基于不同生态风险度的水库调度方法研究

生态调度是平衡生态效益与其它效益的一种环保措施。当效益间发生矛盾时,可选择不同生态风险度作为决策依据,开展水库调度。以坝下典型断面的水深和流速为约束,提出基于鱼类产卵期生境断面水力需求和考虑不同生态风险度的生态调度模型。以元江桥头电站的华南鲤产卵场为例,评估5种典型日设计调度方案的生态风险度,结果显示2个方案的风险度为0,3个方案的风险度大于0.5。设计0.14、0.29、0.43三种目标风险度,分别对上述3个调度方案进行优化,得到9个优化方案。结果显示,优化方案的发电量与设计方案相比减小比例最小为16.29%,最大为36.37%。该模型可为生态约束的形成和生态调度方案的制定提供理论参考。

太湖流域主要城市洪涝灾害生态风险评价

太湖流域有上海、苏州、无锡、常州、镇江、杭州、嘉兴、湖州八个大中城市 ,是我国产业最集中、工农业最发达的地区之一。但该地区洪涝灾害频繁 ,这不仅制约了流域中各城市经济的发展 ,还严重威胁到该地区城市的生态平衡。本文根据生态风险评价原理 ,结合太湖流域的自然特点 ,提出成因分析法的指标模型 ,并通过分析太湖流域八个大中城市的汛期降雨量和地形地貌因子对洪涝灾害生态风险的影响度 ,得出各个城市洪涝灾害的生态风险度。最后还根据各城市风险度的大小及其主导因素的不同 。

重庆市黔江区阿蓬江镇土地生态安全评价研究

土地生态安全评价为优化土地资源配置、制定土地利用规划和强化环境管理提供科学依据。以阿蓬江镇为例,选取植被覆盖指数、土地承载力指数、土地生态系统服务价值指数、土地生态风险强度指数、坡耕地指数等5个指标构建土地生态安全评价指标体系,采用最优组合赋权法确定指标权重,计算该区域2011年各村土地生态安全综合指数,并进行分区和评价。结果表明,麒麟村、细水村、青杠村、黄莲村、石合村、彭家村、柒坨村处于良好级,其余6村处于敏感级。由此说明,土地生态安全程度的高低主要与土地利用类型的数量结构和空间布局有关。

Source analysis and ecological risk assessment for heavy metals in the sediments of the Yangshan Deepwater Harbor in autumn and winter

Temporal and spatial variations of concentrations of heavy metals including mercury （Hg）, zinc （Zn）, lead （Pb）, arsenic （As）, copper （Cu）, and cadmium （Cd） in the sediments of the Yangshan Deepwater Harbor were determined based on 6 cruises in autumn and winter, respectively, from 2010 to 2013. The results demonstrated that the overall concentrations of heavy metals were low and distributed in uniform patterns. The concentrations of Hg, Zn, Pb, and Cd in autumn were significantly higher than those in winter with small fluctuations for As and Cu in terms of seasonal variations. Results of factor analysis showed that Pb, Cd, and Zn were derived from inland industrial and shipping discharges as well as the degradation of organic pollutants in marine environment. While agricultural pollutions, cargo shifting and construction debris from reclamation projects contributed to the sources of Cu, As, and Hg. Ecological risk assessment by Mean Sediment Quality Guideline Quotient （SQG-Q） revealed that the degree for eco-risk of the sediments was low-and-moderate in autumn, higher than that in winter. Hg and Cu were the dominant eco-risk factors. The results of Index of geoaccumulation （Igeo） showed that the whole sites of the sea area were barely influenced by Hg, As, Zn, and Pb, and the extents of Cd and Cu contaminations were in low grade. Contamination degree of all the six heavy metals could be ranked as the following： Cd〉Pb〉Zn〉Hg〉As. According to the results of integrated score of factor analysis, the contamination degree for heavy metals in sediments of the Yangshan Deepwater Harbor was low, despite sites No.5, No.4 and No.3, which were heavily contaminated compared with others.

Soil Contamination by Heavy Metals and Evaluations on Potential Ecological Risks in an Antimony Mine

To study the status of soil quality in an antimony mine, soil samples were collected from different regions and the elements＇ contents of Sb, Cd, Cr, Cu, Zn, Pb, Hg, Ni and As were analyzed using single factor pollution index, Nemerow index and potential ecological risk index. The heavy metal contamination of soils were evaluated. The results showed that Nemerow index for each sampled point was less than 0.7, meaning a clean state. When potential ecological risk assessment was conducted, the sampled point was less than 150, belonging to light pollution.

