Nitrate pollution of wells: pollution prevention policy options

Irrigated agriculture is a major sector of agricultural economy where high value crops are grown with substantial input of fertilizers and pesticides. High concentrations of nitrate and pesticides have been observed in ground water beneath irrigated areas in humid regions, where irrigation is practiced on sandy soils that have low water-holding capacity. Data from these areas indicate that irrigation wells are typically screened in the bottom part of the aquifer (which contain coarser deposits) whereas the domestic wells are screened just below the water table. Monitoring results from several irrigated areas have shown the stratification of dissolved inorganic and organic chemicals in the aquifer. Nitrate in such systems is typically highest near the surface. This has serious health implications for the rural population that relies upon shallow ground water for drinking. Current environmental policy towards pollution reduction focuses on improved management practices to reduce the loading of the chemicals to ground water. However, an engineering issue, dealing with the design of the irrigation and domestic wells has not been addressed. A design modification for the irrigation and domestic wells can reduce the risk of high nitrate ground water being pumped by domestic wells. A proposal to convert a deep vertical irrigation well to a series of small-capacity shallow vertical wells or a large-capacity horizontal well and slight deepening of the domestic wells was examined through simulations. This can reduce the nitrate concentration of ground water in domestic wells dramatically and use the high nitrate water for crop irrigation.     

Nitrate pollution of wells: pollution prevention policy options

Irrigated agriculture is a major sector of agricultural economy where high value crops are grown with substantial input of fertilizers and pesticides. High concentrations of nitrate and pesticides have been observed in ground water beneath irrigated areas in humid regions, where irrigation is practiced on sandy soils that have low water-holding capacity. Data from these areas indicate that irrigation wells are typically screened in the bottom part of the aquifer (which contain coarser deposits) whereas the domestic wells are screened just below the water table. Monitoring results from several irrigated areas have shown the stratification of dissolved inorganic and organic chemicals in the aquifer. Nitrate in such systems is typically highest near the surface. This has serious health implications for the rural population that relies upon shallow ground water for drinking. Current environmental policy towards pollution reduction focuses on improved management practices to reduce the loading of the chemicals to ground water. However, an engineering issue, dealing with the design of the irrigation and domestic wells has not been addressed. A design modification for the irrigation and domestic wells can reduce the risk of high nitrate ground water being pumped by domestic wells. A proposal to convert a deep vertical irrigation well to a series of small-capacity shallow vertical wells or a large-capacity horizontal well and slight deepening of the domestic wells was examined through simulations. This can reduce the nitrate concentration of ground water in domestic wells dramatically and use the high nitrate water for crop irrigation.     

Prenatal diagnosis of autosomal dominant microcephaly and postnatal evaluation with magnetic resonance imaging

A case of fetal autosomal dominant microcephaly was prenatally diagnosed with ultrasonography in a woman with previously undiagnosed microcephaly. At the time of initial ultrasonographic assessment, the mother was identified to have a markedly small cranium, consistent with maternal microcephaly. The ultrasonographic examination showed the fetal head size to be four standard deviations below the mean for gestational age. Gesta-tional dating from the other biometric parameters and from the last menstrual period was consistent with 31 weeks' gestation. Neurosonographic evaluation of the fetus revealed no obvious structural abnormalities. Serial ultrasonographic examinations at 35 and 38 weeks' gestation showed no changes in the fetal head size. A 2·64 kg male fetus was delivered at term. Neonatal assessment showed the fetal head circumference to be less than the second percentile for gestational age. Neurologic assessment of the neonate with magnetic resonance imaging showed abnormal development of the brain, with small cerebellar and cerebral hemispheres, and pachygyria. These images are compared with the magnetic resonance images of the mother. Our findings of maternal and fetal microcephaly are consistent with autosomal dominant microcephaly. To our knowledge, this is the first report of the prenatal diagnosis of autosomal dominant microcephaly.     

Metallothione in-like protein in lobsters ( )

A metallothionein-like protein (MLP) was isolated from naturally cadmium-contaminated lobster hepatopancreas, gills, and green glands. Between 76–99% of the total cadmium was associated with this protein (molecular weight 9,500 daltons) while the remainder was associated with both high (68,000 daltons) and low (<6,000 daltons) molecular weight proteins. MLP was not present in uncontaminated lobster hepatopancreas and only 1% of the total cadmium was associated with the gel filtration fraction corresponding to the protein.     

