渔网围栏介质对太湖梅梁湾富营养化水体的改善

在太湖梅梁湾强化净化示范区内布设了渔网围栏工程,研究了围栏介质对水体的净化效果.研究结果表明,围栏介质能显著提高水体透明度,在1月份的试验中水体透明度提高了20cm,在6月份的试验中水体透明度提高了30cm;2次试验中的水体叶绿素a、总磷(TP)和总氮(TN)的削减率分别为62.5%、22.5%、37.8%和43.8%、30.9%、60.5%;据此估算,示范工程区的渔网围栏每年大约能去除TP和TN的量分别为40.5,963.6kg.     

Invasive species impacts on ecosystem structure and function: A comparison of the Bay of Quinte, Canada, and Oneida Lake, USA, before and after zebra mussel invasion

As invasion rates of exotic species increase, an ecosystem level understanding of their impacts is imperative for predicting future spread and consequences. We have previously shown that network analyses are powerful tools for understanding the effects of exotic species perturbation on ecosystems. We now use the network analysis approach to compare how the same perturbation affects another ecosystem of similar trophic status. We compared food web characteristics of the Bay of Quinte, Lake Ontario (Canada), to previous research on Oneida Lake, New York (USA) before and after zebra mussel (Dreissena polymorpha) invasion. We used ecological network analysis (ENA) to rigorously quantify ecosystem function through an analysis of direct and indirect food web transfers. We used a social network analysis method, cohesion analysis (CA), to assess ecosystem structure by organizing food web members into subgroups of strongly interacting predators and prey. Together, ENA and CA allowed us to understand how food web structure and function respond simultaneously to perturbation. In general, zebra mussel effects on the Bay of Quinte, when compared to Oneida Lake, were similar in direction, but greater in magnitude. Both systems underwent functional changes involving focused flow through a small number of taxa and increased use of benthic sources of production; additionally, both systems structurally changed with subgroup membership changing considerably (33% in Oneida Lake) or being disrupted entirely (in the Bay of Quinte). However, the response of total ecosystem activity (as measured by carbon flow) differed between both systems, with increasing activity in the Bay of Quinte, and decreasing activity in Oneida Lake. Thus, these analyses revealed parallel effects of zebra mussel invasion in ecosystems of similar trophic status, yet they also suggested that important differences may exist. As exotic species continue to disrupt the structure and function of our native ecosystems, food web network analyses will be useful for understanding their far-reaching effects.     

EFFECTS OF LAND COVER AND GEOLOGY ON STREAM CHEMISTRY IN WATERSHEDS OF CHESAPEAKE BAY1

ABSTRACT: We measured the base‐flow stream chemistry in all the major physiographic provinces of the Chesapeake Bay drainage basin. The spatial variation of stream chemistry was closely related to differences in geology and land cover among the sampled watersheds. Some stream chemistry variables were strongly affected by geological settings in the watersheds while others were more influenced by land cover. The effects of land cover differed among chemical constituents and regions. Concentrations of Ca²⁺, Mg²⁺, pH, total alkalinity, and conductivity were mainly functions of carbonate bedrock, especially in the Great Valley. Nitrate‐N and total dissolved N were closely related to cropland and increased as the percentage of cropland increased. The rate of increase varied from region to region with the highest in the Piedmont. Na⁺ and Cl^? were mainly affected by the percentage of developed area in a watershed, especially in the Coastal Plain and Piedmont. We observed no significant effects of region or land cover on species of phosphorus because samples were collected under base flow conditions and only dissolved forms were measured. Dissolved silicate (DSi) was not related to any other water chemistry variables. DSi increased as developed area decreased and cropland increased in the Coastal Plain, but these patterns were reversed in the Piedmont. There was no consistent pattern in the spatial variation of land cover effects on the reduced forms of N, dissolved organic P, dissolved organic matter, and K⁺.     

