ISSN:0730-7268    

DOI:10.1002/etc.5620100301

出版商:Wiley Periodicals, Inc.    

年代:1991

数据来源: WILEY

摘要:

AbstractThe theoretical‐profile‐shape (TPS) method for estimating pesticide evaporative flux from soil was compared to the aerodynamic‐profile (AD) method in an intraplot field experiment using dacthal (DCPA) herbicide. Flux values measured by the TPS method were approximately 20% higher than values found by the AD method. Linear regression analysis of soil concentration over an 84‐d period showed a soil half‐life of 33.8 d. Of the amount lost from soil, 52 and 36% were accounted for by volatilization with the TPS and AD methods, respectively. The volatilization half‐life of dacthal based on the 21‐d cumulative flux measurements from actual and estimated daily fluxes were 59 and 83 d for the TPS and AD methods, respectively. The results were compared to the 138‐d prediction of a published environme

ISSN:0730-7268    

DOI:10.1002/etc.5620100302

出版商:Wiley Periodicals, Inc.    

年代:1991

数据来源: WILEY

摘要:

AbstractToxic cyanobacteria (blue‐green algae) waterblooms have been found in several Chinese water bodies since studies began there in 1984. Waterbloom samples for this study containedAnabaena circinalis, Microcystis aeruginosaandOscillatoriasp. Only those waterblooms dominated byMicrocystis aeruginosawere toxic by the intraperitoneal (i.p.) mouse bioassay. Signs of poisoning were the same as with known hepatotoxic cyclic peptide microcystins. One toxic fraction was isolated from eachMicrocystis aeruginosasample. Two hepatotoxic peptides were purified from each of the fractions by high‐performance liquid chromatography and identified by amino acid analysis followed by low and high resolution fast‐atom bombardment mass spectrometry (FAB‐MS). LD50 i.p. mouse values for the two toxins were 245 μg/kg (Toxin A) and 53 μg/g (Toxin B). Toxin content in the cells was 0.03 to 3.95 mg/g (Toxin A) and 0.18 to 3.33 mg/kg (Toxin B). The amino acid composition of Toxin A was alanine [1], arginine [2], glutamic acid [1] and β‐methylaspartic acid [1]; for Toxin B it was the same, except one of the arginines was replaced with a leucine. Low‐ and high‐resolution FAB‐MS showed that the molecular weights were 1,037 m/z (Toxin A) and 994 m/z (Toxin B), with formulas of C49H76O12N13(Toxin A) and C49H75O12N10(Toxin B). It was concluded that Toxin A is microcystin‐RR and Toxin B is microcystin‐LR, both known cyclic heptapeptide hepatotoxins isolated from cyanobacteria in other parts of the world. Sodium borohydride reduction of microcystin‐RR yielded dihydro‐microcystin‐RR (m/z = 1,039), an important intermediate in the preparation of tritium‐labeled toxin f

ISSN:0730-7268    

DOI:10.1002/etc.5620100303

出版商:Wiley Periodicals, Inc.    

年代:1991

数据来源: WILEY

摘要:

AbstractThis study investigated the effects of chlorobenzenes on the diatomCyclotella meneghinianausing DNA measurement as a toxicity parameter and related toxicity to different physicochemical properties of chlorobenzenes. The organisms were exposed to chlorobenzene solutions for 48 h to obtain effective concentration (EC50) values (in terms of percent DNA reduction). The toxicity (EC50) increased with increasing degree of chlorination, as follows: monochlorobenzene (235.74 mg/L), dichlorobenzenes (23.33‐51.88 mg/L), trichlorobenzenes (0.59‐6.42 mg/L), tetra‐chlorobenzenes (0.27‐1.39 mg/L), pentachlorobenzene (0.008 mg/L) and hexachlorobenzene (0.002 mg/L). Quantitative structure‐activity relationships were developed showing high correlations, as follows: water solubility (r2= 0.96); molecular volume (r2= 0.92); zero‐order connectivity index (r2= 0.92); second‐order connectivity index (r2= 0.92); molecular surface area (r2= 0.92); octanol/water partition coefficient (r2= 0.86); bioconcentration factor (r2= 0.86); and inorganic/organic character (r2= 0.83). A poor correlation, however, was obtained with the molecular negentropy index (r2= 0.25). The toxic effect (EC50) was explained in terms of a partitioning process as a function of the aqueous solubility of the chlorobenzenes and was found to occur at similar degrees of exposu

ISSN:0730-7268    

DOI:10.1002/etc.5620100304

出版商:Wiley Periodicals, Inc.    

