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A high performance liquid chromatography-inductively coupled plasma-mass spectrometry (HPLC-ICP-MS) method has been developed for the separation and quantification of ~g kg-1 levels of arsenobetaine, monomethylarsonic acid (MMAA), dimethylarsinic acid (DMAA) , arsenite and arsenate. Using this coupling, arsenic species in fruit and vegetables grown on soils containing up to 1.4% w\w arsenic have been surveyed and DMAA, MMAA, arsenite and arsenate identified in the plants. Although extraction efficiencies were poor, typically 10%, total arsenic determinations demonstrated that arsenic uptake by the plants was low, with the highest arsenic level being 60-70 mg kg-1 dry weight in unpeeled potato. Provided the plants are washed thoroughly they pose no dietary risk. Using the same HPLC-ICP-MS coupling non-toxic arsenobetaine was identified as the major arsenic species in cod, dab, haddock, lemon sole, mackerel, plaice and whiting. Levels ranged between 1.0 mg kg-1 dry weight in the mackerel, to 187 mg kg-1 in the plaice. Mackerel also contained DMAA and possibly a lipid bound arsenic species. No degradation of arsenobetaine to more toxic species was observed when an enzymatic digestion procedure, based on the action of trypsin, was applied to fish except in the case of one of the plaice specimens for which DMAA was characterised in the digest at the mg kg-1 level. Ten volunteers participated in a dietary trial in which they were given set conventional meals. The main source of arsenic was fish and the predominant species was arsenobetaine. All of the arsenic, as arsenobetaine, was excreted in the urine within 72 hours of consumption. Urinary levels of MMAA, DMAA and inorganic arsenic were all below 10 µg. For total arsenic determination in the urine nitrogen introduction ICP-MS was used to overcome the polyatomic ion 40Ar 35Cl+. This method gave good agreement between observed and certified values for a range of reference materials.

Anthropocene is the current era in which human activities modify various environmental properties, which have implications for many coastal processes. Anthropogenic stressors increasingly affect coasts and push these environments to a new altered equilibrium state. However, monitoring such pollution is a challenging task because coastal systems are highly dynamic and integrate the physicochemical forces at work on freshwater bodies, estuaries and lagoons with the oceanographic characteristics of adjacent seas. The current thesis addresses pollution of coastal environments in a broad way, with special attention to the current and historic problematic of estuarine contamination by metals. Firstly, it introduces the chemical (e.g. metals, persistent organic pollutants, and emerging contaminants), physical (e.g. microplastics, sediment loads, temperature), and biological (e.g. microbiological contamination, invasive species) pervasive anthropogenic influence in coastal areas. This introductory chapter is followed by a discussion on the limitations towards holistic environmental health assessments that are imposed by the scarcity of tools and multidisciplinary approaches. At that juncture, we perform a deep investigation of metal fate and its effects in estuaries. The review of the scientific literature in the third chapter provides a transdisciplinary conceptual framework for the estuarine behaviour of metals and its impacts on fauna and flora. This comprehensive overview and conceptual model are further accompanied by an elaboration on empirical models, as well as discussion of data on metal behaviour under laboratory and field conditions. While our review postulates that most studies had observed a non-conservative behaviour of metals in estuaries, our data suggests that at local scale such phenomenon is greatly explained by a high metal mobilisation driven by biogeochemical gradients. In fact, our results demonstrate that iron mobilisation regulates the pollution levels of iron and potentially other metals in an intertidal area under strong anthropogenic influence. In summary, estuarine physicochemical gradients, biogeochemical processes, and organism physiology are jointly coordinating the fate and potential effects of metals in estuaries, and both realistic model approaches and attempts to postulate site-specific water quality criteria or water/sediment standards must consider such interactions.

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The aim of this study was to analyze water chemical samples and diatoms to determine if there are any differences between the sample points in deformations, tax numbers and metal contents. Furthermore the aim is to investigate whether there is a correlation between metals and deformations, to study the bioavailable content of metals and whether deformations and tax loss are area specific. The data is from the years 2015-2018 and comprises 114 sample points from water streams in northern Sweden. The data includes diatoms, deformations, tax numbers and content measurements from the metals As, Cu, Cd, Ni, Pb, U and Zn. Regression analysis was performed between the bioavailable content of metal (Cu, Ni, Pb, Zn) and dissolved content, and also between the metal contents and the deformations to investigate a possible correlation. Two different regression analyzes where made for the metal contents and the deformations, because there are two test points that have very high deformations (10,5% and 9,5%). The comparison between the different sample points shows that it is not obvious that elevated metal contents have an influence on the diatom community. The first regression analysis (n=114) for metals and deformations indicates that Ni and Zn are significant, both the bioavailable- and the dissolved content. The second regression analysis (n=112) indicates that the bioavailable content of Cu and the dissolved content of U are significant. For both analysis the coefficient of determination is far too low for it to be reliable. More studies need to be done, including more metals and diatom species.

