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

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.

Abstract. Samples of forty sewage sludges taken in England during 1979 were analysed for ten heavy metals using a rapid flameless atomic absorption spectroscopic technique. For all metals the mean concentrations were influenced by a small number of sludges containing exceptionally high concentrations. Typically, the concentration ranges showed approximately a 100-fold spread. Calculations based on U.K. guidelines for limiting the addition of toxic metals in sludge to agricultural soils indicated that application rates would theoretically be limited for more than 75% of the sludges by the concentrations of Zn, Cu and Ni, expressed additively as the Zn equivalent. Calculations of the theoretical maximum quantities of sludges which could be applied to land on an annual basis suggested that a significant proportion of the sludges would be unsuitable for application to agricultural land at rates of more than 2 t ha('-1) yr('-1).