The Presence of Calcium Oxalate Dihydrate (Weddellite) in Street Sediments from Niterói, Brazil and Its Health Implications

Established research in first world urban environments has shown street sediments to be effective sinks for heavy metals and emphasises the health risks to children by its inhalation or ingestion. In third world countries with fewer pollution controls, contamination may be augmented by additional pollutants such as sewage discharge into urban streets and/or periodic inundation with sewage-laden run-off. This pollutant not only contains heavy metals and organic matter, but calcium oxalates that may derive directly from the sewage itself. To study this premise street sediments were collected from sites of varying industrialisation and sewage contamination within the city of Niteroi, Brazil. Calcium oxalate dihydrate (weddellite) was identified by X-ray diffraction, fourier transform infra red and scanning electron microscopy techniques and oxalate concentrations in <63m and colloidal (clay and organic matter) fractions, were determined by ion chromatography. Oxalate in colloidal fractions averaged 43601mgkg^–1 in sewage contaminated industrialised urban zones, 4519mgkg^–1 in suburban areas and 17477mgkg^–1 in suburbs with favelas (shantytowns-of Niterói). Oxalate concentrations coincide with high levels of metal ions (Fe, Mn, Zn, Pb, Ni, Cr) that stabilise calcium oxalate dihydrate and prevent its dehydration to the monohydrate (whewellite). Lower levels of oxalate were found in lichen-covered roof sediment, plaster and mortar samples. Oxalate concentration coincides with sewage contamination and street sediments appear to act as a sink for calcium oxalate dihydrate derived from sewage. Previous studies have shown that low levels of exposure can damage kidneys and the nervous system, while prolonged exposure can cause severe corneal, retinal and skin damage, cyanosis and possibly gangrene. Contact with blood serum may result in hypocalcemia, muscular stimulation, convulsions and finally collapse. The conditions described are common throughout urban areas of the developing world and may suggest a particular environmental hazard in these regions.     

Digenean trematodes infecting the tropical abalone <Emphasis Type="Italic">Haliotis asinina</Emphasis> have species-specific cercarial emergence patterns that follow daily or semilunar spawning cycles

Approximately 1–2% of the tropical abalone Haliotis asinina inhabiting Heron Island Reef are infected with opecoelid digeneans. These largely inhabit the haemocoel surrounding the cerebral ganglia and digestive gland–gonad complex, and infected abalone typically have significantly reduced or ablated gonads. Observations of infected abalone reveal two distinct cercarial emergence patterns, one which correlates tightly with the abalone’s highly regular and synchronous fortnightly spawning cycle, and the other which occurs in a circadian pattern. The former appears to be a novel emergence strategy not previously observed in digeneans. While the cercariae in all abalone are morphologically indistinguishable, comparison of sequences from the internal transcribed spacer 2 (ITS 2) region of the ribosomal DNA reveals a 5.7% difference between cercariae displaying different emergence patterns, indicating these are two distinct species that probably belong to the same genus. The ITS 2 sequences of the species with the daily emergence pattern are identical to that of an undescribed adult opecoelid from the gut of the barramundi cod, Cromileptes altivelis. Combined molecular, morphological and emergence data suggest that while these opecoelid cercariae use the same first intermediate host and are closely related species—members of the genus Allopodocotyle—they fill different ecological niches that are likely to include different definitive hosts.     

Secondary metabolite and inorganic contents in<Emphasis Type="Italic"> Cystodytes</Emphasis> sp. (Ascidiacea): temporal patterns and association with reproduction and growth

Temporal variation is one of the least known components of defence production in marine organisms. Here we examined whether there is a predictable temporal pattern in the production of chemical and structural defences by a marine invertebrate. To assess the seasonal variation in chemical defence, we measured ascididemin, the main pyridoacridine alkaloid in the blue Mediterranean morph of the ascidian Cystodytes sp. Structural defence variability was assessed on the basis of colony ash content, as it contains mainly spicules. Ascididemin concentration and the colony ash content displayed an annual cycle, reaching a minimum in spring and peaking in summer. Cross-correlation analyses with existing data on growth and reproduction suggested a significant trade-off between investment in reproduction and the other biological parameters considered (growth, inorganic content and ascididemin concentration). Our results suggest that optimization of resource allocation, probably influenced by biotic interactions and physical factors, shaped the temporal trends observed in secondary metabolite concentration and inorganic content.     

