微生物光电还原CO2合成乙酸对外电压的响应机制

以TiO₂光阳极结合自养型生物阴极,构建双室微生物光电合成（MPES）系统,以光能作为主要的能量来源,探究MPES还原CO₂合成乙酸的性能及其限制因素.结果表明,光阳极取代纯电化学阳极显著降低了MPES生物阴极对外电压的需求.MPES能持续稳定运行,平均产乙酸速率为（1.18 ±0.11） mmol/（L·d）,法拉第效率为45.75%±3.97%.光阳极驱动阴极产生氢气,推测阴极微生物倾向于利用氢转移的方式来进行电子传递.外加电压通过影响光阳极的给电子能力从而对MPES的性能产生显著的影响,当外电压从0.4V升高至0.6V时,MPES的电流,乙酸产量和法拉第效率都显著提高,系统的性能主要受限于阳极.当外电压高于0.6V,系统电流,乙酸产量的增速减缓,法拉第效率在外加电压0.8V时达到最大值,随后下降,表明生物阴极的得电子能力已经达到饱和,此时MPES的性能主要受限于阴极.作为电子传递中间体,H₂的不完全利用是法拉第效率没有随着外电压的增加进一步提升的原因.     

基于InVEST-PLUS模型的碳储量空间关联性及预测——以广东省为例

构建土地利用碳储量数据库,基于InVEST模型Carbon模块,得到广东省1990~2020年碳储量时空分布情况.用Moran’s I指数和Getis-Ord Gi^*分析格网尺度下碳储量时空分布特征,用Anselin Local Moran’s I得到LISA集聚图.然后运用PLUS模型和14个土地利用驱动因子预测2050年土地利用及其碳储量分布.结果表明,土地利用变化直接影响区域碳储量高低,林地、草地等具有生态服务功能地类碳密度最高,分别是188.44,329.34Mg/hm².碳储量空间格局整体呈现出中部低、北部高、东西中等的特点.碳储量空间分布特征与土地利用特征一致,碳储量显著高值集聚区域分布在建设用地少、生态用地多且连片的粤北地区,显著低值区域分布在国土开发强度和生态用地破碎化程度高的珠三角地带.在自然发展情景下,到2050年广东省土地利用碳储量将减少4327.21万Mg,随着国土空间进一步开发,环珠江口沿岸城市碳储量持续下降.增加植被生态系统碳储量,是实现碳中和的重要手段之一.要继续维持粤北山区生态保护屏障的重要地位,减缓珠三角城市土地开发强度,提高建设用地集约节约能力,形成平衡协调的土地利用和碳储量格局.     

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。     

高空间分辨率环境数据库及其应用

高空间分辨率环境数据库的构建和应用对于解决日益突出的环境问题至关重要。高空间分辨率数据能够在精细尺度上体现研究对象的具体分布和特点,识别环境污染重点地区,有助于制定因地制宜的环境管控政策。国内外学者已构建大量的高分辨率环境数据库并将其应用于解决多种环境问题。然而,目前尚未有学者对高空间分辨率环境数据库的类型和应用进行系统性阐述。因此,从尺度和物质类型2个方面总结了常见的高空间分辨率环境数据库,并对这些数据集在排放源分析、环境影响评估和经济影响因素分析3个方面的应用进行疏理,并对未来研究提出了进一步提高分辨率、提高数据质量、拓宽应用研究范围的建议。     

土壤修复产业碳达峰碳中和路径研究

土壤修复产业迎来爆发式增长,未来即将突破万亿市场,是环保产业中最具发展潜力的行业。CO₂排放影响世界气候变化,关乎人类生存。中国提出在2030年实现碳排放达到峰值,2060年达到碳中和这一目标,旨在优化能源结构,维护全球CO₂平衡,保护地球家园。土壤修复产业中碳排放量随土壤修复市场发展逐渐增加,若不采取碳减排措施,势必会增加实现"双碳"目标的压力。通过土壤修复产业碳达峰碳中和路径研究,对土壤修复产业中"双碳"时间节点进行预测,分析了土壤修复产业中的碳排放量,并提出土壤修复产业中实现"双碳"目标的路径。     

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 ...     

Extracellular polymeric substance induces biogenesis of vivianite under inorganic phosphate-free conditions

Vivianite is often found in reducing environments rich in iron and phosphorus from organic debris degradation or phosphorus mineral dissolution. The formation of vivianite is essential to the geochemical cycling of phosphorus and iron elements in natural environments. In this study, extracellular polymeric substances (EPS) were selected as the source of phosphorus. Microcosm experiments were conducted to test the evolution of mineralogy during the reduction of polyferric sulfate flocs (PFS) by Shewanella oneidensis MR-1 (S. oneidensis MR-1) at EPS concentrations of 0, 0.03, and 0.3 g/L. Vivianite was found to be the secondary mineral in EPS treatment when there was no phosphate in the media. The EPS DNA served as the phosphorus source and DNA-supplied phosphate could induce the formation of vivianite. EPS impedes PFS aggregation, contains redox proteins and stores electron shuttle, and thus greatly promotes the formation of minerals and enhances the reduction of Fe(III). At EPS concentration of 0, 0.03, and 0.3 g/L, the produced HCl-extractable Fe(II) was 107.9, 111.0, and 115.2 mg/L, respectively. However, when the microcosms remained unstirred, vivianite can be formed without the addition of EPS. In unstirred systems, the EPS secreted by S. oneidensis MR-1 could agglomerate at some areas, resulting in the formation of vivianite in the proximity of microbial cells. It was found that vivianite can be generated biogenetically by S. oneidensis MR-1 strain and EPS may play a key role in iron reduction and concentrating phosphorus in the oligotrophic ecosystems where quiescent conditions prevail.     

