Robust trend tests with application to toxicology

In most real data situations in the one-way design both the underlying distribution and the shape of the dose-response curve are a priori unknown. The power of a trend test strongly depends on both. However, tests which are routinely used to analyze toxicological assays must be robust. We use nonparametric tests with different scores—powerful for different distributions—and different contrasts—powerful for different shapes—and use the maximum of all test statistics as a new test statistic. Simulation results indicate that this maximum test, which is a nonparametric multiple contrast test, stabilizes the power for various shapes and distributions. The investigated tests are applied to the data of a toxicological assay.     

Biomonitoring of polychlorinated biphenyls in Bavaria/Germany—long-term observations and standardization

In the 1980s, it was demonstrated that semi-volatile organic compounds (SVOCs) like polychlorinated biphenyls (PCBs) accumulate in plant leaves. Plants are at the base of the food chain, and therefore a starting point for transfer of PCBs to animals and related human exposure. For two decades, the Environment Agency of the German federal state of Bavaria (LfU) has been operating long-term monitoring stations to measure the impact of organic air pollutants. Standardized ryegrass, curly kale, and spruce needles are used as bioindicators for the atmospheric entries of PCBs into vegetation. From the end of 1990s to 2009, there was a marked decline in the concentrations of indicator PCBs (i-PCBs) and a minor decline in PCB-TEQ levels. After 2009, the concentrations leveled off. In rural areas, the median concentrations of Σ6 i-PCB in ryegrass and curly kale were about 3 and 4 μg/kg dm in 2000, and have been about 0.5 and 1 μg/kg dm since 2009, respectively. Concentrations in spruce needles fell from 0.9 to 0.4 μg/kg dm. Median PCB-TEQ concentrations in the bioindicator plants ranged from 0.05 to 0.23 ng/kg dm between 2002 and 2009 and from 0.15 to 0.05 ng/kg dm after 2009. Indicator PCB and PCB-TEQ concentrations were several times higher at the urban station in Munich than at the rural areas, reflecting the emissions from in-use PCB stocks in the building sector. The likely reason of the slower decrease of PCB-TEQ compared to i-PCBs is the formation of PCB-126 by dechlorination of industrial PCBs in open applications.     

Mediterranean land systems under global change: current state and future challenges

Regional Environmental Change -     

Swamp reclamation in tropical monsoon regions by appropriate refuse landfilling

Summary This paper is based on a research study to evaluate the feasibility of reclaiming low-lying swamplands by filling them with refuse, rather than with dirt, sand or other inert materials. A supplementary study was also initiated to prepare a preliminary evaluation of disposing of solid waste from the Bangkok Metropolis region. This included a preliminary assessment of available filling areas and of costs for filling them, together with projected values of reclaimed land. The latter study was included to determine if a feasibility study for utilising refuse landfilling for Bangkok solid-waste disposal is warranted, and to prepare the feasibility study terms of reference if so justified. Results of the literature review, practices of refuse landfilling in swamps, and methods and materials employed in conduct of the study are described. This is followed by evaluations of the feasibility of disposing solid wastes utilising swamplands, an environmental analysis of the same, and the conclusions of the study.The authors are Consulting Engineers at Seatec International, Bangkok. The views in this paper are those of the authors and do not necessarily reflect World Bank policies.