摘要:

AbstractFenthion (Baytex), an organophosphate insecticide, is frequently applied to salt‐marsh environments to control mosquitoes. Shake‐flask tests were used to study rates of abiotic and biotic degradation of fenthion and the environmental parameters that affect these rates. Water or water‐sediment (500 mg dry weight/L) slurries from salt marshes located along the Northwest Florida Gulf Coast were used. Flasks contained 200 μg fenthion/L, and degradation rates were determined by following decrease of fenthion over time. Hydrolysis and biodegradation in water were relatively insignificant fate processes; fenthion disappeared from flasks containing water, formalin‐sterilized water, or formalin‐sterilized sediment very slowly (half‐life ≥ 2 weeks). The presence of nonsterile sediment resulted in a rapid exponential disappearance of fenthion (half‐life ≥ 3.8 d). Biodegradation was assumed since sterile sediment systems showed a much slower decrease of fenthion, and the production of polar compounds (hexane‐unextractable) from radiolabeled fenthion was greater in the presence of sediment than sterilized sediment. The effect of environmental pH levels (5.0–7.0) on degradation was insignificant. No biotic degradation occurred at low oxygen concentration. An 8°C decrease in incubation temperature decreased the rate of sediment biodegradation 2.5‐fold. Light caused a slight, but significant, increase in the biotic and abiotic degradation rates of fenthion in water. A two‐fold variation in sediment‐mediated degradation was noted among sediment samples from three stations within one field site. Inclusion of whole marsh plants or plant parts increased the disappearance rat

ISSN:0730-7268    

DOI:10.1002/etc.5620080901

出版商:Wiley Periodicals, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe fate of fenthion was examined in laboratory microcosms to describe interaction between sediment and biodegradation in the field. A mathematical model also was calibrated to calculate distribution of fenthion in microcosms. Intact sediment cores, with and without a salt‐marsh plant,Juncus roemerianus(black needlerush), were placed in microcosm vessels to simulate an undisturbed sediment bed of a salt marsh and areas containingJuncus. In a formalin‐sterilized microcosm without plants, fenthion disappeared exponentially from the water column with a half‐life of 105.0 h. Fenthion had a half‐life of 35.5 h in a nonsterile microcosm without plants. In the nonsterile microcosm with plants, the half‐life was slightly shorter, 33.2 h. The sediment was fractionated into 0.5 cm layers. Fenthion was found at greater sediment depths in nonsterile systems than predicted by diffusion and sorption in the sterile microcosm, possibly because of bioturbation. Distribution of fenthion in sediment was not appreciably different between microcosms with and without plants. Fenthion appeared to be biodegraded in the upper (1 to 7 mm) sedime

ISSN:0730-7268    

DOI:10.1002/etc.5620080902

出版商:Wiley Periodicals, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe photolysis of [2,6‐14C]pyridine‐labeled picloram (4‐amino‐3,5,6‐trichloro‐2‐pyridine carboxylic acid) was studied at 25°C in sterile, buffered water at pH 7 and in a natural water sample taken from a forest ecosystem. The first‐order half‐life for picloram photodegradation was the same in both systems, averaging 2.6 d at 25°C for a 40°N latitude location, midsummer time frame. The photolytic decay of picloram in solution produced two major photoproducts. Thermospray liquid chromatography‐mass spectrometry (TSP/LC/MS) and gas chromatography/mass spectrometry (GC/MS) in the electron impact and chemical ionization mode were used to elucidate the structures of the photolysis products. The two major14C‐labeled photoproducts were conclusively identified through comparison with analytical standards as oxamic acid (C2H3O4N) and 3

ISSN:0730-7268    

DOI:10.1002/etc.5620080903

出版商:Wiley Periodicals, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe relationship of tissue PCB levels to hepatic microsomal monooxygenase activity in rainbow trout (Salmo gairdneri) was assessed. This was accomplished by injecting individual trout with corn oil vehicle or with a [14C]PCB mixture in corn oil. At 3 to 70 d after injection, tissue [14C]PCB concentrations were determined by scintillation counting of solubilized tissue samples, and hepatic microsomes were prepared and assayed for ethoxyresorufin‐O‐deethylase and ethoxy‐coumarin‐O‐deethylase activities. At three days after injection only the highest doses of PCBs caused elevation of hepatic microsomal monooxygenase activity. At later times, muscle and liver concentrations of PCBs at or lower than 250 ng/g were associated with hepatic microsomal monooxygenase activity at or near control levels. Elevated hepatic microsomal monooxygenase activity was associated with muscle and liver PCB concentrations 300 ng/g or higher, but not all fish with tissue PCBs above this concentration had elevated hepatic microsomal monooxygenase

