Effects of extreme rainfall events on the distribution of selected emerging contaminants in surface and groundwater: The Guadalete River basin (SW, Spain)

This study is focused on the Guadalete River basin (SW, Spain), where extreme weather conditions have become common, with and alternation between periods of drought and extreme rainfall events. Combined sewer overflows (CSOs) occur when heavy rainfall events exceed the capacity of the wastewater treatment plants (WWTP), as well as pollution episodes in parts of the basin due to uncontrolled sewage spills and the use of reclaimed water and sludge from the local WWTP. The sampling was carried out along two seasons and three campaigns during dry (March 2007) and extreme rainfall (April and December 2010) in the Guadalete River, alluvial aquifer and Jerez de la Frontera aquifer. Results showed minimum concentrations for synthetic surfactants in groundwater (<37.4μg·L^-1) during the first campaign (dry weather conditions), whereas groundwater contaminants increased in December 2010 as the heavy rainfall caused the river to overflow. In surface water, surfactant concentrations showed similar trends to groundwater observations. In addition to surfactants, pharmaceuticals and personal care products (PPCPs) were analyzed in the third campaign, 22 of which were detected in surface waters. Two fragrances (OTNE and galaxolide) and one analgesic/anti-inflammatory (ibuprofen) were the most abundant PPCPs (up to 6540, 2748 and 1747ng·L^-1, respectively). Regarding groundwater, most PPCPs were detected in Jerez de la Frontera aquifer, where a synthetic fragrance (OTNE) was predominant (up to 1285ng·L^-1).

Assessment of mercury in muscle of fish from Cartagena Bay, a tropical estuary at the north of Colombia

Fish belonging to several trophic levels from Cartagena Bay, a tropical estuary, were collected and analyzed for total mercury (T-Hg) concentrations in muscle. T-Hg concentrations varied from 0.010-0.526 microg/g, and the overall average was 0.051 +/- 0.002 microg/g. Carnivorous species presented the highest T-Hg mean value (0.100 +/- 0.006 microg/g), followed by omnivorous (0.076 +/- 0.014 microg/g) and detritivorous (0.028 +/- 0.001 microg/g). The relationships between weight and T-Hg content were found for the carnivorous species Sciades herzbergi (r = 0.508, p < 0.001) and not for the detritivorous Mugil incilis (r = 0.086, p = 0.207). Although results suggest fish from the bay pose a low health threat for humans in terms of Hg exposure, vulnerable groups such as pregnant women, should avoid eating large size carnivorous species. Knowledge about species with low Hg content should be widespread within fishing communities, guaranteeing adequate nutrition by including fish in the diet and reducing the risk of Hg poisoning.