshine duration. Fluoride and arsenic concentrations in most urban lakes exhibited a significant positive correlation with temperature/precipitation, which is mainly caused by rainfall induced diffuse pollution. A negative correlation was observed between volatile phenols and temperature/precipitation, and this could be explained by their enhanced volatilization and biodegradation rates caused by higher temperature. Selenium did not show a significant response to climatic factor variations, which was attributed to low selenium contents in the lakes and soils. Moreover, the response degrees of contaminants to climatic variations differ among lakes with different contamination levels. On average, temperature/precipitation contributed to 8%, 15%, and 12% of the variations in volatile phenols, arsenic, and fluorides,respectively. Beijing is undergoing increased temperature and heavy rainfall frequency during the past five decades. This study suggests that water quality related to fluoride and arsenic concentrations of most urban lakes in Beijing is becoming worse under this climate change trend.     

杭州西湖“香灰土”沉积物轻、重有机质组成特征及其环境意义

为探索城市浅水湖泊高有机质含量沉积物中有机质污染特征及其与氮、磷等营养元素的关系,调查了西湖8个湖区沉积物柱状样不同深度泥层有机质含量及其轻、重组分和氮磷污染特征,通过与国内相关湖泊有机质组分的比较,定量刻画了西湖"香灰土"沉积物的有机质特征.结果表明,西湖沉积物属典型高有机质含量底质,不同湖区底泥有机质含量平均值为28~251 g·kg-1;不同湖区沉积物有机质含量差别很大,引水入口湖区比其他湖区的有机质含量明显偏低;垂向上,大多湖区有机质含量随深度增加而增加,反映出有机质在西湖丰富的沉积历史.有机质轻/重组分离研究表明,西湖沉积物中轻组有机质含量为0.57~9.17 g·kg-1,平均占总有机质的2.83%,重组含量为5.35~347.41 g·kg-1,平均占总有机质的90%;与玄武湖、月湖、太湖、白洋淀等浅水湖泊相比,西湖底泥轻组有机质含量与之相当,但重组有机质含量明显偏高,反映出西湖作为历史悠久的城市湖泊,有机质污染负荷高,底泥腐殖化程度高.西湖底泥轻组有机质与总磷、总氮显著相关,而重组有机质含量仅与总氮含量显著相关,与磷没有相关性,表明轻组有机质对氮、磷内源释放潜力具有较大的影响.研究表明,西湖"香灰土"型沉积物有机质含量高、重组有机质比例高,对内源氮磷释放的缓冲能力强,在西湖营养盐内源负荷控制及水体富营养化治理中应予以充分考虑.     

Modeling the Fate and Transport of Plunging Inflows to Onondaga Lake

The transport and fate of two plunging tributaries, Onondaga and Ninemile Creeks, in Onondaga Lake, New York, are quantified based on application of hydrodynamic/transport models. Short‐term transport is simulated with a three‐dimensional Estuary Lake and Coastal Ocean Model (ELCOM), while the longer term fate is represented by a previously validated one‐dimensional model (UFILS4). The validation of ELCOM for the vertical distribution of tributary inflow into the lake's water column is demonstrated for four dye tracer experiments. The models are applied for three years to represent the dynamics of transport and fate for the two tributaries, with ELCOM predictions serving as input for UFILS4. The models together quantify the distribution of these inflows between the upper mixed layer (UML) and stratified depths, and the subsequent transport from stratified depths to the UML by vertical mixing. Substantial short‐term variations are predicted for both tributaries in response to variability in hydrology and weather. Increased inflow to the UML is predicted for high runoff periods. The fraction of Ninemile Creek's inflow directly entering the UML is predicted to be 50% greater than for Onondaga Creek due to Ninemile's lower negative buoyancy. The plunging phenomenon has important water quality implications, by reducing the effective loading to the UML, particularly for constituents with large rates of loss/transformation relative to the rate of vertical transport from stratified depths.     

