Statistical comparison and correlation of zinc and lead in estuarine sediments along the western coast of Mauritius

Cr, Zn and Pb were quantified using atomic absorption spectrometry (AAS) from urban and rural estuarine sediments collected along the western coast of Mauritius during the period July 2002-January 2003. The mean concentration of Cr (225.4 mg kg(-1)), Zn (107.0 mg kg(-1)) and Pb (27.0 mg kg(-1)) in sediments along the six estuaries can be considered below those from contaminated estuarine sediments. Zn and Pb were significantly higher in urban sediments downstream St. Louis River compared to a rural estuary at Tamarin at 5% significance level. Zn was also significantly lower in Tamarin compared to Petite Riviere Noire estuary. Cr was however not significantly different in sediments from the six estuaries and could be considered of basaltic origin and were correlated to neither lead nor zinc. The concentration of Zn and Pb were greatest in the more urbanised upper and lower reaches of the St. Louis estuary during the period of study and were also significantly positively correlated in the estuarine sediments indicating that the cycling of Pb and Zn were linked indicating a common source for Pb and Zn. The potential sources of Pb and Zn in the urban estuarine sediments were considered to arise from road runoff causing significant quantities to be trapped. At present, compared to contaminant levels found in the UK and elsewhere, Mauritius still looks relatively uncontaminated but there is growing concern about heavy metal contamination in urban estuaries. There is therefore a need for long-term studies in estuarine management to involve integrated strategies in which water-sediment interactions in estuaries need to be considered and international standards for sediment quality developed. Such studies undertaken in the future would further the understanding of the biogeochemical processes of estuarine systems in Mauritius which could then be used in environmental development schemes and effective coastal zone management.     

Soil-plant transfer of plutonium and americium in contaminated regions of Belarus after the Chernobyl catastrophe

Experimental data are presented for the soil to plant transfer of plutonium and americium into the main species of grass vegetation of Belarusian grasslands contaminated as a result of the Chernobyl catastrophe of 1986. The content of radionuclides in pore soil solutions and the total reserve of biologically available forms of plutonium and americium in rooting layers of different soil varieties have been established. The distribution coefficients of (239,240)Pu and 241Am between the solid phase and pore waters of soils have been evaluated. The migration ability and biological availability of radionuclides in soils with different structures of the absorbing complex have been analyzed for various landscape conditions. The dependence of soil to plant transfer of plutonium and americium on the content and composition of organic matter, and other characteristics of the soil complex has been studied. On the basis of these data, predictions of the contamination levels of the main grass species of natural and agricultural ecosystems by 241Am are presented.     

The ecological effects of trichloroacetic acid in the environment

Trichloroacetic acid (TCAA) is a member of the family of compounds known as chloroacetic acids, which includes mono-, di- and trichloroacetic acid. The significant property these compounds share is that they are all phytotoxic. TCAA once was widely used as a potent herbicide. However, long after TCAA's use as a herbicide was discontinued, its presence is still detected in the environment in various compartments. Methods for quantifying TCAA in aqueous and solid samples are summarized. Concentrations in various environmental compartments are presented, with a discussion of the possible formation of TCAA through natural processes. Concentrations of TCAA found to be toxic to aquatic and terrestrial organisms in laboratory and field studies were compiled and used to estimate risk quotients for soil and surface waters. TCAA levels in most water bodies not directly affected by point sources appear to be well below toxicity levels for the most sensitive aquatic organisms. Given the phytotoxicity of TCAA, aquatic plants and phytoplankton would be the aquatic species to monitor for potential effects. Given the concentrations of TCAA measured in various soils, there appears to be a risk to terrestrial organisms. Soil uptake of TCAA by plants has been shown to be rapid. Also, combined uptake of TCAA from soil and directly from the atmosphere has been shown. Therefore, risk quotients derived from soil exposure may underestimate the risk TCAA poses to plants. Moreover, TCE and TCA have been shown to be taken up by plants and converted to TCAA, thus leading to an additional exposure route. Mono- and di-chloroacetic acids can co-occur with TCAA in the atmosphere and soil and are more phytotoxic than TCAA. The cumulative effects of TCAA and compounds with similar toxic effects found in air and soil must be considered in subsequent terrestrial ecosystem risk assessments.     

Effect of Climatic Factors on the Growth of Representatives of the Genus Pinus (Pinaceae) under Conditions of Introduction

Four introduced and one aboriginal species of the genus Pinus L. have been studied in the middle taiga subzone of southern Karelia. Significant interspecific differences in the dates of onset, cessation, and peak of the growth of shoots and needles have been revealed. It has been shown that their annual increment depends on the rate of growth, rather than on its duration. The dynamics of shoot and needle growth in introduced and aboriginal species, though largely similar, differ in some respects. These differences reflect species-specific responses to hydrothermal conditions in a certain growing season.     

