Residue levels of organochlorine pesticides in cattle meat and organs slaughtered in selected towns in West Shoa Zone,Ethiopia

Residue levels of organochlorine pesticides (OCP) in a total of 90 cattle samples comprising meat, liver and kidney collected from carcasses slaughtered in six towns in West Shoa Zone, Ethiopia, (Ambo, Guder, Ginchi, Gedo, Holeta and Tikur Inchini), have been determined. The pesticides were extracted by solid phase extraction (SPE) and quantification was carried out using gas chromatography-mass spectrometry (GC-MS). A good linearity (r² > 0.998) was found in the range 0.001–7.00 mg/kg for the samples studied. Most of the pesticides had recoveries in the range 81–99% and values of relative standard deviation (RSD) <7.2% for repeatability and reproducibility, showing good accuracy and precision of the method. The concentration level of the studied organochlorines followed the order: p, p’ dichloro-diphenyl-trichloroethane (DDT) > endosulfan>o,p′-DDT >lindane>dieldrin>endrin>aldrin>chlorothanolin while the order of contamination in the analyzed organs was liver > kidney > meat. Heat treatment of the meat, kidney and liver samples (boiling for 90 min.) produced an overall reduction of 62.2%, 44.5%, 37.7%, 29%, 31%, 34.3% and 30.8% in lindane, o, p′-DDT, endosulfan, p, p′-DDT, chlorothanolin, aldrin, dieldrin, and endrin, respectively. Although the residual contents of the organochlorines detected in all the contaminated samples analyzed from the six cities were below the respective maximal permissible levels set by international organizations, samples from Holeta town were more contaminated and may necessitate effective monitoring as bioaccumulation of these residues may pose health problems in human beings.     

Panel Bed Filters for Simultaneous Removal of Fly Ash and Sulfur Dioxide:

Experimental studies of the filtration of dilute aerosols of Dow microspheres by beds of sand have been conducted with flows passing vertically upward, vertically downward, and horizontally. With the use of Happel’s “free surface” model for a granular bed, the results can be correlated reasonably well by semiempirical, semitheoretical considerations taking into account collection by diffusion, gravity settling, direct interception, and inertial impaction. The results are preliminary to experiments to be made on filtration of aerosols by a filter cake of fly ash resting upon a sand bed.     

Offspring genetic diversity increases fitness of female Atlantic salmon (Salmo salar)

Inbreeding has negative effects on individual and population performances. Therefore, enhancement of offspring genetic diversity is believed to play a major role in shaping mating systems. However, no study has clearly separated the direct effect of having multiple partners from the indirect effect of having more outbred offspring on the resulting reproductive success of individuals in the wild. In this study, we report significant associations between both multiple mating and within-individual genetic diversity of offspring, and an increased reproductive success of wild female Atlantic salmon, Salmo salar. Specifically, we found that females with a higher number of mates also have more outbred offspring (within-individuals), and that both of these characteristics increased their reproductive success expressed in terms of offspring surviving when combining all freshwater juvenile stages. Our findings also indicate that determinants of fitness are different among sexes as within-individual offspring genetic diversity was not a strong predictor of male reproductive success, while the number of mates was important. We also show that females mated with more outbred males than on average, which potentially increased their chances of producing outbred offspring. These results therefore suggest that there could be more important indirect genetic benefits of multiple mating for females than for males.Communicated by M. Abrahams     

Emission Standards for the Control of Solid Particles,A New Approach by New Jersey

Existing chapters of the New Jersey Air Pollution Control Code are described, followed by an explanation of a proposed new chapter to control emissions of coarse solid particles and fine solid particles from industrial processes. The chapter is designed to limit dustfall of coarse particles off the premises of the emitter to WO tons per square mile per year, and the methods used to relate this criterion to stack emissions are explained. Fine particles, suspended in the air off the premises, are limited to 0.615 milligrams per cubic meter during average weather conditions. Measures taken for the protection of buildings, where the plant property line is less than 10 stack heights from the base of the stack, are described.     

