Terrestrial Biotic Ligand Model. 2. Application to Ni and Cu Toxicities to Plants, Invertebrates, and Microbes in Soil

Ghent University, Gand, Flemish, Belgium
Environmental Science and Technology (Impact Factor: 5.33). 12/2006; 40(22):7094-100. DOI: 10.1021/es061173c
Source: PubMed


The Terrestrial Biotic Ligand Model (TBLM) is applied to a number of noncalcareous soils of the European Union for Cu and Ni toxicities using organisms and endpoints representing three levels of terrestrial organisms: higher plants, invertebrates, and microbes. A comparison of the TBLM predictions to soil metal concentration or free metal ion activity in the soil solution shows that the TBLM is able to achieve a better normalization of the wide variation in toxicological endpoints among soils of disparate properties considered in this study. The TBLM predictions of the EC50s were generally within a factor of 2 of the observed values. To our knowledge, this is the first study that incorporates Cu and Ni toxicities to multiple endpoints associated with higher plants, invertebrates, and microbes for up to eleven noncalcareous soils of disparate properties, into a single theoretical framework. The results of this study clearly demonstrate that the TBLM can provide a general framework for modeling metals ecotoxicity in soils.

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Available from: Colin Janssen, Dec 18, 2014
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    • "} between different treatments were observed , suggesting the limitation of using free ion activity for predicting Ni toxicity and emphasizing the importance of tak - ing into account toxicity - modifying factors ( i . e . , coexisting cations ) in estimating Ni toxicity ( De Schamphelaere and Janssen , 2002 ; Thakali et al . , 2006 ) . In the present study , LC50{Ni 2+ } significantly increased with increasing activities of Ca 2+ , Mg 2+ and Na + in test solutions , with the order of importance : Ca 2+ > Mg 2+ > Na + . A pro - tective effect of Ca 2+ and Mg 2+ was also reported for Ni toxicity to Hordeum vulgare and Daphnia pulex ( Li et al . , 2009 ; Kozlova et a"
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    ABSTRACT: Biotic ligand models (BLMs) predicting metal toxicity for a fixed exposure time are available, but it is uncertain how to extrapolate predictions to a dynamic environment with time-variable exposure. Three BLM-based models were developed to describe change of Ni toxicity to Enchytraeus crypticus in time. These models assumed that: (a) biotic ligand binding constants of Ni and competing cations (KNiBL and KCBL) and the fraction of biotic ligands occupied by Ni to produce 50% mortality (f50) are fixed with time, (b) KNiBL and KCBL remain constant while f50 varies with time, and (c) KNiBL, KCBL, and f50 are all time-dependent. Model (a) successfully described the 7-d toxicity of Ni but failed in explaining Ni toxicity at longer exposure times. Both models (b) and (c) well described Ni toxicity, within a factor of 2, at varying solution chemistries and different exposure times. This shows that the acute BLM cannot directly be applied for predicting chronic metal toxicity and that some BLM parameters may vary with time. Our findings provide plausible explanations for differences in mechanisms of acute and chronic toxicity, offering a framework for incorporating toxicokinetic and toxicodynamic processes in describing Ni toxicity in time. Copyright © 2014 Elsevier Ltd. All rights reserved.
    Full-text · Article · Jan 2015 · Chemosphere
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    • ", with the free metal ions and the complexation of the free metal ions with organic and inorganic ligands (e.g., dissolved organic matter, DOC), biotic ligand models (BLMs) have been developed to predict the binding of metals to contact surfaces of organisms and consequently, their toxicity (Di Toro et al., 2001; Thakali et al., 2006). Since metal availability is influenced by environmental factors such as soil properties and other ligands present in the soil solution, internal concentration would be the best measure of metal bioavailability. "
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    ABSTRACT: Uptake and elimination kinetics of metals in soil invertebrates are a function of both soil and organism properties. This study critically reviewed metal toxicokinetics in soil invertebrates and its potential use for assessing bioavailability. Uptake and elimination rate constants of different metals are summarized. Invertebrates have different strategies for essential and non-essential metals. As a consequence, different types of models must be applied to describe metal uptake and elimination kinetics. We discuss model parameters for each metal separately and show how they are influenced by exposure concentrations and by physiological properties of the organisms. Soil pH, cation exchange capacity, clay and organic matter content significantly affect uptake rates of non-essential metals in soil invertebrates. For essential metals, kinetics is hardly influenced by soil properties, but rather prone to physiological regulation mechanisms of the organisms. Our analysis illustrates that toxicokinetics can be a valuable measurement to assess bioavailability of soil-bound metals.
    Full-text · Article · Jul 2014 · Environmental Pollution
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    • "In order to predict these risks it is necessary to understand the solid-solution partitioning of As at varying soil conditions. Solid-solution partitioning and solution speciation of trace elements are the key factors influencing the accumulation, mobility and bioavailability of these elements in soil profiles (Belooti, 1998; Sauv e et al., 2003; Luo et al., 2006; Thakali et al., 2006; Groenenberg et al., 2010). A soil solution is a chemically reacting system (Smal and Misztal, 1996), it is in intimate contact with the soil solid phase (Weng et al., 2001) and the aqueous phase processes (McBride, 1994). "
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    ABSTRACT: To predict the long-term behavior of arsenic (As) in soil profiles, the solid-solution partitioning of As was studied in four paddy soil profiles obtained from agricultural areas in Chengdu Plain, Southwest China. Paddy soil profile samples were collected and soil solution samples were extracted. Total As contents in soil solution and soil solid were analyzed, along with the soil solid phase properties. The As in soil solution was significantly higher in the upper layer (0–20 cm) and had a definite tendency to decrease towards 40 cm regardless of the sampling locations. When the concentration of arsenic in soil solution decreased, its content in solid phase increased. Field-based partition coefficient (Kd) for As was determined by calculating the ratio of the amount of As in the soil solid phase to the As concentration in the soil solution. Kd values varied widely in vertical samples and correlated well with soil pH, total organic carbon (TOC) and total As. The results of this study would be useful for evaluating the accumulation trends of arsenic in soil profiles and in improving the management of the agricultural soils.
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