基于景观结构和空间统计学的区域生态风险分析

以农牧交错带的典型区域——内蒙古翁牛特旗为研究对象,基于景观结构中的景观干扰度指数和景观脆弱度指数构建区域生态风险指数,并借助空间统计学中的空间自相关和半方差分析方法,进行区域生态风险空间分布和梯度变化特征分析,得出如下结论：（1）研究区内的生态风险度存在着一定的正相关关系,并随着粒度增大,呈现出下降的趋势;（2）1985～2000年的15a中,研究区生态环境质量整体有所下降,生态风险指数较高的地区有所增加;（3）研究区内的沙地坨甸区生态风险度高,相邻区域的生态风险度也较高;（4）研究区生态风险指数空间分异的步长都比较大,为410.9km。     

Distribution and potential eco-risk of chromium and nickel in sediments after impoundment of Three Gorges Reservoir,China

The impoundment of the Three Gorges Reservoir (TGR) altered the hydrodynamic conditions and modulated the accumulation and behaviors of heavy metals in the sediments. In this study, the sediments from the riparian and submerged areas of the entire TGR mainstream were collected in 2014 to investigate the spatial distribution of chromium (Cr) and nickel (Ni), and to assess their contamination state and potential eco-risk to aquatic environment by multiple indices. Results showed that the concentrations of Cr and Ni in the sediments increased toward the dam. The concentrations of Cr were significantly higher in the riparian sediments than in the submerged sediments, whereas the Ni concentrations were comparable. The relatively high storages of Cr and Ni in the sediments existed near the dam. The physiochemical properties of sediments and local human activities controlled the spatial variations of Cr and Ni in the sediments. Currently, the TGR sediments are not heavily contaminated by Cr and Ni and show low eco-risk. Nevertheless, considering the decrease in sediment loads from the upper Yangtze River and the rapid urbanization in the TGR catchment, much more attentions should be paid to the geochemical behaviors and the eco-risk of Cr and Ni in the sediments.     

露天矿区景观生态风险空间分异

以露天矿区为研究对象,评价矿区景观生态风险,并采用ESDA方法定量研究矿区生态风险空间分异特征.结果表明,矿区景观生态风险空间分布以高风险区域为核心,由高到低呈环形包围特征.其中,高风险主要分布在矿业生产及城市生活区域,以土地破坏、压占及城市建设为主要风险来源;中等风险主要分布于自然、半自然功能区,以城市生活与农业生产为主要风险来源;低风险区域以林地、荒草地等植被覆盖区域为主,但大面积植被退化、水土流失导致该区域生态基底较差、环境脆弱,加之露天煤矿作业频繁,整体生态环境质量堪忧.同时,不同功能区的风险高低排序(人工区＞半自然区＞自然区)特征符合常规的区域生态风险等级差异规律.此外,基于ESDA分析矿区景观生态风险,其空间自相关性高达0.7521,风险的空间集聚效应明显;而对比矿区景观生态风险的空间分异特征发现,景观干扰度是高、低风险区域的主要驱动因子;而景观脆弱度则是中等风险区域的驱动因子;基于以上研究结果可对矿区环境管理和风险决策提供一定的数据支撑和理论依据.     

基于突变理论的近岸海域生态风险综合评价方法——以罗源湾为例

基于突变理论建立了“海水水质-沉积物-生物体”三相一体、“富营养化-重金属-有机污染”3种类型的近岸海域生态风险综合评价指标体系和递级突变模型,综合相关质量标准,建立了近岸海域生态风险4级评判标准（无、低、中、高）,采用2007和2009年监测数据对罗源湾进行生态风险综合评价.结果表明： 2007-2009年,罗源湾生态风险空间变化特征表现为从湾顶到湾口呈降低趋势;2009年罗源湾生态风险等级总体小于2007年;罗源湾关键生态风险因素为富营养化.本文所建方法能够识别近岸海域生态风险的时空变化特征,能较好地反映出关键风险因素,为近岸海域生态风险有效预测预警提供了基础方法.