Showing papers by "Government of Canada published in 1986"

Importance of insects in environmental impact assessment

Abstract: Insects are particularly suited for use in environmental impact assessment (e.i.a.) because of their high species diversity, ubiquitous occurrence, and importance in the functioning of natural ecosystems. Examples are given of the use of insects in the predictive phase of e.i.a., in the monitoring and assessment phase, and in the much rarer instance of an e.i.a. that includes both of these phases. The importance of working at the species level to understanding the results of e.i.a. is emphasized.

Mechanisms of hydrogen ion neutralization in an experimentally acidified lake

Abstract: The experimental acidification of Lake 223 (Experimental Lakes Area, northwestern Ontario) with sulfuric acid in 1976-1983 allowed a detailed examination of the capacity of the lake to neutralize hydrogen ion. A whole-lake alkalinity and ion budget for Lake 223 showed that 6681% of the added sulfuric acid was neutralized by alkalinity production in the lake. Nearly 85% of in situ alkalinity production was accounted for by net loss of sulfate through bacterial sulfate reduction, coupled with iron reduction and iron sulfide formation, in littoral sediments (60%) and in the hypolimnion (25%). Exchange of hydrogen ion for calcium and manganese in the sediments accounted for 19% of the alkalinity generated, while other cations were net sinks for alkalinity. Alkalinity input from the watershed of Lake 223 was very small, averaging about 5% of that produced in the lake. The seasonal production of 1,000 peq liter-* alkalinity in the anoxic hypolimnion of this softwater lake could be attributed to bacterial sulfate reduction coupled with iron sulfide formation, ammonium production, and iron (II) production. Only the alkalinity produced from bacterial sulfate reduction coupled with iron sulfide formation remained throughout the annual cycle.

The Significance of In-Lake Production of Alkalinity

Abstract: Alkalinity production in terrestrial and aquatic ecosystems of Canada, the U.S.A., Norway and Sweden is calculated from either strong acid titrations or budgets for base cations and strong acid anions, using mass-balance budgets. Where alkalinity budgets for lakes and their catchments are calculated in acid-vulnerable geological settings, in-lake processes often contribute more to lake alkalinity than yield from terrestrial catchments. Nitrate and sulfate removal, and Ca exchange with sediments are the predominant alkalinity generating mechanisms in lakes.

The effects of simulated acid rain on germinative capacity, growth and morphology of forest tree seedlings

Abstract: Summary Acid rain-induced direct injury to forest tree seedlings was investigated in specially designed controlled-environment simulated-rainfall chambers. Seed germinative capacity, seedling survival, seedling growth and morphological responses to simulated rains of pH 5.6, 4.6, 3.6 and 2.6 were examined during the first growth cycle in 11 commercially important north temperate tree species. Germinative capacity was weakly responsive to rain pH, while seedling survival was more sensitive. No evidence of macroscopic foliar injury was observed at rain pH > 2.6. 1 reatment with pH 4.6 rain was sufficient to induce statistically significant growth reductions and morphological changes in coniferous seedlings. Response varied with species, treatment pH and parameter measured. No consistent growth stimulations were observed. Initiation of Primary needles, axillary meristems and shoot apex height were most affected by simulated pH. Deciduous species were considerably more resistant than coniferous species. Treatment with ram of pH 2.6 was generally required to induce significant growth reductions in deciduous seedlings.

Biological Indicators of Lake Acidification

Abstract: Indicator taxa are identified, based on both synoptic surveys and whole lake acidification experiments, for lake acidification in the pH 6.0 to 5.0 range. Acidobiontic diatoms (e.g Asterionella ralfsii, Fragillaria acidobiontica, etc.), periphyton (Mougeotia and related species), macroinvertebrates (e.g. Hyalella azteca, Orconectes sp., etc.), leeches, and cyprinid fishes (e.g. Pimephales promelas, Notropis cornutus, etc.) are identified as target organisms during early phases of lake acidification.

Phytoplankton Community Responses to Acidification of Lake 223, Experimental Lakes Area, Northwestern Ontario

Abstract: From 1976 to 1983 the pH of Lake 223 was artificially lowered by additions of H2SO4. From an initial level of 6.7, the pH was lowered at a rate of 0.5 pH units a year until it reached 5.0 and was held there for 3 yr. The decrease in pH caused major changes in the epilimnetic phytoplankton community in this lake. Biomass increased as pH decreased. Chlorophyte (Chlorella) abundance increased as pH decreased from 6.1 to 5.6 while Cyanophytes (Merismopedia and Chroococcus) and dinoflagellates (Gymnodinium and Peridinium) dominated once pH decreased below 5.6. Community diversities decreased because of these species shifts and a decrease in the number of species. The amount of edible biomass increased as the pH decreased from 6.7 to 5.6, then declined as pH decreased to 5.0.

