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Sampling of plant material for chemical analysis
Selected Bibliography showed the highest POCP values with halocarbons the lowest. Using the POCP index, motor vehicle exhaust is seen to exhibit the highest ozone-forming potential of all the hydrocarbon emission source categories evaluated. Toluene, n-butane, ethylene and the xylenes, alone account for over one third of the ozone forming potential of European emissions. Certain hydrocarbons, including acetone and methyl acetate, show significantly lower POCPs and have considerable potential as candidates for substitution in industrial or chemical processes and as solvents.
Fertilizer-N use efficiencyand nitrate pollution of groundwater in developing countries. Bijay-Singh, Yadvinder-Singh and Sekhon G. S. Agricultural University, Department of Soils, Punjab Ludhiana 141 004, India. J. Contam. Hydrol., 1995, 20/34 (167-184). Summ. in Engl. Around 76% of the world’s population lives in developing countries where more fertilizer-N is currently applied than in developed countries. Fertilizers are applied preferentially in regions where irrigation is available, and soil and climatic conditions are favorable for the growth of crop plants. Due to low N application rates during the last 3 or 4 decades, negative N balances in the soil are a characteristic feature of the crop production systems in developing countries. In the future, with increasing fertilizer-N application rates, the possibility of nitrate pollution of groundwater in developing countries will be strongly linked with fertilizer-N use efficiency. A limited number of investigations from developing countries suggest that, in irrigated soils of Asia or in humid tropics of Africa, the potential exists for nitrate pollution of groundwater, especially if fertilizer-N is inefficently managed. In a large number of developing countries in West and Central Asia and North Africa, the small amount of fertilizer applied to soils (mostly Aridisols) that remain dry almost all the year, do not constitute a major threat for nitrate pollution of groundwater, except possibly when soils are irrigated. In Asia and the Pacific regions, where 70% of the fertilizers are used to grow wetland rice on soils with low percolation rates, leaching of nitrates is minimal. Climatic water balance and soil moisture conditions do not favor leaching of nitrates from the small amount of fertilizer-N applied to Oxisols and Ultisols in Latin America. In developing countries located in the humid tropics, attempts have not been made to correlate fertilizer-N with nitrate level in groundwater; however, fertilizers are being increasingly used. Besides high rainfall, irrigation is becoming increasingly available to farmers in the humid tropics and substantial leaching of N may also increase.
Metal concentrations of resident and transplanted freshwater mussels Hj~rideua menziesi (Unionacea: Hyriidae) and sediments in the Waikato River, New Zealand. Hickey C. W., Roper D. S. and Buckland S. J. NIWA Ecosystems, National Institute of Water/Atmospheric Research, PO Box 1 l-l 15, Hamilton, New Zealand. Sci. Total Environ., 1995, 175/3 (163-177). Summ. in Engl. Heavy metals and metalloids were measured in freshwater mussels (Hyridella menziesi) and sediments in the upper Waikato River, New Zealand. Mercury (Hg) concentrations ranged 35-fold in sediments (0.025-0.87 mg kg-’ dry wt) and 144-fold in mussels (0.091-13.1 mg kg-’ dry wt). Arsenic (As) concentrations ranged 190-fold in sediments (7.9-1520 m $ kg-’ dry wt) and only IO-fold in mussels (15.&l 53 mg kgdry wt). There was no significant correlation between sediment total concentrations of either Hg or As and mussel tissue levels. Sediment quality guidelines were exceeded for Hg and As at most sites and for copper, chromium, iron and manganese
at a few sites. Tissue concentrations exceeded levels considered to be safe for human consumption for Hg at Lake Aratiatia and As at several sites. Transplant experiments with caged mussels were used to measure uptake and depuration rates of Hg and As. Half-lives for mussel uptake and depuration of Hg were 6-12 months. Arsenic uptake rates could not be determined but the depuration showed a half-life of about 2.5 months. Physiological measurements were consistent with increased food availability at some sites rather than contaminant effects. These results highlight the need to understand biochemical changes induced by factors that are independent of environmental concentrations of contaminants, such as the influence of food levels and the potential for metabolic adaptation in biomonitoring organisms.