渤海湾可溶性无机氮时空变异状况分析

以渤海湾17个监测点11年来可溶性无机氮(DIN)监测数据为研究对象,采用箱线图,相关分析,Mann-Kendall及样条插值等技术方法,分析渤海湾1996—2006年17个监测点ρ(DIN)的统计学特征、季节差异性和时空变化状况,以及引起ρ(DIN)时空变化的原因.结果表明:各监测时期渤海湾ρ(DIN)大多表现为正偏态分布. 在33个监测时段内,2号,4号和6号监测点所在海区ρ(DIN)最高,说明陆源污染及港口发展对渤海湾ρ(DIN)的贡献不容忽视. 丰水期ρ(DIN)与平水期显著相关,而枯水期ρ(DIN)与丰水期和平水期的相关性不显著. 在时间特征上,ρ(DIN)表现为先增加后平稳而后快速增加的趋势;在空间分布上,ρ(DIN)表现为北高南低,近岸高离岸低的趋势.      

渤海湾天津段表层沉积物重金属分布特征及其来源解析

年8月对渤海湾天津段沉积物进行采样分析,结果表明,渤海湾天津段表层沉积物中常量重金属质量分数为w(Fe)>w(Al)>w(Mn),微量重金属质量分数为w(Cr)>w(Zn)>w(Cu)>w(Pb)>w(Cd). 空间分布上,5种微量重金属在入海口海域和中部海域的质量分数较高. 利用I_geo(地累积指数)法评价重金属污染程度,结果显示,Cd、Cr和Zn的I_geo处于2级(中度污染),而Cu和Pb的污染较轻,其I_geo处于1级(未污染到中度污染). 多元统计结果表明:①渤海湾天津段表层沉积物中微量重金属质量分数与w(Fe)、w(Al)显著相关(P<0.01),说明微量重金属在海洋沉积过程中与常量重金属具有类似的地球化学行为;②在聚类分析中,所有重金属聚为一类,说明其具有相似的来源,都受陆源输入的影响;③所有重金属均在第一主成分上表现出较高正载荷,说明微量重金属与常量重金属具有相同的地球化学过程和环境行为. 根据重金属空间分布特征和多元统计结果,结合渤海湾的环流等情况可以推测,渤海湾天津段表层沉积物中微量重金属主要来源于环渤海地区入海河流的外源输入,并且大部分来源于工业源;其在渤海湾中的分布和迁移受到Fe和Al等常量重金属的影响.      

大亚湾浮游植物DNA指纹及其与群落结构的关系

于2012年5月、6月采集了大亚湾9个站点的表层水样,利用PCR-变性梯度凝胶电泳(PCR-DGGE)技术对浮游植物DNA指纹进行了分析,同时通过显微镜观察对浮游植物进行了定性定量分析.研究结果显示,大亚湾浮游植物种类丰富,共分析鉴定出浮游植物72种;浮游植物DNA指纹也较为丰富,2个月份指纹条带数分别为26条和28条.DGGE指纹条带数一般远远低于浮游植物种类数,在剔除了相对含量小于0.1%的非优势种后,DNA条带数与种类数变化趋势相近,说明DNA指纹图谱能较大程度地反映浮游植物优势种群的组成,而对于相对含量较少的物种,可能会由于优势种的屏蔽作用而被掩盖.DNA指纹图谱与浮游植物群落结构的聚类分析结果相近,富营养化的近岸站点聚在一起,而远岸站点聚为一类.虽然目前大亚湾浮游植物群落结构中以硅藻占据优势,但在某些站点大量出现的甲藻和蓝细菌值得进一步关注.本研究结果表明PCR-DGGE技术可在一定程度上运用于浮游植物群落结构分析.     

