CAREER: Impact of Urbanization on Organic Carbon-Metal Interactions and Trophic Transfer in Streams

University Of Connecticut, Storrs CT

Investigators

Abstract

1454448 Vadas CAREER: Impact of Urbanization on Organic Carbon-Metal Interactions and Trophic Transfer in Streams In an increasingly urbanizing landscape, the negative impact of metals from both stormwater and wastewater effluent on organisms in streams will continue to rise. While the focus of most metal bioavailability models for stream organisms is on ambient exposure to dissolved metal phases, this proposed research also addresses the integral role of attachment and ingestion of organic matter in controlling bio-uptake of metals. At the ecosystem scale, the biodynamics of metal uptake and retention relate to both metal and organic matter characteristics, exposure patterns and feeding behavior of stream organisms. Assessment of metal speciation and size distribution as well as organic matter characteristics as related to metal uptake is required knowledge for the development of ecosystem level exposure assessment models that are useful for establishing management strategies for streams. In addition to the proposed research, the education plan will support the training of 1 M.S. and 1 Ph.D. student and at least 2 undergraduate researchers. Enhanced student training will focus on additional coursework in related disciplines and communication skills to promote interdisciplinary research in the future. Educational modules will be developed for K-12 classrooms according to State education guidelines. These modules will be disseminated through the DaVinci program at the University of Connecticut to broaden their reach beyond an individual classroom. A significant aspect of this project will be integrating ecology and environmental engineering across all levels of education through a focus on basic understanding and communication across disciplines: Several interdisciplinary problem-based learning exercises will be developed for university level education and K-12 education modules related to stream impairment will be developed and distributed widely. This career development plan addresses the research and education challenges associated with developing more effective management strategies for impaired streams in urban areas. The existing framework to assess and manage impaired streams does not address the dynamic and unique conditions present in streams. Metals such as copper and zinc are both necessary and toxic depending on the concentration, and are one of the most common causes of impairment. However, the strong interaction with organic matter across all size ranges and differences in exposure patterns of the effluent and stormwater sources of impairment are dramatic. Total metal loads are not necessarily good indicators of bio-uptake and both metal lability and ingestion of the different organic-metal particulates must be considered. In order to address the stream impairment issues associated with different metal sources, a more complete understanding of metal bio-uptake under urban stream conditions is required. To accomplish this, the following objectives and approach will be: 1) Quantify the variability of metal speciation and size distribution in different stream source waters across space and time: Automated samplers will collect time interval and flow-weighted samples of effluent and stormwater runoff, respectively, at impaired sites across a range of urban to suburban sites. Samples will be separated into size fractions relevant to biotic uptake and analyzed for total metals, organic matter, colloidal metal and organic matter size distribution, and organic matter optical, chemical and metal binding characteristics. 2) Identify metal speciation and size distribution predictors of biological uptake in primary producers and higher trophic level organisms and the dependence on metal loading dynamics: Metal uptake and attachment will be analyzed as a function of size distribution and chemical characteristics of the organic matter in different source waters. Biodynamic modeling will assess the net metal uptake into algae and subsequent transfer to higher trophic level organisms. These will be examined under exposure regimes that mimic the stream, e.g. with different ratios of source water to stream water for effluent sources and varying exposure concentrations for stormwater runoff.