Exposure,epidemiology, and mechanism of the environmental toxicant manganese

It has become increasingly apparent that global manganese (Mn) pollution to air and water is a significant threat to human health. Despite this recognition, research is only beginning to comprehend the detrimental effects of exposure. Mn, while essential, is particularly harmful to the central nervous system, and overexposure is symptomatic of several neurological disorders. At-risk populations have been identified, but it is still unclear whether typical exposure levels have any long-term consequences. Those at an elevated risk have diminished intellectual function, learning and memory, and mental development. While the overall mechanism of toxicity is undetermined, Mn has been found to induce oxidative stress, exacerbate mitochondrial dysfunction, dysregulate autophagy, and promote apoptosis, ultimately enhancing neurodegeneration. Extrapolation of this in vitro and in vivo data to humans is difficult. There is a definite need to correlate epidemiological studies with causative effects. It is imperative that research efforts endure, so threats are appropriately identified and exposure properly regulated.     

Heavy metal accumulation, heat shock protein expression and cytogenetic changes in Tetrix tenuicornis (L.) (Tetrigidae, Orthoptera) from polluted areas

The orthopteran insect Tetrix tenuicornis, collected from polluted and unpolluted areas, was used to study heavy metal accumulation and its impact on stress protein levels and on changes in the number and morphology of chromosomes in mitotic and meiotic cells. During two consecutive years, insects were collected from polluted areas of zinc-lead mine spoils near Boles?aw (Poland) and from unpolluted areas near Busko and Staszów (Poland). T. tenuicornis from the polluted area showed 1.5, 4.03, 4.32 and 41.73 times higher concentrations of copper (Cu), zinc (Zn), lead (Pb) and cadmium (Cd), respectively, than insects of the same species collected from unpolluted areas. Insects exposed to heavy metals showed only small changes, and rather a decrease in the concentration of constitutive and inducible heat shock proteins Hsp70, the level of which increases under stress conditions. A cytogenetic study of T. tenuicornis revealed intra-population anomalies in chromosome number and morphology in mitotic and meiotic cells and the presence of an additional B chromosome in germinal cells. In 50% of females collected from polluted areas, mosaic oogonial mitotic chromosome sets and diploid, hypo- or hypertetraploid, tetraploid, and octoploid chromosome numbers were detected. In turn, 14.6% of males showed a heterozygous deficiency of chromatin in L2 and M3 bivalents in addition to the presence of B chromosomes.     

The dynamics of dissolved nitrogen in a blanket peat dominated catchment

Precipitation, soil solution and drainage water were collected from a blanket peat catchment at Moor House National Nature Reserve in the Northern Pennine Uplands, UK, an area of moderately high N deposition. Two tributaries of the main stream were also sampled. Between 1993 and 1995 samples were analysed for NH4+ and NO3- and for part of the period for organic N. Inputs of N in precipitation exceeded outputs in stream water. Organic N represented a small proportion of N inputs while inputs of inorganic N averaged 10.2 kg ha(-1) a(-1). Soil solution from 10 cm depth in the peat was dominated by organic N whereas at 50 cm NH4+ slightly exceeded organic N. NO3- was rarely detected at either depth except during a period of exceptionally warm and dry weather in 1995. Output fluxes in stream water of organic N (5.7 to 6.5 kg ha(-1) a(-1)) were much greater than those of inorganic N (0.6 to 2.2 kg ha(-1) a(-1)). Inorganic N in streams was predominantly NO3- except in the smallest stream which had the largest concentrations of NH4+. This suggests that N transformations, particularly nitrification, may be taking place in the mineral soils adjacent to the streams or within the stream channel of the larger catchment.     

Eco-Compatible Use of Olive Husk as Filler in Thermoplastic Composites

A study on the possibility of recycling waste materials, such as olive husk, the solid phase derived from an olive oil mill, in blend with thermoplastic polymers to produce new materials for manufacturer of, for example, containers and formworks, has been carried out. The present paper describes the methodology used for the preparation and the characterization of composite samples prepared by mixing various percentages of olive husk and polypropylene. A screening on the chemical-physical characteristics of the olive husk is reported, as well as a set of tests applied to evaluate the mechanical properties of the manufactured products obtained.     

Allozyme variation in European populations of the oyster Ostrea edulis

Variations at 22 enzyme coding loci were surveyed in 11 populations of the oyster Ostrea edulis L., which were sampled between 1988 and 1990 along the Atlantic and Mediterranean coasts of Europe. Atlantic oyster beds suffered a steady decline during the last century, and restocking of beds with oysters of foreign origin has probably resulted in a high degree of interbreeding of natural oyster stocks from all Atlantic Europe. Our study confirms the low levels of genetic variability previously reported for the oyster populations from the Atlantic coasts, and extends it to the Mediterranean coasts. The locus arginine-kinase (ARK ^*) exhibited a high degree of interpopulation differentiation (F _ST=0.289), resulting from extensive variation in gene frequencies along a geographical cline. However, the overall genetic differentiation between populations was slight, and similar to that reported for other local populations of bivalves (mean genetic distance between populations is 0.010, mean F _ST=0.062). A general pattern of increasing differentiation along the coastline in an Atlantic-mediterranean direction emerged; but genetic differentiation among the Atlantic populations was not significantly lower than that observed among the Mediterranean populations. This and other results suggest that the effects of extensive transplantation of oysters among various areas in Europe are detectable only in some particular localities. The geographical distribution of low-frequency alleles suggests a restriction to gene flow outwards from the Mediterranean Sea, across the Straits of Gibraltar.     