Bioconcentration and disposition of 1,3,6,8-tetrachlorodibenzo-p-dioxin and octachlorodibenzo-p-dioxin by rainbow trout and fathead minnows

Abstract: Accumulation of 14C-labeled 1,3,6,8-tetrachlorodibenzo-p-dioxin (TCDD) and octachlorodibenzo-p-dioxin (OCDD) from water by rainbow trout fry (Salmo gairdneri) and fathead minnows (Pimephales promelas) was studied using a 5-d uptake and 24 to 48-d depuration period. Average exposure concentrations ranged from 4 to 211 ng/L for 1,3,6,8-TCDD and from 9 to 415 ng/L for OCDD. Equilibrium bioconcentration factors for total 14C in fish, calculated by use of a two-compartment first-order rate model, were 2,100 and 5,702 for 1,3,6,8-TCDD in trout fry and minnows, respectively, and 85 and 2,226 for OCDD in the same species. Elimination rates of both isomers were rapid, with half-lives of 14C ranging from 6 to 9 d for 1,3,6,8-TCDD and from 5 to 13 d for OCDD. The highest concentrations of radiolabeled 1,3,6,8-TCDD and OCDD were found in bile. A metabolite of 1,3,6,8-TCDD in bile was identified as a conjugate of a hydroxylated tetrachloro-derivative. Dietary exposure of rainbow trout resulted in low accumulation factors, ranging from 0.034 for OCDD to 0.018 for 1,3,6,8-TCDD, based on toluene-extractable radioactivity.

Increase in the Abundance of Cladocera at pH 5.1 in Experimentally-Acidified Lake 223, Experimental Lakes Area, Ontario

Abstract: Lake 223 in the Experimental Lakes Area, northwestern Ontario was experimentally-acidified with H2S0i+ from 1976 to the present. Cladocerans increased in absolute and relative abundance and in total biomass when the pH of Lake 223 was lowered from 6.7 to 5.1. Comparing the cladoceran community at pH 6.7 (1974) with that at pH 5.1 (1981 to 1983), Daphnia galeata mendotae disappeared, Diaphanosoma birgei became rare, Holopedium gibberum increased in abundance and Daphnia catawba, recorded for the first time in 1980, became abundant. Bosmina longirostris became more abundant. Except for the decline in D. birgei, the changes in cladoceran species composition with acidification are consistent with known responses of these species to low pH. The increase in importance of cladocerans in 1981 to 1983 was at the expense of copepods. It was hypothesized to be caused by the decline in predation by small fish during 1981 to 1983 as acidification reduced minnow populations and inhibited reproduction in trout and sucker. The loss of the population of the invertebrate predator, the opposum shrimp, Mysis relicta, in 1979 had little effect on cladoceran biomass.

Acid deposition and ion leaching from a podzolic soil under hardwood forest

Abstract: The contribution of atmospheric acids to cation leaching from a podzolic soil under mature maple-birch forest in central Ontario was examined during 1983. The movement of base cations was associated largely with NO 3 − , SO 2− and organic acid anions in surface soil horizons, with SO 4 2− and NO 3 − below the effective rooting zone, and SO 4 2− and HCOO 3 − in streamflow. Mineral soil horizons could adsorb little additional SO 4 2− or associated cations at current soil solution SO 4 2− concentrations. Therefore, it is concluded that the soil in situ lacks a strong affinity for SO 4 2− . Current annual inputs to the forest of SO 4 2− and NO 3 − in bulk precipitation (26.4 and 18.2 kg ha−1, equivalent to 8.8 kg S and 4.1 kg N ha−1, respectively) contributed significantly to cation leaching from the soil. In order to maintain exchangeable cations in soil at current levels, a rate of weathering yielding 29.6, 5.0, 4.4 and 2.2 kg ha−1 yr−1 of Ca2+, Na+, Mg2+ and K+, respectively, would be required.

