Determination of metals by total reflection X-ray fluorescence and evaluation of toxicity of a river impacted by coal mining in the south of Brazil.

Metal (Fe, Mn, Zn, Ni, Cd, and Pb) concentrations in the region of Criciuma (Brazil), a region impacted by coal mining, were determined in water and sediments using total reflection X-ray fluorescence (TXRF) spectroscopy. Samples were collected from the Mãe Luzia River (south Brazil) at five different stations, from the source down to the river mouth (Ararangua estuary). Water and sediment toxicity were also evaluated using bioassays with Daphnia magna as the bioindicator. The metal present in the highest concentrations both in water (1.3-11 mg L(-1)) and in sediments (34-142 mg L(-1)) was iron. Results suggest an influence of coal mining on the aquatic receptors, showing a clear relationship between metal content (mostly Fe) and ecotoxicity.

Removal of methylene blue from aqueous solution by peat.

In this study, the removal of methylene blue (MB) from aqueous solution by peat was analyzed. The peat was collected from a peatland at Arroio do Silva Beach, in Santa Catarina state, in the south of Brazil. Adsorption was conducted using varied initial concentrations of the MB solutions and three different temperatures (35, 45 and 60 degrees C). An adsorption time of around 4.5h was sufficient to reach the equilibrium for all temperatures, in the concentration range studied. Percentage removal was greater for diluted solutions, but the absolute amount of MB adsorbed by the peat at equilibrium increased with an increase of the initial concentration, corroborating the efficacy of the material as an adsorbent. Temperature influenced slightly the reaction, which was endothermic. Results indicated a multi-layered process and the data were analyzed considering pseudo-first-order, pseudo-second-order and intraparticle diffusion approaches. The latter two mechanisms seem to be significant in the rate-controlling step.

Evaluation of remediation of coal mining wastewater by chitosan microspheres using biomarkers.

Acidic mine waters have a marked influence on the surrounding environment and pose a serious threat through long-term environmental degradation. Therefore, it is important to improve and monitor water quality with the aim of decreasing the hazard presented by this effluent emission. The aim of this work was to evaluate the remediation of mining wastewater effluents by chitosan microspheres using biomarkers of exposure and effect. DNA damage (Comet assay) and several biomarkers of oxidative stress, such as lipoperoxidation levels (TBARS), superoxide dismutase (SOD), catalase (CAT), and glutathione S-transferase (GST) activities, and contents of reduced glutathione (GSH), were measured in blood and liver of tilapia (Oreochromis niloticus) exposed for 7, 15, and 30 days to dechlorinated tap water, 10% coal mining wastewater (CMW), and coal mining wastewater treated with chitosan microspheres (RCM). The results indicate that hepatic TBARS levels were significantly higher in fish exposed to CMW after 7, 15, and 30 days (100%, 86%, and 63%, respectively), and after remediation there was no significant difference in relation to the control group. Hepatic GSH concentrations were lower than control values for CMW after 7 and 15 days of exposure (34% decrease at both times), and this concentration was normalized by treatment with chitosan. SOD showed increased activity in liver after 15 and 30 days of exposure, 30% and 36%, respectively, and in fish exposed to RCM there was no change in this activity compared with the control group. Increased CAT activity in liver was observed during all experimental periods in fish exposed to CMW (46%, 50%, and 56% at 7, 15, and 30 days, respectively) compared with the control or treated-water groups. The highest increase in hepatic GST activity (106%) was observed only in fish exposed to CMW for 30 days. There was an increase in DNA damage in liver (50% at 7 and 15 days) and blood (79%, 77%, and 48% at 7, 15, and 30 days, respectively) after exposure to CMW. In contrast, the fish exposed to wastewater treated with chitosan microspheres exhibited DNA fragmentation indexes similar to the control group. The results obtained indicate the use of oxidative stress biomarkers as useful tools for the toxicity evaluation of coal mining effluents and also suggest that chitosan microspheres may be used as an alternative approach for remediation of coal mining wastewaters.

Remediation of coal mining wastewaters using chitosan microspheres.

This study aimed to evaluate the potential use of chitosan and chitosan/poly(vinylalcohol) microspheres incorporating with tetrasulphonated copper (II) phthalocyanine (CTS/PVA/TCP) in the remediation of coal mining wastewaters. The process was monitored by toxicity tests both before and after adsorption treatments with chitosan and microspheres. Physicochemical parameters, including pH and trace-metal concentration, as well as bioindicators of water pollution were used to that end. Wastewater samples colleted from drainage of underground coal mines, decantation pools, and contaminated rivers were scrutinized. Acute toxicity tests were performed using the Brine Shrimp Test (BST) in order to evaluate the remediation efficiency of different treatments. The results showed that the pH of treated wastewater samples were improved to values close to neutrality. Chitosan treatments were also effective in removing trace-metals. Pre-treatment with chitosan followed by microsphere treatment (CTS/PVA/TCP) was more effective in decreasing toxicity than the treatment using only chitosan. This was probably due to the elimination of pollutants other than trace-metals. Thus, the use of chitosan and microspheres is an adequate alternative towards remediation of water pollution from coal mining.