Toxicity and bioaccumulation of reduced TNT metabolites in the earthworm Eisenia andrei exposed to amended forest soil

Soils contaminated with 2,4,6-trinitrotoluene (TNT) and TNT primary reduction products have been found to be toxic to certain soil invertebrates, such as earthworms. The mechanism of toxicity of TNT and of its by-products is still not known. To ascertain if one of the TNT reduction products underlies TNT toxicity, we tested the toxicity and bioaccumulation of TNT reduction products. 2-Amino-4,6-dinitrotoluene (2-ADNT), 4-amino-2,6-dinitrotoluene (4-ADNT), 2,4-diamino-6-nitrotoluene (2,4-DANT) and 2,6-diamino-4-nitrotoluene (2,6-DANT) were tested separately in adult earthworms (Eisenia andrei) following a 14-d exposure to amended sandy loam forest soil. TNT, 4-ADNT, and 2-ADNT were lethal to earthworms (14-d LC(50) were: 580, 531 and 1088 micromol kg(-1), or 132, 105 and 215 mgkg(-1) dry soil, respectively) and gave the following order of toxicity: 4-ADNT>TNT>2-ADNT. Exposure to 2,4-DANT and to 2,6-DANT caused no mortality at 600 micromol kg(-1) or 100 mgkg(-1) dry soil. We found that all four TNT reduction products accumulated in earthworm tissues and 2-ADNT reached the highest levels at 3.0+/-0.3 micromol g(-1) tissue. The 14-d bioaccumulation factors were 5.1, 6.4, 5.1 and 3.2 for 2-ADNT, 4-ADNT, 2,4-DANT and 2,6-DANT, respectively. Results also suggest that some TNT metabolites are at least as toxic as TNT and should be considered when evaluating the overall toxicity of TNT-contaminated soil to earthworms.     

Multiphase flow and transport through fractured heterogeneous porous media

The migration of Dense, Non-Aqueous Phase Liquid (DNAPL) and dissolved phase contamination through a fractured heterogeneous porous medium has been investigated through the use of a multiphase compositional model. The sensitivity of the timescales of migration and the distribution of contaminant in the subsurface to the mean permeability, the variance of the permeability, and the degree of fracturing of the domain were examined. It was found that increasing the mean permeability of the domain allowed the DNAPL to penetrate deeper into the subsurface, while decreasing the mean permeability caused the DNAPL to pool at shallower depths. The presence of fractures within the system was found to control the infiltration only in the most fractured domain. Moment analysis of the nonwetting phase showed that large-scale movement had ceased after approximately 9 years (maximum duration of the source-on condition was approximately 4.5 years). This tended to be due to a redistribution of the DNAPL towards a residual configuration, as was evidenced by the gradual trending of average nonwetting phase saturations within the domain to a static value. The dissolved phase plume was found to migrate at essentially the same rate as the nonwetting phase, due to the reduced relative permeability of lenses containing DNAPL, and due to diffusive losses of mass to the matrix of fractured clay and silty-clay lenses. Some exceptions to this were found when the DNAPL could not overcome the displacement pressure of a lens, and could not by-pass the lens due to the lack of available driving force after the source had been shut off.     

Spatial and temporal shifts in stable isotope values of the bottom-dwelling shrimp<Emphasis Type="Italic"> Nauticaris marionis</Emphasis> at the sub-Antarctic archipelago