年代:1991

数据来源: WILEY

摘要:

AbstractIt has been assumed that the water‐soluble paralytic shellfish toxins are extracted and concentrated by the organic‐solvent extraction method used for diarrhetic shellfish toxins. As diarrhetic toxin extracts of mussels with high levels of paralytic toxins are found nontoxic, it appears that paralytic toxins are not present in those extra

ISSN:0730-7268    

DOI:10.1002/etc.5620100305

出版商:Wiley Periodicals, Inc.    

年代:1991

数据来源: WILEY

摘要:

AbstractBiological and physical degradation, and metabolite and soil‐bound residue formation, of [U‐ring‐14C]atrazine (2‐chloro‐4‐[ethylamino]‐6‐[isopropylamino]‐1,3,5‐triazine) were characterized in a western Tennessee soil using laboratory and field assays. Biological mineralization of [14C]atrazine was examined in the laboratory using intact surface soil cores in sealed microcosms. Physical mineralization was determined using gamma‐radiation‐sterilized soil microcosms. Metabolites measured were deethylatrazine (DEA), deisopropylatrazine (DIA), dealkylatrazine (DAA) and hydroxyatrazine (HYA). Atrazine was applied at a rate of 2.2 kg/ha (˜ 5.6 μg/g soil) to soil microcosms in two studies and 3.2 kg/ha to the field. Evolution of14CO2from [14C]atrazine in nonirradiated soil microcosms increased to 12 and 28% of the radiolabel added after 180 d incubation. Irradiated soil microcosms evolved less than 0.07% of the radiolabel as14CO2for both studies after the same period. The concentrations of metabolites throughout the laboratory and field studies were: HYA>DEA>DIA>DAA. The highest concentration of HYA detected during microcosm and field studies was approximately 0.5 μg/g soil. Atrazine dissipation rates and metabolite production in nonirradiated microcosms were comparable to field results. Atrazine concentrations after 180 d in nonirradiated microcosm and field samples were lower than HYA, and either equivalent to or greater than DEA. The DAA was not detected throughout microcosm or field studies. Rates of dissipation for atrazine followed first‐order kinetics. Atrazine half‐life, based on extractable residues, was approximately 21 d in the microcosm studies, compared to 14 d in surface field soil. Extractable14C residues sampled from nonirradiated microcosms decreased in concentration during the incubation period. Soil‐bound14C residues increased and, at the termination of the two studies, accounted for 39 and 43% of the radioactivity added to nonirradiated microcosms. Bound14C residues in irradiated microcosms accounted for 49 and 48% of the activity after 180 d. Similarity of results between microcosm and field studies suggests that those microcosms may be useful for predicting the

ISSN:0730-7268    

DOI:10.1002/etc.5620100306

出版商:Wiley Periodicals, Inc.    

年代:1991

数据来源: WILEY

摘要:

AbstractAtrazine (2‐chloro‐4‐[ethylamino]‐6‐[isopropylamino]‐1,3,5‐triazine) can be degraded to several metabolites in soil that include the dealkylated metabolites, deethylatrazine (DEA), deisopropylatrazine (DIA) and dealkylatrazine (DAA), and the dechlorinated metabolite, hydroxyatrazine (HYA). Biological and physical degradation and soil‐bound residue formation from uniformly14C ring‐labeled DEA, DIA, DAA and HYA were characterized in a western Tennessee soil using intact surface soil core microcosms.Metabolites were applied to soil microcosms at a rate of 0.5 kg/ha (˜1.2 μg/g soil). Concentrations of the dealkylated metabolites in nonirradiated soil microcosms decreased to less than 2% of the applied compound or were not detected after 180 d incubation. Hydroxyatrazine residues decreased to 33% of the applied concentration. In nonirradiated microcosms after 180 d, evolution of14CO2from radiolabeled DEA, DIA, DAA and HYA increased to 25, 16, 59 and 21%, respectively, of the total radiolabel added. Irradiated soil microcosms evolved 0.6, 1.7, 0.1 and 0.9%, respectively, of the total radiolabel added. Rates of dissipation for the four metabolites followed first‐order kinetics. Half‐lives for the dealkylated metabolites, based on extractable residues, ranged from 17 to 26 d, whereas HYA was 121 d. Soil‐bound14C residues increased in concentration in nonirradiated microcosms and ranged from 28% of the applied radiolabel for HYA to 60% for DEA after 180 d. In irradiated microcosms the range was from 24% for HYA to 72% for DAA on day 180. Extractable14C residues in all microcosms decreased in concentration during this study and, after 180 d, ranged from 4% of the radioactivity added for DAA to 40% for HYA. Extractable14C residues in irradiated microcosms ranged from 31% of the initial activity for DAA to 68% for HYA at the

ISSN:0730-7268    

DOI:10.1002/etc.5620100307

出版商:Wiley Periodicals, Inc.    

