河口泥沙再悬浮对悬沙中重金属元素的影响

基于1997年3月9日和7月27日长江口南槽定点连续观测资料。分析了河口泥沙再悬浮对重金属元素的影响。研究结果表明，在长江口南槽，近底悬沙浓度和悬沙中重金属含量均随时间变化而变化，且两者具有良好的对应关系；因子分析结果显示对所有金属元素都占绝对优势的F1因子为泥沙再悬浮，泥沙再悬浮现象对本次观测中近底泥沙中重金属含量变化起主导作用。泥沙再悬浮一方面会导致悬沙和床沙的混合。另一方面有可能导致重金属从泥沙中向水体中再释放，在长江口南槽，枯季近底悬沙中重金属含量的变化主要缘于悬沙、床沙的混合；而洪季除悬沙和床沙混合之外，还存在泥沙再悬浮过程泥沙中重金属的释放，这可能与洪季高水温、低溶氧等环境因素以及强烈的水动力条件有关。     

Estuary planning and management: the case of Vouga Estuary (Ria de Aveiro), Portugal

Estuarine areas often concentrate complex and conflicting sets of natural, economic and social resources and activities with multiple challenges to planning and management approaches as well as to governance practices. Using a set of integration factors depicted from the literature review, the paper analyzes the main features of the new set of the Portuguese estuary types of plans and assesses their potential added value, while focusing the analysis on the estuary of the Vouga River (Ria de Aveiro). The results are twofold. On the one side, their uniqueness, by treating the estuary as a planning unit, integrating the water resources and the land use planning systems and by establishing mandatory rules for the estuary uses, embodies relevant potential for reducing boundary tensions and to improve integrative approaches. On the other side, while at the level of plan content the contribution of the Portuguese Estuary Land Use and Management Plans (Planos de Ordenamento de Estuário) legislation brings strong new prospects for integration, at the level of planning process and implementation, further efforts should be undertaken. Their added value, especially in complex institutional and societal estuarine contexts, such as the Ria de Aveiro, strongly depends on more robust participation schemes through which knowledge, institutions, aims and measures are articulated in a collective vision and shared governance process.     

Occurrence of pesticides and polychlorinated biphenyls in water of the Nile river at the estuaries of Rosetta and Damiatta branches,north of delta,Egypt

Abstract

A study was conducted from summer 1995 to summer 1997 to assess the seasonal occurrence of pesticide residues and other organic contaminants, polychlorinated biphenyls (PCBs), in water at the estuaries of Rosetta and Damiatta branches of the Nile river. The results indicated that organochlorine compounds (OCs) including HCB, lindane, p,p‘‐DDE, p,p‘DDD, p,p‘‐DDT, aroclor 1254 and aroclor 1260 were present in all the water samples at concentration levels ranging between 0.195–0.240, 0.286–0.352, 0.035–0.067, 0.019–0.033, 0.024–0.031, 0.390–0.70 and 0.166–0.330 μg/l, respectively. The levels of these compounds were higher in water of Damiatta branch than those found in water of Rosetta branch. Aldrin, dieldrin and endrin were not detected in all water samples. Only 4 compounds from 36 organophosphorus insecticides, fungicides and s‐triazine herbicides tested were detected in water samples collected during summer and autumn seasons from Rosetta branch. The concentration levels of these detected compounds, dimethoate, malathion, captan, and ametryne, ranged from 0.011 to 0.340 μg/l, respectively. Similar compounds during the same seasons as found in water of Rosetta branch were also detected in water of Damiatta branch except ametryne. The levels of the detected compounds (dimethoate, malathion and captan) ranged between 0.030 and 0.330 μg/l. The levels of detected organophosphorus insecticides, fungicides and s‐triazine herbicides were in the order: dimethoate > malathion > captan > ametryne.     

Using Parasitic Trematode Larvae to Quantify an Elusive Vertebrate Host

Abstract: Digenean trematode parasites require multiple host species to complete their life cycles, and their abundance can often be strongly correlated with the abundance of their host species. Species richness and abundance of parasites in easily sampled host species may yield an accurate estimate of the species richness and abundance of other hosts in a parasite's life cycle that are difficult to survey directly. Accordingly, we investigated whether prevalence and mean abundance of trematodes could be used to estimate the abundance of one of their host species, diamondback terrapins (Malaclemys terrapin), which are difficult to sample and are designated as near threatened (by the International Union for Conservation of Nature [IUCN Red List]) along some U.S. coasts. As an adult the trematode Pleurogonius malaclemys is specific to terrapins. Its larval stages live first inside mud snails (Ilyanassa obsoleta) and are subsequently shed into the environment where they form external metacercarial cysts on hard surfaces such as snail opercula. The life cycle of P. malaclemys is completed when terrapins ingest these cysts. At 12 sites along the coast of Georgia (U.S.A.), we determined the prevalence of internal P. malaclemys larvae in mud snails (proportion of infected snails in a population) and the prevalence and mean abundance of external trematode cysts. We examined whether these data were correlated with terrapin abundance, which we estimated with mark‐recapture methods. The abundance of external cysts and salinity explained ≥59% of the variability in terrapin abundance. We suggest that dependent linkages between the life stages of multihost parasites make them reliable predictors of host species’ abundance, including hosts with abundances that are challenging to quantify directly.     

