Evaluation of plant availability of soil trace metals by chemical fractionation and multiple regression analysis

Soil samples with a range of chemical and physical properties were collected from 10 different rural regions of China. Trace metals (Ni, Co, Cu, and Pb) in the soils were partitioned by a sequential extraction procedure into Mg(NO(3))(2) extractable (F1), CH(3)COONa extractable (F2), NH(2)OH.HCl extractable (F3), HNO(3)?H(2)O(2) extractable (F4), and residual (F5) fractions. Chemical fractionation showed that F1 fraction of the metals was less than 1% and residue was the dominant form for Cu and Ni in all samples, and for Co in most of the samples. Significant interrelationships of the fractions varied considerably with the different metals. Winter wheat (Triticum aestivum L.) and alfalfa (Medicago sativa L.) had been grown on the soils in a pot-culture experiment under greenhouse conditions for 40 days. Metal availability to the plants was evaluated by simple and multiple regression analysis. The Mg(NO(3))(2) extractable Co (F1) was significantly correlated with Co concentrations in different parts of wheat and in the whole of alfalfa. For the other metals, the independent variables of the multiple regression models, chosen by stepwise selection, were given as: F1 and F2 + F3 + F4 for Ni; F1, F2 + F3 and F4 for Cu; and F3 + F4 for Pb. The results of this study demonstrate that the sequential extraction procedure, in conjunction with multiple regression models using a combination of correlated fractions as an independent variable, may be useful for the prediction of plant absorption of trace metals in soils.     

Persistent organic pollutants in source-separated compost and its feedstock materials--a review of field studies

Composting and the application of compost to the soil follow the principle of recycling and sustainability. Compost can also have a positive effect on physical, chemical, and biological soil parameters. However, little is known about the origin, concentration, and transformation of persistent organic pollutants (POPs) in compost. We therefore compiled literature data on some priority POPs in compost and its main feedstock materials from more than 60 reports. Our data evaluation suggests the following findings. First, median concentrations of Sigma 16 polycyclic aromatic hydrocarbons (PAHs), Sigma 6 polychlorinated biphenyls (PCBs), and Sigma 17 polychlorinated dibenzo-p-dioxins and -furans (PCDD/Fs) were higher in green waste (1803, 15.6 microg/kg dry wt., and 2.5 ng international toxicity equivalent [I-TEQ]/kg dry wt.) than in organic household waste (635, 14.6 microg/kg dry wt., and 2.2 ng I-TEQ/kg dry wt.) and kitchen waste (not available [NA], 14.9 microg/kg dry wt., 0.4 ng I-TEQ/kg dry wt.). The POP concentrations in foliage were up to 12 times higher than in other feedstock materials. Second, in contrast, compost from organic household waste and green waste contained similar amounts of Sigma 16 PAHs, Sigma 6 PCBs, and Sigma 17 PCDD/Fs (1915, 39.8 microg/kg dry wt., and 9.5 ng I-TEQ/kg dry wt., and 1715, 30.6 microg/kg dry wt., and 8.5 ng I-TEQ/kg dry wt., respectively). Third, concentrations of three-ring PAHs were reduced during the composting process, whereas five- to six-ring PAHs and Sigma 6 PCBs increased by roughly a factor of two due to mass reduction during composting. Sigma 17 PCDD/Fs had accumulated by up to a factor of 14. Fourth, urban feedstock and compost had higher POP concentrations than rural material. Fifth, the highest concentrations of POPs were usually observed in summer samples. Finally, median compost concentrations of POPs were greater by up to one order of magnitude than in arable soils, as the primary recipients of compost, but were well within the range of many urban soils. In conclusion, this work provides a basis for the further improvement of composting and for future risk assessments of compost application.     

Analysis of ingredient and heating value of municipal solid waste

ＩｎｔｒｏｄｕｃｔｉｏｎＭＳＷｉｎｃｌｕｄｅｓｖａｒｉｏｕｓｗａｓｔｅｓｇｅｎｅｒａｔｅｄｆｒｏｍ ｐｅｏｐｌｅ’ｓｄａｉｌｙｌｉｆｅａｎｄｉｎｄｕｓｔｒｉａｌｐｒｏｃｅｓｓ.Ｗｉｔｈｔｈｅｉｍｐｒｏｖｅｍｅｎｔｏｆｐｅｏｐｌｅ’ｓｌｉｆｅ ,ｔｈｅｉｎｃｒｅａｓｉｎｇａｍｏｕｎｔｏｆＭＳＷｉｓｂｅｃｏｍｉｎｇａｐｒｏｂｌｅｍｂａｆｆｌｉｎｇｅｖｅｒｙｇｏｖｅｒｎｍｅｎｔ(Ｓｉｎｏ ＵＮ ,1999) .Ｗｉｔｈｏｕｔｅｆｆｅｃｔｉｖｅｈａｎｄｌｉｎｇ ,ＭＳＷｍａｙｓｅｒｉｏｕｓｌｙｔｈｒｅａｔｅｎｐｅｏｐｌ…     

Extraction kinetics of phenol with N, N-di (1-methyl-heptyl) acetamide-kerosene using hollow fiber membrane extractor

