摘要:

AbstractResearch was conducted on an 18‐ha, bermed, single‐field watershed in west Tennessee to characterize soil and nutrient losses during storm events over a 12‐month period. Total soil loss was approximately 104 metric tons, which is high for the nation but typical for west Tennessee. Minimums of 2% of applied phosphorus and 6% of applied nitrogen were lost from the field through storm water runoff. First‐flush analysis indicated that total suspended solids, orthophosphate, ammonia, and total Kjeldahl nitrogen migrated from the field faster than if proportional to the flow. In general, orthophosphate came off the field early in the runoff event, whereas other forms of phosphorus came off late in th

ISSN:0730-7268    

DOI:10.1002/etc.5620070801

出版商:Wiley Periodicals, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractPesticide migration from agricultural fields may stress receiving stream ecosystems as well as contaminate ground water. Research was conducted on an 18‐ha single‐field watershed in west Tennessee to characterize the fate of atrazine during a 12‐month period after pesticide application. Rainfall runoff and soil cores were sampled and analyzed for atrazine residues. Total loss of atrazine by runoff accounted for approximately 1.5% of the total atrazine applied. Concentrations as high as 0.25 mg/L were detected in the field discharge. By the fourth storm event after pesticide application, the atrazine concentration was below detection limits (0.1 μg/L). Atrazine loss in the upper 10 cm of soil followed a first‐order decay trend, with only 1.88% of the initial concentration remaining 238 d after pesticide application. The mean half‐life for atrazine in the upper 10 cm was approximately 21.5 d. Atrazine was detected in the 10‐ to 20‐cm soil level after the first rainfall. Atrazine was not detected below 20 cm at any sampling date during the 238

ISSN:0730-7268    

DOI:10.1002/etc.5620070802

出版商:Wiley Periodicals, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractThe PHYTOTOX database was analyzed to determine the taxonomic and geographical scope of information published on the toxicity of organic chemicals to terrestrial vascular plants. The data tabulated show the 20 most frequently tested chemicals, the 35 most often used plant genera and species, and the frequency of toxicity testing conducted on plants maintained under different growth conditions (greenhouse, cultivated field, wild, etc.). This information is discussed with regard to its applicability to environmental issues of concern. Examination of the data indicated that the influence of toxic waste compounds on plants is virtually unknown and that little research attention has been focused on the influence of chemical insult on the growth and development of wild plants.

ISSN:0730-7268    

DOI:10.1002/etc.5620070803

出版商:Wiley Periodicals, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractEnvironmental conditions can affect the metabolic transformation and accumulation of pollutants in aquatic organisms. Changes in temperature and feeding regimes had marked effects on the hepaticO‐deethylation of 7‐ethoxyresorufin (EROD) activity in bluegill sunfish. Animals that were denied food and acclimated for 2 weeks to 4, 13 or 26°C water exhibited low and relatively uniform EROD activity at all temperatures. In contrast, fed fish acclimated at 26°C exhibited a sevenfold higher level of activity compared with those acclimated to 4°C. Starved fish acclimated to 26°C were capable of EROD induction following intraperitoneal (i.p.) injection with benzo[a]pyrene (BaP). Doses of 10 and 20 mg BaP kg−1body weight increased EROD activity to 100 and 300 nmol min−1mg−1respectively, compared with 10 nmol min−1mg−1in fish injected with corn oil. Wild fish obtained from various stations along a polluted stream exhibited EROD activity levels comparable with those in laboratory fish injected with 20 mg BaP kg−1fish. When starved fish were injected i.p. with a Purina Trout Chow extract, EROD activity was induced to levels comparable with those in laboratory‐fed (Trout Chow) fish; this suggests the presence of an inducer in the Trout Chow. Exposure of fed fish to pH 5, 7 and 9 for a 2‐week period at 26°C had no effect on the mixed function oxidase (MFO) activity in fish liver microsomes. The results of this study indicate that environmental variables can affect the levels of MFO activity. A better understanding of these effects is needed before these indicators can be used routinely a