TMDL Balance: A Model for Coastal Water Pollutant Loadings

Bacterial contamination accounts for more than 60% of the impairments included on the 2008 Texas 303(d) List. Many of these bacterial impairments are along the Texas Gulf Coast because coastal waters often are regulated for oyster harvesting, which have strict water quality standards. Under the Clean Water Act, each one of these impaired waterbodies requires a total maximum daily load (TMDL) study to be performed. A recent, statewide study recommended the development and application of simple modeling approaches to address the majority of Texas's bacteria TMDLs, including “… simple load duration curve, GIS [geographic information systems], and/or mass balance models.” We developed the TMDL Balance model in response to this recommendation. TMDL Balance is a steady state, mass balance, GIS‐based model for simulating pollutant loads and concentrations in coastal systems. The model uses plug‐flow reactor and continuously‐stirred tank reactor equations to route spatially distributed point and nonpoint source loads through a watershed via overland flow, non‐tidal flow, and tidal flow, decaying the loads via first‐order kinetics. In this paper, we explain the development of the watershed loading portion of the TMDL Balance model, demonstrating the methodology through a case study: computing bacterial loads in the Copano Bay watershed of southeast Texas. The application highlights an example of distributing bacterial sources spatially based on land use data.     

MATHEMATICAL MODELING OF GULF COAST ESTUARIES1

The environmental pollution problems prevalent in gulf coast estuaries are a cause of great concern to those in water quality management. This paper outlines the dominant characteristics which affect the properties of these estuaries including geography, tide and current effects, wind effects, salinity and density regime, nature and level of waste discharge, low inflow levels, dredging effects and present quality levels. Two basic levels of analytical modeling which are useful in water quality management are presented. The first is a relatively crude completely mixed estuarine model which permits economical evaluation of varying parameters. The second is a very general steady state model which permits analysis of stratified systems. The ESTPOL computer language designed to simplify the use of the steady state model is described. The practical use of the analytical models as management tools for the solution of Texas Estuarine quality problems is demonstrated.     

TEMPORAL VARIABILITY OF WATER QUALITY IN THE ST. LUCIE ESTUARY,SOUTH FLORIDA1

ABSTRACT: Four years of monthly freshwater discharge and constituent concentration data from three tributaries were related to a concurrent series of data for three segments of the St. Lucie Estuary in South Florida using multiple regression and time-series analysis techniques. Water quality parameters examined were dissolved inorganic and total nitrogen and phosphorus, chlorophyll a, total suspended solids, turbidity, and color. On monthly time scales, a multiple regression, which included freshwater discharge, freshwater constituent concentration, and dilution with ocean water (salinity) as independent variables, explained 50 percent or less of the variability in estuarine constituents. No single independent variable explained more variation than another. By contrast, on seasonal (wet, dry) time scales, freshwater discharge explained the bulk of variation in estuarine water quality (up to 93 percent). On monthly time scales, variability in concentrations of nutrients and other constituents may be largely controlled by processes internal to the system. At seasonal time scales, freshwater discharge appears to drive variability in most estuarine water quality parameters examined. Results indicate that management of tributary input on a seasonal basis, with the expectation of achieving seasonal concentration goals in the estuary, would have a higher probability of success than managing on a monthly basis.     

Assessing perceptions about ecosystem health and restoration options in three east coast estuaries

Increasingly public and governmental agencies are concerned aboutrevitalizing coastal environments. Understanding how the publicuses these areas, and what they see as the most important improvements to these regions is critical to their assessment andmanagement. Uses of three estuaries, and perceptions of possiblemanagement and restoration options, were examined for people whowere interviewed in the New York/New Jersey Harbor, Manasquan Inlet, and Barnegat Bay, New Jersey. Nearly 90% of the people interviewed listed pollution as New Jersey's most important environmental problem. Most people (68%) used the habitat for outdoor sports, but rated communing with nature, walking, and the provision of open `green' space as the most valued uses. Pollution prevention was the most often mentioned habitat improvement desired, and people rated removing pollution, cleaning up garbage, and creating more fish breeding habitat the highest. There were significant locational differences inhow people used the estuaries, and in how they thought they should be improved. People from Barnegat Bay ranked most uses higher than did people from elsewhere, while the people from Manasquan Inlet rated the importance of most remediation and restoration actions higher. Many of the improvements fall withinenvironmental management, including (rank order from high to low)creating more fish breeding habitat, improving native vegetation,improving habitat for birds, increasing plant diversity,improving habitat for butterflies, and enlarging adjacentmarshes. The data provide clear support for the importance ofthese coastal habitats for communing with nature and having open`green space' spaces, and for providing recreationalopportunities. To enhance their value, people want to removepollution and improve both the habitat quality and the educational and recreational facilities.     

Environmental Monotoring and Assessment Program: Current Status of Virginian Province (U.S.) Estuaries

Monitoring of indicators of the ecological condition of bays, tidal rivers, and estuaries within the Virginian Biogeographic Province (Cape Cod, Massachusetts to Cape Henry, Virginia) was conducted annually by the U.S. EPA's Environmental Monitoring and Assessment Program (EMAP) during the summer months of 1990 to 1993. Data were collected at 425 probability-based stations within the Province. Indicators monitored included water quality (temperature, salinity, water clarity, and dissolved oxygen concentration), sediment contamination, sediment toxicity, benthic community structure, fish community structure, and fish gross external pathology. Data were used to estimate the current status of the ecological condition of Virginian Province estuarine resources, and provide a baseline for identifying possible future changes. Estimates, with 95% confidence limits, of the areal extent of impacted resources within the Province are provided. Data are also presented by estuarine class (large estuaries, small estuarine systems, and large tidal rivers). Results show that, overall, approximately half of the estuarine waters of the Virginian Province can be classified as impacted based on multiple indicators, with hypoxia being the major stressor.