Geospatial and Temporal Analysis of a 20‐Year Record of Landsat‐Based Water Clarity in Minnesota's 10,000 Lakes

A large 20‐year database on water clarity for all Minnesota lakes ≥8 ha was analyzed statistically for spatial distributions, temporal trends, and relationships with in‐lake and watershed factors that potentially affect lake clarity. The database includes Landsat‐based water clarity estimates expressed in terms of Secchi depth (SD_Landsat), an integrative measure of water quality, for more than 10,500 lakes for time periods centered around 1985, 1990, 1995, 2000, and 2005. Minnesota lake clarity is lower (more turbid) in the south and southwest and clearer in the north and northeast; this pattern is evident at the levels of individual lakes and ecoregions. Temporal trends in clarity were detected in ~11% of the lakes: 4.6% had improving clarity and 6.2% had decreasing clarity. Ecoregions in southern and western Minnesota, where agriculture is the predominant land use, had higher percentages of lakes with decreasing clarity than the rest of the state, and small and shallow lakes had higher percentages of decreasing clarity trends than large and deep lakes. The mean SD_Landsat statewide remained stable from 1985 to 2005 but decreased in ecoregions dominated by agricultural land use. Deep lakes had higher clarity than shallow lakes statewide and for lakes grouped by land cover. SD_Landsat decreased as the percentage of agriculture and/or urban area increased at county and catchment levels and it increased with increasing forested land.     

Managing mercury in the great lakes: an analytical review of abatement policies

Mercury, a toxic metal known to have several deleterious affects on human health, has been one of the principal contaminants of concern in the Great Lakes basin. There are numerous anthropogenic sources of mercury to the Great Lakes area. Combustion of coal, smelting of non ferrous metals, and incineration of municipal and medical waste are major sources of mercury emissions in the region. In addition to North American anthropogenic emissions, global atmospheric emissions also significantly contribute to the deposition of mercury in the Great Lakes basin. Both the USA and Canada have agreed to reduce human exposure to mercury in the Great Lakes basin and have significantly curtailed mercury load to this region through individual and joint efforts. However, many important mercury sources, such as coal-fired power plants, still exist in the vicinity of the Great Lakes. More serious actions to drastically reduce mercury sources by employing alternative energy sources, restricting mercury trade and banning various mercury containing consumer products, such as dental amalgam are as essential as cleaning up the historical deposits of mercury in the basin. A strong political will and mass momentum are crucial for efficient mercury management. International cooperation is equally important. In the present paper, we have analyzed existing policies in respective jurisdictions to reduce mercury concentration in the Great Lakes environment. A brief review of the sources, occurrence in the Great Lakes, and the health effects of mercury is also included.     

洮滆水系湖库富营养化生态风险的特点与比较

茅东水库、长荡湖、涌湖、太湖竺山湾是洮滆水系从上游到下游排列的4大典型湖库,2008年的监测分析表明,氮、磷是该水系湖库富营养化的主要污染因子,并沿流域呈加剧趋势,上下游TP质量浓度为0.081～0.296 mg/L,差异小,而TN质量浓度为0.314～5.67 mg/L,差异大,长荡湖到涌湖是洮滆水系首要污染物TN快...     

基于MODIS的西藏典型湖泊叶绿素a浓度反演

叶绿素a浓度是反映湖泊富营养化状态的一个重要参数。以MODIS L1B数据为基础，结合叶绿素a浓度实测数据，基于经验分析法实现了西藏典型湖泊叶绿素a浓度反演研究，并探索了西藏典型湖泊2019年春、夏、秋季叶绿素a浓度的时空变化特征。首先，利用叶绿素a浓度实测数据和MODIS L1B影像不同波段的反射率值进行组合试验，选择最佳波段组合建立模型；其次，分别选用2015年、2017年叶绿素a浓度实测值和反演值对模型进行对比验证；最后，利用叶绿素a浓度反演模型对西藏典型湖泊2019年春、夏、秋季叶绿素a浓度的时空变化特征进行分析。结果表明：在空间尺度上，西藏典型湖泊叶绿素a浓度整体上呈现出周围高、中部低的分布特征，且湖岸水体叶绿素a浓度变化较大；在季节尺度上，不同湖泊叶绿素a浓度的季节变化存在较大差异，格仁错和色林错的季节变化幅度较大，纳木错、塔若错和羊卓雍错的季节变化幅度较小。     

山水林田湖草生态保护修复江苏实践与思考

“实施山水林田湖草生态保护和修复工程，全面提升自然生态系统稳定性和生态服务功能”是习近平生态文明思想的重要创新成果，为开展生态环境保护修复工作提供了重要指引和根本遵循。2019年以来，江苏省开展山水林田湖草生态保护修复省级试点工程共5类59个工程项目。在总结了试点地区工作经验做法的基础上，针对存在的生态保护修复和绿色发展协同理念认识不足、生态修复保护整体性和系统性不够、生态修复经验总结及全周期管理有待加强、打破界限的体制机制改革创新亟需完善等问题及难点，提出了相应的工作政策建议，以期打造全国生态保护修复的江苏样板。