Role of interfacial electron transfer reactions on sulfamethoxazole degradation by reduced nontronite activating H2O2

It has been documented that organic contaminants can be degraded by hydroxyl radicals ( • OH) produced by the activation of H₂ O₂ by Fe(II)-bearing clay. However, the interfacial electron transfer reactions between structural Fe(II) and H 2 O 2 for • OH generation and its effects on contaminant remediation are unclear. In this study, we first investigated the relation between • OH generation sites and sulfamethoxazole (SMX) degradation by activating H₂O₂ using nontronite with different reduction extents. SMX (5.2–16.9 μmol/L) degradation first increased and then decreased with an increase in the reduction extent of nontronite from 22% to 62%, while the • OH production increased continually. Passivization treatment of edge sites and structural variation results revealed that interfacial electron transfer reactions between Fe(II) and H 2 O 2 occur at both the edge and basal plane. The enhancement on basal plane interfacial electron transfer reactions in a high reduction extent rNAu-2 leads to the enhancement on utilization efficiencies of structural Fe(II) and H 2 O 2 for • OH generation.However, the • OH produced at the basal planes is less efficient in oxidizing SMX than that of at edge sites. Oxidation of SMX could be sustainable in the H 2 O 2 /rNAu-2 system through chemically reduction. The results of this study show the importance role of • OH generation sites on antibiotic degradation and provide guidance and potential strategies for antibiotic degradation by Fe(II)-bearing clay minerals in H 2 O 2 -based treatments.     

京津冀化工场地地下水污染修复治理对策研究

京津冀化工场地地下水污染问题突出,严重威胁当地饮水安全和可持续发展,亟待开展修复治理.针对京津冀化工场地地下水污染现状,分析了化工场地地下水污染修复面临的挑战,提出了分区分级的修复治理对策.结果表明:①针对可能存在NAPL(非水相液体污染物)的高风险污染源区,采取高强度修复措施,以实现污染物总量的快速削减;②针对中度污染区,采取单位能耗强度更低的长效修复措施,降低修复成本和二次污染风险;③针对低风险的轻度污染区,采取风险管控措施.结合对典型化工场地地下水污染修复技术的分析,提出的分区分级修复治理对策具有以下特点:①多技术耦合,形成互补效应,可提高修复效率;②节约修复成本,降低二次环境影响;③体现基于风险的原则,避免过度修复.      

活性炭强化热活化过硫酸盐降解对硝基苯酚

热活化过硫酸盐（PS）可降解有机污染物,但通常需要较高的反应温度,成为制约降解效率的关键因素之一.为提高热活化PS效率,向反应体系中加入活性炭（AC）并以对硝基苯酚（PNP）为目标污染物,考察AC强化热活化PS降解PNP的效率,分析pH值、PS浓度和AC投加量等因素对PNP降解的影响,确定最佳反应条件.结果表明,AC可以明显强化热活化PS降解PNP,在AC=1.0g/L,PS=2.0mmol/L,PNP=10.0mg/L,T=50℃和pH=3.5条件下,120min时AC/PS体系对PNP降解率可达100.00%,而PS体系对PNP降解率仅为31.69%.自由基猝灭实验表明,AC/PS/PNP体系为自由基反应,SO₄·^-和·OH共同参与PNP降解且以SO₄·^-为主导.机制分析阐明AC上的表面缺陷为活性位点,其与PS中O—O键作用导致O—O键键能降低,进而O—O在热活化下均裂形成SO₄·^-.PNP降解中间产物分析表明AC仅提高了热活化PS降解PNP反应速率,未改变PNP的降解路径.     

