SEDIMENT RESUSPENSION AND DRAWDOWN IN A WATER SUPPLY RESERVOIR1

ABSTRACT: The magnitudes and patterns of sediment resuspension are assessed in Cannonsville Reservoir, New York, to quantify and characterize this internal source of sediment. The assessment is based on analyses of sediment trap collections from 10 sites over the spring to fall interval of two years. Temporal and spatial patterns in sediment deposition are demonstrated to be driven by resuspension/redeposition processes. Sediment that had been resuspended and redeposited represented 80 to 96 percent, on average, of the depositing solids collected along the main axis of the lake. About 90 percent of the redeposited sediment was inorganic. Increased resuspension caused by drawdown of the reservoir surface and fall turnover resulted in 10 to 50‐fold increases in deposition rates compared to levels observed when the reservoir was full and strongly thermally stratified. Elevated levels of redeposition from resuspension in the reservoir have been driven by both higher water column concentrations of suspended solids and settling velocities. Recurring longitudinal and lateral gradients in resuspension are delineated, establishing that resuspended solids are transported from the riverine to the lacustrine zone and from near‐shore to pelagic areas. Resuspension is demonstrated to cause increases in inanimate particle (tripton) concentrations. Higher tripton levels have been observed in years with greater drawdown. Water quality impacts of the resuspension phenomenon are considered.     

WATER QUALITY IMPACTS AND INDICATORS OF METABOLIC ACTIVITY OF THE ZEBRA MUSSEL INVASION OF THE SENECA RIVER1

ABSTRACT: The conspicuous shifts in summertime values of common measures of water qualify that have persisted for 10 years (1993 to 2002) in the Seneca River, New York, as a result of the zebra mussel invasion are documented. Resolution of patterns in time and space is supported by water quality monitoring that extends back to the late 1970s. Patterns are evaluated to describe the stability of impacts and quantify metabolic activity of the invader. The water quality impacts that have persisted unabated for 10 years since the invasion are the most severe documented for a river in North America. Changes in summer median conditions since the invasion include: (1) a 16‐fold decrease in chlorophyll concentration (Chi), (2) a 2.5‐fold increase in Secchi disc transparency, (3) a 17‐fold increase in soluble reactive phosphorus concentration, (4) a 3.7‐fold increase in total ammonia concentration, (5) a greater than 25 percent decrease in dissolved oxygen (DO) concentration, and (6) a decrease in pH of 0.55 units. The strength of these signatures has been driven by anthropogenic influences that include upstream nutrient loading and morphometric modifications of the river, and the functioning of Cross Lake, through which the river flows. This hypereutrophic lake sustains dense zebra mussel populations and related water quality impacts in the river downstream of the lake outflow by acting as a source of veligers and suitable food for this bivalve. Evidence is presented that levels of metabolic activity of the zebra mussel in this river have been resource limited, manifested through increased consumption of Chl and DO with increased delivery of these constituents in the lake's outflow.     

Use of lignin degrading fungi in bioremediation

The use of lignin degrading fungi for decomposition of a wide variety of xenobiotics has become an area of intensive research. One distinct advantage of lignin degrading fungi over bacteria is that they do not require preconditioning to a particular pollutant prior to transformation. This degradative ability has been attributed to a nonspecific and nonstereoselective extracellular lignin-degrading enzymatic system (ligninase) which is induced by the fungi under nitrogen or carbon-limiting conditions (Reid, 1979). Ligninases (lignin-peroxidases) are responsible for the initial oxidative attack on lignin and other complex molecules via formation of a free radical thereby leading to depolymerization of complex molecular structures. Potential degradative ability of peroxidases may extend to include (1) sorbed contaminants, (2) high molecular-weight, hydrophobic contaminants, and (3) complex mixtures of chemicals typical of a contaminated site.     

Role of heavy polar organic compounds for water repellency of sandy soils

Separation and chemical characterisation of specific compounds responsible for soil water repellency has not previously been achieved. Here we describe the extraction, separation and analysis by gas chromatography-mass spectrometry of organic compounds found in wettable and water repellent sandy soils from the Netherlands and United Kingdom. Fatty acids (C₁₆–C₂₄), amides (C₁₄–C₂₄), alkanes (C₂₅–C₃₃), aldehydes/ketones (C₂₃–C₃₁) and complex ring-containing structures were detected in all samples. We found a greater abundance of high molecular mass polar compounds in the water repellent samples.     