Predicting extinctions as a result of climate change

Widespread extinction is a predicted ecological consequence of global warming. Extinction risk under climate change scenarios is a function of distribution breadth. Focusing on trees and birds of the eastern United States, we used joint climate and environment models to examine fit and climate change vulnerability as a function of distribution breadth. We found that extinction vulnerability increases with decreasing distribution size. We also found that model fit decreases with decreasing distribution size, resulting in high prediction uncertainty among narrowly distributed species. High prediction uncertainty creates a conservation dilemma in that excluding these species under-predicts extinction risk and favors mistaken inaction on global warming. By contrast, including narrow endemics results in over-predicting extinction risk and promotes mistaken inaction on behalf of individual species prematurely considered doomed to extinction.     

Critical Loads and Exceedances of Acid Deposition and Associated Forest Growth in the Northern Hardwood and BorealConiferous Forests in Québec,Canada

We used the Québec forest monitoring network (`Réseaud'Étude et de Surveillance des Écosystèmes Forestiers' or RESEF)along with its atmospheric monitoring stations to assess criticalS and N loads and their combined soil acidification exceedancesfor natural ecosystems of the northern hardwood and borealconiferous forests in Québec, Canada. Critical loads (CL) forforest soil acidification were calculated using the simple mass-balance (SMB) approach and with the steady-state PROFILE model.Atmospheric deposition rates for water, S, N, Ca, Mg, Na, and K,for the years 1989–1993, and detailed, plot-specific forest andsoil characteristics were used as input. The SMB model alsorequired information regarding nutrient uptake and storage in theaboveground woody biomass. The CL calculations indicated that,from the 31 RESEF plots, 18 received atmospheric acidic inputs inexcess of their CL (55 and 61% of the hardwood and coniferousplots, respectively). The range of CL exceedance varied from 60to 470 eq ha^-1 yr^-1 for the hardwood stands, and from 10to 590 eq ha^-1 yr^-1 for the coniferous stands. The standswith CL exceedance were mainly located in the western and centralpart of the province. Stand growth associated with exceedanceclass of acidity was determined using the RESEF plots along withselected permanent forest survey plots having similar sitecharacteristics, but for which longer growth records wereavailable. We found a significant negative correlation betweenforest growth rates and critical soil acidification exceedancefor both the northern hardwood and the boreal conifer sites.Specifically, plots with critical load exceedances were found tohave a growth reduction of about 30% during the 1974–1982 andthe 1972–1990 measurement (plots with no soil acidificationexceedance served as a control). While this correlation is notnecessarily causal, it is nevertheless consistent with theexpectation that increased losses of soil base cations on accountof increased soil acidification should and could lead todeteriorating forest health conditions.     

Water management strategies against toxic Microcystis blooms in the Dutch delta.

To prevent flooding of the Dutch delta, former estuaries have been impounded by the building of dams and sluices. Some of these water bodies, however, experience major ecological problems. One of the problem areas is the former Volkerak estuary that was turned into a freshwater lake in 1987. From the early 1990s onward, toxic Microcystis blooms dominate the phytoplankton of the lake every summer. Two management strategies have been suggested to suppress these harmful algal blooms: flushing the lake with fresh water or reintroducing saline water into the lake. This study aims at an advance assessment of these strategies through the development of a mechanistic model of the population dynamics of Microcystis. To calibrate the model, we monitored the benthic and pelagic Microcystis populations in the lake during two years. Field samples of Microcystis were incubated in the laboratory to estimate growth and mortality rates as functions of light, temperature, and salinity. Recruitment and sedimentation rates were measured in the lake, using traps, to quantify benthic-pelagic coupling of the Microcystis populations. The model predicts that flushing with fresh water will suppress Microcystis blooms when the current flushing rate is sufficiently increased. Furthermore, the inlet of saline water will suppress Microcystis blooms for salinities exceeding 14 g/L. Both management options are technically feasible. Our study illustrates that quantitative ecological knowledge can be a helpful tool guiding large-scale water management.