Estimation Of Metal Concentration Research Articles

Estimation of metal concentrations in marine biota and associated health risk assessment for inhabitants of a coastal region in Northwestern Mexico.

Marine ecosystems are subject to contamination by metals and metalloids and other elements and compounds that are emitted due to various human activities. These substances subsequently induce changes in marine biota after entering the marine environment. Marine organisms are frequently consumed worldwide because they constitute relatively cheap and accessible food items of high nutrient quality. The aim of this study was to estimate metal accumulation in frequently consumed marine species and to evaluate the associated health risks for particular population groups in a coastal region of northwestern Mexico. The marine species were consumed in different quantities between spring (from 0.29kgyear-1 for white clam, to 38.40kgyear-1 for blue crab) and autumn (from 0.34kgyear-1 for white clam, to 15.02kgyear-1 for leopard grouper). The general distribution of metal concentrations in the marine species (n = 13 in each season) evaluated in this study followed the trend of Fe > Zn > Cu > Mn > Cr with the highest metal concentrations detected during autumn. Although many metal concentrations were above the international standards of the Food and Agriculture Organization of the United Nations (FAO) and the World Health Organization (WHO), the hazard quotient (HQ) and hazard index (HI) values for the women in this study indicated that their health was not at risk due to the consumption of either fish or seafood. In contrast, the HQ and HI values determined for groups of men and children indicated that they are at risk due to the frequent consumption of most species evaluated in this study.

High‐frequency multi‐solute calibration using an in situUV–visible sensor

AbstractMonitoring the temporal variation of solute concentrations in streams at high temporal frequency can play an important role in understanding the hydrological and biogeochemical behaviour of catchments. UV–visible spectrometry is a relatively inexpensive and easily used tool to infer those concentrations in streams at high temporal resolution. However, it is not yet clear which solutes can be modelled with such an in‐situ sensor. Here, we installed a UV–visible spectrometer probe (200–750 nm) in a high‐altitude tropical Páramo stream to record the wavelength absorbance at a 5‐min temporal resolution. For calibration, we simultaneously sampled stream water at a 4‐h frequency from February 2018 to March 2019 for subsequent laboratory analysis. Absorbance spectra and laboratory‐determined solute concentrations were used to identify the best calibration method and to determine which solute concentrations can be effectively inferred using in situ spectrometry through the evaluation of six calibration methods of different mathematical complexity. Based on the Nash–Sutcliffe efficiency (NSE) and Akaike information criterion metrics, our results suggest that multivariate methods always outperformed simpler strategies to infer solute concentrations. Eleven out of 21 studied solutes (Al, DOC, Ca, Cu, K, Mg, N, Na, Rb, Si and Sr) were successfully calibrated (NSE >0.50) and could be inferred using UV–visible spectrometry even with a reduced daily sampling frequency. It is worth noting that most calibrated solutes were correlated with wavelengths (WLs) in the low range of the spectra (i.e., UV range) and showed relatively good correlation with DOC. The latter suggests that estimation of metal concentrations could be possible in other streams with a high organic load (e.g., peat dominated catchments). In situ operation of spectrometers to monitor water quality parameters at high temporal frequency (sub‐hourly) can enhance the protection of human water supplies and aquatic ecosystems as well as providing information for assessing catchment hydrological functioning.

Metal concentrations in soil paste extracts as affected by extraction ratio.

Saturated paste extracts are sometimes used to estimate metal levels in the soil solution. To assess the significance of heavy-metal concentrations measured in saturation extracts, soil paste extracts were prepared with distilled water in amounts ranging from 60–200% of the moisture content at saturation. Trace metals behaved as if a small pool consistently was dissolved independent of the extraction ratio applied. Metal concentrations in the solution hence were not buffered by the solid phase, but the observed behaviour would allow the estimation of metal concentrations in the soil solution as a function of moisture content. The behaviour of iron and manganese suggested that some microbial reduction occurred. The intensity increased with increasing extraction ratio but not to the extent of affecting dissolution of trace elements.

Estimation of cadmium, lead, and mercury concentrations in estuarine waters using the mussel Mytilus edulis planulatus L.

AbstractAccumulation of cadmium, lead, and mercury in the tissues of the mussel Mytilus edulis planulatus L. from the Derwent Estuary, Hobart, Australia was linear over a range of metal concentrations in the ambient water, provided that the condition index of the mussels (meat weight/shell weight) indicated that the organisms were not under environmental stress. Polynomial regression analysis of accumulation rates against ambient concentrations of the respective metals in the water column in the vicinity of the mussels showed that the relationships depended upon the physical speciation of the metals (i.e., filtrable vs particlate metals). The results indicated that it may be feasible to use metal accumulation rates in mussels to provide broad‐based estimates of metal concentrations in marine waters, provided that the organisms have been calibrated under conditions similar to those prevailing at the proposed monitoring sites. © 1994 by John Wiley & Sons, Inc..