Total arsenic in marine organisms from Cienfuegos Bay, Cuba

Full text: Levels of total arsenic were determined in muscle tissues of species of finnish, crustaceans and molluscs from Cienfuegos Bay, Cuba. The arsenic contents in the samples were determined using an Energy Dispersive X Ray Fluorescence (EDXRF) method. The highest values of Total arsenic were found in crustaceans. Averages found for fish, crustaceans and molluscs were 10.2, 26.5 and 22 μg g-1 dry wt, respectively. These results are considered to be characteristic for normal or naturally altered areas. Cienfuegos Bay, situated in the Southern part of Cuba, is a semi-enclosed bay with a surface area of 90 km2 and an average depth of 14 m. It is connected to the Caribbean Sea by a narrow channel 3 km long. The bay is divided in two well defined hydrographic basins, due to the presence of a submerged ridge 1m below the surface. The Northern basin receives most of the anthropic impact from the outfall of Cienfuegos city (150,000 inhabitants), industrial pole in the country, and the freshwater input of Damuji and Salado rivers. The Southern basin is subjected to a smaller degree of anthropic pollution originating from the Caonao and Arimao rivers. Part of the Southern basin is a natural park, which represents a niche for protected migratory birds and marine species. The bay represents the most important natural resource in the province, due to fishing activities, maritime transport, tourism industry and natural parks. During the last decade it has acquired an important economic and social development, resulting in an increase of industrial and domestic wastes which are discharged into the bay. Direct input of Arsenic to Cienfuegos bay occurs through the Nitrogen Fertilizer Factory, which was authorized to release Arsenic residuals up to 1981 and where two accidental As spills took place in 1979 and 2001. Marine organisms represent an important component of the diet of the population of Cienfuegos. In particular, people from the coastal areas of Castillo de Jagua, Las Minas and O'bourque have an average ingestion rate of fish of 51 kg yr-1, varying from 21 to 116. Only a few studies have investigated the total As content in marine organisms from Cuba. In particular, a survey of marine products from the Western coast, displayed concentrations of Arsenic ranging from 0.01 to 4.82 μg g-1d.w.. Total Arsenic in fish and crustaceans was also measured in Cienfuegos Bay in 1974 and results showed low concentrations of this compound (1.2 μg g-1 d.w. in fish and 1.7 in crustaceans). Sixteen species of fish, two of molluscs and three of crustaceans were caught in Cienfuegos Bay. The target species were selected among those of dietary importance for the population. The arsenic contents in the samples were determined using an Energy Dispersive X Ray Fluorescence (EDXRF) method (Si/Li detector with 180 eV for Mn Kα and Cd-109 annular source. The elaboration of the spectra and quantitative analysis was carried out using the QSAX System. Compton peak was used for the matrix effects correction. Several Biological Certified Reference Materials (NRCC DOLT-2 Dogfish Liver, NRCC TORT-2 Lobster Hepatopancreas, NIES CRM-9 Sargasso, NRCC DORM-1 Dogfish Muscle and IAEA-140/TM Seaweed Fucus sp.) were measured for calculating the As concentrations in the samples. The highest values of Arsenic were found in crustaceans, which showed a mean value of 26.5 μg g-1 d.w. (values ranging from 6.9 to 53.9). These levels are in agreement with others found in literature for shrimps and marine crabs captured in estuaries and enclosed bays. The higher Arsenic content in tissues of bottom dwellers such as shrimps and crabs, can be attributed to their habitat being close to the sediment. Sediments are always higher in Arsenic than water and bottom water usually contains higher As concentration than surface water. When comparing the obtained values from this study with those reported in 1974 for shrimps from Cienfuegos bay, we observed that the mean value of Arsenic in crustaceans was 18 times higher than at the time. This could be explained through the increase of antrophic activity in the area during the last decades, when artificial sources of As were established in the coastal zone. In particular, the routine and accidental release of Arsenic residuals from the Nitrogen Fertilizer Factory could be responsible for the observed pattern. In the fish muscle, the mean As concentration was 10.21 μg g-1 d.w. (values ranging from 2 to 42.6). These results are considered to be characteristic for normal or naturally altered areas. The international reports consulted indicate that marine fish can reach total As contents up to 150 μg g-1 d.w., without any risk for the population that consumes it. However, as for the crustaceans, the Arsenic levels obtained in this study are 12 times higher than those reported in fish from Cienfuegos bay in 1974, and are considerably larger that those reported by in fish captured from Western Cuba. (author)