Modeling Streamflow and Water Quality Sensitivity to Climate Change and Urban Development in 20 U.S. Watersheds

Watershed modeling in 20 large, United States (U.S.) watersheds addresses gaps in our knowledge of streamflow, nutrient (nitrogen and phosphorus), and sediment loading sensitivity to mid‐21st Century climate change and urban/residential development scenarios. Use of a consistent methodology facilitates regional scale comparisons across the study watersheds. Simulations use the Soil and Water Assessment Tool. Climate change scenarios are from the North American Regional Climate Change Assessment Program dynamically downscaled climate model output. Urban and residential development scenarios are from U.S. Environmental Protection Agency's Integrated Climate and Land Use Scenarios project. Simulations provide a plausible set of streamflow and water quality responses to mid‐21st Century climate change across the U.S. Simulated changes show a general pattern of decreasing streamflow volume in the central Rockies and Southwest, and increases on the East Coast and Northern Plains. Changes in pollutant loads follow a similar pattern but with increased variability. Ensemble mean results suggest that by the mid‐21st Century, statistically significant changes in streamflow and total suspended solids loads (relative to baseline conditions) are possible in roughly 30‐40% of study watersheds. These proportions increase to around 60% for total phosphorus and total nitrogen loads. Projected urban/residential development, and watershed responses to development, are small at the large spatial scale of modeling in this study.     

δ 13C and δ 15N variations in organic matter pools, Mytilus spp. and Macoma balthica along the European Atlantic coast

Stable carbon (δ ¹³C) and nitrogen (δ ¹⁵N) isotope (SI) values of sedimentary organic matter (SOM), seston and two dominant bivalves, Mytilus spp. and Macoma balthica, were studied at 18 stations along the European coast in spring and autumn 2004. Three main regions, the Baltic Sea (BS), the North Sea and English Channel (NS), and the Bay of Biscay (BB), were tested for possible geographic (latitudinal) differences in the SI values. In spring, only BS showed lower δ ¹³C values of seston and Mytilus spp., and higher δ ¹⁵N values of SOM, than NS and BB. No significant differences between the 3 regions were found in autumn. Irrespective of season and regions, Mytilus spp. was more ¹³C-depleted than M. balthica. δ ¹³C values of M. balthica, but not those of Mytilus spp., were significantly correlated with SOM. These results are consistent with differences in feeding behavior of Mytilus spp. and M. balthica, as the two species are known as obligatory-suspension and facultative-deposit feeders, respectively. In contrast, no differences in the δ ¹⁵N values of Mytilus spp. and M. balthica were found at individual stations, indicating the same trophic level of the two bivalves within the food webs. At some stations, irrespective of geographic location, both bivalves showed δ ¹⁵N values up to 18–20 ‰. These were two trophic levels higher than those found at the other stations, indicating local and/or episodic eutrophic conditions, probably due to waste water discharge, and the effectiveness of both Mytilus spp. and M. balthica as bio-indicators of anthropogenic eutrophication. Overall, our results suggest that pathways of energy flow from OM pools to dominant bivalves is more related to local environmental conditions than to geographic regions across the European coastline. This has implications for food web studies along the Atlantic coast because most of the values are consistent over a large area and show no significant differences. Therefore, the present study can be used twofold for the determination of trophic baselines and for the correction of the trophic position of consumers higher up in the food web in the case of differences in waste water discharge.     

Verhinderung einer Polymervernetzung durch Rühren

The Science of Nature -     

Seasonal and tidal changes in the length of the crystalline style intertidally living Macoma balthica (Mollusca,Bivalvia)

Samples of Macoma balthica were collected during 1978 and 1979 from the westernmost part of the Dutch Wadden Sea. The length of the crystalline style in the stomach of this intertidal bivalve was studied through tidal and annual cycles. The length of the style was ca. half the shell length and changed slightly with the season. Maximum lengths were recorded in spring, the season of high food intake, and minimal values in autumn and winter. Changes in the length of the style also exhibited a tidal cycle, but with two maxima and two minima. Tidal fluctuations in style length amounted to ca. 5% only. The influence of enzymes and waste products from the digestive diverticula, the food intake as well as the influence of the pH on the length of the style are discussed.Communication No. 401 of the Delta Institute     

Perspectives of a large scale environmental survey for chlorinated dioiins: water analyses

During 1983 and 1984, The Dow Chemical Company conducted a study to determine the extent of dioxin contamination at its Midland, Michigan plant and the surrounding area. The primary objectives of this study were to identify, rank order, and when possible quantify potential sources of dioxins to the environment and also to determine the extent of contamination in areas affected by the Dow facility. Early in the study, it was estimated that approximately 0.6g/year of 2378-TCDD was being emitted in 2.5 × 10¹⁰L of wastewater effluent. Data will describe observed sources of TCDD (both current and historical), environmental levels, existing water treatment methods, control measures taken, and future improvements on the water system to reduce TCDD in the effluent.     

A comparative assessment of heavy metal accumulation in soft parts and byssus of mussels from subarctic, temperate, subtropical and tropical marine environments

Existing data on metal concentrations in mussels from subarctic, temperate, subtropical and tropical waters were analyzed using multivariate statistics in order to assess regional variations in metal contamination. Potential errors were reduced by only analyzing data from surveys that employed the same protocols, analytical methodologies and analysts. Factor analysis demonstrated that mussels inhabiting extremely contaminated areas (e.g. from Japanese and Swedish metallurgy sources) could be separated from mussels from other contaminated areas, and that metals such as Cd, Pb, Cu and Zn could be used to identify heavily contaminated samples while Co, Fe, Cr and Ni concentrations were good markers for exposure to inputs from different industrial sources. Furthermore byssus, like soft tissue, selectively and sensitively reflects variations of certain metal concentrations in ambient waters and thus serves as a reliable biomonitor for these contaminants in a variety of coastal and estuarine areas.