Lipid content of some Caribbean corals in relation to depth and light

Three procedures for the extraction of coral lipids were compared and a rapid and effective method for future use is suggested. This method was used to measure the lipid content of the branching coral Porites porites (Pallas) and the massive corals Montastrea annularis (Ellis and Solander) and Siderastrea siderea (Ellis and Solander) during July and August 1991. P. porites and M. annularis were sampled on two fringing reefs, each characterised by different water quality affecting light transmission, and at depths of down to 30 m on a barrier reef on the west coast of the island. m. annularis contained, on average, 29% of dry weight as lipid, and there were no significant differences in lipid levels between corals sampled on either fringing reef at 3 and 6 m, or between fringing reefs and the barrier reef at 13, 20 or 30 m depth. Five samples were also taken from a single massive colony of S. siderea at 3 m on a fringing reef and at 13, 20 and 30 m depth on the barrier reef. Values for lipid ranged from 26 to 35% of dry tissue weight. P. porites from 3 and 6 m depth on both fringing reefs contained the same amount of lipid (11% of dry tissue weight). However, at 13 m depth on the barrier reef this coral contained significantly less lipid (8.5% of dry tissue weight). This difference may be attributable to a higher nutritional intake by P. porites on the fringing reefs.     

Delivering on the Promise of Agroforestry

Agroforestry – the traditional practice of growing trees on farms for the benefit of the farm family and for the environment – was brought from the realm of indigenous knowledge into the forefront of agricultural research less than two decades ago. It was promoted widely as a sustainability-enhancing practice that combines the best attributes of forestry and agriculture. Based on principles of natural resource management and process-oriented research, agroforestry is now recognized as an applied science, that is instrumental in assuring food security, reducing poverty and enhancing ecosystem resilience at the scale of thousands of smallholder farmers in the tropics.Trees on farms provide both products and services: they yield food, fuelwood, fodder, timber and medicines, which farm families can use at home or take to market to bring in much-needed cash; they replenish organic matter and nutrient levels in soils and they help control erosion and conserve water. The International Centre for Research in Agroforestry, and its partners, are working to integrate the functions of trees with policy and institutional improvements that aim at facilitating wide-scale adoption by farmers.Two examples described in this paper are replenishing soil fertility in sub-Saharan Africa using short-term improved tree and shrub fallows and the results of agroforestry research to support significant land tenure policy in southeast Asia.Although just one option in sustainable land-use, science-based agroforestry has the potential to produce economically, socially and environmentally sound results for the billions of people who depend on this ancient practice and modern science.     

Physical resuspension and vertical mixing of sediments on a high energy continental margin (Sydney, Australia)

Four sediment cores from the continental margin adjacent to Sydney were analyzed for 210Pb, 137Cs, trace metals (Ag, Cd, Co, Cu, Mn, Ni, Pb, Zn), iron, dry bulk density, mud and moisture content. The concentrations of trace metals in the total sediment are low at all sites, although slightly elevated concentrations of Ag, Cu, Pb and Zn are present in the fine fraction of sediment (< 62.5 microns) near a major ocean outfall. Concentrations of trace metals in the fine fraction of sediment are similar in the upper 10-15 cm, indicating strong vertical mixing of the sediments, whereas an upward coarsening grain size in the upper 1-3 cm of sediment supports physical resuspension during storms. Sediment accumulation rates on the middle shelf adjacent to Sydney were estimated from downcore profiles of 210Pb and 137Cs and range between 0.2 and 0.4 cm yr-1. Although the mass fluxes of Cu, Pb and Zn within a distance of 2 km from the outfall (up to 36.1, 30.8 and 86.2 micrograms cm-2 yr-1, respectively) are greater than 20 km north of the outfall (< 23.5 micrograms cm-2 yr-1), the low concentrations of trace metals in sediments near the outfall support an efficient dispersal of anthropogenic contaminants on this continental margin.     

Physiological ecology of four Polysiphonia species (Rhodophyta,Ceramiales)

Photosynthesis and respiration of 4 species of the marine red algal genus Polysiphonia were evaluated under a variety of light, temperature and salinity conditions. The manometric results were compared with the local distribution and abundance of each species. The species can be separated into two distinct categories based on their overall distribution and temperature optima: (1) cold water plants [P. lanosa (L.) Tandy and P. elongata (Hudson) Sprengel], with peak photosynthesis at 21° to 24°C, but with active photosynthesis as low as 5°C; (2) plants with warm-water affinities [P. nigrescens (Hudson) Greville and P. subtilissima Montagne], having photosynthetic optima at 27° to 30°C, and exhibiting little or no photosynthesis below 10°C. The plants from the first group exhibit thermal injury at temperatures of 25°C and show a narrow tolerance to low salinities during periods of high temperatures. The plants from the second group show thermal injury at 30°C and have a wider tolerance to low salinities. The horizontal distribution of the 4 Polysiphonia species within the Great Bay Estuary System of New Hampshire, USA, is primarily governed by their tolerances to high temperatures and low salinities. The temperature optimum for each of the species corresponds to its particular estuarine distribution. Thus, P. subtilissima, having the highest temperature optimum, penetrated furthest into the Estuary, while P. lanosa, having the lowest temperature optimum, was restricted to the more coastal stations. There was a good correspondence between the natural distribution patterns and the manometric results.Published with the approval of the Director of the New Hampshire Agricultural Experiment Station as Scientific Contribution No. 731.Scientific Contribution No. 4 of the Jackson Estuarine Laboratory.