年代:1991

数据来源: WILEY

摘要:

AbstractRainbow trout (Oncorhynchus mykiss) were exposed for 21 d to sublethal levels of No. 2 fuel oil (2FO). The four exposure concentrations ranged from 12 to 100 mg/L 2FO dispersed in water and resulted in 0 to 12% mortality. Following this exposure period (preexposure) the ability of preexposed trout to survive exposure to acutely lethal levels of 2FO was observed. Preexposure to either 50 or 100 mg/L 2FO consistently resulted in decreased survival and a lower LC50 for a given observation period. Unfortunately, because the LC50 determinations were not obtained independently, they could not be used to test statistically the effects of preexposure on survival. Therefore, two proportional hazard modeling techniques were applied to the data to test for effects due to preexposure. Both modeling techniques indicated that preexposure results in decreased survival of rainbow trout exposed to acutely toxic levels of 2FO. Thus, in contrast to preexposure to metals, which results in acclimation, preexposure to 2FO results in decreased survival.

ISSN:0730-7268    

DOI:10.1002/etc.5620100308

出版商:Wiley Periodicals, Inc.    

年代:1991

数据来源: WILEY

摘要:

AbstractSeveral biochemical indicators were evaluated as monitoring techniques in rainbow trout (Oncorhynchus mykiss) exposed to No. 2 fuel oil (2FO) for their ability to predict the exposure concentration. The principal factor affecting the response of the ratio of liver weight to body weight, microsomal and cytosolic protein, reduced glutathione (GSH), 7‐ethoxyresorufinO‐deethylation (EROD) and metallothionein (MTN) was the length of exposure, not the exposure concentration. Two patterns of response were observed, depending on the length of exposure. In rainbow trout exposed for 3 d to 12 to 100 mg/L 2FO, cytoplasmic protein and EROD activity were elevated and GSH was depleted; in fish exposed for 21 d, liver size, microsomal and cytoplasmic protein, EROD activity, GSH and MTN were all increased. The appearance of an MTN response due to 2FO exposure causes us to question the use of this protein as a metal bioindicator. Furthermore, we did not observe a dose‐dependent response in any of the biochemical responses and suggest that toxicity was responsible for the lack of concentration dependence. This lack of a concentration‐dependent response will complicate the use of these biochemical indicators in a biomonitoring

ISSN:0730-7268    

DOI:10.1002/etc.5620100309

出版商:Wiley Periodicals, Inc.    

年代:1991

数据来源: WILEY

摘要:

AbstractEndosulfan‐contaminated muddy sediments were collected from a tidal creek bottom after rain runoff from an agricultural watershed and tested for their effects on larval settlement/growth, survival and reproduction of cultured meiobenthic polychaetes and copepods. Endosulfan (ES) strongly inhibited larval colonization and early juvenile growth of the cosmopolitan, euryhaline polychaeteStreblospio benedicti.In laboratory microcosms, ES concentrations as low as 50 μg·kg−1sediment significantly reduced the number of larval colonists by>50% relative to ES‐free control sediments. Higher concentrations closer to actual field levels suppressedStreblospio benedicticolonization completely. Early growth of newly metamorphosed juveniles was depressed 36 and 40% relative to controls at ES concentrations of 50 and 100 μg·kg−1, respectively. In contrast, when the common benthic harpacticoid copepodPseudobradya pulchellawas chronically exposed to sediment ES as high as 200 μg·kg−1, survival and egg production were unaffected despite many examples of high ES toxicity to other crustaceans. Of more than 1,600Pseudobradya pulchellatested, more than 95% survived ES concentrations of at least 200 μg·kg−1, and over 98% of 1,200 females produced normal clutches of eggs. Similarly, survival of another common benthic copepod,Nannopus palustris, was not significantly affected below a threshold concentration of 200 μg·kg−1ES. At 200 μg·kg−1, however,Nannopus palustris' survival was significantly reduced relative to control

ISSN:0730-7268    

DOI:10.1002/etc.5620100310

出版商:Wiley Periodicals, Inc.    

年代:1991

数据来源: WILEY