ISSN:0730-7268    

DOI:10.1002/etc.5620080904

出版商:Wiley Periodicals, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe topological methods of molecular connectivity and kappa shape analysis have been applied to a set of 65 substituted benzenes and their toxicities to fathead minnowPimephales promelas. The three variables1χ,1kα and6χvpalong with anortho/para‐dinitro indicator variable yield a QSAR equation withr= 0.940,s= 0.26 andF= 114. This equation is then used to estimate toxicities for 22 compounds not in the original data set. Twelve of the predicted compounds contain substituents in the original data set but 10 contain substituents new to the data, including fluoro‐, cyano‐ a

ISSN:0730-7268    

DOI:10.1002/etc.5620080905

出版商:Wiley Periodicals, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe effect on nitrogen fixation of 100, 200, 300, 400 and 500 μg metolachlor per gram of soil was studied in nonsterile soil incubated under aerobic conditions and sterilized soil inoculated withAzotobacter chroococcum. Metolachlor at concentrations of 400 and 500 μg/g significantly reduced dinitrogen fixation in nonsterile soil and sterile soil inoculated withAzotobactersp. However, this inhibitory effect on nitrogenase activity disappeared after 24 h, showing that acrobic diazotrophs populations present in the soil can tolerate high concentration of this herbicide without significant changes in their nitrogenase activit

ISSN:0730-7268    

DOI:10.1002/etc.5620080906

出版商:Wiley Periodicals, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractA distinct pattern of consistently most abundant PCB congeners is identified in caged juvenile fish during a developmental monitoring study of bioaccumulation in the upper Hudson River, 1985. An identical qualitative congener pattern is recognized in juvenile fish after 28‐d exposures in the late spring, summer and fall, even though each period is characterized by a different temperature and flow regime in the river. The same congener pattern is evident after only 3 d of exposure and persists until at least 42 d. Due to their physicochemical properties, biological half‐life in fish and site‐specific abundance in the upper Hudson River sediments, 1 tri‐CB, 13 tetra‐CBs and 3 penta‐CBs (3,4,4′; 2,2′,3,4′; 2,2′,3,5′; 2,2′,4,4′; 2,2′,4,5; 2,2′,4,5′; 2,2′,5,5′; 2,3,3′,6; 2,3,4,5; 2,3′,4,4′; 2,3′,4′,5; 2,3′,5′,6; 2,4,4′,6; 2′,3,4,5; 2,2′,3,5,6; 2,2′,3,5′,6; and 2,

ISSN:0730-7268    

DOI:10.1002/etc.5620080907

出版商:Wiley Periodicals, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe ciliated protozoan,Euglena gracilis, was cultured in the presence of aflatoxin B1(AFB1) (10, 100, and 1000 ng/ml) or T‐2 toxin (10, 100 and 1000 ng/ml) for 6 d. During this period, the control culture size progressively increased, while both AFB1and T‐2 toxin reduced culture size in a dose‐dependent manner. The sensitivity of the changes inEuglena gracilisgrowth rate to AFB1suggests that this organism may have only limited application as a bioassay. Protozoal motility (as assessed by changes in turbidity) was reduced by both toxins, but not in a dose‐dependent

ISSN:0730-7268    

DOI:10.1002/etc.5620080908

出版商:Wiley Periodicals, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe acute toxicities of dilutions of a herbicide spray formulation suggested for use in salt‐marsh environments to eradicateSpartinasp. have been estimated for six estuarine animal species using two complementary laboratory bioassay procedures. Responses of the test species ranged from highly sensitive for the whitebait (Galaxias maculatus) (2‐h LC50 of 0.45% corresponding to active ingredient concentrations of 36, 26 and 6 mg/L for dalapon, amitrole and NH4CNS, respectively) to extremely resistant for the mud crab (Helice crassa) (no mortality during a 4‐h exposure after direct spraying with the full‐strength mixture). Intermediate levels of toxicity were observed for the cockle (Chione stutchburyi), the mud snails (Amphibola crenataandPotamopyrgus estuarinus) and the estuarine prawn (Palaemon affinis). The results suggest that acute (lethal) effects on estuarine fauna would in most cases be minimal during actual spraying except where animals or shallow‐pooled areas covering animals are sprayed

ISSN:0730-7268    

DOI:10.1002/etc.5620080909

出版商:Wiley Periodicals, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe relationship between octanol/water partition coefficient (Kow) and bioconcentration factor (BCF) of 14 monochloro‐ to pentachloronitrobenzenes were examined in rainbow trout through waterborne and dietary exposure studies. The results indicated BCF was not significantly correlated withKowfor this chemical group. The role of chemical half‐lives and chemical absorption efficiencies are examined as factors that could explain why the BCF of some chemical groups are lower than predic

ISSN:0730-7268    

DOI:10.1002/etc.5620080910

出版商:Wiley Periodicals, Inc.    

年代:1989

数据来源: WILEY