Pore-water chemistry explains zinc phytotoxicity in soil.
Zinc (Zn) is a widespread soil contaminant arising from a numerous anthropogenic sources. However, adequately predicting toxicity of Zn to ecological receptors remains difficult due to the complexity of soil characteristics. In this study, we examined solid-solution partitioning using pore-water data and toxicity of Zn to cucumber (Cucumis sativus L.) in spiked soils. Pore-water effective concentration (ECx, x=10%, 20% and 50% reduction) values were negatively related to pH, indicating lower Zn pore water concentration were needed to cause phytotoxicity at high pH soils. Total dissolved zinc (Znpw) and free zinc (Zn(2+)) in soil-pore water successfully described 78% and 80.3% of the variation in relative growth (%) in the full dataset. When the complete data set was used (10 soils), the estimated EC50pw was 450 and 79.2 µM for Znpw and Zn(2+), respectively. Total added Zn, soil pore water pH (pHpw) and dissolve organic carbon (DOC) were the best predictors of Znpw and Zn(2+) in pore-water. The EC10 (total loading) values ranged from 179 to 5214 mg/kg, depending on soil type. Only pH measurements in soil were related to ECx total Zn data. The strongest relationship to ECx overall was pHca, although pHw and pHpw were in general related to Zn ECx. Similarly, when a solution-only model was used to predict Zn in shoot, DOC was negatively related to Zn in shoot, indicating a reduction in uptake/ translocation of Zn from solution with increasing DOC.
Centre for Environmental Risk Assessment and Remediation, University of South Australia, Building X, Mawson Lakes, SA 5095, Australia; Cooperative Research Centre for Contamination Assessment and Remediation of the Environment (CRC CARE), University of South Australia, Building X, Mawson Lakes, SA 5095, Australia; Global Centre for Environmental Remediation (GCER), Faculty of Science and Information Technology, The University of Newcaslte, Callaghan, NSW, 2308, Australia, Callaghan.
Mohammed
M
Kader
Centre for Environmental Risk Assessment and Remediation, University of South Australia, Building X, Mawson Lakes, SA 5095, Australia; Cooperative Research Centre for Contamination Assessment and Remediation of the Environment (CRC CARE), University of South Australia, Building X, Mawson Lakes, SA 5095, Australia; Global Centre for Environmental Remediation (GCER), Faculty of Science and Information Technology, The University of Newcaslte, Callaghan, NSW, 2308, Australia, Callaghan. Electronic address: dane.lamb@newcastle.edu.au.
Dane T
DT
Lamb
Centre for Environmental Risk Assessment and Remediation, University of South Australia, Building X, Mawson Lakes, SA 5095, Australia.
Ray
R
Correll
Centre for Environmental Risk Assessment and Remediation, University of South Australia, Building X, Mawson Lakes, SA 5095, Australia; Cooperative Research Centre for Contamination Assessment and Remediation of the Environment (CRC CARE), University of South Australia, Building X, Mawson Lakes, SA 5095, Australia; Global Centre for Environmental Remediation (GCER), Faculty of Science and Information Technology, The University of Newcaslte, Callaghan, NSW, 2308, Australia, Callaghan.
Mallavarapu
M
Megharaj
Centre for Environmental Risk Assessment and Remediation, University of South Australia, Building X, Mawson Lakes, SA 5095, Australia; Cooperative Research Centre for Contamination Assessment and Remediation of the Environment (CRC CARE), University of South Australia, Building X, Mawson Lakes, SA 5095, Australia; Global Centre for Environmental Remediation (GCER), Faculty of Science and Information Technology, The University of Newcaslte, Callaghan, NSW, 2308, Australia, Callaghan.
Ravi
R
Naidu
D018553:Cucumis sativus / Q000187:drug effects* / Q000254:growth & development; D008962:Models, Theoretical; D012987:Soil / Q000737:chemistry*; D012989:Soil Pollutants / Q000032:analysis / Q000633:toxicity*; D014867:Water / Q000737:chemistry*; D015032:Zinc / Q000032:analysis / Q000633:toxicity*
D012987:Soil; D012989:Soil Pollutants; D014867:Water; D015032:Zinc
Dissolved organic carbon; Plants; Soil solution; Soil toxicology