The N balance has been studied in detail in the basins of small rivers under agricultural management and forest use. The N content of the watershed territory of large forests was found to be practically balanced. In the river basin where the land was intensively farmed for 10 yr, N input increased five times through mineral fertilizers, and one-and-a-half times through organic fertilizers. Consequently, the amount of N returned to the atmosphere as a result of denitrification increased by one-and-a-half times, and that leached into the ground water, increased from 0.8 to 6.5 mg 1('-1) N.

Laboratory experiments were conducted to determine the effects of Kepone on the larval development of the mud-crab, Rhithropanopeus harrisii, and the commercial blue-crab, Callinectes sapidus, from the time of hatching until the 1st crab stage was reached. Differential survival of R. harrisii from hatching to 1st crab stage occurred in a range of 35 to 125 ppb Kepone, whereas differential survival of C. sapidus over the same period of development occurred in a range of 0.1 to 1.0 ppb. Statistical analysis indicated that, for every 10 ppb Kepone added, duration from hatching to 1st crab stage of R. harrisii was increased by 0.391+/-0.043 days; whereas for each increase of 0.1 ppb, the duration from hatching to 1st crab stage of C. sapidus is prolonged by 0.38+/-0.10 days. The 1st and 2nd zoeal stages of R. harrisii were the most sensitive developmental stages to Kepone, but the 1st zoeal stage of C. sapidus was not sensitive, statistically, to any concentration of Kepone tested. In zoeal stages II, III and IV, there were significant increases in mortality of C. sapidus over the previous stage in all media tested.

In order to ensure adequate performance and warn of potential ground water contamination, land application systems must be monitored. The monitoring system for the Lake George Village Sewage Treatment Plant land application system is described, including suction Isyimeters, observation wells and tracer studies.

A simple marine algal bioassay method is described for short- and long-term studies on pesticides and industrial wastes. It can be used for rapid screening of a variety of substance with single-species and multiple-species tests and gives relative toxicities of the pollutants tested. Algae are grown in optically matched culture tubes that fit directly into spectrophotometer, allowing population density to be estimated by absorbance without removal of samples. 96h EC50 values for some pesticides and the diatom Skeletonema costatum are: EPN, 340 micro-g/l; carbophenothin, 109 micro-Gg/l; DEF,366 micro-g/l; ethoprop, 8.4 micro-g/l; methylparathion, 4.3 micro-g/l, and phorate, 1.3 micro-g/l. Presence of the chelator EDTA in medium had no effect on toxicity of carbaryl to S. costatum, Nitzschia angularum, Chorococcum sp. and Chlorella sp. Liquid industrial wastes either stimulated growth, inhibited growth, or stimulated growth at low concentrations but inhibited it at higher concentrations. In mixed species studies with the herbicide neburon, presence of a resistant species protected the sensitive species. Liquid industrial wastes from a paper products plant caused changes in relative numbers, as compared to controls, when S. costatum and Porphyridium cruentum were grown together.

The herbicide bromacil was applied annually or once in 2 yr to a railway track on a sand bed. Once a year, in the Spring, just before a possible next application, samples were taken from various depths down to at least 80 cm for residue-analysis by gas chromatography. The procedure for extraction was adapted in order to eliminate interfering substances originating from the dark top layer of the soil. Bromacil contents were always highest in the 10 to 20 cm layer. Within the first 2 yr of the experiments the compound penetrated down to depths around 100 cm. Calculations showed that deeper penetration of bromacil was probable. On account of the low conversion rate of the herbicide it seems possible that a part of the bromacil dosage leached to the groundwater later on

The aim of the process under consideration is the degradation of organic pollutants contained in waste water from olive processing. Degradation takes place by processing the polluted water in a tank which contains soil that has certain chemical and biochemical characteristics. The effect of the treatment is an enrichment of the soil with readily-assimilable nutrient substances to the extent that the soil pollutant mixture becomes soil-compost. Neither sludge nor solid residual products are formed in the process, since they too undergo degradation. The treatment of water and sludge is completed on parcels of land underlain with a water-tight base. The watertight floor prevents filtration of polluting substances in the treated water from percolating into the underlying soil.

A quantitative index of synergism, anatagonism and additivity has been measured experimentally in the fish Mystus vittatus for three pesticides viz. Thiotox (Endosulfan) (T), Dichlorvos (D) and Carbofuran (C). For a combination of two pesticides, the dose of the one pesticide of a pair was fixed at the no-effect level while the dose of the second pesticide was increased until the entire dose response curve was obtained. To evaluate interactions of three pesticides, the previous pair of pesticides was kept fixed at their combined TL(,0) level, and the third pesticide was increased and again a dose-response curve was obtained. From the results obtained, it is shown that a particular combination could be synergistic, antagonistic or additive, depending on the relative doses employed. In the present study (T + D)/C combination was most synergistic (toxic) in nature while D/T and C/T were least toxic antagonistic in their effects. However, T/D, (C + T)/D, C/D and D/C combinations were additive in nature. (D + T)/C, (D + C)/T, (T + C)/D and (C + D)/T combinations were found less synergistic in nature than (T + D)/C.

The aerobic and anaerobic degradation of phenol and selected chlorophenols was examined in a clay loam soil containing no added nutrients. A simple, efficient procedure based on the high solubility of these compounds in 95 per cent ethanol was developed for extracting phenol and chlorophenol residues from soil. Analysis of soil extracts with UV spectrophotometry showed that phenol, o-chlorophenol, p-chlorophenol, 2,4-dichlorophenol, 2,6-dichlorophenol and 2,4,6-trichlorophenol were rapidly degraded, while m-chlorophenol, 3,4-dichlorophenol, 2,4,5-trichlorophenol and pentachlorophenol were degraded very slowly by microorganisms in aerobically-incubated soil at 23 deg C. Both 3,4,5-trichlorophenol and 2,3,4,5-tetrachlorophenol appeared to be more resistant to degradation by aerobic soil microorgamisms at 23 deg C. None of the compounds examined were degraded by microorganisms in anaerobically-incubated soil at 23 deg C. Direct microscopic observation revealed that phenol and selected chlorophenols stimulated aerobic and to a lesser extent, anaerobic microbial growth in soil, and aerobic soil bacteria were responsible for the degradation of 2,4-dichlorophenol in aerobically-incubated soil at 23 deg C. Phenol, o-chlorophenol, m-chlorophenol, p-chlorophenol and 2,4-dichlorophenol underwent rapid non-biological degradation in sterile silica sand. Non-biological decomposition contributed, perhaps substantially, to the removal of some chlorophenols from sterile aerobically-incubated soil and both sterile and non-sterile anaerobically-incubated soil

This analysis measures trade-offs between soil loss and food production costs. It is made by means of multigoal interregional programming model. The trade-off curve is derived by means of the prior weighing technique. The results indicate that soil loss from agricultural land can be decreased considerably with very little increase in cost in efficiency in food production. However, the trade-off curve has a "corner" in it, and further reductions in soil loss give rise to sharp increases in food production costs. As higher costs are assigned soil loss, important shifts take place in the interregional patterns of crop production and land use. Also, further decreases in soil loss and increases in food production costs raise food prices for consumers.