光电催化降解壬基酚影响因素研究

采用sol-gel法制备TiO2薄膜光电极,以该电极为工作电极,铂丝作对电极,饱和甘汞电极为参比电极,对壬基酚的光电催化降解进行了研究。结果表明:该电极具有n型半导体的特征行为。在外加偏压为+0.8V、pH=5、、30mg/L的H2O2中对初始浓度为20mg/L的壬基酚溶液光照180min降解率达62.22%。讨论了氧的存在、外加偏压、pH等因素对光电催化反应的影响。     

水溶液中活性成分对壬基酚聚氧乙烯醚光降解的影响

采用长波紫外灯(UV365)和模拟日光灯研究光化学活性成分对水溶液中壬基酚聚氧乙烯醚(NPEOs)光降解效率的影响,并讨论了光降解导致NPEOs成分分布的变化.研究表明,在UV365辐射下,亚硝酸根,Fe(Ⅲ),H2O2和腐殖酸(HA)等的存在对NPEOs96h的降解效率有较明显的促进作用;在模拟日光下,Mn(Ⅱ),Fe(Ⅲ),H2O2等对NPEOs的光降解也有一定的促进,而此条件下HA的存在则表现为对光降解的抑制作用.此外,还考察了NPEOs在不同比例的Fe(Ⅲ)-HA和Fe(Ⅲ)-H2O2复合体系中的光降解效率.除了导致光降解效率的提高外,活性成分的存在也会导致降解后NPEOs成分分布的变化.以在UV365辐射下为例,H2O2(1000 μmol·l-1)或Fe(Ⅲ)(10和100 μmol·l-1)的加入使反应后短链NPEOs所占比例从初始的22.52%明显提高至29.75%,29.89%和51.89%.这种成分分布的变化可能是由于长链NPEOs在降解过程中发生EO链衰减,从而使短链NPEOs成为其降解中间产物;或是由于长链NPEOs比其短链同系物具有更高的敏化降解速率所导致的.     

两株壬基酚和双酚A高效降解菌株的筛选和降解特性

以桂林市上窑污水处理厂污泥脱水车间剩余污泥、上窑堆肥厂的堆肥堆料和桂林雁山镇森林土壤为菌源进行驯化,分离纯化并筛选得到2株能分别以壬基酚(NP)和双酚A(BPA)为唯一碳源和能源生长的降解菌株N-1和B-1。通过对菌株的16S r DNA序列同源性分析,初步鉴定N-1和B-1菌分别为Cupriavidus(贪铜菌属)、Acinetobacter(不动杆菌属)。通过两菌株分别降解NP和BPA的单因素实验,确定了降解动力学以及时间、温度、p H值对降解过程的影响。研究结果表明,细菌N-1,B-1的最佳初始目标污染物质量浓度为5~10 mg/L,降解40 h,N-1去除率可达49.63%,B-1去除率可达62.34%。细菌N-1对NP的去除半衰期t1/2为41.44~48.02 h;B-1对BPA的去除半衰期t1/2为35.23~37.33 h。细菌N-1,B-1的最佳降解温度均为30℃,最佳p H值均在6.5~7.5之间,即两种细菌在中温、中性条件下对NP和BPA降解效果最佳。     

Metabolism of the Nonylphenol Isomer [Ring-U-14c]-4-(3′,5′-Dimethyl-3′-Heptyl)-Phenol by Cell Suspension Cultures of Agrostemma githago and Soybean

