Contamination assessment and prediction of 27 trace elements in sediment core from an urban lake associated with land use.

A sediment core was sampled in an urban lake in southern Brazil, and the presence of 27 trace elements was assessed. The geochronology showed that the core corresponds to the period from 1914 to 2012. Accumulation of metals and the level of pollution was measured by the geoaccumulation index (Igeo) and enrichment factor (EF). According to Igeo and EF, the lake showed a high concentration of Ag, Se, Na, Au, S, Ca, Mg, Ba, Sb, Bi, and Sr with 5 ≤ EF ≤ 45 and Igeo class = 2-6. The EF to Au = 45 and Ag = 40. In contrast, Fe, Al, As, Cr, Ga, La, Sc, and Th do not represent pollution (Igeo ≤ 0 and EF ≤ 1.6). A principal component analysis and Spearman correlation showed a first group composed of Ca, Mg, P, Ba, Sr, Na, K, Ag, Bi, Au, Mo, sand, silt, and total organic carbon with positive correlation ≥ 0.70 and > 0.95 to Sr, Ag, sand, and silt. These were negatively correlated ≥- 0.70 with Fe. The second group: Fe, La, Ga, Ti, V, Cr, As, Al, Th from lithogenic source. Prediction models for the concentration for Mg, Na, P, Sr, Fe, Ga, and total organic carbon to years 2020-2050 were obtained with R2 > 0.65. In the anthropogenic source analyses, a watershed land use map indicates multiple uses of the land, with 53% urban area, 14.6% agriculture, and 14.5% forest.

PAHs in Water, Sediment and Biota in an Area with Port Activities.

The study reports concentration of 16 PAHs in sediment, water, plankton and in muscle and liver of sampled fishes from Paranagua Bay in Southern Brazil. According to the range of PAHs concentration found in sediments (ΣPAHs 15.33-133.61 µg g-1) and water (ΣPAHs 51.20-162.37 µg L-1), the area was characterized as slightly polluted. In contrast, significant concentration of PAHs was found in fish and plankton, ranging from 26.52 to 2055.00 µg g-1 and 175.41 to 2096.10 µg g-1, respectively. The concentrations were 15 times more than in sediments. Even though the concentration of PAHs in water and sediments are low, the concentration in fish tissues are alarmingly. The hypothesis of bioaccumulation is not discharged. Accumulation levels of PAHs in the biota were used to calculate biota-sediment accumulation factor (BSAF) and bioaccumulation factor (BAF). For example, fish sampled from site 11 had a BAF of 49 and BSAF of 2.3, whereas for plankton the BAF was 16.3 and BSAF 0.7. Mean values of BAF and BSAF were higher in plankton samples. It is known that PAHs are enzymatically metabolized by organisms, thus the lower BSAF in fish might have resulted from biochemical transformation. Statistical analysis indicates no significant correlation between total PAHs concentration in fish tissues and total lipid content in fishes (p > 0.1).Accumulation in tissues is controlled by lipid content, although factors, such as spatial distribution of compounds, trophic level, and behavior of each species in the environment, must be considered. Besides, size and nutritional conditions can affect both absorption as well as metabolic process and excretion. A positive and significant correlation was found between total PAHs and trophic positions obtained from FishBase data (r2 = 0.784; p < 0.05). Thus, it seems that the area, with great influence of urban and industrial activities, and the bioaccumulation compounds, such as PAHs, depend on others factors, as well as resuspension of sediments and releasing of compounds for biota.