Predictions of the complex annual cycle of temperature changes in a lake or reservoir are necessary if proper water quality control is to be achieved. Many lakes and reservoirs exhibit horizontal homogeneity and thus a time-dependent, one-dimensional model describing the temperature variation in the vertical direction is adequate. A discretized mathematical model was developed based on the absorption and transmission of solar radiation, convection due to surface cooling and advection due to inflows and outflows. The model contains provision for simultaneous or intermittent withdrawal from multi-level outlets and time of travel for inflows within the reservoir.

Nuclear magnetic resonance spectra have been recorded, interpreted, and published for organophosphorus pesticides, DDT and related compounds, and carbamate pesticides and some of their degradation products. A Varian HA-100 NMR spectrometer with a variable-temperature probe and a homonuclear spin decoupler was used to record the spectra of 114 compounds. Chemical shifts and coupling constants are shown for each spectrum. The chemical name and source of each pesticide are listed.

Deicing agents for removal of ice and snow from highways and streets are essential to wintertime road maintenance in most areas of the U.S. Due to the ever-increasing use of highway deicing materials, there has been growing concern as to environmental effects resulting from these practices. The state-of-the-art report critically reviews the available information on methods, equipment and materials used for snow and ice removal; chlorides found in rainfall and municipal sewage during the winter; salt runoff from streets and highways; deicing compounds found in surface streams, public water supplies, groundwater, farm ponds and lakes; special additives incorporated into deicing agents; vehicular corrosion and deterioration of highway structures and pavements; and effects on roadside soils, vegetation and trees. Highway deicing can cause injury and damage across a wide environmental spectrum. Recommendations describe future research, development and demonstration efforts necessary to assess and reduce the adverse impact of highway deicing.

To determine the feasibility of eutrophication control by controlling carbon, three major areas were studied: the steady state, in which the growth rates of algae at various constant, maintained dissolved carbon dioxide concentrations were determined; the non-equilibrium, where natural atmospheric replenishment was the sole carbon source; and algal growth with inorganic bicarbonate as the sole carbon source. In studying growth rates of Chlorella, Microcystis, and Anabaena with respect to carbon availability, it was found that algae can utilize dissolved concentrations of carbon dioxide much lower than those from atmospheric equilibria.

A survey of 452 eutrophic lakes was compiled based on responses from 40 states requesting information as to (a) Name, location, size, depth; (b) Description of the problem, including accounts of previous corrective treatments, if any; (c) Remedial action that might be appropriate; (d) A description of available background data, indicating whether sufficient data exists to document a change if rehabilitation were undertaken. Categories of the problems in the survey were: nuisance algal growth, nuisance aquatic vegetation, fishkills, bacterial contamination, toxic contamination, oil brines, unstable water levels, siltation, excessive dissolved solids, and unspecified eutrophic conditions. Sources contributing to these problems were classified in two general categories--concentrated sources and diffused sources. Indication is given, where available, whether progress has been made to eliminate the pollution source.

Diatoms comprise the major group of algae in Iowa waters. Their ecological significance, important in pollution evaluation studies, cannot be fully appreciated without a thorough knowledge of their taxonomy. A scale for abundance rating was used giving at least a rough estimate if data permitted. The names of 50 diatom genera occurring in Iowa are listed and for each genus, the number of taxa in the master list and the number in the 'more common' list are presented. A pollen analysis is tabulated; the samples in this analysis extended through 35 ft. of sediment to the postglacial interface at Little Miller's Bay, Lake West Okoboji. Dating was conducted by the radiocarbon technique for samples taken between 34 ft. and 35 ft. in the sediment core. Since this level had the maximum spruce pollen concentration and the pollen percentage decreased progressively above this level, it was considered as the postglacial interface. Some interesting problems lie in consideration of those diatoms which have disappeared from the original lake flora and those which have become common only since the middle of the postglacial period.