Kepone effects on larval development of mud-crab and blue-crab     

C. G. Bookhout  J. D. Costlow Jr.  R. Monroe 《Water, air, and soil pollution》1980,13(1):57-77

Laboratory experiments wer conducted to determine the effects of Kepone on the larval development of the mud-crab,Rhithropanopeus harrisii, and the commercial blue crab,Callinectes sapidus, from the time of hatching until the 1st crab stage was reached. Differential survival ofR. harrisii from hatching to 1st crab stage occurred in a range of 35 to 125 ppb Kepone, whereas differential survival ofC. sapidus over the same period of development occurred in a range of 0.1 to 1.0 ppb. Statistical analysis indicated that, for every 10 ppb Kepone added, duration from hatching to 1st crab stage ofR. harrisii was increased by 0.391±0.043 days; whereas for each increase of 0.1 ppb, the duration from hatching to 1st crab stage ofC. sapidus is prolonged by 0.38±0.10 days. The 1st and 2nd zoeal stages ofR. harrisii were the most sensitive developmental stages to Kepone, but the 1st zoeal stage ofC. sapidus was not sensitive, statistically, to any concentration of Kepone tested. In zoeal stages II, III and IV, there were significant increases in mortality ofC. sapidus over the previous stage in all media tested.  相似文献   

Intermediate mixing of thermal discharges into a uniform current     

John Eric Edinger  Edward M. Polk Jr. 《Water, air, and soil pollution》1971,1(1):7-31

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Effects of increasing acidity on aquatic protozoan communities     

B. R. Niederlehner  John Cairns Jr. 《Water, air, and soil pollution》1990,52(1-2):183-196

Laboratory tests were conducted to evaluate the chronic effects of increased acidity on protozoan communities. Taxonomic richness of the protozoan component of these communities was severely affected at pH ≤ 5.33. Taxonomic composition was significantly affected at much higher pH. A permissible concentration was defined as the pH affecting no more than 20% of the species and estimated from concentration-response regression as 6.92 (5.92 to 8.04) pH units. A similar value estimated from more conventional chronic toxicity tests was 6.28 (6.16 to 6.45) pH units. Bacterial abundance decreased at pH levels ≤ 5.34 pH units. Other nontaxonomic responses (e.g., biomass, algal biomass, fungal biomass, net oxygen metabolism) were not sensitive to increases in acidity.  相似文献   

Ionic composition of acid lakes in relation to airborne inputs and watershed characteristics     

Gary E. Glass  John A. Sorensen  Barbara W. Liukkonen  George R. Rapp Jr.  Orie L. Loucks 《Water, air, and soil pollution》1986,31(1-2):1-15

Present acid forming emissions to the atmosphere have the potential to alter significantly the chemistry of rain, snow, and surface water of weakly buffered lakes in the Upper Midwest. Average precipitation pH from field measurements during 1979–1983 declined from west to east from 4.8, 4.6, and 4.3 along a cross-section of sites in Minnesota, Wisconsin, and Michigan respectively where 990 lake and stream sampling sites were studied. Measurements of weakly buffered lakes show a parallel decline in lake water pH with the lowest values measured, 5.1, 4.6 and 4.4, respectively in the same regions. Correspondingly, the percentage of lakes sampled with little or no acid neutralizing capacity (ANC) was found to increase from 0 to 4 and 13%, respectively. The geographic patterns in ionic composition of airborne acids and bases, and the resultant surface water concentrations are compared. The acid forming capacity (AFC) from airborne inputs is calculated using mass balance and in-lake processes. Stoichiometric acid-base reactions are used to balance the observed chemical differences between airborne inputs and surface water composition considering nitrification, denitrification, other oxidation-reduction reactions, and the evaporation concentration process. Microbial activity in surface water can result in a net decrease in ionic strength from the conversion of most of the ammonium and nitrate to neutral compounds and biomass, but only a partial reduction of about 20% of the sulfate inputs to weakly buffered lakes. The resulting AFC of airborne inputs are calculated to range from 30 to 60, 50 to 90, and 80 to 130 μeq H+L-l, respectively, in northeastern Minnesota-Ontario, northcentral Wisconsin and northern Michigan-Ontario. The differences in AFC of airborne inputs from west to east, and differences in in-lake processes explain the observed acidity of weakly buffered lakes across the region.  相似文献   

A characterization of the detroit wintertime aerosol     

J. M. Masters  R. A. Gorse Jr.  S. M. Japar  J. M. Norbeck 《Water, air, and soil pollution》1986,27(3-4):277-285

The physical characterization of winter-time aerosol in the Detroit area studied over a 7-week period (January–March, 1983) is presented. Total suspended particle levels (<15 μm) were 56 ± 29 μg m^?3, with 66% of the material in the fine (<2.5 μm) particle fraction. Coarse and fine particle masses were reasonably correlated, indicating that local sources, not long-range transport, influenced winter-time aerosol at the site. Mobile sources were responsible for a marked diurnal variation in the nuclei mode particle count and accounted for about 10% of the submicron aerosol mass. Decreases in submicron aerosol concentrations during precipitation appear to be associated with advection of clean air into the area during frontal passage rather than to precipitation scavenging.  相似文献   

In Reply to Dr Bornatowski     

Vidal Haddad Jr MD  PhD 《The Forestry Chronicle》2011,22(3):286

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Long-term impacts of even-aged timber management on abundance and body condition of terrestrial amphibians in Northwestern California     

