title: Chemical speciation of dissolved Cu, Ni, and Co in a contaminated estuary in southwest Spain and its influence on plankton communities.
abstract: Four surveys of the Huelva Estuary in southwest Spain and its sources, the Tinto and the Odiel Rivers, were carried out between 1996 and 1998. The surveys investigated the impact of metalliferous mining of sulfide-rich ores in the catchment area on metal speciation, metal concentrations in a macrophyte, and phytoplankton diversity and abundance. Chemical speciation measurements in the lower Tinto Estuary showed that metals were predominantly electrochemically labile (> 99% of total dissolved Cu, Co, and Ni at 10 microM Cu, 424 nM Co, and 500 nM Ni, S = 28). Concentrations of Cu complexing ligands and free cupric ions [Cu2+] in the Gulf of Cádiz ranged between 5.3 and 38 nM and 0.2-7.9 pM, respectively, with conditional stability constants of the ligands of log K'(CuL) = 11.7-12.6. At enhanced dissolved Cu concentrations in the lower Huelva Estuary, Cu complexing ligands were saturated with Cu, resulting in nanomolar [Cu2+], which increased upstream. Metal tissue concentrations of the macrophyte Blindingia marginata were high, and a clear relationship between dissolved labile Cu and macrophyte tissue Cu concentrations was observed. A low biodiversity was observed in the Huelva system (Shannon-Wiener indices (H) typically < 0.2). Nevertheless, the maximum biomass was observed in the lower Tinto Estuary, which showed high labile metal and nutrient concentrations and a low biodiversity (H < 0.02), thereby suggesting adaptation through evolutionary processes of the phytoplankton community to the harsh conditions.
authors.affiliation: University of Plymouth, School of Earth, Ocean, and Environmental Science, Plymouth PL4 8AA, United Kingdom.
authors.forename: Charlotte B
authors.initials: CB
authors.lastname: Braungardt
authors.forename: Eric P
authors.initials: EP
authors.lastname: Achterberg
authors.forename: Martha
authors.initials: M
authors.lastname: Gledhill
authors.forename: Malcolm
authors.initials: M
authors.lastname: Nimmo
authors.forename: Francoise
authors.initials: F
authors.lastname: Elbaz-Poulichet
authors.forename: Antonio
authors.initials: A
authors.lastname: Cruzado
authors.forename: Zoila
authors.initials: Z
authors.lastname: Velasquez
mesh_terms: D000460:Chlorophyta / Q000187:drug effects* / Q000378:metabolism; D003035:Cobalt / Q000032:analysis* / Q000737:chemistry / Q000494:pharmacology; D003300:Copper / Q000032:analysis* / Q000737:chemistry / Q000494:pharmacology; D008024:Ligands; D009532:Nickel / Q000032:analysis* / Q000737:chemistry / Q000494:pharmacology; D010839:Phytoplankton / Q000145:classification / Q000187:drug effects* / Q000378:metabolism; D011157:Population Dynamics; D012623:Seawater / Q000737:chemistry*; D013030:Spain; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000737:chemistry / Q000494:pharmacology
chemical_list: D008024:Ligands; D014874:Water Pollutants, Chemical; D003035:Cobalt; D003300:Copper; D009532:Nickel