In Washington, D.C., Rock Creek tributary was sampled on a monthly or bimonthly interval during base-flow conditions. For comparison, the Potomac Estuary was sampled once each during the winter and summer of 1997. Upstream, trace element loadings are dominantly dissolved in primary watersheds and tributaries. Downstream, the loadings are dominantly particulate at the fall-line, unlike most tributaries. A comparison of dissolved tributary concentrations indicate some downstream retention.
Instantaneous loadings show both midstream weathering and downstream urban sources.
Basin yields show both sources to be important, equal for crustal and urban for pollutant elements. Estuarine concentrations are comparable to that at the fall line, but dissolved processing from biota and marshes is evident. Tables and charts are included throughout the report. Glossary of Zoning, Development and Planning Terms , May 2000. The glossary, published by the American Planning Association, contains 2,887 terms, some of which are accompanied by graphics or photos to illustrate the terms.