Formerly the Limnology Department, the Patrick Center for Environmental Research concerns itself with applied ecology. Founded in 1947 by Ruth Patrick, formerly of the Diatom Herbarium, it was one of the earliest U.S. environmental consulting concerns. Its attachment to the Academy led it to become the first to employ interdisciplinary teams of scientists to study freshwater systems and the first to regard biodiversity as a central criterion of water quality. Its 1948 biological survey of the Conestoga River Basin in Pennsylvania, a milestone in environmental research, led to similar surveys and studies throughout much of the United States. Characteristically, these earlier projects were joint projects of the Limnology Department and private industry. Since the rise of the environmental movement in the 1960s and 1970s and the resulting increases in governmental regulation of water pollution, the environmental assessments pioneered at the Academy are increasingly conducted by private environmental consulting firms.  , much of the research at the Patrick Center is conducted with regulatory agencies and other governmental bodies, in fields such as diatom autecology, environmental chemistry and toxicology, habitat restoration, long-term environmental trends, species conservation, and watershed management. Some of the work employs most of the center's expertise and capabilities, such as recent studies on the ecological effects of small dams or the ecological benefits of riparian reforestation. Other studies may involve only one or a couple of the research programs. For example, a current project sampling sediment cores in tidal marshes throughout the Delaware Estuary. This undertaking, possibly the most comprehensive core sampling in any estuary, relies extensively on the center's expertise in biogeochemistry and phycology. Once the sampling is completed, scientist will be able to investigate historical trends in marsh development, carbon, nitrogen and phosphorus cycling, water pollution, salinity variations, and climatic change by analyzing the core's sediments, chemistry, and diatom assemblages. The Biogeochemistry Section of the Patrick Center is concerned with the influence of aquatic organisms on the sources, fate and transport of chemicals in aquatic systems. Studies frequently deal with the carbon and nutrient cycling as well as those of trace elements (e.g., lead, copper, mercury, and zinc) and organic contaminants such as polychlorinated biphenyls (PCBs), and polycyclic aromatic hydrocarbons (PAHs). The section regularly provides water, sediment and tissue analyses for government, intergovernmental agencies, and private companies from around the country. In addition to the sediment core project mentioned above, it has recently studied the effects of small dams on sediment contaminants, photochemical transformation of marsh-derived dissolved organic matter, and sedimentation and eutrophication in salt marshes.