A study for evaluation of contaminant transport characteristics through fine-grained soil.

Transport of soluble toxic substances through porous media lead to some significant geoenvironmental problems, for example, leachate migration from municipal and industrial solid waste resulting from unregulated disposal. Advection, dispersion, diffusion, and decay are reported to be the principal mechanisms in such phenomena. Geotechnical properties of the soil also play a significant role in this deterioration. In the present study, laboratory tests were conducted to formulate an appropriate method for assessment of migration of metal ions, such as nickel, through the soil. Relevant kinetic and process parameters, such as aquifer data, surface area, dielectric constant, pH of zero point charge (pHzpc), and permeability were also studied. One-dimensional mathematical modeling was used to describe the dynamics of the process. The present investigation was carried out at an ash pond site of a thermal power plant situated in West Bengal, India.     

Removal process estimation of population size for a population with a known sex ratio

A removal model for estimating population size which uses the known population sex ratio is studied. A maximum likelihood estimate and an optimal martingale estimate of the population size are proposed. Their standard errors and large sample properties are obtained. Simulation studies are reported, and the performance of the proposed estimators are compared with the standard maximum likelihood estimator which ignores the sex ratio information. An example on a capture study of deer mice is given.     

Sex-biased costs in nest defence behaviours by lesser snow geese (Chen caerulescens): consequences of parental roles?

Nest defence behaviours, such as attacking predators and defending against predator attacks, expose birds to risk of injury and death. However, direct costs of such behaviours are poorly documented. To evaluate potential costs of nest defence behaviours in lesser snow geese (Chen caerulescens), we (1) estimated the proportion of interactions between arctic foxes (Alopex lagopus) and geese that resulted in physical contact and (2) examined how nest defence behaviours varied between male and female geese. We separated interactions into attacks initiated by foxes (attacks by foxes) and attacks initiated by geese (attacks by geese). Risks associated with attacks by geese were considerably lower than the risks associated with attacks by foxes; only 1 of 1,179 attacks by geese resulted in physical contact between foxes and geese, whereas 26 of 89 attacks by foxes involved such contact (two female geese were killed during these attacks). Attacks by geese were made almost exclusively by male geese (>97%), whereas female geese were involved in 75% of all attacks by foxes that resulted in physical contact with geese. There was, thus, a considerable difference in risks associated with male and female nest defence behaviours. We suggest that parental roles during nesting (i.e., females incubate and males guard) expose female geese to greater risk of injury and death. Male geese may, however, reduce the risk of injury or death to their mates with pre-emptive attacks on foraging foxes.     

Radioactive contamination from medical uses and recent regulatory activity in the U.S.A.

Recent publications relating to environmental radioactive contamination from medical uses are described. It appears that the unprecented growth of medical uses of radionuclide continues in the United States; hospital effluents are not a measurement problem; and the regulatory climate is uncertain. The major need, appears to be in the reduction or control of medical radiation exposure to the patient from diagnosis and therapy.     

Polycyclic aromatic hydrocarbons storage by Fusarium solani in intracellular lipid vesicles

Accumulation and elimination of polycyclic aromatic hydrocarbons (PAHs) were studied in the fungus Fusarium solani. When the fungus was grown on a synthetic medium containing benzo[a]pyrene, hyphae of F. solani contained numerous lipid vesicles which could be stained by the lipid-specific dyes: Sudan III and Rhodamine B. The fluorescence produced by Rhodamine B and PAH benzo[a]pyrene were at the same locations in the fungal hyphae, indicating that F. solani stored PAH in pre-existing lipid vesicles. A passive temperature-independent process is involved in the benzo[a]pyrene uptake and storage. Sodium azide, a cytochrome c oxidation inhibitor, and the two cytoskeleton inhibitors colchicine and cytochalasin did not prevent the transport and accumulation of PAH in lipid vesicles of F. solani hyphae. F. solani degraded a large range of PAHs at different rates. PAH intracellular storage in lipid vesicles was not necessarily accompanied by degradation and was common to numerous other fungi.