Land-cover changes in an urban lake watershed in a mega-city, Central China

Urbanization can exert a profound influence on land covers and landscape characteristics. In this study, we characterize the impact of urbanization on land cover and lacustrine landscape and their consequences in a large urban lake watershed, Donghu Lake watershed (the largest urban lake in China), Central China, by using Landsat TM satellite images of three periods of 1987, 1993 and 1999 and ground-based information. We grouped the land covers into six categories: water body, vegetable land, forested land, shrub-grass land, open area and urban land, and calculated patch-related landscape indices to analyze the effects of urbanization on landscape features. We overlaid the land cover maps of the three periods to track the land cover change processes. The results indicated that urban land continuously expanded from 9.1% of the total watershed area in 1987, to 19.4% in 1993, and to 29.6% in 1999. The vegetable land increased from 7.0% in 1987, 11.9% in 1993, to 13.9% in 1999 to sustain the demands of vegetable for increased urban population. Concurrently, continuous reduction of other land cover types occurred between 1987 and 1999: water body decreased from 30.4% to 23.8%, and forested land from 33.6% to 24.3%. We found that the expansion of urban land has at least in part caused a decrease in relatively wild habitats, such as urban forest and lake water area. These alterations had resulted in significant negative environmental consequences, including decline of lakes, deterioration of water and air quality, and loss of biodiversity.     

PCB Levels and Trends Within the Detroit River-Western Lake Erie Basin: A Historical Perspective of Ecosystem Monitoring

An international workshop held in the spring of 2002 convened a group of technical experts to address monitoring, modeling, and management of PCBs within the Detroit River-Western Lake Erie basin. Participants shared and discussed a diverse set of research data bases pertaining to PCB levels within the region, discussed observed changes within different components of the local ecosystem, and identified several primary issues impacting future PCB management strategies. Results presented at the workshop indicate dramatic reductions in PCB contamination levels have been observed in much of study area between the late 1970s and mid-1990s. Estimates of loadings attributable to water and atmospheric sources have generally declined, as have PCB concentrations in herring gull eggs, smelt and walleye. Nevertheless, additional improvements have not been observed during recent years and elevated contamination levels remain a concern within local hot spots, particularly in the lower Detroit River and Trenton Channel. A primary recommendation broadly supported by workshop participants is the need to maintain, support, and coordinate a comprehensive ecosystem monitoring program for the Detroit River-Western Lake Erie basin, one that incorporates both near-field and far-field monitoring elements. Such a program is crucial to provide necessary data in support of understanding ecosystem trends, calculating annual mass loadings to the system, assessing impacts of remediation actions, developing improved modeling frameworks, and formulating cost-effective management strategies for the future.     

The Status of Pesticide Residues in the Drinking Water Sources in Meiliangwan Bay, Taihu Lake of China

The study was carried out to assess the levels of pesticide residues in the water of Meiliangwan Bay, Taihu Lake of China. The most commonly employed organochlorine pesticides (OCPs), organophosphorus pesticides (OPPs) and herbicide atrazine were analyzed. The water samples were collected seasonally from Meiliangwan Bay within a period of one year. The pesticides were analyzed by gas chromatography (GC) with μECD or NPD after solid-phase extraction (SPE), which was confirmed by GC with an ion trap mass spectrometry (MS). The mean concentrations were 1.98 ng/l for lindane, 0.378 ng/l for heptachlor epoxide, 0.367 ng/l for p,p′-DDE, 0.496 ng/l for p,p′-DDD, 1.06 ng/l for p,p′-DDT and 51.6 ng/l for dichlorvos, 39.0 ng/l for demeton, 346 ng/l for dimethoate, 4.12 ng/l for methyl parathion, 11.6 ng/l for malathion, 2.17 ng/l for parathion and 217 ng/l for atrazine. Generally, low concentrations of OCP were found, whereas the concentrations of the OPPs and atrazine in the water of Taihu Lake were relatively high. Heptachlor epoxide and lindane were the two most commonly encountered OCPs while dichlorvos, demeton and dimethoate were found to have much higher concentrations and occurrences than other OPPs.     

