Effects of Waste Disposal Operations in Estuaries and the Coastal Ocean

Abstract

Since about 1800, human activities have significantly altered shorelines, bottom topography, sediment characteristics, and marine life in estuarine and coastal waters. The first man-induced changes of thc ocean were restricted to nearshore waters and most were small, scattered, and primarily associated with food production or port development (Klimm 1956). Sediment deposition caused by erosion of agricultural lands resulted in extensive delta building and shoreline changes in the Persian Gulf, the Adriatic Sea, and the Mississippi Delta, to name a few examples (Davis 1956). Diking and draining of wetlands, shallow ocean areas, and lakes to form agricultural land has greatly altered shorelines in the Netherlands and England (Davis 1956). Not all wastes are placed directly in the ocean. Some are brought there by normal sediment transport processes. For example, mining is a prolific sediment producer and has also caused extensive changes in wetlands and shorelines due to downstream sediment deposition. Perhaps the best studied case is the hydraulic mining of gold in California's Sierra Nevada (Gilbert 1917). Between 1850 and 1914, 1.8 x 109 m3 of debris was mobilized by mining and erosion in the San Francisco Bay drainage system. About 1.1 x 109 m 3 was deposited in the bay system or on wetlands (Gilbert 1917). Movement and deposition of this material apparently persisted for approxi­ mately 50 years after cessation of mining (Smith 1965). More recently, rapid growth of coastal cities and associated industry has led to greatly incrcascd construction, demolition, and dredging, and the disposal of wastes produced from these activities has emerged as a geologic process causing significant changes in coastal areas. Because waste solids have caused the most obvious geologic changes, this review deals primarily with these materials. Effects of dissolved wastes such as nutrients have been extensively discussed elsewhere (NAS 1969, Likens 1972).