Long Term Effects of Acid Irrigation at the Höglwald on Seepage Water Chemistry and Nutrient Cycling

In order to test the hypothesis of aluminium toxicity induced by acid deposition, an experimental acid irrigation was carried out in a mature Norway spruce stand in Southern Germany (Höglwald). The experiment comprised three plots: no irrigation, irrigation (170 mm a^?1), and acid irrigation with diluted sulphuric acid (pH of 2.6–2.8). During the seven years of acid irrigation (1984–1990) water containing 0.43 mol_c m^?2 a^?1 of protons and sulphate was added with a mean pH of 3.2 (throughfall?+?acid irrigation water) compared to 4.9 (throughfall) on both control plots. Most of the additional proton input was consumed in the organic layer and the upper mineral soil. Acid irrigation resulted in a long lasting elevation of sulphate concentrations in the seepage water. Together with sulphate both aluminium and appreciable amounts of base cations were leached from the main rooting zone. The ratio between base cations (Ca?+?Mg?+?K) and aluminium was 0.79 during acid irrigation and 0.92 on the control. Neither tree growth and nutrition nor the pool of exchangeable cations were affected significantly. We conclude that at this site protection mechanisms against aluminium toxicity exist and that additional base cation runoff can still be compensated without further reduction of the supply of exchangeable base cations in the upper mineral soil.     

攀枝花市攀钢工业区土壤重金属污染特征及评价

本文对攀枝花市攀钢工业区土壤中五种重金属元素（Cu、Pb、Zn、Cr、Cd）的空间的分布特征、形态分布特征进行了研究，并应用污染负荷指数法对各重金属的污染程度进行了评价。研究发现，Cu、Pb、Zn、Cr的最大值与最小值分别相差2．98、3．4、5．2、2．7倍，cd的最大值与最小值甚至相差15．7倍。重金属元素相关性特征可分为Cd—Pb—Zn和Cu—Cr两组。形态分布特征表现在Cu、Zn、Pb、Cr主要以稳定的残渣态存在，Cd主要以可利用性最强的可交换态和碳酸盐结合态存在。污染较严重的是攀钢机关、攀钢原料场。     

A soil alteration index based on phospholipid fatty acids

Phospholipid fatty acid (PLFA) analysis has gained great importance in the study of soil microbial community structure. This structure can give indication of the soil status. Purpose of the present paper is to analyse PLFA patterns in altered agricultural soils in order to develop a soil status alteration index. Soils subjected either to intensive agricultural exploitation, or to overflow by municipal and industrial wastes, or to irrigation with saline waters were analysed for PLFA content and compared to adjacent untreated soils by means of different statistical techniques.

Principal component analysis separated PLFAs in three groups: unsaturated PLFAs (first axis, 48% of total variance), monounsaturated and cyclopropane PLFAs (second axis, 28% of total variance) and polyunsaturated PLFAs (third axis, 24% of total variance).

By means of canonical discriminant analysis, a soil alteration index (SAI) was produced from 15 PLFAs using two data sets. A third data set was used to test the SAI general validity together with other data sets reported in literature. The index validity was confirmed in most cases: SAI gave higher scores for control soils and was generally able to classify soils according to their reported degree of alteration.     

土壤氮素矿化模型研究进展

土壤氮素矿化研究对从农田生态系统氮素平衡到全球变化和环境问题均具有重要意义。土壤氮素矿化模型的研究方面．目前主要还是以简单功能模型模拟和预测氮素矿化量为主,以双组分一阶动力学模型和一阶-零阶混和动力学模型拟合效果较好;对机理模型的研究还处于探索阶段。从目前的研究看,土壤氮素矿化模型研究应当集中在建立机理模型以阐明主要生态系统的氮素矿化过程。     

Effect of the water–oil ratio on brine/surfactant/alcohol/oil systems optimized for soil remediation

The optimum middle-phase microemulsion used for remediation of oily contaminated soils is often obtained by mixing a certain amount of a surfactant/alcohol mixture with oil and adjusting the salinity concentrations at a constant water–oil ratio. Upon introduction to the subsurface, however, the system may not be in the optimum state throughout the remediation process owing to the change in the water–oil ratio. This research has attempted to investigate the effect of the water–oil ratio on the phase behavior of systems containing brine, anionic surfactant, alcohols, and different oils. By systematically changing the water–oil ratio, while keeping the others variables constant, the systems exhibited different phase behavior. The results revealed that the effect of the water–oil ratio on system behavior was significant, and analogous to that of salinity. Increasing the water–oil ratio led the system change from winsor I → winsor III → winsor II. The greater the water–oil ratio the lower the salinity required to produce the middle-phase microemulsion, but the narrower the salinity range of the three-phase region. An empirical correlation has been developed in order to predict the changes in phase behavior with the changes in water–oil ratio. This provides a useful tool for designing optimum formulations suitable for soil remediation. Received: October 5, 1999 / Accepted: March 27, 2000     

