Time series analysis for determining ecologically acceptable Cu concentration from species sensitivity distribution with biotic ligand models in soil pore water

Abstract

A site-specific, ecologically acceptable concentration of Cu in soil pore water was determined with four trophic levels of soil-residing organisms. Specifically, soil pore water was periodically collected from a site contaminated with heavy metals using in-situ samplers. Dissolved Cu concentration, Ca2+, Mg2+, Na+, K+, Cl-, SO42-, NO3-, dissolved organic carbon, pH, and temperature were analyzed to derive a half-maximal effective concentration of Cu (EC50[Cu]T) using a biotic ligand model (BLM). The BLM parameters, such as binding constants (logKXBL) and the fraction of biotic ligand sites occupied by Cu ions (f), were adapted from previous studies. The EC50{Cu2+,} values were used to construct a species sensitivity distribution (SSD) curve from which the hazardous concentration, protecting 95% of the soil-residing organisms (HC5), was determined. Using ten BLM-based acceptable concentrations of Cu obtained by combining BLM and SSD, time series analysis was conducted with the fixed monitoring benchmark method to obtain maximum Cu concentration as an endpoint exhibiting no-adverse-effect which was found to be 0.084 mg/L of Cu in soil pore water at the test site. This study provides a systematic tool for determining an ecologically acceptable concentration of Cu in the soil by incorporating soil pore water chemistry and time series analysis.

Exploiting Catabolite Repression and Stringent Response to Control Delay and Multimodality of Bioluminescence Signal by Metal Whole-Cell Biosensors: Interplay between Metal Bioavailability and Nutritional Medium Conditions

“…In Equation ( 5), the 'pristine' internalization conductance k int K H is that when there is no limitation in the energy that is required for the active transfer of M across the membrane via dedicated protein transporters, i.e., k int K H is independent of emission mode i. k int K H corresponds to the ratio J * u /K M , where J * u (mol m −2 s −1 ) is the maximum biouptake flux reached at the full saturation of the internalization sites by M, and K M (mol m −3 ) is the characteristic affinity of M for these sites. Pinheiro et al [44] extended Equation (5) for cases where metal complexation by ligands L in solution is significant (see Equation (19) in [44]) and L are in excess over M. For orientational consideration, we hereafter consider the strongest ligand L that feature the highest affinity to M. Then, the result by Pinheiro et al [44] can be rewritten in the form…”

“…In turn, these rate constants, together with the diffusion properties of the various metal forms, determine the lability of the complexed metal species, i.e., their contribution to the dynamic supply of free metals to the biosensor surface [12,15]. Though the Biotic Ligand Model (BLM) [17][18][19][20] and related thermodynamic metal speciation computations (e.g., Visual-MINTEQ program [21]) are commonly adopted to link empirically bioluminescence and the concentration of bioavailable metal ions (a priori assimilated by BLM to the bulk concentration of free, non-complexed metals) [22][23][24][25][26], their failure to predict metal bioaccumulation has long been reported for a variety of organisms under both metal complexing and non-complexing medium conditions ( [17,27] and references in [28]). The limits of BLMs include [17,28] the restrictive and often oversimplified equilibrium-based assessment of the necessarily dynamic processes that control the reactive transfer of metal species to the surface of metal-accumulating cells and the coupling with metal biouptake and bioaccumulation [15].…”

Determination Procedure of Ecotoxicologically Acceptable Cu Concentration in River Considering the Change of Environmental Factors

“…의 활용을 권장하고 있다. 2,12) 동일한 중금속 농도로 노출되더라도 중금속의 독성영향은 다양한 수생생물에 따라 다르며, 13) 다양한 수생생물에 대한 대상 중금속의 독성영향을 고려하여 수생생물 중금속 보호 수준을 산정하기 위해 SSD를 활용할 수 있다. 14) SSD는 다양 한 수생생물에 대한 중금속 독성 예측 값을 사용하여 누적 확률 분포 곡선을 구축하며, 전체 생물종의 95%를 보호할 수 있는 수준의 농도인 5% hazardous concentration (HC5) 및 생 물에게 유해한 영향이 나타나지 않는다고 예측되는 환경 중 농도인 예측 무영향농도(predicted no effect concentration; PNEC)를 산정할 수 있는 방법이다.…”