Enhanced metronidazole removal by binary-species photoelectrogenic biofilm of microaglae and anoxygenic phototrophic bacteria

High efficient removal of antibiotics during nutriments recovery for biomass production poses a major technical challenge for photosynthetic microbial biofilm-based wastewater treatment since antibiotics are always co-exist with nutriments in wastewater and resist biodegradation due to their strong biotoxicity and recalcitrance. In this study, we make a first attempt to enhance metronidazole (MNZ) removal from wastewater using electrochemistry-activated binary-species photosynthetic biofilm of Rhodopseudomonas Palustris (R. Palustris) and Chlorella vulgaris (C. vulgaris) by cultivating them under different applied potentials. The results showed that application of external potentials of -0.3, 0 and 0.2 V led to 11, 33 and 26-fold acceleration in MNZ removal, respectively, as compared to that of potential free. The extent of enhancement in MNZ removal was positively correlated to the intensities of photosynthetic current produced under different externally applied potentials. The binary-species photoelectrogenic biofilm exhibited 18 and 6-fold higher MNZ removal rate than that of single-species of C. vulgaris and R. Palustris, respectively, due to the enhanced metabolic interaction between them. Application of an external potential of 0V significantly promoted the accumulation of tryptophan and tyrosine-like compounds as well as humic acid in extracellular polymeric substance, whose concentrations were 7.4, 7.1 and 2.0-fold higher than those produced at potential free, contributing to accelerated adsorption and reductive and photosensitive degradation of MNZ.     

云浮市2018—2020年颗粒物和臭氧污染特征及污染案例研究

为探究云浮市颗粒物和臭氧(O₃)污染特征,利用多元统计分析方法分析了云浮市2018—2020年6项环境空气污染物浓度、气象因子等监测数据,并对2020年12月25—29日冬季PM_2.5和O₃污染过程进行了研究. 结果表明:①PM_2.5、PM₁₀、NO₂、CO月均浓度呈夏季低、冬季高的变化特征;O₃-8 h第90百分位数呈夏秋季高、冬春季低的变化特征. ②PM₁₀、PM_2.5和CO小时浓度日变化呈波浪型变化特征,PM_2.5、CO小时浓度最大值均出现在09:00,PM₁₀小时浓度最大值出现在02:00. O₃、SO₂小时浓度日变化呈单峰型变化特征,O₃、SO₂小时浓度最大值分别出现在16:00、10:00. NO₂小时浓度日变化呈单谷型变化特征,最小值出现在14:00. ③PM_2.5-10、SO₂、NO₂、O₃小时浓度与PM_2.5小时浓度均呈正相关,说明PM_2.5-10、SO₂、NO₂、O₃与PM_2.5具有一定程度的同源性. O₃小时浓度与NO₂、CO小时浓度呈负相关,且O₃小时浓度与NO₂小时浓度相关性更强. 夏秋季NO₂、CO、O₃、PM_2.5小时浓度与气温的相关性比冬春季的更强. SO₂、PM₁₀、PM_2.5、O₃小时浓度均与湿度呈负相关,其中O₃小时浓度与湿度的相关性最强,相关系数为?0.586. ④2020年12月25—29日云浮市城区PM_2.5污染受到静稳天气影响,O₃污染与28日午后太阳高温辐射以及来自珠三角地区O₃污染气团的输入影响有关. 利用ART-2a对该时段采集的颗粒物进行成分分析,得到K、EC、OC、ECOC、HM、LEV、Na、SiO₃这8种单颗粒物. 整个时段EC、OC、ECOC谱图中都存在明显的硫酸盐峰和硝酸盐峰. PM_2.5小时浓度与硫酸盐离子、硝酸盐离子、硅酸盐离子、铵离子、氯离子的数量均呈显著正相关,二次反应和老化过程对PM_2.5污染有显著影响. 研究显示,云浮市PM_2.5和O₃复合污染防控需要关注本地污染物变化特征和排放源影响,也需关注外来污染气团特别是来自珠三角地区污染气团输入的影响.      

聚合反应时间对聚酰亚胺基碳膜结构和性能的影响研究

目的 系统研究前驱体聚合反应时间对PI膜及其碳化、石墨化后薄膜结构和性能的影响规律。方法 通过调整聚合合成聚酰胺酸(PAA)溶液过程中的反应时间,制备石墨膜前驱体聚酰亚胺(PI)原膜,将不同工艺条件下制得的PI膜进行碳化、石墨化处理,得到高导热率石墨膜。利用扫描电镜、红外光谱、拉曼光谱仪和LFA激光闪射仪对制备的PI膜、碳化膜及石墨膜的微观结构和热导率进行检测。结果 随聚合反应时间的延长,PI膜酰亚胺化程度和石墨膜的石墨化程度及导热性能先增高、后降低。反应时间为3 h时,制得的石墨膜结构致密,石墨片层取向性好,导热性能最好,热导率可达765.2 W/(m.K)。结论 PI膜前驱体聚合反应时间显著影响PI膜酰亚胺化的程度和有序度,进而影响石墨膜的定向性和导热性能。