Phytoplankton productivity responses to direct addition of sulfuric and nitric acids to the waters of a double-basin lake

Abstract: The two basins of Lake 302, in the Experimental Lakes Area, northwestern Ontario, were separated by means of vinyl barriers. Beginning in 1982 and continuing through 1984, H2SO4. was added to the south basin during the ice-free months. Alkalinity was reduced rapidly and pH was lowered from near 6.6 to 5.6 by 1984. Transmission of light increased, resulting in a deeper euphotic zone. Over the same time period, HNO3 was added to the north basin of Lake 302. Alkalinity was reduced much less in this basin and the pH dropped only to about 6.2 by 1984. Transmission of light did not increase. Mean epilimnetic phytoplankton production rates were greater in the HNO3 basin than in the H2SO4 basin. However, in the basin receiving H2SO4, epilimnetic rates remained at or above those in reference lakes, and mean production rates below the mixed layer were greater than in the HNO3 basin, probably because of increased light penetration. Mean euphotic zone production was similar in both basins and comparable to that measured in reference lakes. Phytoplankton community photosynthesis was not adversely affected by the additions of either HNO3 or H2SO4.

Trace element distribution within the tree phytomass and forest floor of a tolerant hardwood stand, Algoma, Ontario

Abstract: An examination of tree phytomass and trace metal concentrations (w/w) and pools in the tree stratum and forest floor of a sugar maple-yellow birch forest was carried out at Turkey Lakes Watershed, Algoma District, Ontario. Estimated aboveground tree phytomass (167,500 kg ha−1) was dominated by stemwood, branches greater > 2 cm, and stem bark. Highest trace metal concentrations were found in foliage (Cu, Fe, Mn, Ni) and stem bark (Cd, Pb, Zn). Concentrations of essential trace metals found in all sugar maple components followed the expected sequence of Mn> Fe> Zn> Cu. Lead and Ni concentations were always higher than those of Cd. Concentrations of essential elements in foliage and other components were comparable to those reported in the literature for other localities in North America. There was no indication that availability of essential trace elements (e.g., Cu) to vegetation had been increased as a result of increased atmospheric deposition. Lead, Ni and Cd levels in vegetation and forest floor were lower than those reported for similar forested areas of the northeastern United States.

A simple method to determine relative volatilities of aqueous formulations of pesticides

Abstract: A simple gravimetric method was developed to determine relative volatilities of aqueous formulations of pesticides. The technique involved evaporation of a liquid film from a plastic mesh surface. The suitability of the method for volatility determinations was tested against liquids of known boiling points, and adjuvant solutions of different concentrations. During the initial stage of evaporation, the percentage of weight remaining at time ‘t’ followed a nearly linear decrease with most formulations. At the second stage, however, a curvilinear decrease was noted, followed by an asymptotic limit at the final stage. Regression analysis of the data obtained during the first two stages of evaporation indicated that the method is sensitive enough to identify small differences in the evaporation rates of aqueous formulations of pesticides.

Trace Elements in the Hydrologic Cycle of a Tolerant Hardwood Forest Ecosystem

Abstract: The concentrations and annual fluxes of Fe, Al, Mn, Cu and Pb were measured during 1983 in bulk precipitation, throughfall, stemflow, forest floor percolate, mineral soil solution below the root zone and streamflow in a maple-birch stand on an acid podzolic soil at the Turkey Lakes Watershed (TLW), Ontario. Inputs of metals to TLW in precipitation were small in comparison with those in the eastern United States and Europe. Considerable loss of Mn and Cu from the vegetation during both the growing and the dormant (leafless) periods was observed and presumed to be due to leaching. The enrichment in soil solution of all metals examined, in relation to throughfall, was greatest for Al (7X) and least for Cu (1.2X). Aluminum was mobilized in both the forest floor and the mineral soil, the latter possibly in association with SO4 2−. Copper was solubilized in the lower forest floor or the mineral soil. Surface soil contents of Al and Cu were reduced by Al and, to a lesser extent, Cu leaching beyond the effective rooting zone. Iron, Mn and Pb were mobilized largely in the F horizon of the forest floor, most likely by organic acids. Leaching of Fe, Mn and Pb was reduced by metal accumulation in vegetation, the lower forest floor, or mineral soil within the effective rooting zone of the vegetation. Most (80 to 99%) of the metals leached from the rooting zone were retained in the watershed and did not appear in streamwater.

Nurses as a social force.

Abstract: Nurses in every continent engage in social action. This, the author argues, has been a fact throughout the ages. The major social issues which contribute to health today are economic, energy, environmental and social welfare problems. Other major issues affecting health are population growth, poverty, education, clean water supply, and family planning. The author shows how individual nurses and nurses' associations can, and should, exercise their influence and power in promoting health at local, national and international levels, making primary health care a priority. By using their levers of power, together with technology and communications, nurses can help create a new world health order, the author concludes.