摘要:

AbstractLake Lansing was treated with sodium arsenite for macrophyte control in 1957. Two 2.5‐m cores from deep portions of the basin showed the historical consequence of this treatment. Maxima of 330–340 μg As g−1dry weight occurred at a depth interval of 0.15–0.30 m; background was 17–20 ppm As. An arsenic mass balance budget for the lake for June 1978 to June 1979 showed it lost more arsenic than it received. Internal loading of the water from the sediments was occurring;>85% of the area of surficial sediments had concentrations two to six times background. From laboratory experiments, we hypothesize Fe3+controls arsenic concentration over aerobic sediments; As(III) increases in anoxic water with conversion of Fe3+to Fe2+and As(V) to As(III) at the sediment surface. As(III) in water diminishes during prolonged anoxia by reaction with S2−. As(III) and Fe2+are oxidized upon aeration of anoxic water, and As(V) is taken out of solution with ferric iron in a manner similar to phosphate. Arsenic concentrations observed in the lake over an annual cycle fit these

ISSN:0730-7268    

DOI:10.1002/etc.5620020101

出版商:Wiley Periodicals, Inc.    

年代:1983

数据来源: WILEY

摘要:

AbstractStatistical regressions that relate rates of transport processes to chemical characteristics of polycyclic aromatic hydrocarbons were used to estimate parameters in a model that predicts the fate of a simulated anthracene spill onto the surface (25 m2) of a 12.5 m3pond ecosystem. During 60 d following a simulated spill of 2.0 g/m2anthracene, predicted concentration in sediments peaked at 550 μg/m2. Predicted bioaccumulation was maximal in rooted macrophytes (0.35 μg/g dry weight), followed by benthic invertebrates (0.23 μg/g dry weight) and zooplankton (0.04 μg/g dry weight). Precision of predicted concentrations depends upon precise estimation of model parameters that define maximum water solubility and that regulate photolytic degradation, volatilization, sorption and bioaccumulation of anthracene. In 200 simulations, values of 29 model parameters were chosen at random from distributions with standard deviations that ranged between 0.5 and 53% of their means. Results demonstrate greater precision in predictions of the relative distribution of anthracene among water, sediments and total biota than precision of predicted concentrations of individual pond compone

ISSN:0730-7268    

DOI:10.1002/etc.5620020102

出版商:Wiley Periodicals, Inc.    

年代:1983

数据来源: WILEY

摘要:

AbstractThe insecticide permethrin was applied (10 applications in 6 weeks) to cotton in field plots separated for morning and afternoon applications in early (August to September) and late (September to October) season spray programs. The compartmentalization of permethrin on the leaves was determined throughout the application programs. In each of the four studies, initial surface permethrin residues were 80–90% of the total leaf load. At the end of each study, surface residues had doubled and total leaf content had quadrupled; the surface residues then were 40–45% of the total load. Thus, throughout each phase of the study, a major portion of the leaf permethrin content was at or near the surface where weathering processes occur. The surface residues from the late‐season afternoon applications were generally higher than the residues from the early‐season afternoon applications. This difference was in line with differences in rainfall, temperature and evaporation rates, which favored higher leaf surface residues in the late season. This residue trend did not appear in the morning samples from the two seasons. Thecis:transisomer ratios of the permethrin residues from the late‐season study showed consistently significant decreases, which may have been due in large part tocis‐to‐trans

ISSN:0730-7268    

DOI:10.1002/etc.5620020103

出版商:Wiley Periodicals, Inc.    

年代:1983

数据来源: WILEY

摘要:

AbstractSurface sediments from 24 stations in the Raritan Bay‐lower New York Bay were analyzed seasonally for size‐grade distributions, percent volatiles and extractable hydrocarbons. Seasonal means of size‐grade fractions were not statistically different, although much inter‐ and intrastation variability occurred. Greater silt‐clay content tended to occur at the head of the bay (especially in winter) and decreased down the bay. During fall and winter, the occurrence of silt‐clay fractions tended to increase throughout the bay.Extractable hydrocarbons exhibited significant seasonal differences (p<0.05). Extractable hydrocarbon ranges were 1–1,273 μg/g dry sediment, with seasonal means of 160–327 μg/g dry sediment, depending on the bay region. Hydrocarbon content and percent volatiles generally increased with increased silt‐clay content. Best correlations of hydrocarbons with silt‐clay occurred in summer and fall. Throughout the seasons, hydrocarbon material appeared to move down the bay, with lowest values in fall‐winter and the h

ISSN:0730-7268    

DOI:10.1002/etc.5620020104

出版商:Wiley Periodicals, Inc.    

年代:1983

数据来源: WILEY

摘要:

AbstractRespiratory responses of juvenile rainbow trout,Salmo gairdneriRichardson, were determined after approximately 26 h of exposure to dechlorinated tap water (at pH 6.0) containing 50, 100, 200 or 500 μg/L of added aluminum. Aluminum exposure produced significant increases in both opercular rate and cough frequency. Changes in the cough rates were proportional to the aluminum level, and the threshold concentration was approximately 100 μg/L. In addition, spontaneous locomotor activity was reduced by aluminum exposur

ISSN:0730-7268    

DOI:10.1002/etc.5620020105

出版商:Wiley Periodicals, Inc.    