Abstract

The biotransformation of the nonylphenol isomer [ring-U-¹⁴C]-4-(3′,5′-dimethyl-3′-heptyl)-phenol (4-353-NP, consisting of two diastereomers) was studied in soybean and Agrostemma githago cell suspension cultures. With the A. githago cells, a batch two-liquid-phase system (medium/n-hexadecane 200:1, v/v) was used, in order to produce higher concentrations and amounts of 4-353-NP metabolites for their identification; 4-353-NP was applied via the n-hexadecane phase. Initial concentrations of [¹⁴C]-4-353-NP were 1 mg L^?1 (soybean), and 5 and 10 mg L^?1 (A. githago). After 2 (soybean) and 7 days (A. githago) of incubation, the applied 4-353-NP was transformed almost completely by both plant species to four types of products: glycosides of parent 4-353-NP, glycosides of primary 4-353-NP metabolites, nonextractable residues and unknown, possibly polymeric materials detected in the media. The latter two products emerged especially in soybean cultures. Portions of primary metabolites amounted to 19–22% (soybean) and 21–42% of applied ¹⁴C (A. githago). After liberation from their glycosides, the primary 4-353-NP metabolites formed by A. githago were isolated by HPLC and examined by GC-EIMS as trimethylsilyl derivatives. In the chromatograms, eight peaks were detected which due to their mass spectra, could be traced back to 4-353-NP. Seven of the compounds were side-chain monohydroxylated 4-353-NP metabolites, while the remaining was a (side-chain) carboxylic acid derivative. Unequivocal identification of the sites of hydroxylation/oxidation of all transformation products was not possible. The main primary metabolites produced by A. githago were supposed to be four diastereomers of 6′-hydroxy-4-353-NP (about 80% of all products identified). It was concluded that plants contribute to the environmental degradation of the xenoestrogen nonylphenol; the toxicological properties of side-chain hydroxylated nonylphenols remain to be examined.     

Risk assessment of xenoestrogens in a typical domestic sewage-holding lake in China

Release of domestic sewage leads to accumulation of xenoestrogens in holding waters, especially in closed or semi-enclosed waters such as lakes. In the study, the occurrence, distribution, estrogenic activity and risk of eight xenoestreogens were evaluated in Lake Donghu, China. Nonylphenol (NP), octylphenol (OP), and bisphenol A (BPA) were identified as the main xenoestrogens ranging from tens of ng L⁻¹ (in the surface water) or ng g⁻¹ dw (in the suspended particles and sediment) to tens of μg L⁻¹ or μg g⁻¹ dw. The sum of 17β-estradiol equivalents (∑EEQs) ranged from 0.32 to 45.02 ng L⁻¹ in the surface water, 0.53 to 71.86 ng g⁻¹ dw in the suspended particles, and 0.09 to 24.73 ng g⁻¹ dw in the sediment. Diethylstilbestrol (DES) was determined as the main contributor to ∑EEQs followed by NP. The risk assessment showed a higher risk in the surface water than in the suspended particles and sediment in such domestic sewage-holding lake.     

3种增塑剂单独和联合暴露对MCF-7细胞增殖的影响

为了探究结构差异较大、应用较为广泛的几类增塑剂雌激素活性的联合效应,选择邻苯二甲酸二丁酯(DBP)、双酚A(BPA)和壬基酚(NP)作为邻苯二甲酸酯、双酚A类和烷基酚类增塑剂的代表物进行试验.用DBP、BPA和NP单独及两两混合处理MCF-7细胞.采用MTT法检测培养24h、48 h、72 h和96h时的细胞增殖情况.采用流式细胞术检测药物培养48h后的细胞生长周期分布,并计算细胞增殖指数(PI).运用效应叠加模型(ES)判定联合效应类型.结果表明,在单独暴露试验中,DBP、BPA和NP组PI均大于1,且均能提高S期(DNA合成期)细胞比例.因此,DBP、BPA和NP均能显著促进MCF-7细胞增殖.混合暴露试验中,1)DBP和BPA在MTT试验中24h、48h、72 h和96h时的效应叠加指数(ESI)分别为1.013 9、1.023 8、0.9999、1.010 8,在流式细胞仪试验中ESI为1.014 1.因此,DBP和BPA的雌激素活性联合效应为加和作用.2)DBP和NP在MTT试验中24 h、48 h、72 h和96 h时的ESI分别为1.004 0、1.008 6、1.011 5、1.010 3,流式细胞仪试验中ESI为0.997 0.因此,DBP和NP的雌激素活性联合效应为加和作用.3)BAP和NP在MTT试验中24h、48 h、72 h和96h时的ESI分别为0.980 6、0.981 8、0.977 7、0.973 3,流式细胞仪试验的ESI为0.912 8.由此可知,BPA和NP的雌激素活性联合效应为拮抗作用.因此,可以采用MCF-7细胞增殖试验研究环境污染物雌激素活性联合效应.     

