外源硫诱导下的Desulfovibrio desulfuricans sub sp.EPS特性及对Zn(Ⅱ)的吸附

研究了3种外源硫(Na₂SO₄、Na₂SO₃和Na₂S₂O₃·5H₂O)对Desulfovibrio desulfuricans sub sp.(D.desulfuricans sp.)的胞外聚合物(EPS)的胁迫/诱导作用。结果表明,在还原性硫源0.50g/L Na₂SO₃的条件下,EPS产量最高,为2104.39mg/g VSS,蛋白质含量为1888.52mg/g VSS,较胁迫/诱导前均提高了300%以上;其对Zn(Ⅱ)的吸附性能最好,为954.4mg/g EPS,提高了98.17%。三维荧光(3D-EEM)结果表明,胁迫/诱导后EPS中类酪氨酸均大量增加;傅里叶红外光谱(FTIR)结果表明,胁迫后-OH、C=O、C-O-C等官能团均大量增加,在Zn(Ⅱ)的吸附中发挥了重要作用;X光电子能谱(XPS)结果表明,在还原性硫源(Na₂SO₃和Na₂S₂O₃·5H₂O)胁迫/诱导后,EPS中C-O/C-N、C=N和某种含氧基团(X)大量增加,可能是吸附Zn(Ⅱ)的主要基团。     

Interactions between lead(II) ions and dissolved organic matter derived from organic fertilizers incubated in the field

This work was to study composition characteristics and the subsequent effect on the lead (Pb) binding properties of dissolved organic matter (DOM) derived from seaweed-based (SWOF) and chicken manure organic fertilizers (CMOF) during a one-year field incubation experiment using the excitation-emission matrix-parallel factor (EEM-PARAFAC) and two-dimensional correlation spectroscopy (2DCOS) analysis. Results showed that high aromatic and hydrophobic fluorescent substances were enriched in CMOF-derived DOM and SWOF-derived DOM and enhanced over time. And phenolic groups in the fulvic-like substances for SWOF-derived DOM and carboxyl groups in the humic-like substances for CMOF-derived DOM had the fastest responses over time, respectively. Moreover, both non-fluorescent polysaccharides and fluorescent humic-like substances or fulvic-like substances with aromatic (C=C) groups first participated in the binding process of Pb to SWOF-derived DOM on day 0 and 180 during the lead binding process. In contrast, humic-like substances associated with aromatic (C=C) and phenolic groups gave a faster response to Pb binding on day 360. Regarding CMOF-derived DOM, the fulvic-like substances associated with aromatic (C=C) and carboxylic groups displayed a faster response to Pb ions on day 0. Nonetheless, polysaccharides and humic-like associated with phenolic groups had a faster response on days 180 and 360. It is noteworthy that the polysaccharides, which participated in Pb binding to CMOF-derived DOM, posed a higher risk of Pb in the environment after 360 days. Therefore, these findings gave new insights into the long-term applications of commercial organic fertilizers for the amendment of soil.     

Hydrothermal-treated Pt/Al2O3 as an excellent catalyst for toluene total oxidation

The preparation of highly active supported noble metal catalysts with a low noble metal loading has always been the ultimate goal of researchers working on catalysis. Hydrothermally treated Pt/Al₂O₃ (Pt/Al₂O₃-H) exhibits better catalytic activity than that (Pt/Al₂O₃-C) treated via the conventional calcination approach. At the high space velocity of 100,000 mL/(g∙hr), the temperature that correspond to 50% toluene conversion (T₅₀) of Pt/Al₂O₃-H is 115°C lower than that of Pt/Al₂O₃-C, and the turnover frequency (TOF) value can reach 0.0756 sec⁻¹. The mechanism by which the hydrothermal approach enhances Pt/Al₂O₃ activity has been investigated. The structure associated with the high catalytic activity of Pt nanoparticles (NPs) can be retained via hydrothermal treatment. Furthermore, the support is transformed to AlO(OH) with numerous surface hydroxyl groups, which in turn can facilitate the adsorption of toluene. And the synergistic effects of Pt NPs and AlO(OH) increases the contents of Pt in oxidation state and active oxygen, which are beneficial for toluene oxidation.     

