In-situ observations of internal dissolved heavy metal release in relation to sediment suspension in lake Taihu, China

Despite laboratory experiments that have been performed to study internal heavy metal release, our understanding of how heavy metals release in shallow eutrophic lakes remains limited for lacking in-situ evidence. This study used automatic environmental sensors and a water sampling system to conduct high-frequency in-situ observations (1-hr intervals) of water environmental variables and to collect water samples (3-hr intervals), with which to examine the release of internal heavy metals in Lake Taihu, China. Under conditions of disturbance by strong northerly winds, sediment resuspension in both the estuary area and the lake center caused particulate heavy metal resuspension. However, the patterns of concentrations of dissolved heavy metals in these two areas were complex. The concentrations of dissolved Se and Mo increased in both areas, indicating that release of internal dissolved Se and Mo is triggered by sediment resuspension. The concentrations of dissolved Ni, Zn, As, Mn, Cu, V, and Co tended to increase in the estuary area but decrease in the lake center. The different trends between these two areas were controlled by pH and cyanobacteria, which are related to eutrophication. During the strong northerly winds, the decrease in concentrations of dissolved heavy metals in the lake center was attributable primarily to absorption by the increased suspended solids, and to growth-related assimilation or surface adsorption by the increased cyanobacteria. The findings of this study suggest that, short-term changes of environmental conditions are very important in relation to reliable monitoring and risk assessment of heavy metals in shallow eutrophic lakes.     

Historical trends of PCBs and PBDEs as reconstructed in a lake sediment from southern Tibetan Plateau

High-altitude lake sediment can be used as a natural archive to reconstruct the history of pollutants. In this work, the temporal distribution of polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) were determined using a high-resolution gas chromatography coupled with high-resolution mass spectrometer (HRGC/HRMS) in an alpine lake sediment core collected from the southern Tibetan Plateau (TP) to examine whether the expected decreasing trends due to the implementation of the international Conventions could be observed. The concentrations of PCBs and PBDEs in the sediment core were in the range of 11.8–142 pg/g dw and ND-457 pg/g dw, and their fluxes were in the range of 2.51–31.7 ng/(m²·yr) and ND-43.2 ng/(m²·yr), respectively. The prevalence of low-chlorinated (tri-CB) PCBs and low-brominated (tri- to tetra-) PBDEs in most sections of the sediment profiles was observed, suggesting that the light molecular weight PCBs and PBDEs have most likely reached lake sediments by long-range atmospheric transport from distant sources. Despite the restrictions on their applications, the sediment records for the concentrations and fluxes showed no corresponding decreasing trend with restrictions for PCBs, which suggested that these POPs (e.g., PCBs) were still emitted to the environment owing to the influence of primary or secondary emissions. To our knowledge, this is the first report on input history of atmospheric PCBs and PBDEs recorded in TP Lake sediment.     

气候变化下汉中盆地水稻产量变化研究

深入分析气候变化下汉中盆地水稻产量变化响应,可在进一步探究影响研究区水稻产量主要气象要素的同时,为地方水稻生长期内气象灾害的防控提供科学依据。为了解研究区水稻生长季主要的气象影响因子,文章基于1951—2014年汉中盆地多测站日气温、降水量、积温及气温日较差数据和水稻单产资料分离的气象单产数据,综合运用线性趋势、趋势系数、HP滤波法、Morlet小波分析等方法,在分析汉中盆地水稻气象产量和生长季各气象要素变化趋势的同时,推求了水稻气象产量和各主要气象要素序列的显著周期。研究结果表明：1）近64 a汉中盆地4—9月水稻生长季平均气温和≥10 ℃活动积温变化均呈上升趋势,气温日较差呈下降趋势,降水量变化趋势不明显;2）汉中盆地各气象要素与水稻气象单产的显著周期分析结果显示水稻气象单产第一主周期与各气象要素的第二主周期相对应,均存在13~14 a时间尺度的主周期变化;3）各气象要素对水稻气象产量的影响各异,不同气候背景下影响水稻气象产量的主导气象因素不同。论文研究结果可为汉中盆地水稻生产的优化布局及地方经济社会发展提供参考依据。     

长江流域干旱时空变化特征及演变趋势

干旱通常被认为是我国最严重的自然灾害之一,其造成的经济损失十分巨大.长江流域作为典型的湿润-半湿润区,干湿交替明显,干旱事件时空分布特征较为复杂.为了深入认识和理解长江流域气象干旱现状及其特征,探究干旱事件发生规律,采用长江流域1951-2015年PDSI（Palmer drought severity index,帕尔默干旱指数,运用Mann-Kendall检验、EEMD（ensemble empirical mode decomposition,集合经验模分解）、REOF（rotation empirical orthogonal function,旋转经验正交函数分解）、森斜率估算等分析方法,探讨长江流域干旱面积时间变化特征、干湿情景时空分布特征以及变化趋势.结果表明:1951-2015年,长江流域发生季节性干旱的面积整体呈扩大趋势,2000年后该趋势有所减缓.流域内呈现6个明显的干湿空间分布型,2000年后流域的东南部呈变旱态势,整体而言,流域内"南涝北旱"特征十分明显.未来,长江流域整体有变湿的趋势,西北部更旱,东北部变湿,南部以及东南部PDSI上升趋势明显,有发生旱涝急转的可能.      

