No abstract

Time series of wind, current, nutrients, chlorophyll, and zooplankton are used to examine the effect of storm events on the food chain dynamics of the New York Bjght. Storms cause dilution of phytoplankton concentration in the vertical plane, but lead to aggregation of chlorophyll in the horizontal field. Nutrients are made available with onshore flow in response to wind events favorable for upwelling.A series of nutrient budgets suggest that storm-induced mixing and upwelling of nitrate may satisfy at least 33% of the productivity demand of this system. Examples of the biological response to storms are drawn from 20 cruises during January, March, April-May, and August-September 1974, 1975, 1976 under mixed and stratified conditions of the water column. The interaction of storms and seasonal stratification suggests predictable structure and frequency of chlorophyll distribution across the shelf which mav influence both the survival strategies of herbivores and the loci of energy transfer to the rest of the food chain.

No abstract

Water-soluble anionic polyacrylamide (WSPAM), which is used to reduce erosion in furrow irrigated fi elds and other agriculture applications, contains less than 0.05% acrylamide monomer (AMD). Acrylamide monomer, a potent neurotoxicant and suspected carcinogen, is readily dissolved and transported in fl owing water. Th e study quantifi ed AMD leaching losses from a WSPAM-treated corn (Zea mays L.) fi eld using continuous extraction-walled percolation samplers buried at 1.2 m depth. Th e samplers were placed 30 and 150 m from the infl ow source along a 180-m-long corn fi eld. Th e fi eld was furrow irrigated using WSPAM at the rate of 10 mg L −1 during furrow advance. Percolation water and furrow infl ows were monitored for AMD during and after three furrow irrigations. Th e samples were analyzed for AMD using a gas chromatograph equipped with an electron-capture detector. Furrow infl ows contained an average AMD concentration of 5.5 μg L −1 . Th e AMD in percolation water samples never exceeded the minimum detection limit and the de facto potable water standard of 0.5 μg L −1 . Th e risk that ground water beneath these WSPAM-treated furrow irrigated soils will be contaminated with AMD appears minimal.

No abstract