ＩｎｔｒｏｄｕｃｔｉｏｎＡｔｐｒｅｓｅｎｔ,ｏｎｅｏｆｔｈｅｍｅｔｈｏｄｓｕｓｅｄｅｘｔｅｎｓｉｖｅｌｙｉｎｔｒｅａｔｍｅｎｔｏｆｗａｓｔｅｗａｔｅｒｃｏｎｔａｉｎｉｎｇｐｈｅｎｏｌｉｓｃｏｎｖｅｎｔｉｏｎａｌｓｏｌｖｅｎｔｅｘｔｒａｃｔｉｏｎ,ｗｈｉｃｈｉｓｕｓｕａｌｌｙｐｅｒｆｏｒｍｅｄｉｎｔｗｏｃｏｍｍｏｎｆｏｒｍｓｕｓｉｎｇｅｉｔｈｅｒｅｘｔｒａｃｔｉｏｎｔｏｗｅｒｏｒｍｉｘｅｒ ｓｅｔｔｌｅｒ.Ｈｏｗｅｖｅｒ,ｗｈｉｃｈｅｖｅｒｆｏｒｍｉｓｔａｋｅｎ ,ｔｈｅａｑｕｅｏｕｓｐｈａｓｅａｎｄｏ…     

Improving the numerical stability of the MAGIC model

ＩｎｔｒｏｄｕｃｔｉｏｎＴｈｅｍｏｄｅｌｏｆａｃｉｄｉｆｉｃａｔｉｏｎｏｆｇｒｏｕｎｄｗａｔｅｒｉｎｃａｔｃｈｍｅｎｔ(ＭＡＧＩＣ)ｉｓｏｎｅｏｆｔｈｅｍｏｓｔｗｉｄｅｌｙｕｓｅｄｍｏｄｅｌｓｗｏｒｌｄｗｉｄｅｆｏｒｐｒｅｄｉｃｔｉｎｇｃａｔｃｈｍｅｎｔａｃｉｄｉｆｉｃａｔｉｏｎａｎｄｉｓｓｔｉｌｌｕｎｄｅｒｆｕｒｔｈｅｒｕｐｇｒａｄｉｎｇ(Ｃｏｓｂｙ,1985;Ｈｉｎｄｅｒｅｒ,1995;Ｃｏｓｂｙ,1995).Ｔｈｅｍｏｄｅｌ,ｈｏｗｅｖｅｒ,ｉｓｉｎｈｅｒｅｎｔｌｙａｓｓｏｃｉａｔｅｄｗｉｔｈｎｕｍｅｒｉｃａｌｉ…     

Soil landscape constraint mapping for coastal land use planning using geographic information system

The aim of the study was to delineate soil landscape constraints to various land uses for urban and regional planning in the coastal areas of New South Wales (NSW), Australia. Soil landscape units mapped at 1:100,000 or coarser were sub-divided into component facets using advanced terrain modelling techniques in a geographic information system (GIS). The output facet grids were further overlain and linked with relevant GIS layers and soil databases to derive soil landscape constraint ratings for various land use purposes such as residential development, cropping and grazing. The constraint ratings for a specific land use were calculated based on objective and rule-based assessments of soil and landscape features such as engineering hazards, intrinsic fertility, drainage and other parameters. A series of soil landscape constraint maps which portray specific land use capability have been produced for the NSW coast. The methodology developed in this study has been demonstrated to be efficient in delineating soil landscape constraints and there is over 90% agreement between the model outputs and the assessment by soil surveyors with local knowledge. The output maps show levels of unprecedented detail of soil and landscape constraint for the coast of NSW and can be readily interpreted by land use planners and land managers for sustainable land use decision making practices.     

Fractionation of Heavy Metals in Surface Sediments of Taihu Lake, East China

The BCR (European Communities Bureau of Reference) three-step sequential extraction procedure was applied to fractionate heavy metals in the sediment of Taihu Lake. For the determination of total metal concentration of the sediments, sample digestion was achieved by using HF/H₂O₂/HNO₃(2/1/1) acid mixture in a microwave-irradiated closed vessel system. The concentrations of Cd, Ni, Cr, Zn, Cu and Pb in various extracts solutions were analyzed by Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES). The results obtained from the BCR three-step sequential extraction indicated relatively high mobility of Zn, Cu, Pb and Ni in the sediments while Cd and Cr were poorly mobile. Enrichment of heavy metals was found in the sediments collected in the northern parts of Taihu Lake. In the sediments collected in the southern and western sides of the Lake, heavy metal concentrations were relatively low. The relationship between total organic carbon (TOC) and heavy metals concentrations in the sediments is discussed.     

Calorimetric studies on the energy metabolism of an infaunal bivalve,Abra tenuis,under normoxia,hypoxia and anoxia

Direct calorimetry was employed to measure the energy metabolism of infaunal bivalves, Abra tenuis, collected from a tidal lagoon in the Fleet, southern England, in June 1989, at various oxygen partial pressures. A significant anaerobic component (i.e., 20% of total metabolic rate) was detected under normoxia, presumably brought about by the intermittent ventilatory activity of this bivalve under these conditions. Under hypoxia (2.3 to 10 kPa, or 11 to 48% of full air saturation), however, the energy metabolism was maintained fully aerobic; the measured heat equivalent of oxygen uptake was not significantly different from the theoretical ranges for fully aerobic catabolism. Under anoxia, the rate of heat dissipation was reduced to 5–6% of the normoxic rate of heat dissipation. This conserves energy expenditure and would thus increase resistance of A. tenuis to anoxia or emersion. Physiological compensation by A. tenuis under conditions of declining oxygen tension involved a marked increase in ventilation rate. Comparison between fed and starved individuals indicated that costly physiological processes, such as digestion, absorption and growth declined at 10 and 5 kPa and were arrested at P_{O 2} (oxygen partial pressure) levels below 2.3 kPa. The present study provides evidence that there are no major differences between the metabolic responses of epifaunal suspension-feeding (eg. Mytilus edulis) and infaunal deposit-feeding (eg. A. tenuis) bivalves when exposed to environmental hypoxic stress.