Mercury contamination and accumulation in sediments of the East China Sea

Mercury (Hg) concentrations in sediment samples collected from the inner and middle shelves of the East China Sea (ECS) were analyzed to evaluate Hg contamination levels and to calculate Hg sedimentation rates and total accumulation in the ECS. The range of Hg concentrations in surface sediments of the inner shelf was 26.5–47.6 ng/g, and that for the middle shelf was 4.1–13.9 ng/g. Hg concentrations correlated well with organic carbon contents but varied inversely with sediment grain size. Enrichment factors indicated that the whole inner shelf and a small portion of the middle shelf were slightly contaminated by Hg. Hg accumulation rates in the ECS ranged between 0.42–48.7 ng/(cm2·yr), with higher values observed in the inner shelf. Total Hg accumulation in the calculated area (accounting for 80% of the ECS continental shelf area) ranged from 25 to 30 tons/yr; approximately 51% and 17% of the accumulated Hg mass was deposited in the Yangtze estuarine zone and the inner shelf, respectively.     

深圳红树林水体浮游植物多样性与营养状态评价

通过监测深圳福田红树林水体浮游植物,掌握浮游植物多样性组成和时空分布特征,并利用浮游植物群落多样性指数结合生物量、数量,对水体营养状态进行评价。结果表明,浮游植物种类少,数量大。硅藻分布广泛,在种类和数量上占主导地位,优势种为微小小环藻(Cyclotella caspia)和诺氏海链藻(Thalassiosira nordenski ldi)等,一些耐污染的藻类,如小颤藻(Oscillatoria minima)、裸藻(Euglenaspp.)在特定季节成为一些站位的优势种。浮游植物种类组成时空变化显著,而数量的空间变化明显,季节差异不大。检测出富营养化指示种15种,中营养化指示种11种,贫营养化指示种9种。浮游植物的生物评价指数显示,深圳红树林水体处于中~富营养化状态,有向富营养化过渡的趋势,水体遭受严重污染,应注意加强对内陆径流和污水排放进入红树林的严格控制和管理。     

Soil resource supply influences faunal size–specific distributions in natural food webs

The large range of body-mass values of soil organisms provides a tool to assess the ecological organization of soil communities. The goal of this paper is to identify graphical and quantitative indicators of soil community composition and ecosystem functioning, and to illustrate their application to real soil food webs. The relationships between log-transformed mass and abundance of soil organisms in 20 Dutch meadows and heathlands were investigated. Using principles of allometry, maximal use can be made of ecological theory to build and explain food webs. The aggregate contribution of small invertebrates such as nematodes to the entire community is high under low soil phosphorus content and causes shifts in the mass–abundance relationships and in the trophic structures. We show for the first time that the average of the trophic link lengths is a reliable predictor for assessing soil fertility responses. Ordered trophic link pairs suggest a self-organizing structure of food webs according to resource availability and can predict environmental shifts in ecologically meaningful ways. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to all users.     

第二阶梯湖泊富营养化自然地理因素及效应

为了明晰影响我国地形地貌第二级阶梯湖泊富营养化的主要自然地理驱动因素,为湖泊富营养化的有效治理提供参考,采用曲线回归方法分析了位于我国第二级阶梯的云南和新疆湖泊中Chl-a以及营养状态综合指数(TLI)与自然地理特征的相关性.结果表明,平均水深、海拔以及年均温与TLI指数具有较好的相关性,拟合模型分别符合三次/对数模型、二次模型和三次模型.Chl-a与年平均日照时数具有较好的相关性,拟合模型符合二次/三次模型.分析富营养化效应,藻类生长对透明度的影响以及营养物质对浮游藻类的生态效应(Chl-a/TP),结果发现,新疆湖泊中Chl-a与透明度呈倒数关系,云南湖泊中Chl-a与透明度呈幂函数关系;Chl-a与总磷的线性方程的斜率分别为177.595(云南)和222.758(新疆).影响我国第二级阶梯湖泊富营养化的主要自然地理驱动因素是湖泊的平均水深、海拔、年均温度及年平均日照时数,透明度与Chl-a含量的相关性以及营养物质TP对浮游藻类的生态效应存在区域差异.     

Trophic State in Voyageurs National Park Lakes before and after Implementation of a Revised Water‐Level Management Plan

We compiled Secchi depth, total phosphorus, and chlorophyll a (Chla) data from Voyageurs National Park lakes and compared datasets before and after a new water‐level management plan was implemented in January 2000. Average Secchi depth transparency improved (from 1.9 to 2.1 m, p = 0.020) between 1977‐1999 and 2000‐2011 in Kabetogama Lake for August samples only and remained unchanged in Rainy, Namakan, and Sand Point Lakes, and Black Bay in Rainy Lake. Average open‐water season Chla concentration decreased in Black Bay (from an average of 13 to 6.0 μg/l, p = 0.001) and Kabetogama Lake (from 9.9 to 6.2 μg/l, p = 0.006) between 1977‐1999 and 2000‐2011. Trophic state index decreased significantly in Black Bay from 59 to 51 (p = 0.006) and in Kabetogama Lake from 57 to 50 (p = 0.006) between 1977‐1999 and 2000‐2011. Trophic state indices based on Chla indicated that after 2000, Sand Point, Namakan, and Rainy Lakes remained oligotrophic, whereas eutrophication has decreased in Kabetogama Lake and Black Bay. Although nutrient inputs from inflows and internal sources are still sufficient to produce annual cyanobacterial blooms and may inhibit designated water uses, trophic state has decreased for Kabetogama Lake and Black Bay and there has been no decline in lake ecosystem health since the implementation of the revised water‐level management plan.     