Analysing countries’ contribution to climate change: scientific and policy-related choices

This paper evaluates the influence of different policy-related and scientific choices on the calculated regional contributions to global climate change (the “Brazilian Proposal”). Policy-related choices include the time period of emissions, the mix of greenhouse gases and different indicators of climate change impacts. The scientific choices include historical emissions and model representations of the climate system. We generated and compared results of several simple climate models. We find that the relative contributions of different nations to global climate change—from emissions of greenhouse gases alone—are quite robust, despite the varying model complexity and differences in calculated absolute changes. For the default calculations, the average calculated contributions to the global mean surface temperature increase in 2000 are about 40% from OECD, 14% from Eastern Europe and Former Soviet Union, 24% from Asia and 22% from Africa and Latin America. Policy-related choices, such as time period of emissions, climate change indicator and gas mix generally have larger influence on the results than scientific choices. More specifically, choosing a later attribution start date (1990 instead of 1890) for historical emissions, decreases the contributions of regions that started emitting early, such as the OECD countries by 6 percentage points, whereas it increases the contribution of late emitters such as Asia by 8 percentage points. However, only including the fossil CO₂ emissions instead of the emissions of all Kyoto gases (fossil and land use change), increases the OECD contributions by 21 percentage points and decreases the contribution of Asia by 14 percentage points.     

A quantitative analysis of beach health and pollution across Southern Britain

We thank the Forestry Commission Conservancies, the Crown Estate (Windsor), the Hertfordshire & Middlesex Wildlife Trust, and the Property Services Agency for the use of trees and sites, C. Palmer for field assistance and Drs. A. Roloff, R. G. Derwent and J. N. Gibbs for discussions.     

Sediment influence on congener-specific PCB bioaccumulation by Mytilus edulis: a case study from an intertidal hot spot, Clyde Estuary, UK

An intertidal site in the Clyde Estuary, UK, was selected to evaluate the role of sediment geochemistry on the bioaccumulation of polychlorinated biphenyls (PCBs) by mussels (Mytilus edulis). The area had previously been identified as showing anomalously high levels of PCB contamination (over 1,500 microg kg(-1) total PCB in sediment, 22 congeners). Samples of surface sediment and M. edulis were collected from two closely located sites, one within the anomalous area and another representing typical PCB contamination in the estuary. Sediment samples were separated into grain size fractions and analysed for a range of biomarker compounds, PCBs and sediment mineralogy. The anomalous site showed an atypical association of PCBs with sediment properties, despite both locations showing influence of both petrogenic and pyrogenic organic contamination. Interrogation of data using correlation and principal component analysis showed that sediment mineralogy as well as organic matter composition influenced PCB congener distribution. One sediment source was found to control the PCB concentration in mussels at both locations and clay mineralogy appears to control PCB uptake by biota with preference for higher molecular weight congeners. Overall bioavailability is determined by sediment TOC.     

National-Level Wetland Policy Specificity and Goals Vary According to Political and Economic Indicators

Environmental Management - Growing recognition of the importance of wetlands to human and ecosystem well-being has led countries worldwide to implement wetland protection policies. Different...     

Apportionment of bioavailable phosphorus loads entering Cayuga Lake,New York

The integration of the phosphorus (P) bioavailability concept into a P loading analysis for Cayuga Lake, New York, is documented. Components of the analyses included the: (1) monitoring of particulate P (PP), soluble unreactive P (SUP), and soluble reactive P (SRP), supported by biweekly and runoff event‐based sampling of the lake's four largest tributaries; (2) development of relationships between tributary P concentrations and flow; (3) algal bioavailability assays of PP, SUP, and SRP from primary tributaries and the three largest point sources; and (4) development of P loading estimates to apportion contributions according to individual nonpoint and point sources, and to represent the effects of interannual variations in tributary flows on P loads. Tributary SRP, SUP, and PP are demonstrated to be completely, mostly, and less bioavailable, respectively. The highest mean bioavailability for PP was observed for the stream with the highest agriculture land use. Point source contributions to the total bioavailable P load (BAP_L) are minor (5%), reflecting the benefit of reductions from recent treatment upgrades. The BAP_L represented only about 26% of the total P load, because of the large contribution of the low bioavailable PP component. Most of BAP_L (>70%) is received during high flow intervals. Large interannual variations in tributary flow and coupled BAP_L will tend to mask future responses to changes in individual inputs.