Forest Ecosystems,Forest Management and the Global Carbon Cycle,edited by M. J. Apps and D. T. Price,NATO Series,Series 1: Global Environmental Change,Vol. 40

Water, Air, &; Soil Pollution -     

Bioavailability of Arsenic and Antimony in Terrestrial Ecosystems: A Review

Arsenic (As) and antimony (Sb) are metalloids that belong to group 15 of the periodic table and exhibit toxic properties in the environment. They mostly occur naturally at low concentrations in soil, although these can be significantly elevated in both aquatic and terrestrial food chains as a result of dispersion from anthropogenic sources, e.g., mining activities. The bioavailability, i.e., the proportion of the contaminant in soil and dust that is available for uptake by plants and other living organisms, presents the greatest risk to terrestrial ecosystems. Various in vivo and in vitro methods have been used to measure As and Sb bioaccessibility in soil and dust. In vivo measurement of bioavailability can be time consuming, expensive, and unethical; thus, in vitro methods are commonly preferred. However, there is considerable uncertainty around the efficacy of in vitro tools used to measure the bioavailable fractions of As and Sb. The results of these methods are dependent on many variables, e.g., soil characteristics, contaminant sources, and chemical composition of in vitro methods. Therefore, substantial variations are observed between in vitro and in vivo results obtained from different test animals and endpoints. In this paper, we review the literature on As and Sb bioavailability in terrestrial ecosystems and current in vivo and in vitro techniques used for assessing bioavailability and bioaccessibility of metalloids. This would reveal research gaps and allow scientists and environmental policy makers to gain a deeper understanding of the potential risks associated with these metalloids in the environment.     

Environmental Radioactivity. From Natural,Industrial and Military Sources (M. Eisenbud and T. Gesell)

Water, Air, &; Soil Pollution -     

干旱胁迫下白花柽柳抑制性消减文库的构建分析

本试验构建了PEG6000渗透胁迫下白花柽柳的抑制性消减杂交(suppression subtractive hybridization, SSH)文库。文库克隆的重组率为95 % ，插入片段大部分集中在100～1000 bp之间。通过对文库阳性克隆的随机测序，并对表达序列标签（expressed sequence tag, EST）分析得到了100个与干旱胁迫相关的EST片断，它们涉及了植物的渗透调节、信号传递、转录调控、活性氧清除、蛋白代谢、跨膜转运和离子平衡及光合作用等方面。此结果对今后进一步研究这些基因的功能奠定了基础。     

Chemical Principles of Environmental Pollution,B.J. Alloway and D.C. Ayres

Water, Air, &; Soil Pollution -     

Morphology and genetic diversity of Marrubium cuneatum Russell and M. parviflorum Fisch. & C.A. Mey

Genetic Resources and Crop Evolution - Marrubium parviflorum Fisch. & C.A. Mey. and Marrubium cuneatum Russell, are naturally distributed in various parts of Iran. It is difficult to...     

Metal-metal interactions in biological systems. Part IV. Freshwater snail Bulinus globosus

The toxicity against title snails of all Al, Cd, Co(II), Cr(III), Cu(II), Fe (III), Mg, Mn(II), Mo(VI), Ni(II), Pb(II), Se(VI), V(V) and Zn ions was checked in 96 h tests in the water of Kariba Lake. Based on the mortality — concentration relationship the toxicity order of the above ions against Bulinus globosus is Cu(II) > Ni(II) > Cd > Pb(II) > Zn > Al > V(V)> Cr(III)> Se(VI) > Fe(III) =Co(II)> Mn(II) > Mg > Mo(VI). Only Mg, Pb(II), Cu(II), Cd, Zn and Ni(II) ions are harmful to these snails as their mortality is observed at the naturally occuring concentrations. Other metal ions cause lethality at naturally unrealistic concentrations. The following pairs of metal ions were also checked for mutual interactions: Cd-Al, Cd-Co, Cd-Cr, Cd-Cu, Cd-Fe, Cd-Mg, Cd-Mn, Cd-Mo, Cd-Ni, Cd-Pb, Cd-Se, Cd-V, Cd-Zn, Cu-Al, Cu-Co, Cu-Cr, Cu-Fe, Cu-Mg, Cu-Mn, Cu-Mo, Cu-Ni, Cu-Pb, Cu-Se, Cu-V, Cu-Zn, Ni-Al, Ni-Co, Ni-Cr, Ni-Fe, Ni-Mg, Ni-Mn, Ni-Mo, Ni-Pb, Ni-Se, Ni-V, Ni-Zn, Pb-Al, Pb-Co, Pb-Cr, Pb-Fe, Pb-Mg, Pb-Mn, Pb-Mo, Pb-Se, Pb-V, Pb-Zn, Zn-Al, Zn-Co, Zn-Cr, Zn-Fe, Zn-Mg, Zn-Mn, Zn-Mo, Zn-Se, Zn-V. Synergism and antagonism were several times observed in various combinations of ions. The effect of metal-metal interactions on an accumulation of those metals in the flesh and shells of snails was also observed and measured.     

Determination of aflatoxicol and aflatoxins B1 and M1 in eggs

Procedures from 2 methods, one for aflatoxins B1 and M1 in eggs and one for aflatoxicol in milk, blood, and liver, have been combined to determine the 3 toxins in eggs. The sample is blended with sodium chloride-saturated water and this mixture is then blended with acetone. After separation from the solid residue, the aqueous acetone extract is defatted with petroleum ether. The toxins are next partitioned into chloroform and separated from interferences on a silica gel column. Aflatoxicol is determined by fluorescence measurement after separation on a C18 reverse phase liquid chromatographic column, and aflatoxins B1 and M1 are determined by fluorescence densitometry after separation on a silica gel thin layer chromatographic plate. In a recovery study with eggs, mean recoveries of aflatoxicol added at levels of 0.1, 0.05, and 0.025 ng/g were 87, 77, and 78%, respectively. Mean recoveries of aflatoxins B1 and M1 added at a level of 0.1 ng/g were 75 and 87%, respectively, and at an added level of 0.05 ng/g were 86 and 75%. The within-laboratory precision (repeatability) ranged from 2 to 13%.     

Alkyl C and hydrophobicity in B and C horizons of an acid forest soil

Aliphatic C most probably derived from ester‐bound moieties was found to be present in sandy subsoil horizons. The hydrophobic nature of such compounds may increase their stabilization potential. Therefore, the aim of this study was to investigate the potential of aliphatic compounds in mineral soil horizons along a Dystric Cambisol profile under beech forest to increase hydrophobicity. The conceptual approach included the analyses of soil samples before and after solvent extraction and base hydrolysis for elemental and isotopic composition. Additionally, the advancing contact angle was measured to quantify hydrophobicity. Curie‐point pyrolysis GC/MS was carried out to characterize the nature of alkyl C present in subsoil samples. A close correlation between the ¹⁴C activity and the stable‐C‐isotope ratio (δ¹³C) indicates isotopic fractionation upon C stabilization in subsoils. Free lipids contributed less than 10% to the organic C found in subsoil horizons. Base hydrolysis revealed very high amounts of hydroxyalkanoic acids in the B horizons of the acid forest soil. Hydrophobicity of SOM was not found to be correlated to esterified‐ or free‐lipid content. The contact angle was in a similar range for all bulk soil horizons, suggesting greater hydrophobicity of organic matter in subsoil horizons considering their very low concentrations of organic C compared to the A horizon. The quantity and nature of pyrolysis products change with increasing depth in the soil profile. Aliphatic products cannot be detected in B and C horizons by Curie‐point pyrolysis GC/MS.