Semiannual report

To understand the dynamics of trace metals in desert environments requires estimates of compartment concentrations or storages (i.e., amounts of elements in soils, plants and animals), determinations of rates of flow between compartments, and estimates of rates at which materials are introduced into and irreversibly lost from the system. This report deals with measurements of amounts of trace elements in the environment surrounding Southern California Edison's Mohave Generating Station in southern Nevada, a collaborative study with Los Alamos Scientific Laboratory of trace elements in the vicinity of the Four Corners Power Plant in New Mexico, and laboratory and field experiments related to cycling of trace elements

Environmental aspects of solar energy technologies

Solar energy technologies have environmental effects, and these may be positive or negative compared with current ways of producing energy. In this respect, solar energy technologies are no different from other energy systems. Where solar energy technologies differ is that no unresolvable technological problems (e.g., CO/sub 2/ emissions) or sociopolitical barriers (e.g., waste disposal, catastrophic accidents) have been identified. This report reviews some of the environmental aspects of solar energy technologies and ongoing research designed to identify and resolve potential environmental concerns. It is important to continue research and assessment of environmental aspects of solar energy to ensure that unanticipated problems do not arise. It is also important that the knowledge gained through such environmental research be incorporated into technology development programs and policy initiatives

Changes in the chemical composition of water percolating through the soil profile in a moderately polluted catchment

Throughfall (TF), stemflow (SF), soil solution below the organic layer (SSorg) and at 50 cm depth (SS50), and output with stream water (SW) were measured and analyzed for four years in a moderately polluted forest catchment in southern poland. The input of water with stemflow was ca. 6 A of input with TP. However, due to higher concentrations of most ions in SF, the input of most elements with SF was from 8% to 9%. Sulphate (SO42-), chloride (Cl-) and magnesium (Mg2+) were the only ions steadily increasing in concentrations in water percolating through the soil profile. Nitrogen reached the forest floor mainly as ammonium (NH4+). In the soil organic layer the NH4+ concentration decreased, while concentrations of nitrate (NO3-) and hydrogen (H+) increased, probably due to nitrification. For NO3-, sodium (Na+) and calcium (Ca2+), the highest concentrations were found in SSorg and SW. This indicates both efficient cycling in the biotic pool of the ecosystem and intensive weathering processes in the mineral soil below the plant rooting zone. The latter was especially pronounced for Mg and Ca. Concentrations of zinc (Zn), lead (Pb) and cadmium (Cd) were the highest in SSorg and SS50. As this was accompanied by a low pH and constant input of H+, NH4+ and heavy metal ions to the catchment area, it may pose a serious threat to forest health