ISSN:0730-7268    

DOI:10.1002/etc.5620070804

出版商:Wiley Periodicals, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractEcosystem‐level responses were examined in microcosms developed from four different natural plankton communities and exposed to nominal concentrations of 0.12, 0.50, 2.0, 5.0 and 10.0 mg/L fluorene, a polynuclear aromatic hydrocarbon. The lowest observed (p<0.05) effect level (LOEL) for dark respiration (Rni) was 0.12 mg/L fluorene in three of the four communities during the first 14 d. The LOEL for Rniin the fourth community was 5.0 mg/L. The LOEL of the net productivity/respiration ratio (Pn/Rni) was 0.12 mg/L in all four communities. These results suggest that the responses of these microcosms were not completely independent of their source communities. The sensitivities or LOEL values from these microcosm experiments were as low as those reported for chronic bioassays of the three most sensitive of seven standard test organisms. Comparisons between the responses of these microcosms and those reported for experimental ponds exposed to the same concentrations of fluorene suggest that these microcosms accurately reflect the types of changes and concentrations that cause change in pond ecosystems. However, slight but significant changes in the ecosystem‐level variables gave no indication of the almost complete elimination of some zooplankton populations at 5.0 and 10.0 mg/L in the ponds and at 2.0, 5.0 and 10.0 mg/L in the microcosms. This lack of correspondence between population‐ and ecosystem‐level measurements suggests that test measurements made at one hierarchical level of organization may not always be appropriate for estimating effects at other

ISSN:0730-7268    

DOI:10.1002/etc.5620070805

出版商:Wiley Periodicals, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractThe use of phytotoxicity (higher plant) tests as a part of ecotoxicology is relatively underdeveloped. The objective of this study was to evaluate phytotoxicity tests for screening and biomonitoring complex effluent samples. Mortality tests using common duckweed and seed germination tests were conducted using eight effluent samples collected from three industrial sources. Duckweed plants were found to be extremely sensitive to two effluents, with nearly 100% mortality occurring. Duckweed plants in some samples showed lesions (breakup of colony structure) and loss of green pigments (chlorosis); others showed localized dead tissues (necrosis). Six kinds of seeds were tested: cabbage, cucumber, millet, Japanese millet, rice and wheat. Cabbage and millet seeds were the most sensitive. The germination of these seeds was 100% inhibited in some samples. The results suggest that phytotoxicity tests with higher plants have potential for use in the biomonitoring of industrial effluents because of their simplicity, sensitivity and cost‐effectivenes

ISSN:0730-7268    

DOI:10.1002/etc.5620070806

出版商:Wiley Periodicals, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractMetal body burdens of larval and adult chironomids varied nonlinearly with H+. Metal loss during emergence was an indicator of metal adsorption to the exoskeleton. This adsorbed portion was lower for chironomids collected from lakes of pH 4.4 or 6.1 than for those from lakes of pH 5.1 to 5.5. Pb accumulation was inversely proportional to pH, but Cd, Al, Cu and Ni body burdens were lower at pH 4.4 than at pH greater than 5.1. Short‐term larval transplant experiments supported the field observations that surface adsorption can be an important component of the total metal burden of larval chironomids and that adsorption processes may be suppressed at low pH. Changes in metal content in live and dead chironomids exposed to different sediment types were not significantly different. Larvae from a lake of pH 4.4 showed an initial rapid phase of accumulation of Cd, Al, Mn, Ni, Zn and Cu when transplanted to sediments from a lake of pH 5.1. Laboratory and field data supported the hypothesis that surface adsorption contributes to total metal content in chironomids and is responsive to lake p

ISSN:0730-7268    

DOI:10.1002/etc.5620070807

出版商:Wiley Periodicals, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractAdjuvants significantly contribute to many commercial herbicide/pesticide formulations and are often present at concentrations approaching those of the active ingredient. The Canadian Forest Service is currently testing alkyl aryl polyether alcohol adjuvants as “acceptable” replacement surfactants in the fenitrothion formulation used to control the spruce budworm,Choristoneura fumiferana. This study describes the toxic effects of these compounds on a common and widespread aquatic vascular plant,Lemna minorL.The parameters monitored during the 14‐d exposure included growth (biomass), frond fluorescence and chlorophyll content, conductivity of the test media and specific ion leakage. At 1 μg/ml, no response of any of the monitored parameters was observed for any of the Tritons, and 10 μg/ml resulted in no response for Triton X‐114. Exposure to 10 μg/ml of the other Tritons tested, however, resulted in toxic effects such that frond development was depressed 25 to 50%. Exposure to 50 μg/ml of the lower ethoxylates, Tritons X‐l5 and X‐35, elicited approximately twofold greater depression of the parameters assessed than did treatments with comparable concentrations of the higher ethoxylates, Tritons X‐100 and X‐114. A positive correlation was obtained between the degree of phytotoxicity and the hydrophilie‐lipophilic balance (HLB), and partition coefficients for t

ISSN:0730-7268    

DOI:10.1002/etc.5620070808

出版商:Wiley Periodicals, Inc.    

年代:1988

数据来源: WILEY