Sampling of plant material for chemical analysis. Ernst W. H. 0. Department of Ecology/Ecotoxicology, Faculty of Biology, Vrije Universiteit, De Boelelaan 1087, 1081 HV Amsterdam, The Netherlands. Sci. Total Environ., 1995, 176 (15-24). Summ. in Engl. Sampling procedure and plant parts which are sampled strongly depend on the scope of the investigation. In contrast to sampling of abiotic components trace element concentrations of plant materials are strongly dependent on plant age, organ and tissue function, genotypic character of uptake, translocation and allocation, and are modified by the impact of other organisms. The consequences of these dynamic processes are considerable differences in element matrices. After the identification of the individual in the field the aim of the investigation will decide on the plant part(s) to be sampled, either at random or selectively. The most frequently taken plant parts in space and time are the leaves, either deciduous or evergreen. Leaf age, their position and insertion on the plant, their longevity, infestations by pathogens, injury by herbivores, and exposure of atmospheric components determine the element concentration; therefore a rigid sampling protocol is necessary. Due to their different chemical compositions, twigs and stems have to be separated into bark inclusive of phloem and wood. Exposure to precipitation and colonisation by epiphytes and bark decomposers have to be noted. In the case of roots, many chemical elements are only adsorbed to the root cell walls and are not, or only to very low degree, translocated to the other root cell components and from roots to shoots. In addition to high fragility of the roots and root hairs and their strong association with soil particles and soil organic matter, roots of most plant species have an intimate symbiotic association with mycorrhizal fungi. The change in the degree of infestation with endomycorrhizal fungi during one growing season and the change of ectomycorrhizal partners during one growing season and the change of ectomycorrhizal partners during life history are important aspects of sampling for monitoring purposes. The great variation of rooting depth during ontogeny, dependent on soil conditions, requires control of this parameter in the field. A protocol for random and selected sampling will be presented.
Methylmercury pollution in the Amazon, Brazil. Akagi H., Maim 0. and Kinjo Y. et al. National Inst. for Minamata Disease, Minamata City, Kumamoto 867, Japan. Sci. Total Environ., 1995, 175/2 (85-95). Summ. in Engl. In order to evaluate the extent of environmental mercury pollution due to goldmining activities in the Amazon, concentrations of total mercury and methylmercury were determined for human hair and fish samples from five fishing villages located mainly in the Tapajos river basin. Abnormally high
Fertilizer-N use efficiencyand nitrate pollution of groundwater in developing countries. Bijay-Singh, Yadvinder-Singh and Sekhon G. S. Agricultural University, Department of Soils, Punjab Ludhiana 141 004, India. J. Contam. Hydrol., 1995, 20/34 (167-184). Summ. in Engl. Around 76% of the world’s population lives in developing countries where more fertilizer-N is currently applied than in developed countries. Fertilizers are applied preferentially in regions where irrigation is available, and soil and climatic conditions are favorable for the growth of crop plants. Due to low N application rates during the last 3 or 4 decades, negative N balances in the soil are a characteristic feature of the crop production systems in developing countries. In the future, with increasing fertilizer-N application rates, the possibility of nitrate pollution of groundwater in developing countries will be strongly linked with fertilizer-N use efficiency. A limited number of investigations from developing countries suggest that, in irrigated soils of Asia or in humid tropics of Africa, the potential exists for nitrate pollution of groundwater, especially if fertilizer-N is inefficently managed. In a large number of developing countries in West and Central Asia and North Africa, the small amount of fertilizer applied to soils (mostly Aridisols) that remain dry almost all the year, do not constitute a major threat for nitrate pollution of groundwater, except possibly when soils are irrigated. In Asia and the Pacific regions, where 70% of the fertilizers are used to grow wetland rice on soils with low percolation rates, leaching of nitrates is minimal. Climatic water balance and soil moisture conditions do not favor leaching of nitrates from the small amount of fertilizer-N applied to Oxisols and Ultisols in Latin America. In developing countries located in the humid tropics, attempts have not been made to correlate fertilizer-N with nitrate level in groundwater; however, fertilizers are being increasingly used. Besides high rainfall, irrigation is becoming increasingly available to farmers in the humid tropics and substantial leaching of N may also increase.