除臭剂对填埋场作业面臭气去除效果的试验研究

在等体积的试验桶中放置相同量的生活垃圾,通过喷洒等量的、不同类型的植物型和生物型除臭剂来进行除臭,采用化验分析及人的嗅觉形式来确定试验效果。试验结果显示,微生物型除臭剂对臭气去除的效果优于植物型除臭剂。在喷洒量为100 m L、质量分数为1.0%的情况下,S-1对H_2S、NH_3、臭气的去除率分别为87.4%,41.4%,99.5%;恶臭强度可维持在2~4 h。在3 000 m~2的填埋场作业面喷洒S-1,取得了良好的效果。     

Restoration planning to guide Aichi targets in a megadiverse country

Ecological restoration has become an important strategy to conserve biodiversity and ecosystems services. To restore 15% of degraded ecosystems as stipulated by the Convention on Biological Diversity Aichi target 15, we developed a prioritization framework to identify potential priority sites for restoration in Mexico, a megadiverse country. We used the most current biological and environmental data on Mexico to assess areas of biological importance and restoration feasibility at national scale and engaged stakeholders and experts throughout the process. We integrated 8 criteria into 2 components (i.e., biological importance and restoration feasibility) in a spatial multicriteria analysis and generated 11 scenarios to test the effect of assigning different component weights. The priority restoration sites were distributed across all terrestrial ecosystems of Mexico; 64.1% were in degraded natural vegetation and 6% were in protected areas. Our results provide a spatial guide to where restoration could enhance the persistence of species of conservation concern and vulnerable ecosystems while maximizing the likelihood of restoration success. Such spatial prioritization is a first step in informing policy makers and restoration planners where to focus local and large‐scale restoration efforts, which should additionally incorporate social and monetary cost–benefit considerations.     

基于BP神经网络的垃圾堆放场稳定化程度的综合判别

分析和判别垃圾堆放场的稳定化程度直接关系到是否需要采取加快稳定化进程，缩短垃圾堆放场的稳定化周期以及是否需要采取措施减少它们对环境的不利影响。本文根据我国垃圾堆放场的具体情况，提出稳定化程度的判别评价指标体系，并且确定稳定化程度的判别标准，运用BP神经网络建立垃圾堆放场稳定化程度的综合判别模型。以三峡库区的一个小型垃圾堆放场为例，采用本文所提出的综合评价模型确定它的稳定化程度，演示模型的运行过程，并为三峡库区的环境保护提供帮助。     

Possible Routes for Lead Accumulation in Feral Pigeons (Columba Livia)

This study examined possible routes for lead (Pb) accumulation in resident pigeons collected from rural, urban, and four industrial sites in Korea. The accumulation pattern of Pb was comparable to the study sites. The highest Pb concentration was found in the bone, followed by kidney, liver, and lung of pigeons. Highest Pb residues in bones were found in urban (Seoul), and two industrial complex areas (Busan and Ulsan), which were about 15 times higher than rural area (Duckjuk island), and followed by Ansan and Yochon industrial areas. Regional Pb variations in liver, kidney, and lung tissues were also similar pattern with the bone Pb difference. These findings indicate that Pb accumulation in tissues of pigeons may be affected by the Pb exposure in their respective habitats. Crop contents and gizzard materials were investigated as representing the ingested items. No difference of Pb concentration was observed in major foods (maize and/or wheat) of crop contents in the study sites except Busan, whereas variations of Pb levels in gizzard materials were indicative of a similar pattern with tissue Pb differences. The Pb concentration in tissues of pigeons did not correspond well to the atmospheric Pb levels. With regard to possible Pb sources, ingested items especially materials present in the gizzard are important sources for Pb contamination to pigeons because Pb-containing sources may be expected to present in roadside particles, dusts, paint chips and building flakes. However, air Pb value being low may not affect significant as the regional variations in tissues of pigeons.     

城市垃圾填埋场生态恢复工程表面覆盖材料的研究

以青岛市湖岛垃圾填埋场作为试验点,对城市垃圾填埋场生态恢复工程的表面覆盖处理技术中的材料选择进行了研究。对城市垃圾场生态恢复工程表面处理中覆盖材料的选择指标主要取决于其投入费用和生态恢复的产出效益,同时因恢复工程的设计方案和填埋地点而异。对以降低投入为优选因子或以获得植物产出效益为主要目的的设计方案,分别推荐已分解的垃圾土和砂土为覆盖材料。