Since it is unrealistic to do an experimental mixture assessment on every possible combination, mathematical model plays an important role in predicting the mixture toxicity. The present study is devoted to the furthe...Since it is unrealistic to do an experimental mixture assessment on every possible combination, mathematical model plays an important role in predicting the mixture toxicity. The present study is devoted to the further application of linear concentration addition（CA）-based model（LCA） and independent action（IA）-based model（LIA） to predict the non-interactive mixture toxicity. The 26 mixtures including 312 data points were used to evaluate the predictive powers of LCA and LIA models. The models were internally validated using the leave-one-out cross-validation and y-randomization test, and the external validations were evaluated by the test tests. Both LCA and LIA models agree well with the experimental values for all mixture toxicity, and present high internally（R2 and Q2 〉 0.98） and externally（Q2F1, Q2F2, and Q2F3 〉 0.99） predictive power. The use of LCA and LIA led to improved predictions compared to the estimates based on the CA and IA models. Both LCA and LIA were found to be appropriate methods for modeling toxicity of non-interactive chemical mixtures.展开更多
Discharge of metals and their mineral flotation collectors into the soil environment causes severe ecological and health impacts, which is still not fully understood. This is of great concern, particularly with regard...Discharge of metals and their mineral flotation collectors into the soil environment causes severe ecological and health impacts, which is still not fully understood. This is of great concern, particularly with regards to their effect on the soil microorganisms whose functions determine not only the soil quality and function but also influence the air and water quality. This study aimed to analyze and compare, microcalorimetrically, the single chemical toxic effect with the combined effect of copper (Cu) and two of its main flotation collectors, potassium amyl xanthate (PAX) and sodium isoamyl xanthate (SIAX), on soil microbial community. All chemicals, individually and as a binary mixture of copper and each of its flotation collectors, exhibited a significant dose-effect relationship, and the highest and lowest microbial activity inhibition being associated with SIAX and Cu, respectively (e.g. IC 50 of 447.5, 158.3 and 83.9 μg·g?1 soil for copper, PAX and SIAX, respectively). For all cases, the microbial activity was more affected by the mixture than by the individual mixture components. Increasing the xanthates dose (from 25 to 100 μg·g?1 soil) in the mixture with a copper dose of 200 μg·g?1 soil led to the increase of the microbial activity inhibition rate, from 23.08 % to 53.85% in case of PAX and from 26.92% to 57.69% in case of SIAX). Similarly, the toxicity level of the mixture of equitoxic components doses increased with the increased mixture doses. Since the observed activity level can be attributed to the surviving microbes, capable of adapting to both chemical and their mixture, a genetically based analysis should be conducted to allow identifying and characterizing the potentially resistant strains that can be useful for the remediation of the pollution by copper and xanthates and for the sustainability of copper mining and flotation, and for all soil, water, and air quality and function interest.展开更多
基金supported by the National Natural Science Foundation of China(21407032,21667013,51578171)Natural Science Foundation of Guangxi Province(2014GXNSFBA118233)Guilin Scientific Research and Technology Development Program(2016012505)
文摘Since it is unrealistic to do an experimental mixture assessment on every possible combination, mathematical model plays an important role in predicting the mixture toxicity. The present study is devoted to the further application of linear concentration addition（CA）-based model（LCA） and independent action（IA）-based model（LIA） to predict the non-interactive mixture toxicity. The 26 mixtures including 312 data points were used to evaluate the predictive powers of LCA and LIA models. The models were internally validated using the leave-one-out cross-validation and y-randomization test, and the external validations were evaluated by the test tests. Both LCA and LIA models agree well with the experimental values for all mixture toxicity, and present high internally（R2 and Q2 〉 0.98） and externally（Q2F1, Q2F2, and Q2F3 〉 0.99） predictive power. The use of LCA and LIA led to improved predictions compared to the estimates based on the CA and IA models. Both LCA and LIA were found to be appropriate methods for modeling toxicity of non-interactive chemical mixtures.
文摘Discharge of metals and their mineral flotation collectors into the soil environment causes severe ecological and health impacts, which is still not fully understood. This is of great concern, particularly with regards to their effect on the soil microorganisms whose functions determine not only the soil quality and function but also influence the air and water quality. This study aimed to analyze and compare, microcalorimetrically, the single chemical toxic effect with the combined effect of copper (Cu) and two of its main flotation collectors, potassium amyl xanthate (PAX) and sodium isoamyl xanthate (SIAX), on soil microbial community. All chemicals, individually and as a binary mixture of copper and each of its flotation collectors, exhibited a significant dose-effect relationship, and the highest and lowest microbial activity inhibition being associated with SIAX and Cu, respectively (e.g. IC 50 of 447.5, 158.3 and 83.9 μg·g?1 soil for copper, PAX and SIAX, respectively). For all cases, the microbial activity was more affected by the mixture than by the individual mixture components. Increasing the xanthates dose (from 25 to 100 μg·g?1 soil) in the mixture with a copper dose of 200 μg·g?1 soil led to the increase of the microbial activity inhibition rate, from 23.08 % to 53.85% in case of PAX and from 26.92% to 57.69% in case of SIAX). Similarly, the toxicity level of the mixture of equitoxic components doses increased with the increased mixture doses. Since the observed activity level can be attributed to the surviving microbes, capable of adapting to both chemical and their mixture, a genetically based analysis should be conducted to allow identifying and characterizing the potentially resistant strains that can be useful for the remediation of the pollution by copper and xanthates and for the sustainability of copper mining and flotation, and for all soil, water, and air quality and function interest.