Metal concentrations of resident and transplanted freshwater mussels Hj~rideua menziesi (Unionacea: Hyriidae) and sediments in the Waikato River, New Zealand. Hickey C. W., Roper D. S. and Buckland S. J. NIWA Ecosystems, National Institute of Water/Atmospheric Research, PO Box 1 l-l 15, Hamilton, New Zealand. Sci. Total Environ., 1995, 175/3 (163-177). Summ. in Engl. Heavy metals and metalloids were measured in freshwater mussels (Hyridella menziesi) and sediments in the upper Waikato River, New Zealand. Mercury (Hg) concentrations ranged 35-fold in sediments (0.025-0.87 mg kg-’ dry wt) and 144-fold in mussels (0.091-13.1 mg kg-’ dry wt). Arsenic (As) concentrations ranged 190-fold in sediments (7.9-1520 m $ kg-’ dry wt) and only IO-fold in mussels (15.&l 53 mg kgdry wt). There was no significant correlation between sediment total concentrations of either Hg or As and mussel tissue levels. Sediment quality guidelines were exceeded for Hg and As at most sites and for copper, chromium, iron and manganese
at a few sites. Tissue concentrations exceeded levels considered to be safe for human consumption for Hg at Lake Aratiatia and As at several sites. Transplant experiments with caged mussels were used to measure uptake and depuration rates of Hg and As. Half-lives for mussel uptake and depuration of Hg were 6-12 months. Arsenic uptake rates could not be determined but the depuration showed a half-life of about 2.5 months. Physiological measurements were consistent with increased food availability at some sites rather than contaminant effects. These results highlight the need to understand biochemical changes induced by factors that are independent of environmental concentrations of contaminants, such as the influence of food levels and the potential for metabolic adaptation in biomonitoring organisms.
Sampling of plant material for chemical analysis. Ernst W. H. 0. Department of Ecology/Ecotoxicology, Faculty of Biology, Vrije Universiteit, De Boelelaan 1087, 1081 HV Amsterdam, The Netherlands. Sci. Total Environ., 1995, 176 (15-24). Summ. in Engl. Sampling procedure and plant parts which are sampled strongly depend on the scope of the investigation. In contrast to sampling of abiotic components trace element concentrations of plant materials are strongly dependent on plant age, organ and tissue function, genotypic character of uptake, translocation and allocation, and are modified by the impact of other organisms. The consequences of these dynamic processes are considerable differences in element matrices. After the identification of the individual in the field the aim of the investigation will decide on the plant part(s) to be sampled, either at random or selectively. The most frequently taken plant parts in space and time are the leaves, either deciduous or evergreen. Leaf age, their position and insertion on the plant, their longevity, infestations by pathogens, injury by herbivores, and exposure of atmospheric components determine the element concentration; therefore a rigid sampling protocol is necessary. Due to their different chemical compositions, twigs and stems have to be separated into bark inclusive of phloem and wood. Exposure to precipitation and colonisation by epiphytes and bark decomposers have to be noted. In the case of roots, many chemical elements are only adsorbed to the root cell walls and are not, or only to very low degree, translocated to the other root cell components and from roots to shoots. In addition to high fragility of the roots and root hairs and their strong association with soil particles and soil organic matter, roots of most plant species have an intimate symbiotic association with mycorrhizal fungi. The change in the degree of infestation with endomycorrhizal fungi during one growing season and the change of ectomycorrhizal partners during one growing season and the change of ectomycorrhizal partners during life history are important aspects of sampling for monitoring purposes. The great variation of rooting depth during ontogeny, dependent on soil conditions, requires control of this parameter in the field. A protocol for random and selected sampling will be presented.
Methylmercury pollution in the Amazon, Brazil. Akagi H., Maim 0. and Kinjo Y. et al. National Inst. for Minamata Disease, Minamata City, Kumamoto 867, Japan. Sci. Total Environ., 1995, 175/2 (85-95). Summ. in Engl. In order to evaluate the extent of environmental mercury pollution due to goldmining activities in the Amazon, concentrations of total mercury and methylmercury were determined for human hair and fish samples from five fishing villages located mainly in the Tapajos river basin. Abnormally high