Economic Growth and Marine Biodiversity: Influence of Human Social Structure on Decline of Marine Trophic Levels

Abstract:  We assessed the effects of economic growth, urbanization, and human population size on marine biodiversity. We used the mean trophic level (MTL) of marine catch as an indicator of marine biodiversity and conducted cross-national time-series analyses (1960–2003) of 102 nations to investigate human social influences on fish catch and trends in MTL. We constructed path models to examine direct and indirect effects relating to marine catch and MTL. Nations' MTLs declined with increased economic growth, increased urbanization, and increased population size, in part because of associated increased catch. These findings contradict the environmental Kuznets curve hypothesis, which claims that economic modernization will reduce human impact on the environment. To make informed decisions on issues of marine resource management, policy makers, nonprofit entities, and professional societies must recognize the need to include social analyses in overall conservation-research strategies. The challenge is to utilize the socioeconomic and ecological research in the service of a comprehensive marine-conservation movement.     

Effect of heavy metals on soil nematode communities in the vicinity of a metallurgical factory

The influence of Cu and Zn on soil nematode communities was examined along a pollution gradient with increasing distance from a metallurgical factory. Total and available heavy metal contents were used to study the effects of heavy metals on nematode abundance, trophic groups and ecological indices. The results demonstrated significant correlations between the number of total nematodes, bacterivores, plant-parasites and the total and available heavy metals. Bacterivores and plant-parasites were the dominant trophic groups. Significant differences in different sampling sites were found only in the number of bacterivores（P〈0.01）. The Shannon-Weaver diversity index（W）, trophic diversity index（TD）, evenness index（J＇） and dominance index（λ） were found to be sensitive to soil pH and C/N ratios. Significant correlations were found between the total nematodes （TNEM）, some genera （A crobeloides, Aphelenchoides, Cephalobus, Ditylenchus, Mesorhabditis, Tetylenchus and Tylenchus） and distance from the factory.     

不同污染程度湖泊沉积物中不同粒级可转化态氮分布

研究了污染程度不同的五里湖、月湖、东太湖和贡湖不同粒级沉积物中总可转化态氮以及各形态可转化态氮的含量与分布.结果表明:4个湖泊的沉积物各粒级中各形态可转化态氮的含量及其地球化学特征均不相同.强氧化剂可提取态氮(SOEF-N)是释放能力最弱的形态,为可转化态氮的主体,占总可转化态氮的66.97%～87.97%.离子交换态氮(IEF-N)结合能力最弱,是最容易被释放的形态,为可转化态无机氮的主体,占总可转化态氮的7.37%～22.25%.同一粒级中,各形态可转化态氮对氮循环的贡献为SOEF-N最大,IEF-N其次,强碱可浸取态氮(SAEF-N)与弱酸可浸取态氮(WAEF-N)最低.随着沉积物粒级的由粗到细,总可转化态氮以及各形态可转化态氮含量均呈逐渐增加趋势.沉积物细颗粒部分对氮循环的可能贡献占绝对的主体,是粗颗粒部分的几倍到几十倍.相比而言,污染程度轻的贡湖和东太湖沉积物无论总可转化态氮还是各形态可转化态氮,细颗粒部分的相对含量均低于污染程度重的五里湖和月湖沉积物.      

NitroScape: a model to integrate nitrogen transfers and transformations in rural landscapes

Modelling nitrogen transfer and transformation at the landscape scale is relevant to estimate the mobility of the reactive forms of nitrogen (N_r) and the associated threats to the environment. Here we describe the development of a spatially and temporally explicit model to integrate N_r transfer and transformation at the landscape scale. The model couples four existing models, to simulate atmospheric, farm, agro-ecosystem and hydrological N_r fluxes and transformations within a landscape. Simulations were carried out on a theoretical landscape consisting of pig-crop farms interspersed with unmanaged ecosystems. Simulation results illustrated the effect of spatial interactions between landscape elements on N_r fluxes and losses to the environment. More than 10% of the total N₂O emissions were due to indirect emissions. The nitrogen budgets and transformations of the unmanaged ecosystems varied considerably, depending on their location within the landscape. The model represents a new tool for assessing the effect of changes in landscape structure on N_r fluxes.     

猫跳河流域梯级水库夏季N2O的产生与释放机理

为了研究河流筑坝对河流氮生物地球化学循环的影响,在夏季水体分层期间对猫跳河梯级水库坝前分层采集水样进行了相关地球化学分析。结果显示,在上游的两座水库存在2个明显的温度分层现象,并影响到了水体N2O的产生和分布。红枫水库整个剖面的氮分布主要受硝化作用控制,而百花湖、修文及红岩水库则表现为上层水体为硝化作用,中层为硝化反硝化共同作用。所有水库表层水和下泄水高饱和度的N2O含量表明这些水体为大气N2O的源。百花湖底层反硝化作用强烈,中间产物N2O大量消耗。底层泄水的方式对于温室气体释放影响重大,因此不同水库下泄水的N2O含量在时间和空间上的变化与水库运行和调蓄模式有关。研究结果表明,梯级水库过程对N2O的排放影响很大,在水电开发的环境保护中应当引起重视。