Spatial and temporal dynamics of carbon and nitrogen stable isotope signatures of the bottom-dwelling caridean shrimp Nauticaris marionis were measured during April and May between 1984 and 2000 in the vicinity of Marion Island (the Prince Edward Islands, Southern Ocean). There was one trophic-level enrichment in bulk ¹⁵N and ¹³C signatures between small (<20 mm long) and large (>20 mm) specimens of N. marionis, suggesting distinct trophic differentiation among major shrimp size groups. Both ¹⁵N and ¹³C values of N. marionis increased with the depth, reflecting changes in their diet. There were no clear temporal trends in bulk ¹⁵N signatures of N. marionis. However, compound-specific ¹⁵N measurements of amino acids indicated that N. marionis from the inter-island realm occupied the trophic level of second order carnivores, while similarly sized shrimps in the near-shore realm were at the trophic level of first order carnivores. Compound-specific measurements also identified a change in the source of inorganic nitrogen at the base of the food web between the inter-island and near-shore realms. In contrast to the bulk ¹⁵N values, a significant shift in bulk ¹³C values of N. marionis was observed between 1984 and more recent years. This temporal change appears to be linked to changes in the overall productivity of the Prince Edward Island inter-island system, which could be linked to global climate change.Communicated by J.P. Thorpe, Port Erin     

Measuring the Welfare Cost of Climate Change Policies: A Comparative Assessment Based on the Computable General Equilibrium Model GEMINI-E3

Measuring the welfare cost of climate change policies is a real challenge, raising difficult issues of micro- and macro-economics: cost-benefit analysis on the one hand, foreign trade and international specialization on the second hand. At the domestic level the possible existence of distortions, in particular in the fiscal system, may either increase or alleviate the welfare cost of a climate change policy, as illustrated by the debate on double dividend. Effects on the prices in international markets and distorted competition between countries committed to abate (Annex B) and uncommitted countries affect both the sharing of the burden, in particular through the change in the terms of trade, and the allocation of activities with the frequently waved threat of delocalization. Based on a companion theoretical analysis, the present paper aims at putting order in the welfare analysis of climate change policy and to present and compare various estimations, issuing from macro- or computable general equilibrium models. Beside the global welfare cost, the paper focuses on the marginal abatement cost and its relation to the carbon price.Most present conceptual and applied analysis is based on the case of a single domestic household-consumer. Taking into account several consumers raises new challenges, concerning equity but even more fundamentally the mere definition of fiscal distortion, which have not yet been really addressed.     

Atmospheric heavy metals in tropical South America during the past 22,000 years recorded in a high altitude ice core from Sajama, Bolivia

V, Co, Cu, Zn, As, Rb, Sr, Ag, Cd, Ba, Pb, Bi and U have been analysed by inductively coupled plasma sector field mass spectrometry in various sections of a dated snow/ice core drilled at an altitude of 6542 m on the Sajama ice cap in Bolivia. The analysed sections were dated from the Last Glacial Stage ( approximately 22,000 years ago), the Mid-Holocene and the last centuries. The observed variations of crustal enrichment factors (EFc) for the various metals show contrasting situations. For V, Co, Rb, Sr and U, EFc values close to unity are observed for all sections, then showing that these elements are mainly derived from rock and soil dust. For the other metals, clear time trends are observed, with a pronounced increase of EFc values during the 19th and 20th centuries. This increase shows evidence of metal pollution associated with human activity in South America. For Pb an important contribution was from gasoline additives. For metals such as Cu, Zn, Ag and Cd an important contribution was from metal production activities, with a continuous increase of production during the 20th century in countries such as Peru, Chile and Bolivia.     

Fate and potential environmental effects of methylenediphenyl diisocyanate and toluene diisocyanate released into the atmosphere

Information from a variety of sources has been collected and summarized to facilitate an overview of the atmospheric fate and potential environmental effects of emissions of methylenediphenyl diisocyanate (MDI) or toluene diisocyanate (TDI) to the atmosphere. Atmospheric emissions of both MDI and TDI are low, both in terms of concentration and mass, because of their low volatility and the need for careful control over all aspects of their lifecycle from manufacture through disposal. Typical emission losses for TDI are 25 g/t of TDI used in slabstock foam production. MDI emission losses are lower, often less than 1 g/t of MDI used. Dispersion modeling predicts that concentrations at the fenceline or beyond are very low for typical releases. Laboratory studies show that TDI (and by analogy MDI) does not react with water in the gas phase at a significant rate. The primary degradation reaction of these aromatic diisocyanates in the atmosphere is expected to be oxidation by OH radicals with an estimated half-life of one day. Laboratory studies also show that this reaction is not expected to result in increased ground-level ozone accumulation.