ID do Resumo: 595

Effects of different land cover on chemical characteristics of streams and flow components in the Cerrado region

The Cerrado is the second largest Brazilian biome and location of the headwaters of three important hydrological basins in Brazil. In spite of the biological and ecological relevance of this biome, there is little information about how land use changes affect the chemistry of surface water, groundwater and streams. In order to evaluate the effects of these changes we selected first-order streams that drain natural, rural and urban areas near Brasília (Federal District), Brazil and collected samples of streamwater during two years. In natural and rural areas we also collected samples of atmospheric deposition (AD), runoff (R), subsurface water (SW) and groundwater (GW). Urban streams presented the highest median values of pH (6), alkalinity (111uM), electrical conductivity (22uS/cm), OD (8mg/L), turbidity (12NTU), dissolved organic carbon (139uM), dissolved total nitrogen (33uM), NH4+ (5uM), NO2- (3uM), NO3- (11uM), Ca+2 (20uM), Mg+2 (10uM), K+ (10uM), Na+ (48uM), Cl- (26uM), SO4- (2uM). Natural streams showed the lowest values, while the rural showed intermediate values. Regarding the comparison of flow components between natural and rural areas, major changes were observed for the nitrogen forms with increasing concentrations in rural areas. The results indicated that differences in land cover are related to changes in streamwater chemistry and to changes in flow components, particularly in the case of nitrogen.

Sessão:  Biogeoquímica - A biogeoquímica das interações entre terra e água: integrando pequenos reservatórios a grande bacia.

Tipo de Apresentação:  Oral