Benthic fluxes of copper, complexing ligands and thiol compounds in shallow lagoon waters

Abstract

a b s t r a c tBenthic fluxes of copper, copper complexing ligands and thiol compounds in the shallow waters of Venice Lagoon (Italy) were determined using benthic chambers and compared to porewater concentrations to confirm their origin. Benthic copper fluxes were small due to small concentration differences between the porewaters and the overlying water, and the equilibrium concentration was the same at both sites, suggesting that the sediments acted to buffer the copper concentration. Thiol fluxes were $10 Â greater at 50-60 pmol cm À2 h À1, at the two sites. Porewater measurements demonstrated that the sediments were an important source of the thiols to the overlying waters. The overlying waters were found to contain at least two ligands, a strong one, L1 (log K 0 CuL1 = 14.2) and a weaker one, L2 (log K 0 CuL2 = 12.5). The concentration of L1 remained relatively constant during the incubation and similar to that of copper, whereas that of L2 was in great excess of copper, its concentration balanced by porewater releases and breakdown, probably due to uptake by microorganisms, similar to that of the thiol compounds. Similarity of the thiol and L2 concentrations and similar complex stability with copper suggest that L2 was dominated by the thiols. The free copper concentration ([Cú ]) in the Lagoon waters was lowered by a factor of 10 5 as a result of the organic complexation.

Dissolved trace metal (Cu, Cd, Co, Ni, and Ag) distribution and Cu speciation in the southern Yellow Sea and Bohai Sea, China

“…In this study, the speciation analysis showed that the highaffinity organic ligands bound > 99.9% of the dissolved Cu, effectively buffering the system against small changes in dissolved Cu concentrations, and controlled the free Cu 21 concentrations well below the possible toxicity threshold (approximately being 10 211 mol L 21 based on Moffett et al [1997], Brand et al [1986], and Sunda et al [1987]). This is similar to what has been observed worldwide in coastal seawater or the open ocean [Buck et al, 2007;Chapman et al, 2009].…”

“…[]). This is similar to what has been observed worldwide in coastal seawater or the open ocean [ Buck et al ., ; Chapman et al ., ].…”

Chemical Speciation of Copper in a Salt Marsh Estuary and Bioavailability to Thaumarchaeota

“…This suggests that as well as a freshwater source, L 1 is both produced and utilized along the estuary and, as a result, local concentrations may vary seasonally. This is consistent with the identification of L 1 as a thiol-type species, since sediment and pore waters are likely sources of thiols (Kiene et al, 1990;Zhang et al, 2004), which have been shown to diffuse out of sediments in similar shallow water marshes (Chapman et al, 2009).…”

“…Synechococcus are the second most abundant bacterioplankton fraction in waters offshore of the Duplin River in summer . As well as water column sources for ligands, likely sources of thiols are benthic microbes and sulfur-containing amino acids within the sediment (Kiene et al, 1990;Chapman et al, 2009), whilst the humics in this type of environment are likely products of relatively recent degradation of local plant matter (Averett et al, 1994) such as fungal breakdown of lignocellulose (Newell, 2001;Buchan et al, 2003). Spartina alterniflora and many of the higher plants in the marsh also release dimethylsulfoniopropionate (DMSP) (Bacic et al, 1998;Kiehn and Morris, 2010), which can add be an additional source of thiols.…”

Simultaneous Determination of Cadmium, Lead, Copper and Mercury Ions Using Organofunctionalized SBA‐15 Nanostructured Silica Modified Graphite–Polyurethane Composite Electrode

“…[a] Signal to noise ratio ( SNR ) of 3 [43] These effects can be related to the different interactions of the metal ions with the bulk modifier. The stability constants of metal complexes with sulfur and nitrogen reported in the literature [39][40][41][42], show that cadmium is the least stable (lg K ¼ 4.6), the stability of copper (lg K ¼ 12.5) and lead (lg K ¼ 12.1) are almost equal and mercury (lg K ¼ 18.8) is more stable. The results in Table 4 showed that cadmium suffered more interference when the concentration of the other species changed, that can be ascribed to the fact that cadmium has a lower stability constant than the other metals.…”