Ozone episodes during and after the 2018 Chinese National Day holidays in Guangzhou: Implications for the control of precursor VOCs

The impact of reducing industrial emissions of volatile organic compounds (VOCs) on ozone (O₃) pollution is of wide concern particularly in highly industrialized megacities. In this study, O₃, nitrogen oxides (NOx) and VOCs were measured at an urban site in the Pearl River Delta region during the 2018 Chinese National Day Holidays and two after-holiday periods (one with ozone pollution and another without). O₃ pollution occurred throughout the 7-day holidays even industrial emissions of VOCs were passively reduced due to temporary factory shutdowns, and the toluene to benzene ratios dropped from ∼10 during non-holidays to ∼5 during the holidays. Box model (AtChem2-MCM) simulations with the input of observation data revealed that O₃ formation was all VOC-limited, and alkenes had the highest relative incremental reactivity (RIR) during the holiday and non-holiday O₃ episodes while aromatics had the highest RIR during the non-pollution period. Box model also demonstrated that even aromatics decreased proportionally to levels with near-zero contributions of industrial aromatic solvents, O₃ concentrations would only decrease by less than 20% during the holiday and non-holiday O₃ episodes and ozone pollution in the periods could not be eliminated. The results imply that controlling emissions of industrial aromatic solvents might be not enough to eliminate O₃ pollution in the region, and more attention should be paid to anthropogenic reactive alkenes. Isoprene and formaldehyde were among the top 3 species by RIRs in all the three pollution and non-pollution periods, suggesting substantial contribution to O₃ formation from biogenic VOCs.     

硫酸盐还原菌对碱性和酸性农田土壤中重金属的钝化效果及其作用机制

通过土壤培养实验考察了硫酸盐还原菌（SRB）包括希瓦氏菌、梭状芽胞杆菌和两者混合菌对碱性和酸性农田土中有效态重金属（Cd、Pb、Cu和Zn）的钝化效果及其作用机制.结果表明,在相同接菌量下,希瓦氏菌处理组对碱性土中有效态重金属的钝化效果优于梭状芽胞杆菌和两者混合菌的处理组;而不同种类的SRB对酸性土中有效态重金属的钝化效果无显著差异.培养第20 d后土壤中有效态重金属的钝化率不再显著变化.SRB处理对碱性土中有效态重金属的钝化率可达80%以上,而对酸性土中有效态重金属的钝化率低于40%.在碱性土中,SRB能够有效还原SO₄^2-,并且提高土壤pH值,使S^2-可与重金属紧密结合,显著提高有效态重金属钝化率.尽管SRB使酸性土壤pH值升高,但土壤仍然呈酸性使SO₄^2-还原受到抑制,不利于有效态重金属的钝化.总体来看,SRB适用于碱性和酸性土壤的重金属污染治理,但与酸性土壤相比,SRB对碱性土壤中有效态重金属的钝化效果更好.     

基于贝叶斯的苯并(α)芘PBPK模型优化与健康风险评估应用

应用基于生理的药代动力学(PBPK)模型预测苯并(α)芘(BaP)暴露的人体内部剂量,基于贝叶斯的马尔科夫链蒙特卡洛模拟(MCMC)方法对模型参数进行校准和优化,最后运用已优化的模型对BaP内暴露基准值进行推导.研究发现,基于贝叶斯的MCMC方法对模型后验参数校准后,模型精度明显提高,两个数据集验证结果显示残差平方和分别降低了72%和94%.PBPK模型以BaP和子代谢物3-羟基苯并(α)芘(3-OHBaP)的体内动力学过程为结构基础,模拟BaP体内浓度分布大小为脂肪>肾脏>皮肤>缓慢灌注组织>快速灌注组织>静脉血>肝脏;3-OHBaP体内浓度分布大小为肾脏>快速灌注组织>脂肪>肺>静脉血>缓慢灌注组织>肝脏>皮肤.敏感性分析显示,快速灌注组织-血分配系数对模型输出影响最大,灵敏度系数超过了200%;排泄系数影响最小,只有肾小球过滤率K_BR的灵敏度系数超过了1%.以美国国家环境保护局推荐的参考浓度2.0×10^-6mg/m³为外暴露安全基准值,基于PBPK模型推导了职业暴露的BaP生物监测当量(BE),结果显示BE值为0.405pmol/mol肌酐(尿液3-OHBaP平均浓度),为基于人体内暴露剂量水平进行定量健康风险评估奠定了基础.     

