Copper Complexation Capacity Research Articles

Copper-complexing capacity of South Pacific waters

The strong copper-complexing capacity of seawater from the western tropical Pacific Ocean and the Coral Sea has been measured by a method based on competition between naturally occurring ligands and Chelex-100 ion-exchange resin. In the nutrient-depleted surface waters, the values ranged from 4 to 72 nM. For deeper waters there were larger variations with values ranging from 2 to 136 nM in the region of the salinity minimum at approximately 800-1000 m. There was no evidence for increased complexing capacity due to the sediment-water interface. Since changes in complexing capacity are ultimately of biological origin, the variability must have arisen when the waters were in the euphotic zone at polar latitudes. The samples were unfiltered and the complexing capacity could be due to either dissolved organic compounds or to particles so small that their settling velocities are negligible compared with the time elapsed since the water parcel was last in the euphotic zone. There is no direct correlation between complexing capacity and water density or concentration of nutrients. The results suggest that parcels of water up to 100 km wide can travel distances up to 10 000 km and maintain a chemical signature different from the surrounding water.

Influence of phytoplankton on complexing capacity of seawater†

Differential Pulse Anodic Stripping Voltammetry (DPASV) was employed to measure Apparent Copper Complexing Capacity (Lt) and Stability Constants (Ks) of related cupric complexes of cell exudates of the phytoplanktonic alga Dunaliella salina. Three natural seawater samples collected 0.1, 2, 5 miles off the Tyrrhenian coast were used as culture medium. The measurements were carried out 1h and 7 days after the inoculum. Furthermore, on one culture the medium was passed through C18‐SEP‐PAK cartridges in order to separate the cell exudates. The results show that Dunaliella salina influences the value of Lt but does not affect the value of Ks . The C18SEP‐PAK retain only 50% of the ligands produced by the cells and capable of complexing copper.

The toxicity of copper to the adult and early life stages of the freshwater clam,Corbicula manilensis

The copper sensitivity of adult and larval stages of the freshwater clamCorbicula manilensis was evaluated. In addition, copper concentrations were determined in adult clams exposed for 4 to 10 weeks to copper in a high-volume, flow-through bioassay. All bioassay systems utilized water that was low in total hardness and alkalinity. The response of the clams to copper depended on life stage. Copper sensitivity of larvae decreased markedly in successive developmental stages. LC5024's of veliger and juvenile larvae were 28 and 600 μg Cu/L, respectively. The mortality of trochophore larvae exposed to 10 μg Cu/L for one hr was 91.5%. The sensitivity to copper decreased with increased amounts of larval shell deposition. Adult clams were resistant to copper; the LC5096 was greater than 2,600 μg Cu/L. By comparison, the incipient lethal concentration (ILC, was lowless than 10 μg Cu/L. Adult clams accumulated more copper as concentrations in the water increased. Evidence was obtained for copper loss near or at death. Labile and total copper, as well as the coppercomplexing capacity, in the bioassay water were determined; the majority of copper was present as labile species. Toxicity was related to the quantities of labile copper in the water.

Trace metals and the productivity of shelf waters off north west Australia

Oceanographic measurements on the North West Shelf of Australia indicated that nutrient enrichment was derived from a combination of terrestrial run-off and interaction with the sediments. There was no evidence for upwelling. In situ fluorescence measurements suggested that the phytoplankton biomass was low and did not increase in regions of nutrient enrichment. On the continental shelf, the concentrations of copper, nickel and cadmium were typical of unpolluted waters and by using a reverse- phase high performance liquid chromatography absorbent (SEP-PAK), about 20% of the copper was found to be organically bound with smaller amounts of organically bound nickel, zinc and iron and even less organically bound cadmium, chromium and manganese. The copper-complexing capacity of the surface waters (5-10 nM) was comparable to the total concentration of trace metals liable to form organic complexes so that the trace metal speciation may change markedly with small changes in trace metal concentration or complexing capacity. Calculations show that the concentration of free copper ions is too low to have any adverse affects on the biota and it is suggested that the productivity of the water may be affected by the limited bioavailability of essential trace metals.

Metal-Humic and Fulvic Acid Interactions in Fresh Water Ultrafiltrate Fractions

Abstract Fresh water samples from Po river (Northern Italy) were filtered and characterized by measuring the most important physico-chemical parameters. The samples were subsequently submitted to ultrafiltration to separate and fractionate the colloidal particle range from > 104 to < 103 M.W. Two different types of ultrafiltration cells were tested; they yielded quite different results due to systematic errors introduced when using the cell operating under pressure. It was found that the largest share of any metal considered was associated with the finest (< 103 M.W.) particle fraction. Correlation analysis applied to analytical data showed that manganese is associated to organic matter in the 103–104 M.W. particle fraction. Positive correlations existing between copper and Apparent Complexing Capacity (ACC) and between cadmium content and Total Organic Carbon (TOC) in the < 103 M.W. particle fraction were also discussed.

Heavy metal enrichment in the surface microlayer of the Nepean-Hawkesbury river system

Copper, lead, cadmium and zinc have been measured in subsurface and surface-film water samples collected from the Nepean-Hawkesbury river system in New South Wales. Positive correlations were obtained between measured surface-film pressures and the surface excesses of lead, zinc and dissolved organic carbon. Measurements of copper-complexing capacity of the surface samples correlated well with dissolved organic nitrogen data. Enriched zinc was present in the surface film, mainly in bound species, as determined by anodic stripping voltammetry; lead was enriched in both labile and bound forms. Copper was also present in bound species, with many samples being depleted in labile copper. The relative concentrations of these heavy metals in surface films at the different sampling stations could be interpreted on the basis of known inputs.

Copper complexation capacity of marine water samples from southern California

Copper complexation capacity of marine water samples from southern California

A biological measurement of the copper complexation capacity of seawater1

Copper titrations of known concentrations of chelators in artificial seawater illustrated that the growth depression of Thalassiosira pseudonana in response to copper could be used to quantitate the chelator levels to within ± 5% at concentrations down to 10−7 M EDTA. These results suggest that measured variations in T. pseudonana—copper bioassays to samples from Narragansett Bay and vicinity could be due to organic chelators in seawater.