Early chemical and ecotoxicological responses of the Varano lagoon (SE Italy) to a flood event.

The effects on coastal lagoons of floods resulting from intense rainfall need to be assessed using a multidisciplinary approach, able to describe in real time the occurrence of changes in sediment quality, anticipating risk situations. In the present study the effectiveness as pre-screening tool of the MOT-test, an innovative bioassay that uses sperm motility as endpoint, has been evaluated; its response has been compared with the sediment chemical characterization, in order to determine the effects of a flood event occurred in the Varano lagoon, a poorly anthropized Mediterranean coastal lagoon. The MOT-test effect percentages ranged from 10% to 30%, fully reflecting data from chemical analyses. Organic pollutants showed concentrations always below the critical levels. The highest metal values were found in the south-eastern area; however, only for few metals (mainly Cd), and in few sites, they reached the limits defined by the sediment quality guidelines; consistently, these sites are located in the area where a higher stressors' impact was expected and the highest MOT-test effect percentages were recorded. In conclusion, even if results exclude the occurrence of serious contamination events as a consequence of the flood, the runoff resulting from the intense rainfall event has caused a pollutant load in the lagoon, consistent with the localization of the main anthropogenic activities in the catchment area. Moreover, preliminary data indicate the validity of the approach adopted for the post-flood quality assessment, proving the usefulness of the MOT-test as early-screening tool in the case of extreme events.

Presence and distribution of current-use pesticides in surface marine sediments from a Mediterranean coastal lagoon (SE Spain).

The spatial and seasonal distributions of current-use pesticides (CUPs), including triazines, organophosphorus pesticides, and tributylphosphate, were characterized in surface sediments from the Mar Menor lagoon during 2009 and 2010. The impact of two flash flood events on the input of CUPs and their distribution in the lagoon were also assessed. The total (dissolved + sorbed phase) input of CUPs in the two flash floods through the El Albujón watercourse into the lagoon was estimated at 38.9 kg, of which 9.9 kg corresponded to organophosphorus pesticides and 5.5 kg to triazines. CUP distribution onto sediments was not homogeneous in the lagoon due to the different contaminant sources, sediment types, and the physicochemical and hydrodynamic conditions of the Mar Menor lagoon. Thirteen CUPs were detected in 2009 and 19 in 2010, including mainly herbicides, insecticides, and the additive tributylphosphate. Mean CUP concentrations in the lagoon were generally below 20 ng g-1, except for chlorpyrifos and tributylphosphate in 2010. The highest concentrations were detected in depositional areas of the lagoon, in the area of influence of the El Albujón watercourse and other wadis with groundwater contributions such as El Mirador (north) and Los Alcázares (east) and that of marine water from El Estacio channel. In fact, the maximum concentration was detected close to El Albujón watercourse (chlorpyrifos, 102.8 ng g-1 dry weight). Four herbicides, two insecticides, two fungicides, and tributylphosphate showed a risk quotient higher than 1, with that for chlorpyrifos ranging from 96 to 35,200 after flash flood events.