Simultaneous biological removal of endosulfan (alpha+beta) and nitrates from drinking waters using wheat straw as substrate

Nitrate and endosulfan (alpha+beta) removal was studied in an upflow biological denitrification reactor packed with wheat straw as carbon source and support particles for microorganisms. While almost complete nitrate elimination and between 65% and 70% endosulfan (alpha+beta) elimination occurred when the temperature was higher than 20 degrees C; below that value, nitrate removal efficiency decreased to about 10%. Nitrate, dissolved organic carbon (DOC), and endosulfan (alpha+beta) removal efficiencies decreased considerably at 1500 microg/l endosulfan concentration in the batch experiments. Although a high removal efficiency was observed for endosulfan (alpha+beta) and nitrate in the biological denitrification continuous reactor, the effluent water could not be used for drinking purpose because of the unacceptable levels of endosulfan (alpha+beta), colour and dissolved organic content. During the continuous study, 23.4% of the initial weight of wheat straw was lost and 24 g was consumed per gram of nitrogen removed. The results of the continuous study showed that 21.3% of the endosulfan removal was achieved by adsorption onto the wheat straw and 68.2% of the endosulfan removal occurred by biological activity and the remaining portion was detected in the effluent water.     

Effect of water pH and total dissolved solids on the species diversity of pelagic zooplankton in lakes: A statistical analysis

Statistical analysis of the combined influence of lake surface area (S), water pH, and total dissolved solids (TDS) on the formation of zooplankton communities in lakes has been made on the basis of available data on the number of species (N _sp ) of pelagic zooplankton in 256 lakes of the temperate zone of Europe, Asia, and North America. Graphic analysis and analysis of variance have shown that extremely high or extremely low values of pH and TDS inhibit lake zooplankton. If the value of one of these factors is extremely high, any increase in the other factor is favorable for the inhibited zooplankton, and this second factor determines the value of N _sp .     

Variation in certain characters and properties of scotch pine needles in geographic cultures

Morphophysiological and anatomical characters of needles that are used for characterizing infraspecific taxa have been studied in Scotch pine geographic cultures established in the forest-steppe zone of Siberia. Variation in these characters has been revealed, which reflects the polymorphic structure of the species and the effect of natural selection on the composition of populations in new natural-cimatic conditions.     

Uptake of deuterium by dead leaves exposed to deuterated water vapor in a greenhouse at daytime and nighttime

Dead leaves were exposed to deuterated water vapor (D(2)O) as a substitute of tritiated water (HTO) in a greenhouse at daytime and nighttime to examine uptake and release of tritium by dead leaves because they cover a wide area of the forest floor and are therefore a major target material to be exposed when HTO is atmospherically derived to the forest. The dead cedar needles showed faster uptake and faster release rates during and after the exposure than the fresh ones, and the equilibrium concentration of the dead cedar needles was about two times higher than the fresh ones, indicating a quick response and a high buffering potential of dead leaves. The relation between uptake of D(2)O and number of stoma was examined for dead deciduous leaves; the species with larger number of stoma accumulated more D(2)O at the daytime and nighttime exposures. However, drying of the dead leaves suppressed D(2)O uptake greatly at daytime, suggesting stomata's opening and closing controls the D(2)O uptake of dead leaves.     

Recent developments in the application of risk analysis to waste technologies

The European waste sector is undergoing a period of unprecedented change driven by business consolidation, new legislation and heightened public and government scrutiny. One feature is the transition of the sector towards a process industry with increased pre-treatment of wastes prior to the disposal of residues and the co-location of technologies at single sites, often also for resource recovery and residuals management. Waste technologies such as in-vessel composting, the thermal treatment of clinical waste, the stabilisation of hazardous wastes, biomass gasification, sludge combustion and the use of wastes as fuel, present operators and regulators with new challenges as to their safe and environmentally responsible operation. A second feature of recent change is an increased regulatory emphasis on public and ecosystem health and the need for assessments of risk to and from waste installations. Public confidence in waste management, secured in part through enforcement of the planning and permitting regimes and sound operational performance, is central to establishing the infrastructure of new waste technologies. Well-informed risk management plays a critical role. We discuss recent developments in risk analysis within the sector and the future needs of risk analysis that are required to respond to the new waste and resource management agenda.     

Local air quality management as a risk management process: assessing, managing and remediating the risk of exceeding an air quality objective in Great Britain

Air quality is managed in Great Britain via an effects-based, risk management process designed to provide a dynamic solution to public health issues associated with elevated concentrations of seven specified air pollutants. This paper is concerned with an examination and evaluation of the process of Local Air Quality Management (LAQM) in Great Britain from the late 1980s to date as a risk management process. The statutory basis of LAQM process is provided by the Environment Act 1995. The Act provides a framework in which national and local actions are required to identify and remediate areas of poor air quality. Within this framework, the implementation of the process at national and local levels is considered, leading to an identification and assessment of risks in the formulation and implementation of air quality management policy and practice. Local Authorities began the process of Review and Assessment in 1999 and the first round of the process concluded in 2001. Following this, some 129 Local Authorities declared one or more Air Quality Management Areas (AQMAs). The Review and Assessment elements of the framework were subjected to an evaluation in 2001 and the essential elements of it were confirmed as fit for purpose. The evaluation led to a confirmation of the process of LAQM but also a simplification based on the experience of Round 1. Now, a two step process is required comprising of an Updating and Screening Assessment and, where a risk of exceeding an Air Quality Objective (AQO) is identified, a Detailed Assessment follows. The Government has identified a time scale for Review and Assessment through to 2010 and also introduced the requirement of a regular Progress Report in order that a Local Authority is able to address routine matters of air quality management. The risks inherent in epidemiological or scientific uncertainty are factored into the LAQM process at an early stage of the process and, by identifying the risks and subjecting them to regular review, the process provides a 'level playing field' across spatial and temporal scales. Whilst the process of LAQM described in this paper has been developed for Great Britain, the generic elements of the process are applicable to other countries challenged by air pollution problems which require both national and local action to resolve them.