Geochemical partitioning and bioavailability of copper to aquatic plants in an artificial oxide-organic sediment

Abstract

This study investigated the effects of competition between binding substrates (organic matter and iron oxide) and between metals (cadmium and copper), on the partitioning of sedimentary copper and its subsequent bioavailability to an aquatic plant. Organic matter and a synthesized iron oxide, ferrihydrite, were added singly and in combination to a series of sand sediments, which were then dosed with environmentally realistic concentrations of cadmium and copper and planted with rice, O0'za sativa.Organic matter controlled copper partitioning and bioavailability, whereas the synthetic ferrihydrite bound negligible amounts of either metal, even in the absence of organic matter. As organic matter concentrations increased, operationally-defined leachable copper decreased, organic-associated copper increased and the survival of rice plants improved in an approximately linear fashion. At a nominal starting copper concentration of 5.8 F~g g dry wt -I , plant survival after four weeks averaged 0-8% in sediments without organic matter, 25% in a sediment containing 0.18% organic matter and 58% in a sediment containing 0.36% organic matter. These results suggest that organic-associated forms of copper are unavailable to plants, and that the operational definition of 'leachable' copper (extracted with dilute ammonium acetate) adequately represents the species of copper that is (are) available to plants. Our study using a well-characterized artificial sediment supports the copper fractionation patterns and correlations between copper partitioning and bioavailability reported from the heterogeneous, poorly characterized sediments of natural lake and river sediments.

Physiological Effects of Copper Oxide Nanoparticles and Arsenic on the Growth and Life Cycle of Rice (Oryza sativa japonica ‘Koshihikari’)

“…The increase in shoot biomass that we observed at high nCuO concentrations (50 and 100 mg/L) was possibly due to the adequate uptake of Cu in the shoot (17.3 and 18.3 mg/kg), which was within the range of 15–26 mg/kg found by other research groups . For example, organic matter decreases the Cu bioavailability, while polyfunctional acids in plant exudates increase Cu bioavailability. , According to our previous 72 h aggregation and dissolution experiment, decreased seedling biomass caused by 0.1 mg/L nCuO, was probably because nCuO equilibrated at a smaller size after the aggregation dominated phase (48 h), and these smaller nCuO particles more readily interacted with plants.…”

“…In contrast, at low nCuO concentration (0.1–1.0 mg/L), dissolution dominated the nCuO behavior in solutions in the first week, and nCuO aggregation was more prominent and decreased Cu concentration in solutions by the end of week 3. nCuO dissolution is influenced by interaction with ligands (e.g., EDTA) in the growth media. However, high organic matter content in the grow media may have facilitated nCuO sorption and decreased nCuO dissolution and Cu bioavailability. , Moreover, research by other groups showed that high ionic strength influenced size distribution and dissolution of nCuO by regulating surface charge of NPs . Particularly, the presence of phosphate may enhance nCuO sedimentation, which would reduce nCuO concentration in solutions .…”

“…However, high organic matter content in the grow media may have facilitated nCuO sorption and decreased nCuO dissolution and Cu bioavailability. 39,40 Moreover, research by other groups showed that high ionic strength influenced size distribution and dissolution of nCuO by regulating surface charge of NPs. 39 Particularly, the presence of phosphate may enhance nCuO sedimentation, which would reduce nCuO concentration in solutions.…”

Review on cadmium removal from aqueous solutions

“…Some of the early work relating to the adsorption of cations and anions on ferrihydrite is summarized by Schwertmann and Taylor (1977) and Dzombak and Morel (1990). Uptake of Cd and Cu by sand sediments to which organic matter and ferrihydrite were added was investigated at pH 6.5 by Warren et al (1995). Mamata et al (2010a) have studied the cation adsorption behaviour on 6-line ferrihydrite for Pb(II), Cd(II) and Cu(II).…”

Role of organic matter in copper mobility in a polymictic lake following copper sulfate treatment (Courtille Lake, France)

“…Numerous studies have established the importance of trace element speciation on metal uptake by organisms and toxicity [6 and references herein]. In aerobic sediments, sediment metal concentration normalised by POC and (or) FeOOH has been shown to be predictive of biological effects [7,8].…”