N.E. Karraker  H.H. Welsh Jr. 《Biological conservation》2006,131(1):132-140

Conservation needs for amphibians in managed timberlands may differ based upon the species present and the timber harvesting methods employed. Clearcuts have been documented to be detrimental to amphibians but the impacts of associated silvicultural edges and alternative harvesting treatments are not well understood. The primary objective of this study was to determine if amphibian abundances and body condition differed in thinned forests and intact forests, and in clearcuts and associated silvicultural edges. We also examined which environmental attributes were important in explaining observed differences. We sampled clearcuts, silvicultural edges, and adjacent late-seral forests at 10 sites in northwestern California from October 1999 to July 2002. Clearcuts at these sites ranged in age from 6 to 25 years. Five of these forest stands were intact and five had been commercially thinned at least 10 years prior to our study. Amphibian abundances were similar in thinned and unthinned forests, but body condition of the most common species was lower in thinned forests. Abundances of amphibians were nearly twice as high in forests and at silvicultural edges than in clearcuts. Clearcutting at these sites appears to have affected amphibian numbers up to 25 years post-harvest, however, silvicultural edges were suitable habitats for amphibians. While commercial thinning did not reduce amphibian numbers, it is an intermediate treatment followed by clearcutting. Where conservation of amphibians is a concern, even-aged silvicultural systems may not provide the most appropriate method for maintaining viable populations on managed forestlands in the northwestern US.  相似文献   

Effects of hexavalent chromium on development of crabs,Rhithropanopeus harrisii and Callinectes sapidus     

C. G. Bookhout  R. J. Monroe  R. B. Forward Jr.  J. D. Costlow Jr. 《Water, air, and soil pollution》1984,21(1-4):199-216

Survival of Rhithropanopeus harrisii larvae from hatching to first crab stage occurred in Na₂CrO₄ concentrations from 1.1 to 29.1 ppm. Estimated LC50 for complete zoeal development was 17.8 ppm Na₂CrO₄ and it was 13.7 ppm for development to first crab stage. A concentration of 1.1 ppm Na₂CrO₄ was nontoxic, while Na₂CrO₄ concentrations of 7.2 and 14.5 ppm were sublethal and concentrations of 29.1 to 58.1 ppm were acutely toxic. Low concentrations of Na₂Cr0₄ caused an increase in swimming speed and high concentrations caused a decline. Survival of Callinectes sapidus larvae occurred in Na₂CrO₄ concentrations from 1.1 to 4.7 ppm. The LC50 for complete zoeal development was estimated to be 2.9 ppm Na₂CrO₄ and the LC50 for development to first crab stage was estimated to be 1.0 ppm Na₂CrO₄ The total Cr in sodium chromate is 32% by weight (Tacey,1981), hence, the total Cr concentrations tested were 32% of the Cr salts given above. Statistical analyses of the data on survival, duration and mortality of larvae are presented.  相似文献   

Atmospheric mercury concentrations above mercury contaminated mill tailings in the Carson River Drainage Basin,NV     

M. Sexauer Gustin  G. E. Taylor Jr.  T. L. Leonard 《Water, air, and soil pollution》1995,80(1-4):217-220

During processing of the historic Comstock Ore, Virginia City, NV, an estimated 5.5 × 10⁹ g of metallic mercury (Hg) were released into the Carson River Drainage Basin. The Bessels Mill site is one of at least 75 locations where Hg was used to amalgamate the gold and silver from the ore. Although the mill is no longer standing, Hg contaminated tailings attest to its past location. Mercury concentrations in samples of tailings from the Bessels Mill site are as high as 1570 μg/g. Mercury concentrations vary spatially over the site. Total Hg concentrations in air measured directly over the site are well above regional background levels (1 to 7.1 ng/m³). The highest average atmospheric Hg concentration measured at the site was 240 ng/m³ for October 1993. The estimated range of Hg flux to the atmosphere from the site was 37 to 500 ng/m² hr. Atmospheric Hg concentrations varied seasonally, diurnally and spatially. Atmospheric Hg concentrations varied as a function of Hg concentration, soil and air temperature, wind speed and surface morphology.  相似文献   

Theology and agricultural ethics at state universities: A rejoinder     

Richard A. Baer Jr. 《Agriculture and Human Values》1989,6(3):99-104

Michael Eldridge's critique of the author's earlier paper on the place of theology in agricultural ethics at state universities fails in at least three places: (1) Eldridge presents an inadequate picture of how basic assumptions function in human thinking and misuses terms like public, private, particular, empirical, and common experience; (2) he wrongly distinguishes between philosophers and theologians on the bais of their openness to new data, ideas, and public criticism; (3) he misunderstands the meaning of the First Amendment. Baer argues that whenever faculty at a state university deal with the Big Questions—who we are, how we should live, and what it all means—they must be seen, for First Amendment purposes, as operating within the realm of religion. Without such a functional definition of religion, the state will inevitably give unfair advantage to nontheistic, secular answers to the Big Questions. Eldridge is wrong to claim that Dewey escapes the liabilities of particularity and parochialism in a way that theologians do not. He also misunderstands the nature of the First Amendment when he argues that public schools may legitimately propagate Dewey's naturalistic variety of religion. Baer claims that when state universities address the Big Questions, the demands of public justice will be met only if theologians participate in the discussion and debate.Richard A. Baer, Jr. is professor of environmental ethics at Cornell University and a Fellow of the Center for Public Justice in Washington, D.C.  相似文献