Abstract
The application of an acid digestion and subsequent solid-phase extraction (SPE) procedure were implemented as preliminary treatments prior to quantifying the levels of potentially endocrine disrupting metals (EDMs) in a variety of solid and liquid matrices. These included (solid) river sediment, leachate sediment and sewage sludge and also (liquid) river water, landfill leachate, concentrated leachate, sewage influent, and sewage effluent, sampled in the Irish Midlands. The total concentrations of cobalt (Co), cadmium (Cd), copper (Cu), chromium (Cr), nickel (Ni), lead (Pb), zinc (Zn), and manganese (Mn), after extraction and preconcentration, were determined by atomic absorption spectroscopy (AAS). Mercury (Hg) in sediment and sludge was determined using cold-vapour atomic fluorescence spectroscopy (AFS). For sewage sludge maximum values (mg/kgdw) of 4700 Ni, 1642 Mn, 100.0 Cd, 3400 Zn, 36.70 Co, 750.0 Pb, 485.8 Cr, and 1003 Cu were determined whilst in leachate sediment, maximum values (mg/kgdw) of 32.10 Ni, 815.0 Mn, 32.78 Cd, 230.3 Zn, 26.73 Co, 3525 Pb, 124.9 Cr, and 50.13 Cu were found. Over several months, the data showed elevated levels in sewage influents, effluents, and sludges compared to a battery of adjacent river water samples and corresponding sediments. There was a definite trend for target values for sediments to be exceeded, while intervention values were only exceeded for cadmium. Overall the pattern in terms of concentration was sewage > leachate > river matrices. A nonparametric assessment of the effect of sewage treatment method on median metal levels in sludge revealed statistically significant differences at the 95% level of confidence for Co, Cr, and Hg and at the 90% level of confidence for Cd.
Highlights
Arising from hydro-geological interactions within riverine systems, elements and metals coexist in relative proportions to each other and these ratios are dependent on geochemical processes such as weathering, atmospheric deposition, rainfall and flow-rates
This study looks at the levels of those metals suggested by Kime [1], amongst other commentators, as being potentially oestrogenic in matrices subject to extensive human inputs in the Irish Midlands
Metal reference standards purchased from Reagecon (Ireland) were diluted in 3 M HNO3 (69% HNO3AnalaR BDH, Sigma-Aldrich; diluted with ultrapure deionised water) on a daily basis to give 0.5, 1.0, 1.5, 2.0, 2.5, and 3.0 μg/mL standard solutions. 47 mm microfibre glass GF/C (1.2 μm), GF/F (0.7 μm), and 0.45 μm nylon filters were obtained from AGB Scientific, Ireland. 3M-Empore metal chelating resin solid-phase extraction (SPE) disks were purchased from JVA Analytical Ltd (Ireland)
Summary
Arising from hydro-geological interactions within riverine systems, elements and metals coexist in relative proportions to each other and these ratios are dependent on geochemical processes such as weathering, atmospheric deposition, rainfall and flow-rates. Overall, this process occurs from a dynamic equilibrium between outside exposure from the environment and uptake, storage, excretion, or degradation within the organism. With medium toxicity and no known biological function, is antimony (not reported here) and the third group includes copper, zinc, and cobalt, which are essential for various biochemical and physiological processes and are toxic above certain concentrations. The toxicity will depend on the oxidation state; for example, Cr (III) is required by the body in trace amounts whilst Cr (VI) is highly toxic
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