Copper Release, Speciation, and Toxicity Following Multiple Floodings of Copper Enriched Agriculture Soils: Implications in Everglades Restoration

Abstract

This study characterizes the effects of water-soil flooding volume ratio and flooding time on copper (Cu) desorption and toxicity following multiple floodings of field-collected soils from agricultural sites acquired under the Comprehensive Everglades Restoration Plan (CERP) in south Florida. Soils from four field sites were flooded with three water-soil ratios (2, 4, and 6 [water] to 1 [soil]) and held for 14 days to characterize the effects of volume ratio and flooding duration on Cu desorption (volume ratio and flooding duration study). Desorption of Cu was also characterized by flooding soils four times from seven field sites with a volume ratio of 2 (water) to 1 (soil) (multiple flooding study). Acute toxicity tests were also conducted using overlying waters from the first flooding event to characterize the effects of Cu on the survival of fathead minnows (Pimephales promelas), cladocerans (Daphnia magna), amphipods (Hyalella azteca), midges (Chironomus tentans), duckweed (Lemna minor), and Florida apple snails (Pomacea paludosa). Acute tests were also conducted with D. magna exposed to overlying water from the second and third flooding events. Results indicate that dissolved Cu concentrations in overlying water increased with flooding duration and decreased with volume ratio. In the multiple flooding study, initial Cu concentrations in soils ranged from 5 to 223 mg/kg (dw) and were similar to Cu concentration after four flooding events, indicating retention of Cu in soils. Copper desorption was dependent on soil Cu content and soil characteristics. Total Cu concentration in overlying water (Cu w ) was a function of dissolved organic carbon (DOC), alkalinity, and soil Cu concentration (Cu s ): log(Cu w )= 1.2909 +0.0279 (DOC)+ 0.0026 (Cu s )−0.0038 (alkalinity). The model was validated and highly predictive. Most of the desorbed Cu in the water column complexed with organic matter in the soils and accounted for 99% of the total dissolved Cu. Although total dissolved Cu concentrations in overlying water did not significantly decrease with number of flooding events, concentrations of free Cu 2+ increased with the number of Water Air Soil Pollut (flooding events, due to a decrease in DOC concentrations. The fraction of bioavailable Cu species (Cu 2+ , CuOH + , CuCO 3 ) was also less than 1% of the total Cu. Overlying water from the first flooding event was only acutely toxic to the Florida apple snail from one site. However, overlying water from the third flooding of six out of seven soils was acutely toxic to D. magna. The decrease in DOC concentrations and increase in bioavailable Cu 2+ species may explain the changes in acute toxicity to D. magna. Results of this study reveal potential for high Cu bioavailability (Cu 2+ ) and toxicity to aquatic biota overtime in inundated agricultural lands acquired under the CERP.

Combined effects of nanoplastics and copper on the freshwater alga Raphidocelis subcapitata

“…Copper (Cu) is an essential micronutrient for both plants and animals at low concentrations but can become toxic when present in higher quantities. Cu concentrations can exceed natural levels (> 100 µg/L) in the aquatic environment as a consequence of anthropogenic activities (Hoang et al 2009, Ma et al 2003, Schuler et al 2008.…”

“…The aim of the present study was to assess whether the presence of PS-COOH NPs, and its interaction with EPS, might affect Cu toxicity to the freshwater microalga Raphidocelis subcapitata. We selected Cu concentrations that are relevant for contaminated freshwater environments (Hoang et al 2009, Ma et al 2003, Schuler et al 2008.…”

Copper Dynamics in a Typic Hapludalf Under Rice-Wheat Cropping System After Twelve Years of AnnualLantana CamaraL. Residue Incorporation

“…Organic amendments that are being looked to be integrated with chemical fertilizers are known to improve soil productivity under rice-wheat cropping (Timsina and Connor, 2001) apparently due to in general soil health improvement, including addition of micronutrients and redistribution of their fractions. The continuous cycle of reduced and oxidized soil conditions and organic amendments have a bearing on the transformation of micronutrients in soil (Han and Banin, 2000;Hoang et. al., 2009;Rupa et al, 2001;Saha and Mandal, 2000).…”

Silicon Differentially Influences Copper Toxicity Response in Silicon-accumulator and Non-accumulator Species

“…Worldwide, some soils are high in Cu leading to the natural occurrence of Cu toxicity (Alonso et al, 2000;Cook et al, 1997). Most reported Cu toxicity is the result of anthropogenic sources including pesticide use (Hoang et al, 2009) and use of young compost or pig manure (Alonso et al, 2000;Brady and Weil, 2001). In protected agriculture, growers have used electrolytically generated Cu (Zheng et al, 2004) for disinfecting irrigation water; it is not clear if U.S. Department of Agriculture (USDA) statistics account for this source of Cu, so the extent of electrolytically generated Cu use is not known.…”