Quantifying sediment-associated metal dispersal using Pb isotopes: Application of binary and multivariate mixing models at the catchment-scale

In this study Pb isotope signatures were used to identify the provenance of contaminant metals and establish patterns of downstream sediment dispersal within the River Maritsa catchment, which is impacted by the mining of polymetallic ores. A two-fold modelling approach was undertaken to quantify sediment-associated metal delivery to the Maritsa catchment; employing binary mixing models in tributary systems and a composite fingerprinting and mixing model approach in the wider Maritsa catchment. Composite fingerprints were determined using Pb isotopic and multi-element geochemical data to characterize sediments delivered from tributary catchments. Application of a mixing model allowed a quantification of the percentage contribution of tributary catchments to the sediment load of the River Maritsa. Sediment delivery from tributaries directly affected by mining activity contributes 42-63% to the sediment load of the River Maritsa, with best-fit regression relationships indicating that sediments originating from mining-affected tributaries are being dispersed over 200 km downstream.     

Heavy Metals in Terrestrial Macroinvertebrates: Species Differences Within and Between Trophic Levels

Whole animal concentrations of Pb, Zn and Cd were measured in herbivorous (1 snail species; 1 dipteran larva species), herbivorous + detritivorous (2 slug species), detritivorous (3 woodlouse species; 3 earthworm species), and carnivorous (1 carabid beetle species; 1 lithobiid centipede species) terrestrial macroinvertebrates collected at a disused Pb/Zn mine site. No evidence was found for an accretion of any metal during transference from herbivores to carnivores; the highest metal concentrations were, in fact, generally found in detritivores. The lack of metal bio-amplification during food chain transference is probably due to the sequestration of metals (notably Pb and Zn) in insoluble inorganic-rich granules within certain target organs and cells.

Earthworms and woodlice, respectively, showed major differences in metal concentrations. These differences between closely related species frequently exceeded differences between unrelated species occupying different trophic levels, and may be attributable to a combination of ill-defined ecological and physiological differences that ensure habitat and resource partitioning.     

Selective metal leaching from technosols based on synthetic root exudate composition

This study focused on metal release from technosols induced by synthetic root exudate (SRE). The effect of SRE composition on metal release was studied using six technosols. This was done by treating the technosols with SRE solutions having varying concentrations of low molecular weight organic acids (LMWOAs), namely oxalic, citric, and malic acids. Consequently, the physico-chemical parameters (pH and electric conductivity), Ca, Mg, Fe, Zn, and Cu release (by atomic absorption spectroscopy, AAS), chemical changes (by Fourier transform infrared, FT-IR), and organic parameters (by fluorescence) were investigated. Metal release showed to be dependent on the SRE composition and technosol characteristics. Citric acid selectively released Ca, Mg, Zn, and Cu from technosols in a concentration-dependent manner; oxalic acid showed a significant role in the release of Mg and Fe. Under relatively high LMWOA concentrations, particulate organo-mineral complexes precipitated. Additionally, technosol weathering was seen by the dissolution of humic substances and ferriallophanes, which in turn caused metal release. However, re-precipitation of these phases showed to re-sorb metals, thus underestimating the role of LMWOAs in metal release. Therefore, the selective metal leaching was highly dependent on the SRE composition and LMWOA concentrations on one hand, and on the mineral, organic, and organo-mineral components of the technosols on the other. The understanding of such processes is crucial for proposing and implementing environmental management strategies to reduce metal leaching or for the beneficial re-usage of metals (e.g., for agromining) from technosols.     

Assessing the feasibility of land application of fly ash, sewage sludge and their mixtures

Land disposal of fly ash (FA) and sewage sludge (SS) is a major problem due largely to their potentially harmful constituents. Combined use of FA and SS however may help reduce the associated pollution potential. In this paper we summarize the results of several case studies designed to assess the feasibility of land application of FA with and without SS. A wide range of application rates was tested under laboratory, greenhouse and field conditions. The leaching of metals from soil columns amended with moderate rates of FA applications (8-16 Mg ha⁻¹) generally had no significant impact on the metal content of leachate or their downward migration in the soil. The application of FA or SS at a much high rate (74.1 Mg ha⁻¹) significantly increased both leaching and downward migration of metals. The use of 1:1 FA+SS mixture at 148.2 Mg ha⁻¹ reduced metal leaching compared to the combined metal quantities leached when FA or SS applied at 74.1 Mg ha⁻¹. The results indicate that combined use of FA and SS at a rational rate of application should not cause any significant effect on drainage water quality. Plant studies conducted using FA and SS mixtures indicated that these materials could be beneficial for biomass production, without contributing significant metal uptake or leaching. The application of FA as high as 560 Mg ha⁻¹ in a long-term field trial had no detectable deterioration in soil or groundwater quality and no substantial increases in plant uptake of metals and other trace elements were observed. Low to moderate rates of FA and SS therefore could be successfully used as soil amendments, particularly so when used as a mixture.     

