The Fate of Copper Added to Surface Water: Field, Laboratory, and Modeling Studies

Abstract

The fate and effects of copper in the environment are governed by a complex set of environmental processes that include binding to inorganic and organic ligands in water, soil, and sediments. In natural waters, these interactions can limit copper bioavailability and result in copper transport from the water column to the sediment. In the present study, data on the fate of copper added to lakes, microcosms, and mesocosms were compiled and analyzed to determine copper removal rates from the water column. Studies on copper behavior in sediment were also reviewed to assess the potential for remobilization. A previously developed, screening‐level fate and transport model (tableau input coupled kinetic equilibrium transport–unit world model [TICKET–UWM]) was parameterized and applied to quantify copper removal rates and remobilization in a standardized lake setting. Field and modeling results were reconciled within a framework that links copper removal rates to lake depths and solids fluxes. The results of these analyses provide converging evidence that, on a large scale, copper is removed relatively quickly from natural waters. For the majority of studies examined, more than 70% of the added copper was removed from the water column within 16 d of dosing. This information may be useful in the context of environmental hazard and risk assessment of copper. Environ Toxicol Chem 2019;38:1386‒1399. © 2019 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals, Inc. on behalf of SETAC.

Weight‐of‐Evidence Approach for Assessing Removal of Metals from the Water Column for Chronic Environmental Hazard Classification

“…Studies on Cu are particularly plentiful given the use of Cu sulfate as an algaecide in ponds, lakes, and reservoirs. In a recent review by Rader et al (), which included many of the references just cited, the time required for 70% removal of Cu varied from 0.84 to 27 d, with one exception of 130 d. For the majority of studies, >70% of the added Cu was removed from the water column within 16 d of dosing. For other metals, the referenced literature supports substantial metal removal on timescales of days to weeks.…”

“…Studies on Cu are particularly plentiful given the use of Cu sulfate as an algaecide in ponds, lakes, and reservoirs. In a recent review by Rader et al (2019), which included many of the references just cited, the time required for Assessing removal of metals from the water column-Environmental Toxicology and Chemistry, 2019;38:1839-1849 literature supports substantial metal removal on timescales of days to weeks. For example, the mesocosm study of Diamond et al (1990b), which assessed the behavior of several metals in the same mesocosms, observed the following half-times (i.e., time at which concentration has decreased by 50%, average of the 2 mesocosms, in days): Co (4.35), Fe (10.8), Zn (17.6), As (19.2), Sn (9.45), Cs (22.65), and Hg (14.45).…”

Statement of the PPR Panel on a framework for conducting the environmental exposure and risk assessment for transition metals when used as active substances in plant protection products (PPP)

“…However, other studies report that although possible the release of metals from sediment is rather limited. Oxidation of anoxic sediments or resuspension events do not lead to the remobilisation of metals and rather indicate an irreversible transfer of metals from water to the sediment (Rader et al., 2019). However, resuspended metals strongly bound to particulate matter may be taken up by filter feeders and remobilised in the gastrointestinal tract (Weltens et al., 2000).…”

Rapid Loss of Copper from the Water Column

“…Diamond et al (1990) measured half‐times for metal radioisotope loss from the water column in lake enclosures. Rader et al (2019) evaluated loss of copper from the water column in laboratory and field experiments and in a unit world model. They concluded, for the majority of studies examined, that >70% of the added copper was removed from the water column within 16 d, hence meeting the criterion of 70% removal in 28 d. It has been shown that metal loss from the water column is principally by sorption to particles and settling.…”