Integrated study of metal behavior in Mediterranean stream ecosystems: a case-study.

The objective of the present work was to assess the ecosystem status of Francolí river (Catalonia, Spain), a Mediterranean stream basin with contrasting human influences. An integrated approach was designed by combining physicochemical, biological and ecotoxicological analyses. The content of metals (As, Cd, Cr, Co, Cu, Hg, Ni, Pb, and Zn) was analyzed in samples of water, benthic sediments and aquatic macroinvertebrates.

Point-source effects on N and P uptake in a forested and an agricultural Mediterranean streams.

We examined the effect of point-source inputs from wastewater treatment plants (WWTP) on in-stream uptake of ammonium, nitrate and phosphate and compared it between two streams draining catchments with contrasting land use. The selected streams were La Tordera and Gurri (NE Spain), draining a forest- and an agriculture-dominated catchment, respectively. In each stream, we compared nutrient uptake metrics, estimated from nutrient additions, between two reaches located upstream and downstream of a WWTP input.

Net changes in nutrient concentrations below a point source input in two streams draining catchments with contrasting land uses.

We examined net changes in ammonium-Nitrogen (NH(4)(+)-N), nitrate-Nitrogen (NO(3)(-)-N), dissolved inorganic nitrogen (DIN), soluble reactive phosphorus (SRP), and dissolved organic carbon (DOC) chloride-corrected ambient concentrations along a reach located below a wastewater treatment plant (WWTP) input in a non-agricultural (12 dates) and an agricultural (6 dates) stream. Based on those net changes, we estimated processing length (Snet) and mass transfer coefficient (Vf) of the cited nutrients. In the agricultural stream, results suggest that diffuse nutrient inputs from adjacent agricultural fields had a greater effect on water chemistry than the WWTP input, and probably overwhelmed the stream capacity to retain and transform nutrients.