固态聚合氯化铝的27Al NMR研究

聚合氯化铝(PAC)是一种水处理混凝剂,可为液态(PAC-L),也可浓缩成固体(PAC-S)、PAC-L在水中稀释时铝的形态的变化已用~(27)Al核磁共振法(NMR)进行了研究。本工作试图用~(27)Al NMR法对PAC-S及其在水中溶解稀释物中铝的形态进行研究,以探讨固化对PAC及其在水中铝的形态的影响。     

Early prenatal diagnosis of the fragile site AT Xq27.3 associated with Martin-Bell syndrome

Early prenatal diagnosis of the fragile X was attempted in 44 pregnancies, including one twin pregnancy at risk of Martin-Bell (MB) syndrome. The sex ratio was 24M:21F. The fragile site was reproducibly demonstrated in cultured chorionic villus (CV) cells in eight male and five female fetuses. Six of the male and three of the female fetuses were terminated. Simultaneous RFLP analysis provided confirmative data with flanking DNA markers in 3 of 13 analysed cases. Recombination and/or non-informativeness at available distal and/or proximal loci were found in nine cases. In one male fetus, discordance between the haplotype and cyto-genetics (fragile-X-negative) suggested the presence of a normal male transmitter, a double meiotic cross-over within the region, or a false-negative cytogenetic diagnosis. However, discordance between prenatal and post-termination/postnatal cytogenetic findings was not observed in this series. The use of excess thymidine for induction of the fragile X in cultured CV cells provided in the majority of cases a safe and rapid method for cytogenetic diagnosis, with options for early induced termination in fragile-X-positive pregnancies, for simultaneous RFLP analysis, and for subsequent second-trimester analysis of fetal blood in complicated cases.     

Has long-term metal exposure induced changes in life history traits and genetic diversity of the enchytraeid worm Cognettia sphagnetorum (Vejd.)?

We studied whether long-term metal exposure has affected life history traits, population growth patterns and genetic diversity of the asexual enchytraeid worm Cognettia sphagnetorum (Vejd.). Enchytraeids from metal contaminated and uncontaminated forest soil were compared by growing them individually in the laboratory and by following their population development in patchily Cu contaminated microcosms. Genetic differences between the two native populations were studied using allozyme electrophoresis. Individuals from the contaminated site had slower growth rate and they produced fewer fragments of larger size when compared to individuals from the uncontaminated site. In patchily Cu contaminated microcosms, C. sphagnetorum from the contaminated site had a slower population growth rate. Most alleles were shared by the two native populations, but there was greater diversity and more unique genotypes in the population living in the uncontaminated site. Overall, long-term exposure to metals has induced only slight changes in life history properties and clonal diversity of C. sphagnetorum.     

Water quality in a mediterranean marine protected area (North Sporades Islands,Greece)

Pollution in the marine protected area of North Sporades Islands was investigated in July 1997. Salinity, temperature, dissolved oxygen, dissolved inorganic nutrients, organic carbon, hydrocarbons as well as dissolved and particulate trace metals were determined at 15 offshore and coastal stations. Dissolved organic carbon and inorganic nutrient concentrations indicate the mesotrophic character of the investigated waters. The dissolved forms of nitrogen were slightly higher at coastal stations. Dissolved and particulate Cu, Zn and Ni, were higher in coastal stations, whereas concentrations of Pb were generally low and likely of atmospheric origin. Dissolved/Dispersed petroleum hydrocarbons (DDPH) were close to detection limits at all stations. Temperature and salinity vertical profiles, nutrient and trace metal concentrations revealed the presence of a slight influence of the Black Sea water coming from Dardanelles straits.     

Bio-processing of solid wastes and secondary resources for metal extraction - A review

Metal containing wastes/byproducts of various industries, used consumer goods, and municipal waste are potential pollutants, if not treated properly. They may also be important secondary resources if processed in eco-friendly manner for secured supply of contained metals/materials. Bio-extraction of metals from such resources with microbes such as bacteria, fungi and archaea is being increasingly explored to meet the twin objectives of resource recycling and pollution mitigation. This review focuses on the bio-processing of solid wastes/byproducts of metallurgical and manufacturing industries, chemical/petrochemical plants, electroplating and tanning units, besides sewage sludge and fly ash of municipal incinerators, electronic wastes (e-wastes/PCBs), used batteries, etc. An assessment has been made to quantify the wastes generated and its compositions, microbes used, metal leaching efficiency etc. Processing of certain effluents and wastewaters comprising of metals is also included in brief. Future directions of research are highlighted.     

Structure of inorganic and carbonaceous particles emitted from heavy oil combustion

The combustion of heavy fuel oil for power generation is a great source of carbonaceous and inorganic particle emissions, even though the combustion technologies and their efficiency are improving. The information about the size distribution function of the particles originated by trace metals present into the fuels is not adequate. In this paper, we focused our attention on the larger distribution mode of both the carbonaceous and metallic particles. Isokinetic sampling was performed at the exhausts of two typical heavy oil flames and the samples were size-segregated by mean of an 8-stages Andersen impactor. Further investigation performed on the samples using electronic microscopy coupled with X-ray analysis (EDX) evidenced the presence of solid spherical particles, called plerosphere(1) as analogy with cenosphere, with typical dimensions ranging between 200 nm and 2-3 microm, whose atomic composition contains a large amount of the trace metals present in the parent oils (Fe, V, Ni, etc). EDX analyses revealed that the metal concentration increases as the plerosphere dimension decreases.