年代:1983

数据来源: WILEY

摘要:

AbstractThe toxicities of chlordecone (CD), mirex (M) and photomirex (PM) were compared in the male mouse after daily oral administration of 10 mg/kg in corn oil vehicle (10 ml/kg). Mortality occurred starting day 10 with M, and day 16 with PM and CD, and LT50values were 132, 265 and 254 mg/kg, respectively. However the LT50values of M, PM or CD were not different (range, 100–125 mg/kg) when animals were intubated with the compounds daily at 25 or 50 mg/kg. Food and water consumption and body weight were decreased after M, but PM and CD increased these parameters. Other symptoms of toxicity included severe diarrhea with M, whereas a moderate diarrhea occurred with PM and little or no diarrhea with CD. The effects of M, PM or CD on the hepatic microsomal mixed function oxidase system were compared 4 d after the administration of 10 mg/kg/d of these compounds. M and PM were equipotent, whereas CD was found to be approximately half as effective in inducing cytochrome P‐450 and associated enzyme activities. CD and M caused a decrease in blood glucose levels due to enhanced oxidation, since liver glycogen levels were also reduced. CD‐induced tremors could not be prevented by restoring the blood glucose level. CD levels in liver, muscle, whole brain and plasma were several‐fold higher than for either M or PM. These results suggest that although structurally similar, these three analogs differ significantly in their biological

ISSN:0730-7268    

DOI:10.1002/etc.5620020106

出版商:Wiley Periodicals, Inc.    

年代:1983

数据来源: WILEY

摘要:

AbstractThe epibenthic mysidMysidopsis bahiawas chronically exposed throughout its entire life cycle to inorganic mercury. The experimental design permitted the precise measurements of survival rates; individual and population growth rates; and sublethal reproductive responses, including time to sexual maturation and first brood release, egg development time, brood size and frequency of reproduction. Mercury was acutely toxic (96‐h LC50) to juveniles at 3.5 μg L−1, chronically toxic (35‐d LC50) at 1.8 μg L−1and differentially toxic to males and females (α = 0.05). Male and female mortality rates were 35 and 18%, respectively, from sexual maturation (day 14) through termination of the assay (day 35). Reproductive effects included delays in sexual maturation and brood release at 1.6 μg L−1, a doubling of brood development time at 2.5 μg L−1and subsequent abortion and significant decreases in the total broods released (and therefore juveniles produced) at 1.6 μg L−1. Intrinsic rates of population increase (r), calculated from life‐tables, decreased with increasing mercury concentration. The critical value (r = 0) for mercury occurs at 1.6 μg L−1, which corresponds well with the upper limit of the maximum acceptable toxicant concentration, the usual endpoint of life‐cycle toxicity tests. The toxicity test system is a sensitive, precise model for studying lethal, sublethal and potential population

ISSN:0730-7268    

DOI:10.1002/etc.5620020107

出版商:Wiley Periodicals, Inc.    

年代:1983

数据来源: WILEY

摘要:

AbstractFlow‐through and static tests were conducted with fathead minnows, rainbow trout andDaphnia magnato determine their relative sensitivities to measured concentrations of the insecticide endosulfan and to compare responses of fish in replicated static and flow‐through exposure procedures. Fathead minnow 96‐h static LC50values were 1.3, 0.8 and 1.3 μg/L endosulfan. The 96‐h LC50values for fatheads in flow‐through tests were 1.7 and 1.0 μg/L. Rainbow trout 96‐h static LC50values were 1.7 and 1.6 μg/L. The 96‐h LC50values for rainbows in flow‐through tests were 0.3 and 0.4 μg/L. Acute 48‐h static EC50values forD. magnawere 343 and 271 μg/L endosulfan. These results suggest that differences in species sensitivity can be as great as thr

ISSN:0730-7268    

DOI:10.1002/etc.5620020108

出版商:Wiley Periodicals, Inc.    

年代:1983

数据来源: WILEY

摘要:

AbstractThe toxicity of 12 freshwater sediments to the water flea,Daphnia magnaStraus, and the mayfly nymph,Hexagenia, were tested in recycling laboratory microcosms. The organisms were tested both together and singly. Significant differences inDaphniamortality between test and control sediments occurred in only two cases in whichDaphniawas tested alone, and in five cases in which it was tested withHexagenia.SignificantHexageniamortality occurred in only two cases. The results imply that (a)Hexageniais a less sensitive indicator of freshwater sediment toxicity than isDaphniaand (b) the presence ofHexageniausually intensifies theDaphniaresponse. Tests that combine these two organisms are recommended, sinceDaphnia, although an open‐water species, responds not only to dissolved materials in the water but also to particulates released from the sediments by the physical activity ofHexagenia.These types of tests could be used, on a standardized, routine basis, as indicators of potential problem

ISSN:0730-7268    

DOI:10.1002/etc.5620020109

出版商:Wiley Periodicals, Inc.    

年代:1983

数据来源: WILEY

摘要:

AbstractThe rate of loss of crickets (Acheta domesticaL.), with and without the presence of an adventitious predator, the gray‐tailed vole (Microtus canicaudus), has been studied in Terrestrial Microcosm Chambers (TMC‐II) treated with pine stakes impregnated with creosote, bis(tri‐n‐butyltin)oxide (TBTO), dieldrin (HEOD), pentachlorophenol (PCP) or a toluene solvent control. The first‐order rate of cricket loss (‐k) increased only for HEOD, to a maximum at 33 d post‐treatment, with oscillations of about a 16‐d period. This result infers a “cricket‐available” compartment of HEOD and/or metabolites with concentrations that must be greater than those measured in air, soil, water or plants and other biota. When a gravid vole was subsequently added to each TMC, the predation index (Δkv) increased for control and PCP, but declined markedly for creosote and HEOD, and to a

ISSN:0730-7268    

DOI:10.1002/etc.5620020110

出版商:Wiley Periodicals, Inc.    

年代:1983

数据来源: WILEY