合肥市环巢湖地区种植业面源污染监测与评价

通过2016—2018年在合肥市环巢湖5个县区主要农田周边沟渠中采集水样,监测农田氮磷流失浓度,并评价该区域种植业面源污染状况.结果表明,这3年该区域种植业TN、TP流失的平均质量浓度分别为3.48 mg/L、0.602 mg/L,均高于地表水Ⅴ类水质标准.2016年与2017年TN、TP浓度差异不大,2018年较前两...     

稀土元素对富营养化水体中藻类增长的影响

利用藻类生长潜力测试方法,在太湖五里湖区水样中分别添加不同浓度轻,中、重３种稀土元素、Ｇｄ（Ⅲ）、Ｙ（Ⅲ）与３种稀土混合物,研究稀土元素对富营养化水体中藻类增长的影响。     

城市河流与湖库中痕量有机污染物的研究

通过采用ＧＤＸ－５０２富集,ＧＣ－ＭＳ分析,对城市河流、湖库中的痕量有机污染物进行分析,共检出５８种有机污染物,其中含有多种美国ＥＰＡ公布的重点污染物,从而为痕量有机污染物的研究建立了灵敏度高,分辨率好的测试方法。     

基于灰色关联分析法的林甸县污水泡中重金属和毒性元素污染情况评价

为了探讨人类活动对水体重金属和毒性元素含量的影响,测量了污水泡8个样点的Mn、Fe、Cu、Zn、Cd、Pb等重金属和As、Se等毒性元素质量浓度。在综合考虑各种水质评价方法的基础上,采用灰色关联分析方法对水中重金属和毒性元素污染情况进行了评价。结果显示,水中重金属和毒性元素污染并不严重,8个采样点中有7个样点符合Ⅰ类水体标准,1个样点为Ⅱ类水体。其原因是污水泡附近没有工业区,排出的污水属生活污水,污染并非重金属和毒性元素造成。     

东平湖高浓度污染水团的发生规律及监测研究

通过对东平湖污染水团的监测和分析 ,研究了污染水团生成的原因及规律 ,并对污染水团对水产养殖的危害做了调查。对防治污染水团的生成及提高东平湖的水质进行了探讨。     

大通湖主要污染物浓度空间分布及其污染来源解析

为了解大通湖主要污染物TN、TP和NH3-N的空间分布特征及污染来源,于2017年9月对大通湖及周边河流进行采样分析。结果表明,大通湖周边入湖河流的ρ(TN)为0. 74～2. 18 mg/L,ρ(NH3-N)为0. 094～0. 874 mg/L,ρ(TP)为0. 02～0. 243 mg/L;湖体ρ(TN)为0. 82～1. 47 mg/L,呈现湖体中间低、四周高的特征,ρ(NH3-N)为0. 14～0. 42 mg/L,但整体差异较大,高值区主要在大通湖西南及东部,ρ(TP)为0. 160～0. 289 mg/L,水质为Ⅴ类或劣Ⅴ类,TP为湖体的主要污染物,湖体的ρ(TP)变化呈现出从四周向中部增加的趋势,高值区主要集中在大通湖正南及湖心处;根据2016年大通湖区域污染源统计及入湖污染物计算,大通湖水环境的TP污染负荷大小排序为农田径流畜禽养殖生活污水工业污染网箱养鱼旅游服务。     

Vertical and horizontal distribution,source identification,ecological and toxic risk assessment of heavy metals in sediments of Lake Aygır,Kars, Turkey

Surface and core sediment samples were collected from Lake Ayg?r, Turkey, to determine heavy metal distribution, probable sources and potential ecological and toxic risks for the lake. Heavy metals, total sulfur, total phosphate, total organic carbon, chlorophyll degradation products, and CaCO₃ content were established. The enrichment factor, PLI, potential ecological risk index, and toxic risk index were calculated. Zn was determined to have the highest accumulation in surface sediment, followed by Cr, Pb, and Cd, respectively. Cd was the only element that exceeded the critical value of 40 and posed a moderate potential ecological risk. According to TRI, no ecotoxic risk was found. It is thought that local fossil fuel consumption is responsible for the accumulation of heavy metals since there is a lack of urbanization, industrialization, and agricultural activities around the lake.