Distribution and transformation behaviors of heavy metals during liquefaction process of sewage sludge in ethanol-water mixed solvents

Liquefaction of sewage sludge(SS)in ethanol-water cosolvents is a promising process for the preparation of bio-oil/biochar products.Effect of the combined use of ethanol and water on the distribution/transformation behaviors of heavy metals(HMs)contained in raw SS is a key issue on the safety and cleanness of above liquefaction process,which is explored in this study.The results show that pure ethanol facilitates the migration of HMs into biochar products.Pure water yields lower percentages of HMs in mobile/bioavailable speciation.Compared with sole solvent treatment,ethanol-water cosolvent causes a random/average effect on the distribution/transformation behaviors of HMs.After liquefaction of SS in pure water,the contamination degree of HMs is mitigated from high level(25.8(contamination factor))in raw SS to considerable grade(13.4)in biochar and the ecological risk is mitigated from moderate risk(164.5(risk index))to low risk(78.8).Liquefaction of SS in pure ethanol makes no difference to the pollution characteristics of HMs.The combined use of ethanol and water presents similar immobilization effects on HMs to pure water treatment.The contamination factor and risk index of HMs in biochars obtained in ethanol-water cosolvent treatment are 13.1-14.6(considerable grade)and 79.3-101.0(low risk),respectively.In order to further control the pollution of HMs,it is preferentially suggested to improve the liquefaction process of SS in ethanol-water mixed solvents by introducing conventional lignocellulosic/algal biomass,also known as co-liquefaction treatment.

Distribution and Accumulation Characteristics of Heavy Metals in Sediments in Southern Sea Area of Huludao City, China

The southern sea area of the Huludao City, Liaoning Province might be polluted by heavy metals because it is close to the Jinzhou Bay, one of the heaviest sea area polluted by heavy metals in China. The undisturbed modem sediment core can be used to analyze the accumulation and source of the pollutants using 137Cs and 21pbex. Thirty-five samples of surface sediment and two core sedi- ments were collected from the southern sea area of Huludao City. The concentrations of copper （Cu）, lead （Pb）, chrome （Cr）, zinc （Zn）, arsenic （As） and mercury （Hg） in the surface sediments as well as Cu, Pb, Zn, Cr, 137Cs and 2~~pbex in the core sediments were deter- mined to research the spatial distribution and accumulation characteristics, and to analyze the sources and the potential risks of heavy metals. The results show that the pollution levels of Zn and Hg are serious, and 26 stations are at moderate or heavy ecological risks. The concentrations of the heavy metals increase from east to west, as well as from open sea to offshore marine area. The concentrations of heavy metals are not high in the sediments adjacent to the Jinzhou Bay, and the influence caused by the seawater exchange with the Jinzhou Bay is little. The concentrations of the heavy metals in the core sediments show low-high-low characteristic, and it coincides with the pollution history of Huludao City. The atmospheric deposition of heavy metals from the Huludao Zinc Plant is likely to be the main source of pollution without direct discharge of wastewater. The high concentrations of heavy metals appear on the upper sediment of 20 cm. The shallow sediment with high heavy metal contents might be exposed to surface when it was disturbed by the ocean engineering and big storm surge, then cause risk to the safety of aouaculture and human honlthy.

Research Framework for Ecosystem Vulnerability:Measurement, Prediction, and Risk Assessment

The fragility of ecosystem health has become a key factor hindering the sustainable development of the ecological environment. Through a review of published research from domestic and foreign scholars, starting from the endogenous logic of studies in the field of ecosystem vulnerability(EV), this paper sorts out the literature on the aspects of measurement models, prediction methods and risk assessment, comprehensively defines the research category and scientific framework of EV, and analyzes the research ideas and development trends. We arrived at the following conclusions: 1) The connotation of ecosystem vulnerability not only embodies the change in the vulnerability of the natural environment, but it also reflects the irreversible damage to the ecosystem caused by excessive development and industrial production activities. 2) The setting of ecosystem vulnerability indices should aim to fully reflect the essential features of that vulnerability, which should include the index systems of natural, social, economic and other related factors. 3) There are many types of ecosystem vulnerability measurement methods, prediction models and risk evaluation models, which have different focuses and advantages. The most appropriate method should be adopted for conducting comprehensive and systematic evaluation, prediction and estimation according to the different representation and evolution mechanisms of the chosen research object and regional ecosystem vulnerability. 4) Based on the regional system characteristics, corresponding risk management measures should be proposed, and pertinent policy suggestions should be put forward to improve the ecological safety and sustainable development of an ecologically vulnerable area.

Gradients in predation risk in a tropical river system

The importance of predation risk as a key driver of evolutionary change is exemplified by the Northern Range in Trinidad, where research on guppies living in multiple parallel streams has pro- vided invaluable insights into the process of evolution by natural selection. Although Trinidadian guppies are now a textbook example of evolution in action, studies have generally categorized predation as a dichotomous variable, representing high or low risk. Yet, ecologists appreciate that community structure and the attendant predation risk vary substantially over space and time. Here, we use data from a longitudinal study of fish assemblages at 16 different sites in the Northern Range to quantify temporal and spatial variation in predation risk. Specifically we ask： 1） Is there evidence for a gradient in predation risk？ 2） Does the ranking of sites （by risk） change with the defi- nition of the predator community （in terms of species composition and abundance currency）, and 3） Are site rankings consistent over time？ We find compelling evidence that sites lie along a contin- uum of risk. However, site rankings along this gradient depend on how predation is quantified in terms of the species considered to be predators and the abundance currency is used. Nonetheless, for a given categorization and currency, rankings are relatively consistent over time. Our study sug- gests that consideration of predation gradients will lead to a more nuanced understanding of the role of predation risk in behavioral and evolutionary ecology. It also emphasizes the need to justify and report the definition of predation risk being used.