Pesticides monitoring journal最新文献

Sediment samples were collected from a subarctic salt marsh on James Bay, Ontario in May 1976. Of 15 organochlorine compounds analyzed, trace amounts mainly of p,p-DDE and polychlorinated biphenyls (PCBs) were detected, but could not be quantitated.

Pacific oysters (Crassostrea gigas Thunberg) from 19 sites in Tasmania were surveyed for pesticide residues. All samples were analyzed for dieldrin and DDT, and five samples were analyzed for hexachlorobenzene (HCB) and lindane. Only DDT was found in all samples. Dieldrin levels were high in oysters from the Tamar River, but were highest (0.39 mg/kg wet weight) in samples from Ruffin's Bay. In contrast, other residue levels were low. Distribution of pesticides in Tamar River samples differed: dieldrin could be correlated with industrial uses upstream and DDT could be correlated with low-level widespread agricultural use.

Organochlorine pesticide residues in various organisms from different aquatic ecosystems in Iran were investigated in spring 1974. DDT levels were high in fish taken from two rivers in southern Iran, whereas low levels were detected in samples obtained from a freshwater lake in the same area. Fish from two of the reservoirs supplying Tehran with potable water contained moderate levels of DDT. The low residue level in pike collected in the Bandar-Pahlavi Mordab in northwest Iran indicates that only a small amount of organochlorine pesticides used in this area enters the pelagic food chain. Sturgeon collected at different places in the Caspian Sea showed similar accumulations of DDT in the muscles and in the eggs. Polychlorinated biphenyls (PCBs) were detected only in samples of sediment from the drainage systems in Tehran.

This report summarizes 1524 analyses of juvenile fish collected semiannually in 144 estuaries nationwide from July 1972 through June 1976. Pooled samples of 25 whole fish were screened for 20 common pesticides and polychlorinated biphenyls (PCBs). The three most common residues, DDT, PCBs, and dieldrin, were found in 39, 22, and 5 percent of the samples, respectively. Data indicate that estuarine pollution levels continue to decline.

Five species of fish from Lake Superior and 12 species from Lake Huron were analyzed for organochlorine pesticides and polychlorinated biphenyls (PCBs) between 1968 and 1975. Mean residues of sigma DDT peaked at 1.72 ppm and 7.60 ppm in lake trout (Salvelinus namaycush) from Lakes Superior and Huron, respectively. By 1975, the mean level of sigma DDT had decreased in lake trout and was highest in bloaters (Coregonus hoi) from both lakes: 1.06 ppm and 1.87 ppm, respectively. Dieldrin levels in fish from Lake Superior changed little over the same period. However, in 1969-70, dieldrin levels in fish from Lake Huron exceeded the 0.3 ppm tolerance level set by Health and Welfare Canada or the Food and Drug Administration, U.S. Department of Health, Education, and Welfare in 5 percent of lake whitefish (Coregonus clupeaformis) and 10 percent of bloaters. By 1975, 50 percent of bloaters caught in Georgian Bay and North Channel had dieldrin levels above 0.3 ppm. PCB residues declined in lake trout and lake whitefish caught in Lake Superior between 1971 and 1975, but increased slightly in bloaters and white sucker (Catostomus commersoni). Mean PCB residues in bloaters caught in Lake Huron in 1969-71 and 1975-76, and splake (Salvelinus fontinalis and S. namaycush) and cisco (Coregonus artedii) caught in 1975 exceeded the 2 ppm tolerance level.

Eighteen species of fish from Lake Saint Clair and 19 species from Lake Erie were analyzed for organochlorine pesticides and polychlorinated biphenyls (PCBs) between 1968 and 1976. Mean residues of sigma DDT peaked at 1.19 ppm in longnose gar (Lepisosteus osseus) caught in Lake Saint Clair in 1970-71, but had declined in all species by 1975-76. Dieldrin levels in fish tissues increased over the same period. White bass (Morone chrysops), caught in 1975 in Lake Erie, had the highest mean residue of dieldrin at 0.17 ppm. PCB residues increased in some species and decreased in others. PCB residues exceeding the tolerance level of Health and Welfare Canada were found in the following: from Lake Saint Clair, smallmouth bass (Micropterus dolomieui) in 1975 and channel catfish (Ictalurus punctatus) in 1971; from Lake Erie, coho salmon (Oncorhynchus kisutch) in 1970, smallmouth bass, alewife (Alosa pseudoharengus), freshwater drum (Aplodinotus grunniens), and gizzard shad (Dorosoma cepedianum) in 1971, and white bass in 1971 and 1976.

The widespread use of herbicides in Florida citrus groves raises the possibility of residue accumulation following repeated applications. To determine residue levels of commonly used herbicides, soil samples were taken from large experimental plots in commercial groves in Polk and Hardee Counties. Bromacil and diuron had been applied in combination at both locations for 7-8 years. Analyses of samples showed low levels of both herbicides at various soil depths to 60 cm. Only a small amount of bromacil was detectable one year after applications, but diuron levels were higher. Continuous applications at recommended rates and frequencies have resulted in maximum bromacil and diuron levels of 3.9 percent and 13.1 percent, respectively, of their total application.

The moratorium on agricultural use of DDT in Arizona that began in January 1969 proved very effective during the first 7 years of enforcement. Residues on green alfalfa declined significantly to a probable inherent level of 0.02 ppm wet weight. Soil residues of sigmaDDT-related degradation products declined significantly, averaging 23 percent; residues in desert soils declined 60 percent. The sigmaDDT half-life in irrigated soils was about 7 years; it decreased to 2.5 years in nonirrigated soils.