CRITICAL ELEMENTS IN DESCRIBING AND UNDERSTANDING OUR NATION'S AQUATIC RESOURCES1

ABSTRACT: Despite spending $115 billion per year on environmental actions in the United States, we have only a limited ability to describe the effectiveness of these expenditures. Moreover, after decades of such investments, we cannot accurately describe status and trends in the nation's aquatic ecosystems or even those in specific regions. Why? This situation has arisen in part because we have excluded the fundamental principles of probability designs that are widely used in other fields and we have often ignored direct measures of biota, the subjects of greatest concern. To demonstrate the results of ignoring these powerful statistical and biological tools, we present four case studies. These studies compare estimates of aquatic resource status derived from using (1) a probability-based study design, often with biological measures of condition; and (2) a nonstatistical study design, often using chemical surrogates. In three of the four cases, the results derived from the nonstatistical perspective underestimate the degree of biological degradation.     

长江中下游 南黄海地震带地震活动趋势分析

对长江中下游 南黄海地震带地震活跃期、幕划分及其发展趋势进行了研究,对江苏及其邻区今后几年的地震大形势及重点危险区进行了判定。分析认为,长南带从１９７１年以来进入第二活跃期的第３幕,该幕地震活动将持续到２０１０年前后,最高活动水平为６．５级左右。今后几年江苏东部至南黄海海域发生５～６级或６级以上地震的可能性较大。     

天津市“蓝天工程”实施前、后大气污染源污染物排放趋势

通过建立天津市2002—2004年大气污染源动态数据库,研究了“蓝天工程”实施前、后大气污染源污染物排放变化趋势,得出了“蓝天工程”实施后天津市在燃煤量增加的情况下,烟尘、SO2排放量逐年减少,环境空气质量明显改善的结论。     

Effects of increased vegetation cover on nesting behavior of sticklebacks (Gasterosteus aculeatus)

To maximize reproductive success, reproductive behaviors have to be adjusted to environmental conditions. The breeding habitats of the threespine stickleback Gasterosteus aculeatus are presently changing in the Baltic Sea due to eutrophication and enhanced growth of filamentous green algae. Earlier studies show that high algae density reduces mate encounter rate and the intensity of selection on a few sexually selected traits, but the willingness of males to nest under the new conditions, and their investment into reproduction, have not been investigated. Here, we investigated the effect that increased algae growth has on nesting behavior of sticklebacks. We allowed males to build nests in aquaria with either a sparse or a dense vegetation structure and recorded male nest building behavior and nest characters. Males that nested in dense vegetation showed a longer latency before commencing nest building and also completed nest building later since there was no difference in time spent building. There was no effect of vegetation cover on nest characters. These results suggest that males prefer to nest in sparser vegetation, but that they eventually nest in dense vegetation if more open habitats are not available. This may arise from a negative effect of vegetation on visibility and mate encounter rate and thus on expected reproductive success. This implies that human-induced changes in the environment may force sticklebacks to breed in non-preferred habitats. Since the intensity of sexual selection is reduced in these areas, this could influence the further evolution of the population.     

The trophic status of two Northern Irish sea loughs

Studies were conducted on nutrient cycling in two coastal embayments; Strangford Lough and Belfast Lough, in order to classify these coastal waters in compliance with the European Union Urban Waste Water Treatment and Nitrates Directives. Analysis of the data suggests that Strangford Lough is nitrogen-limited throughout much of the growing season with chlorophyll-a levels comparable to the open Irish Sea. In contrast, much of Belfast Lough is never nitrogen-limited and, with chlorophyll-a levels at time exceeding 50 μg/l, is exhibiting symptoms of eutrophication.     

Mapping the intertidal vegetation of the harbours of southern England for water quality management

This paper discusses a research project dealing with the mapping of the intertidal vegetation of several harbours along the southern coastline of England. It describes in detail the methods used to map the vegetation and gives examples of the results from these studies. This paper then goes on to explain how these results are applied by the Environment Agency of England and Wales to improve water quality in the harbours. This type of vegetation mapping is useful in monitoring the development of the intertidal species includingSpartina, Zostera and of particular importance to this study the green algaeUlva andEnteromorpha. The work was undertaken with funding from the Environment Agency and at present has taken place over a four year period. The data collected will be used by the Environment Agency to assess macro-algae covervalues for the intertidal area of the harbours concerned. This forms part of the Agency's commitment to the EU Nitrates Directive and the Urban Waste Water Treatment Directive. Some of the species mapped act as suitable indicators of water quality and are symptoms of entrophication. Other species are of interest for nature conservation and were recorded to provide a record for longer-term trends in vegetation patterns within the harbour. This paper aims to provide readers with an understanding of the techniques involved as well as an evaluation of the methodology.