Urban geochemical mapping studies: how and why we do them

Geochemical mapping is a technique rooted in mineral exploration but has now found worldwide application in studies of the urban environment. Such studies, involving multidisciplinary teams including geochemists, have to present their results in a way that nongeochemists can comprehend. A legislatively driven demand for urban geochemical data in connection with the need to identify contaminated land and subsequent health risk assessments has given rise to a greater worldwide interest in the urban geochemical environment. Herein, the aims and objectives of some urban studies are reviewed and commonly used terms such as baseline and background are defined. Geochemists need to better consider what is meant by the term urban. Whilst the unique make up of every city precludes a single recommended approach to a geochemical mapping strategy, more should be done to standardise the sampling and analytical methods. How (from a strategic and presentational point of view) and why we do geochemical mapping studies is discussed.

Protective values for soil lead with respect to child health: a critique of UK guidelines

In 2002, The (UK) Department for Environment, Food and Rural Affairs (DEFRA) together with the Environment Agency published document SGV10 “Contaminants in soil: collation of toxicological data and intake values for humans. Lead”. This publication sets out the derivation of Soil Guideline Values for lead contamination. Values for soil lead that are protective of the health of children and also for adults are derived using the model recommended by an international task force working under the auspices of the Society for Environmental Geochemistry and Health (SEGH) (Wixson and Davies 1993, 1994). Detailed examination of the DEFRA publication shows it uses unrealistic values for two variables in the SEGH model. The consequence is both actual and has potential adverse societal impacts. These impacts could be avoided if the appropriate scientific community were regarded as stakeholders in the legislative outcome and not simply the providers of the research data.     

Dual <Superscript>14</Superscript>C/residue analysis method to assess the microbial accessibility of native phenanthrene in environmental samples

The aim of this work was to develop a method to assess the microbial accessibility of native phenanthrene present in soils and sediments. We developed an accelerated biodegradation assay, characterized by (a) inoculation with a sufficient number of phenanthrene-degrading microorganisms, (b) monitoring of the biodegradation activity through ¹⁴C-mineralization measurements, and (c) single-step chemical analysis of the native compound in the residue. The use of ¹⁴C-labeling allowed the determination of the time period needed for biodegradation of the bioaccessible fraction of the native chemical. The method was tested with environmental samples having a wide range of phenanthrene concentrations, i.e., from background levels (μg kg^-1) originating in soil from atmospheric deposition, to acute concentrations (g kg^-1) corresponding to industrial pollution of soils and sediments. The results showed a wide range of bioaccessibility (15–95% of the initial amount). The method can be used for the assessment of bioaccessibility involved in the management of polycyclic aromatic hydrocarbon (PAH) pollution.     

A first generation dynamic ingress,redistribution and transport model of soil track-in: DIRT

This work introduces a spatially resolved quantitative model, based on conservation of mass and first order transfer kinetics, for following the transport and redistribution of outdoor soil to, and within, the indoor environment by track-in on footwear. Implementations of the DIRT model examined the influence of room size, rug area and location, shoe size, and mass transfer coefficients for smooth and carpeted floor surfaces using the ratio of mass loading on carpeted to smooth floor surfaces as a performance metric. Results showed that in the limit for large numbers of random steps the dual aspects of deposition to and track-off from the carpets govern this ratio. Using recently obtained experimental measurements, historic transport and distribution parameters, cleaning efficiencies for the different floor surfaces, and indoor dust deposition rates to provide model boundary conditions, DIRT predicts realistic floor surface loadings. The spatio-temporal variability in model predictions agrees with field observations and suggests that floor surface dust loadings are constantly in flux; steady state distributions are hardly, if ever, achieved. A contribution from ESF Center for the Urban Environment.     

Human geography of New Orleans’ high-lead geochemical setting

Previous soil lead studies in New Orleans focused on the geochemical footprint and its health impacts. This study examines the human geography of race, income, and age in pre-Katrina metropolitan New Orleans within the context of lead accumulation in soils. Sample points of soil lead data (n = 5,467) collected in 1998–2000 were mapped in a geographic information system (GIS), binned into 9 ranges, and queried by (1) 2000 Census racial demographic data, (2) 1999 median household income, and (3) 2000 age data. The absolute population generally declines as lead levels increase except at lead levels from 200–400 to 400–1,000 mg/kg when population increases; the African–American population comprises a disproportionate share of this cohort. The high-lead areas occur in the inner city, home to the largest populations of African-Americans in New Orleans. The mean household income curve indicates that lower economic groups are at risk to higher levels of lead. A total of 44,701 children under the age of 5 years, plus 123,579 children aged 5–17, lived in census block groups containing at least one sample point with over 100 mg/kg lead, and these include 23,124 and 64,064 young people, respectively, who live near at least one point over 400 mg/kg. Lead exposure affects a panoply of outcomes that influence the health and welfare of the community. Unless corrected, children are likely to return to the same or, because of lack of lead-safe practices during renovation, even higher exposure risks than before the flooding of New Orleans.