Spatial distribution and contamination assessment of heavy metals in urban topsoils from Las Tunas City, Cuba.

Concentrations of Cr, Co, Ni, Cu, Zn, Pb and Fe in the topsoils (0-10 cm) from Las Tunas city were measured by X-ray fluorescence analysis. The mean Cr, Co, Ni, Cu, Zn and Pb contents in the urban topsoil samples (97 ± 30, 14 ± 2, 35 ± 36, 94 ± 26, 199 ± 87 and 42 ± 29 mg kg⁻¹ dry weight, respectively) were compared with mean concentrations for other cities around the world with similar population. Cr content in school grounds, parks and residential areas exceed in 20 % the average Cr background level. Highest content for Ni was determined in residential areas, for Zn in market gardens soils and as for Pb, the highest topsoil-background content ratios were observed for market gardens (2.7) and residential areas (2.3). Spatial distribution maps indicated the same behaviour for Cr-Co-Ni and Pb-Zn, respectively, whereas the spatial distribution of Cu differs from other heavy metals. On the other hand, the metal-to-iron normalisation, using (10-20 cm) bottom soil contents as background, showed that topsoils in Las Tunas city are severely enriched with lead and not enriched with the rest of the determined metals. The average values of integrated pollution index (IPI) indicated that soils are moderately contaminated by heavy metals (1.17 ≤ IPI(ave) ≤ 1.39), but enrichment index values shows that metal concentrations on the studied locations are not above the permissible levels for urban agriculture.

Assessment of metal pollution in soils from a former Havana (Cuba) solid waste open dump.

Concentrations of cobalt, nickel, cooper, zinc and lead in the top-soils (0-10 cm) from a former Havana solid waste open dump were estimated by X-ray fluorescence analysis. The mean metal contents in the dump topsoil samples (in mg kg(-1): 8.4 ± 2.7 for cobalt, 50 ± 27 for nickel, 252 ± 80 for copper, 489 ± 230 for zinc and 276 ± 140 for lead) were compared with mean concentrations from Havana urban soils and from other solid waste disposals around the world. The comparison with Dutch soil quality guidelines showed a serious cooper contamination and a slight contamination with the rest of determined metals. The values of the integrated pollution index (mean index = 3.5) indicated that dump soils are highly contaminated by metals, and the enrichment index values shows that metal concentrations on the studied locations are above the permissible levels for urban agriculture.

Chromium, cobalt and nickel contents in urban soils of Moa, northeastern Cuba.

Iron, chromium, cobalt and nickel concentration levels in urban soil samples collected from Moa city (Holguín province), northeastern Cuba were determined. Both chromium and nickel contents exceed the Dutch Intervention Value soil quality standard in 2.8-5.4 and 1.3-3.3 times, respectively. Furthermore, cobalt content exceeds the Target Value in 1.3-1.8 times. Metal-to-Iron normalization predicts a natural origin for nickel and cobalt (Enrichment Factor <1), and also a moderate chromium enrichment (Enrichment Factor = 1.5-4.0) in all studied stations. The application of the Urban Environment Entropy Model show that residential area located near to industrial area is slightly affected by industrial chromium emissions and not affected by cobalt and nickel possible emissions. A chromium speciation in soil samples is recommended in order to evaluate the real impact of the current chromium content in Moa urban soils to local urban and suburban agricultures.

Copper, zinc and lead bioaccumulation in marine snail, Strombus gigas, from Guacanayabo Gulf, Cuba.

Levels of copper, zinc and lead were determined in sediments and edible muscle of marine snail Strombus gigas collected from Guacanayabo Gulf, Cuba. The concentration range of each metal in marine snail muscle on mg kg(-1) wet weight varied as follows: Cu = 6.4-32.6, Zn = 20.4-31.1 and Pb = 0.2-2.3; and in corresponding sediments (on mg kg(-1) dry weight) as: Cu = 157-186, Zn = 56-94 and Pb = 20-37. The average biota-sediment accumulation factors (BSAFs) obtained for studied metals are less than unity in all cases, indicating that only a little fraction of metal content in the sediments is bioavailable, independently of their possible enrichments in the sediments. The concentrations of copper and lead in some of the marine snails are above typical public health recommended limits.

Copper, zinc and lead enrichments in sediments from Guacanayabo Gulf, Cuba, and its bioaccumulation in oysters, Crassostrea rhizophorae.

Levels of iron, copper, zinc and lead were determined in sediments and soft tissue of the oyster Crassostrea rhizophorae collected from Guacanayabo Gulf, Cuba. Metal-to-Iron ratio in sediments shows an average enrichment for Cu (5,1), Pb (11,7) and Zn (1,3) in the last 20 years. Metal concentrations found in soft tissue of C. rhizophorae are site dependent. The average biota-sediment accumulation factors (BSAFs) obtained for Fe, Cu and Pb are less than unity in all cases, indicating that only a little fraction of Cu and Pb in the sediments is bioavailable, independently of their enrichments. Zinc has an average BSAF value of 2.4 and may represent a serious impact in the area. The concentrations of zinc and copper in some of the oysters are above typical public health recommended limits.

Distribution of doses received by Cuban population due to environmental sources of radioactivity.

Doses received by Cuban population due to exposure to the environmental sources of radiation were studied for their evaluation. Estimations of doses from the different components of the total dose were obtained and published. From the results obtained estimations of total doses to Cuban population from environmental radiation sources and the contributions of different dose components were made. A Monte Carlo simulation of the sum of doses was carried out and the distribution of obtained values was assumed as a lognormal distribution. Parameters for characterisation of this lognormal distribution were estimated, and on the basis of the estimations the average total effective dose to the Cuban population owing to exposure to the environmental sources was estimated as 1.1 +/- 0.3 mSv y(-1). This low dose value is in the range of doses estimated by UNSCEAR for world population due to natural background and can be explained by the specifics of the Cuban environment.

Studies on internal exposure doses received by the cuban population due to the intake of radionuclides from the environmental sources.

Studies for the determination of radionuclide concentrations in foodstuffs, water and air were carried out in Cuba for the estimation of annual committed effective doses to members of the public as a result of environmental radionuclides via ingestion and inhalation. As a result of these studies, it was possible to determine the concentrations of 226Ra, 210Pb, 210Po, 232Th, 90Sr and 137Cs in different food groups that constitute the diet of the Cuban population, as well as the 222Rn concentrations in air. Based on these results and using previously obtained results for doses due to the 40K body content, the annual committed effective doses due to the intake of studied radionuclides were estimated. An average value of 120+/-4 microSv y-1 was obtained for doses due to ingestion of food and water and the obtained value for 222Rn inhalation was 240+/-1 microSv y-1. Using the representative value obtained previously for 40K (150+/-40 microSv y-1) and assuming a dose of 50+/-50 microSv y-1 for the probable contribution of 220Rn by inhalation, a representative value of 560+/-20 microSv was estimated for the average annual committed effective doses due to ingestion and inhalation of radionuclides for the Cuban population. Obtained values are consistent with the expected results, taking into account the characteristics of Cuban exposure scenarios, with low-activity concentration levels in environmental objects and high air exchange rates in dwellings: These results are in the same order of magnitude as results obtained by other authors and the reference values established by the USNCEAR.