Influence of human activity and monsoon dynamics on spatial and temporal hydrochemistry in tropical coastal waters (Sanya Bay,South China Sea)

Human activities and oceanic influences like mixing and/or upwelling define the hydrochemical and biological characteristics of coastal regions. In Sanya Bay, northern South China Sea, the balance between these two influences on spatial and temporal scales is poorly understood. The influence from human activities was due to discharge from Sanya River, whereas the most important marine influence was related to seasonal changes in hydrodynamics. Spatial differences (p<0.05) in total nitrogen (TN) and chlorophyll-a (Chl-a) were observed. Seasonal differences were observed for temperature and nutrients. Human activities are the dominant factor influemcing hydrochemistry in the inner bay. This region exhibited the maximum influence of discharge from Saya River as estimated by higher nutrient levels. Oceanic influences like upwelling and mixing caused by monsoons are the dominant factors influencing hydrochemistry in the central and outer bay. Both human activities and oceanic influences play important roles in coastal ecosystems in Sanya Bay. This study has defined these characteristics so that better management policies can be enacted.     

2004—2008年辽东湾水质污染特征分析

根据2004—2008年5年对辽东湾各海域的监测数据,阐述了该海域水体营养盐和重金属的空间、季节分布特征规律,并对辽东湾海域的综合水质现状,海域营养结构及营养水平进行了评价.结果表明:基于Ⅰ类海水标准,辽东湾的主要污染指标为无机氮(DIN),局部海域出现活性磷酸盐(DIP)、铜、铅超标现象. 营养盐和重金属的空间分布趋势均为北部海域污染最重,东部海域污染最轻,污染主要集中在锦州、盘锦、营口海域,且这3个海域处于富营养化状态,随时可诱发赤潮. 营养盐质量浓度的季节变化趋势为平水期>丰水期>枯水期.      

渤海湾潮滩不同粒径沉积物中多环芳烃的分布

利用湿筛分离的方法,将采自渤海湾潮间带的沉积物分成0.063mm 3个不同的粒径组分,测定其16种EPA规定的多环芳烃(PAHs)含量、总有机碳(TOC)和碳黑(BC)含量.结果表明,不同粒径沉积物中∑PAHs含量范围在714~4870ng/g之间.在岐口(TS3)沉积物中,∑PAHs含量最高值出现在0.063mm粒径组分中.所有站点沉积物的0.031~0.063mm粒径组分中∑PAHs含量均为最低.尽管如此,有机碳标准化∑PAHs含量则随着沉积物粒径的增大呈现增加趋势.不同粒径沉积物中∑PAHs含量与BC含量之间呈现显著正相关关系,而与有机碳(OC=TOC-BC)含量之间的相关性较差.因此,不同粒径沉积物中BC的分布很可能在其中扮演着更重要的作用.     

莱州湾表层沉积物重金属分布特征及污染评价

莱州湾属半封闭海湾,水体交换能力较弱,受多条河流入海影响,污染日趋加重。根据区域特征,于2008年5月对莱州湾30个采样点表层沉积物中的Cu、Pb、Zn、Cd、Hg、As、粒度和总有机碳进行测定,探讨了重金属含量和污染特征与粒度、总有机碳间的相关关系,利用污染评价法和潜在生态风险评价法进行污染和风险分析。结果表明：重金属平均含量较低,大部分低于国家海洋沉积物一类标准。Cu、Pb、Zn、Cd和As在莱州湾中部区域出现高值区,同时Cd在小清河口、Hg在莱州湾东部出现高值区。Cu、Pb、Zn、Cd、As重金属之间（除了Cd和As之间）及与沉积物粘土、有机碳含量之间显著正相关。莱州湾表层沉积物重金属单因子污染程度总体较轻,属于低污染水平,污染程度排序为CdPbZnCuAsHg,约30%的站位重金属综合污染指数大于5,达到中等污染水平,主要分布于小清河口、莱州湾中部和东部区域。莱州湾表层沉积物重金属潜在生态风险总体处于较低水平,风险排序为HgCdAsPbCuZn,风险指数高值区出现在莱州湾东部区域,主要受Hg的高风险水平影响。