壬基酚的环境生物地球化学研究进展及对新污染物管理的建议

近年来,我国大气环境、水环境和土壤环境质量得到一定的改善,“碧水蓝天”已经成为常态.但随着持久性有机污染物、内分泌干扰物、抗生素和微塑料等新污染物在环境中不断被检出,新污染物正逐步受到广泛的关注,壬基酚作为一种典型的内分泌干扰物也备受研究人员的关注.系统地概括了我国水体中壬基酚的环境行为和暴露水平,并基于风险商法和联合概率曲线法对壬基酚可能造成的生态风险进行了评估.结果表明,壬基酚对水生生物的毒性效应主要包括急性毒性、生长发育毒性、雌激素效应和繁殖毒性;壬基酚在我国主要流域水体中普遍存在,其浓度平均值在60～1 000 ng·L^-1,浓度最高值可达4 628 ng·L^-1;基于风险商法和联合概率曲线法的风险评估结果表明,壬基酚对我国主要流域里的水生生物均存在一定的风险.最后,总结了目前比较常用的壬基酚处理处置和风险管控技术,比较了国际上内分泌干扰物的监管方法,针对我国在新污染物环境管理中存在的问题,提出了针对性政策建议,研究结果可以为我国新污染物管理和管控提供参考.     

藻类对壬基酚微生物降解的影响

壬基酚(NP)为在水环境中广泛存在的一种典型环境内分泌干扰物质。为了探讨NP在自然水体中的归趋,研究了水体中藻类对微生物降解NP的影响。结果表明,本研究筛选的耗氧混合菌可以有效降解NP,在暗环境下半衰期为1.16d,光照不利于NP的微生物降解,半衰期增加到5.19d;藻类和藻胞外分泌物可以提高光照条件下NP的微生物降解,这是藻类和菌加和作用的结果;而破碎的藻对降解作用改善不大。藻类和微生物相互作用对于有机污染物降解的影响还鲜见报道,本研究为全面理解NP在水环境中的归驱提供了重要的数据。     

壬基酚对羊角月牙藻的毒性效应研究

为研究壬基酚（NP）对淡水微藻的毒性效应特点,选取模式生物羊角月牙藻（Selenastrum capricornutum）为受试对象,设置5个暴露处理浓度：0.1,0.3,0.6,0.9,1.2mg/L.观察并测定羊角月牙藻的生长情况、叶绿素含量、超氧化物歧化酶（SOD）、过氧化氢酶（CAT）活性和丙二醛（MDA）含量等指标,并通过植物光合效率仪测定叶绿素荧光诱导动力学参数,分析NP对光系统Ⅱ（PSⅡ）的影响.结果表明,NP限制羊角月牙藻生长的96h EC50为0.979mg/L;NP处理浓度为0.3mg/L时,可以对羊角月牙藻生长产生抑制效应,与对照组相比,主要光合色素（叶绿素）含量下降,MDA含量显著增加,过氧化氢酶（CAT）和超氧化物歧化酶（SOD）活性显著上升,最大光能转化效率（Fv/Fm）显著下降,ABS/RC（单位反应中心吸收光能）显著上升,DI0/RC（单位反应中心耗散能量）、ET0/RC（单位反应中心捕获用于电子传递的能量）、TR0/RC（反应中心用于还原QA的能量）也随之升高;当处理浓度≥0.9mg/L后,CAT和SOD活性、TR0/RC显著下降,DI0/RC显著升高,表明PSⅡ受到损伤.由此可知,NP能够破坏膜系统完整性、诱发抗氧化系统响应并造成PSⅡ损伤,降低光能转化效率,对羊角月牙藻具有毒性效应,对水域生态系统具有潜在风险.     

1株异养脱氮菌降解壬基酚聚氧乙烯醚的研究

研究了异养脱氮菌Bacillus sp.LY降解壬基酚聚氧乙烯醚(NPEOs)的性能.结果表明,该菌株具有较强地降解NPEOs的能力,且在实现NPEOs降解去除的同时表现出一定的异养脱氮性能.降解14d后, Bacillus sp.LY对NPEOs去除率达95.6%,对体系中的总氮去除率为43.9%.该菌株对NPEOs的降解去除符合一级动力学特征,其降解速率常数为0.224d-1.该菌株通过无氧化过程的乙氧基链的逐渐缩短的途径降解去除NPEOs,可避免产生危害性更大的NPEOs的羧酸化产物(NPECs).在分别以氨态氮(NH4C1)、硝态氮(NaNO3)和亚硝态氮(NaNO2)3种不同氮素为氮源的条件下,菌株对NPEOs均具有一定的降解效果,其中以氨态氮为氮源时菌株对NPEOs降解效果最好.研究结果可为消除壬基酚聚氧乙烯醚与氮素复合污染提供理论依据.