Environmental Science and Pollution Research - Mercury pollution has become one of the most concerned environmental issues in the world because of its high toxicity, non-degradability, and... 相似文献
Electrokinetic (EK) remediation technology can enhance the migration of reagents to soil and is especially suitable for in situ remediation of low permeability contaminated soil. Due to the long aging time and strong hydrophobicity of polycyclic aromatic hydrocarbons (PAHs) from historically polluted soil, some enhanced reagents (oxidant, activator, and surfactant) were used to increase the mobility of PAHs, and remove and degrade PAHs in soil. However, under the electrical field, there are few reports on the roles and combined effect of oxidant, activator, and surfactant for remediation of PAHs historically contaminated soil. In the present study, sodium persulfate (PS, oxidant, 100 g L?1) or/and Tween 80 (TW80, surfactant, 50 g L?1) were added to the anolyte, and citric acid chelated iron(II) (CA-Fe(II), activator, 0.10 mol L?1) was added to catholyte to explore the roles and contribution of enhanced reagents and combined effect on PAHs removal in soil. A constant voltage of 20 V was applied and the total experiment duration was 10 days. The results showed that the removal rate of PAHs in each treatment was PS + CA-Fe(II) (21.3%) > PS + TW80 + CA-Fe(II) (19.9%) > PS (17.4%) > PS + TW80 (11.4%) > TW80 (8.1%) > CK (7.5%). The combination of PS and CA-Fe(II) had the highest removal efficiency of PAHs, and CA-Fe(II) in the catholyte could be transported toward anode via electromigration. The addition of TW80 reduced the electroosmotic flow and inhibited the transport of PS from anolyte to the soil, which decreased the removal of PAHs (from 17.4 to 11.4% with PS, from 21.3 to 19.9% with PS+CA-Fe(II)). The calculation of contribution rates showed that PS was the strongest enhancer (3.3~9.9%), followed by CA-Fe(II) (3.9~8.5%) (with PS), and the contribution of TW80 was small and even negative (?1.4~0.6%). The above results indicated that the combined application of oxidant and activator was conducive to the removal of PAHs, while the addition of surfactant reduced the EOF and the migration of oxidant and further reduced the PAHs removal efficiency. The present study will help to further understand the role of enhanced reagents (especially surfactant) during enhanced EK remediation of PAHs historically contaminated soil.
Environmental Science and Pollution Research - Bisphenols are endocrine disruptor chemicals that disrupt thyroid hormone homeostasis. However, evidence on the effects of bisphenol mixtures on... 相似文献
Environment, Development and Sustainability - Global climate change due to greenhouse gas emissions has observable impacts on environment. Among the GHG emissions, carbon dioxide is the primary... 相似文献
The aim of this study was to investigate the detailed metal speciation/fractionations of a Cu contaminated soil before and after electrokinetic remediation as well as their relationships with the soil microbial and enzyme activities. Significant changes in the exchangeable and adsorbed-Cu fractionations occurred after electrokinetic treatment, while labile soil Cu in the solution had a tendency to decrease from the anode to the cathode, and the soil free Cu2+ ions were mainly accumulated in the sections close to the cathode. The results of regression analyses revealed that both the soil Cu speciation in solution phase and the Cu fractionations in solid phase could play important roles in the changes of the soil microbial and enzyme activities. Our findings suggest that the bioavailability of soil heavy metals and their ecotoxicological effects on the soil biota before and after electroremediation can be better understood in terms of their chemical speciation and fractionations. 相似文献
This paper proposes a welfare criterion that balances the need for development and the concern for the least advantaged generations, and explores its implications. This criterion, called the mixed Bentham–Rawls criterion, moderates the effect of discounting, yet permits some degree of intertemporal trade-off. It is a weighted average of two terms: (a) the sum of discounted utilities and (b) the utility level of the least advantaged generation. We derive necessary conditions to characterize growth paths that satisfy our criterion, and show that in some models with familiar dynamic specifications, an optimal path exists and displays appealing characteristics. 相似文献
Abstract The difference between fishermen’s fishing catch and the optimal fishing catch is the basic reason for the transaction of marine fishing rights (TMFR). The effects of productive cost, non-productive cost, use-cost, transaction cost, productive revenue and non-productive revenue on the TMFR and the optimal fishing catch are analyzed. This paper draws following conclusions: the non-productive revenue has a positive effect on the TMFR, and other factors, such as non-productive cost, use-cost and transaction cost, have a negative effect; the TMFR will promote the resource allocation; the high transaction cost may affect the implementation of TMFR. 相似文献
Abstract This paper analyzes the impact of income distribution gap on consumption demand from a theoretical view, and draws the conclusion that there is an inverse relationship between income distribution gap and consumption demand. Then, the paper finds that the existing widening income distribution gap in China has a negative impact on consumption demand, but this is not the key factor for the insufficient consumption demand because of the low level of per capital income. At last, it suggests that governments should improve the income level of entire residents and adjust income distribution structure simultaneously. 相似文献