<p> This study analyzed fossil and modern freshwater bivalve mollusc shells, from in and around lakes Ontario and Erie, for the following trace metals: Cu, Ni, Zn, As, Pb, and Mn. Elliptio dilatata, Elliptio complanata, and Lampsilis radiata siliquoidea shells were analyzed by ICPMS for differences in shell metal levels between species and genera, through time and due to anthropogenic inputs. </p> <p> Regardless of age, all three species showed high concentrations of Zn and Mn, and little or no changes in Cu, Ni, Zn, and Pb concentrations with time. E. comp1anata shells were generally poorer in Pb, but richer in As and Mn, than were the E. dilatata and L. radiata siliquoidea shells. Fossil Elliptio samples did not posses low background, or baseline, trace metal concentrations. These samples were richer in As, Pb, and Mn than were modern samples from post-industrial environments. Among the modern shells, the E. complanata showed no differences in metal concentrations between samples from high- and low-contamination· sites, while the L. radiata siliquoidea showed changes in Ni, As, and Mn concentrations among the same sites. Modern L. radiata siliquoidea may be more likely to represent environmental metal changes than are modern E. complanata. Historical change in environmental metal concentrations of the Great Lakes region is not recorded as a simple change in shell metal concentrations of these freshwater bivalve molluscs. </p> / Thesis / Bachelor of Science (BSc)

Thesis (Ph.D. (Biochemistry)) --University of Limpopo, 2010 / A heavy-metal resistant bacterium (GM 16) was isolated from a South African antimony mine, and the non-viable cells of the isolate were used to investigate its biosorption capacity for Cd(II) and Cu(II) from aqueous solution in a batch process. The biosorption of both metals were found to be influenced by factors such as pH of the metal solution, initial metal ion and biomass concentrations, rate of agitation, presence of other metal ions, contact time of the metal solution with the biomass and temperature. The initial biosorption of both Cd(II) and Cu(II) was rapid and equilibrium was reached within 1 hour of biomass contact with the metal solutions. The sorption of both metal ions was higher in weak acid than in strong acid conditions and the optimum pH values for Cd(II) and Cu(II) biosorption were 7 and 6, respectively. The presence of the other metal ions in the metal adsorption media influenced the biosorption of both Cd(II) and Cu(II). Mg2+ ions decreased the uptake of Cu(II) and Cd(II) by 4.7 and 6.5 %, respectively. Whereas K+, Na+ and Ca2+ ions increased the uptake of Cd(II) by 12.3, 8.7, and 3.2 %, respectively, they slightly decreased the sorption Cu(II) (2-6.4 %). Increases in initial metal ion (40-120 mg L-1) and biomass (0.8-4.8 g L-1) concentrations enhanced the sorption of Cd(II) and Cu(II) by GM16 biomass. When the biomass concentration was increased from 0.8 to 4.8 g L-1, the biosorption capacity of Cd(II) increased from 5.5 to 14.5 mg g-1 while that of Cu(II) increased from 2.8 to 14.7 mg g-1 at optimum pHs and a temperature of 40 °C. Maximum adsorption of both metals occurred at an agitation rate of 100 rpm. In addition, increase in initial metal ion concentration from 40-120 mg L-1 increased the initial adsorption rates (h) and the equilibrium metal sorption capacity (qe) of the GM 16 biomass from 6.07 to 16.51 mg g-1 for Cu(II) and 8.9 to 17.9 mg g g-1 for Cd(II). Adsorption equilibrium data for both metal ions fitted well to the Langmuir adsorption model with high correlation coefficients (r2 > 0.90) but the data for Cu(II) could also be described by the Freundlich adsorption model. Increase in temperature from 25-40 °C only caused marginal increases in maximum metal sorption capacities (qmax). The results on kinetic analysis showed that the biosorption processes of Cd(II) and Cu(II) ions by the non-viable GM 16 cells followed pseudo-second order kinetic model betterthan the pseudo-first order model, although the calculated metal sorption capacities obtained with the model were overestimated. The calculated thermodynamic parameters showed that the biosorption of Cd(II) and Cu(II) ions was feasible, spontaneous and slightly endothermic for Cd(II) but slightly exothermic for Cu(II) under examined conditions. Based on 16S ribosomal DNA sequencing, the bacterial isolate (GM 16) was identified as a Bacillus sp. and is closely related to Bacillus thuringiensis and Bacillus cereus strains. The biosorption capacity of the non-viable GM 16 biomass was higher than the biosorption capacity reported for the viable GM 16 cells, 65 % of Cd(II) was removed by non-viable biomass whereas 48 % was removed by the viable biomass. For the biosorption of Cu(II), the % metal ion adsorbed for the non-viable GM 16 cells was slightly higher than the % adsorbed for the viable cells although not statistically significant. Only 67 % of Cu(II) was removed by the non-viable cells whereas 65 % was removed by the viable cells. / National Research Foundation