Soil mercury levels in the area surrounding the Cerro Prieto geothermal complex, MEXICO.

Even though geothermal energy is a renewable energy source that is seen as cost-effective and environmentally friendly, emissions from geothermal plants can impact air, soil, and water in the vicinity of geothermal power plants. The Cerro Prieto geothermal complex is located 30 km southeast of the city of Mexicali in the Mexican state of Baja California. Its installed electricity generation capacity is 720 MW, being the largest geothermal complex in Mexico. The objective of this study was to evaluate whether the emissions generated by the geothermal complex have increased the soil mercury concentration in the surrounding areas. Fifty-four surface soil samples were collected from the perimeter up to an approximate distance of 7660 m from the complex. Additionally, four soil depth profiles were performed in the vicinity of the complex. Mercury concentration in 69 % of the samples was higher than the mercury concentration found at the baseline sites. The mercury concentration ranged from 0.01 to 0.26 mg/kg. Our results show that the activities of the geothermal complex have led to an accumulation of mercury in the soil of the surrounding area. More studies are needed to determine the risk to human health and the ecosystems in the study area.

First insight into plastics ingestion by fish in the Gulf of California, Mexico.

Plastic particle occurrence in the digestive tracts of fishes from a tropical estuarine system in the Gulf of California was investigated. A total of 1095 fish were analysed, representing 15 species. In total 1384 particles of plastic debris were recovered from the gastrointestinal tracts of 552 specimens belonging to 13 species, and all consisted of threads, the majority of which were small microplastics (0.23 to 1.89), followed by large microplastics (2.07 to 4.49), and few mesoplastics (5.4 to 19.86). Plastic particles were identified using ATR-FTIR spectroscopy. The mean frequency of occurrence of plastics in the gastrointestinal tracts of fishes from this system was 50.5%, which is higher than frequencies reported in similar systems in other areas. The polymers identified by ATR-FTIR were polyamide (51.2%), polyethylene (36.6%), polypropylene (7.3%), and polyacrylic (4.9%). These results show the first evidence of plastic contamination for estuarine biota in the Gulf of California.

Nitrate leaching from construction sites to groundwater in the Nottingham, UK, urban area.

Nitrate pollution has been identified as a major water quality issue in the UK. The aim of this project is to research the rate of nitrate leaching to groundwater that arises from construction works. The study area is situated in Nottingham UK, which is situated on the Triassic Sandstone aquifer. Soil samples up to a depth of 2.50 m were taken from three sites under construction and other land use. The results have shown a high variability in the concentrations of soil-nitrate. The reasons for this variability include soil type, past land use, soil treatment and type of vegetation prior to construction works. The average nitrogen load was 65 kg N ha(-1) which is higher than the nitrate leaching observed when temporary grassland is ploughed during autumn. The highest nitrate concentrations were observed in an allotment site (133 kg N ha(-1)) due to the high amount of manure applied at this location. The construction practice of top soil stripping can produce a reduction of nitrate leaching because it removes the part of the soil that contains most of the potentially mineralizable nitrogen.