介质阻挡放电等离子体老化微塑料及对Zn (II)吸附的影响

为了在实验中缩短微塑料的老化时间,更真实地模拟自然老化条件,采用介质阻挡放电（DBD）等离子体老化聚乙烯微塑料（PE-MP）和聚丙烯微塑料（PP-MP）,同时研究了老化前后PE-MP和PP-MP对Zn （II）的吸附过程和机理.随着放电时间延长和输入电压升高,微塑料表面出现微小裂纹或孔洞,形成含氧官能团.老化后PE-MP和PP-MP对Zn （II）的吸附容量分别提高了22.7%和14.8%.老化前后微塑料对Zn （II）的吸附均符合准二级动力学模型.颗粒内扩散模型表明,Zn （II）在微塑料上的吸附过程可分为快速吸附,慢速吸附和吸附平衡3个阶段.同时,老化前后微塑料对Zn （II）的吸附均符合Langmuir吸附等温线模型.热力学结果表明,微塑料对Zn （II）的吸附是自发的吸热过程.Ca²⁺、腐殖酸和低pH值不利于微塑料对Zn （II）的吸附.     

Do trace metal(loid)s in road soils pose health risks to tourists? A case of a highly-visited national park in China

Nowadays, more people tend to spend their recreational time in large national parks, and trace metal(loid)s in soils have attracted long-term attention due to their possible harm to human health. To investigate the pollution levels, potential sources and health risks of trace metal(loid)s in road soils, a total of eight trace metal(loid)s (including As, Cd, Cr, Cu, Ni, Pb, Zn and Hg) from 47 soil samples along roads were studied in the Huangshan National Park in Southeast China. The results showed that the concentrations of As, Cd, Pb, Zn and Hg appeared different degrees of pollution compared with their corresponding background values. According to the pollution indices, Hg and Cd were recognized as significant pollutants presenting moderate to high ecological risk. Combining principal component analysis and positive matrix factorization model, the results showed that traffic, industrial, agricultural and natural sources were the potential origins of trace metal(loid)s in this area, with contribution rates of 39.93%, 25.92%, 10.53% and 23.62%, respectively. Non-carcinogenic risks were all negligible, while the carcinogenic risk of As was higher than the limit (1 $\times$ 10⁻⁶). Moreover, children were more susceptible to trace metal(loid)s by ingestion which appeared to be a more important exposure pathway than dermal contact and inhalation. The contribution rates of different sources to non-carcinogenic risks and carcinogenic risks were similar among children and adults, while traffic and industrial sources have a significant impact on health risks. This study will give more insights to control the environmental risks of trace metal(loid)s in national parks.     

Ambient volatile organic compounds at a receptor site in the Pearl River Delta region: Variations, source apportionment and effects on ozone formation

We present the continuously measurements of volatile organic compounds（VOCs） at a receptor site（Wan Qing Sha, WQS） in the Pearl River Delta（PRD） region from September to November of 2017. The average mixing ratios of total VOCs（TVOCs） was 36.3 ± 27.9 ppbv with the dominant contribution from alkanes（55.5%）, followed by aromatics（33.3%）. The diurnal variation of TVOCs showed a strong photochemical consumption during daytime,resulting in the formation of ozone（O₃）. Five VOC sources were ...     

Enhancing anoxic denitrification of low C/N ratio wastewater with novel ZVI composite carriers

External organic carbon sources are needed to provide electron donors for the denitrification of wastewater with a low COD/NO₃^--N（C/N） ratio, increasing the treatment cost. The economic strategy is to enhance the bioactivity and/or biodiversity of denitrifiers to efficiently utilize organic substances in wastewater. In this study, novel zero-valent iron（ZVI） composite carriers were prepared and implemented in a suspended carrier biofilm reactor to enhance the bioactivity an...