雷州半岛地下水化学特征及控制因素分析

雷州半岛地下水资源为雷州半岛经济社会发展提供有力的资源支撑,厘清该区地下水化学特征及形成机制对水资源的合理开采及可持续利用具有重要意义.本研究采集43组雷州半岛地下水样品,运用描述性统计分析、Piper三线图、ArcGIS空间插值、Gibbs图以及离子比值等方法分析地下水水化学特征及其控制因素.结果表明：①研究区地下水阴阳离子以HCO₃^-、Ca²⁺和Na⁺为主,水化学类型以HCO₃-Cl-Na-Ca、HCO₃-Cl-Na-Ca-Mg、HCO₃-Cl-Na-Mg和HCO₃-Na型为主.研究区地下水中的Cl^-、SO₄^2-和Na⁺在雷州市西部含量较高,在其他区域均较低,HCO₃^-、NO₃^-、Ca²⁺、Mg²⁺和K⁺这5种离子含量较高的区域主要集中在西南和东部沿海.②地下水化学演化过程主要受水岩作用、阳离子交替吸附和人类活动的影响.Na⁺和K⁺来源主要是蒸发盐岩和硅酸盐岩,Ca²⁺和Mg²⁺主要来源于碳酸盐岩溶解,NO₃^-主要来源于人类活动.     

平朔矿区不同水体水化学特征及氟分布成因

为了探明采煤驱动下平朔矿区所在流域内不同水体水化学特征及氟分布成因,综合运用水化学图解、主成分分析和地球化学模拟等方法,对2020~2021年采集的468组地表水、地下水和矿井水样品进行分析.结果表明,地表水、地下水和矿井水均呈近中性至弱碱性;地表水和矿井水中优势阴离子为SO₄^2-,地下水中优势阴离子为HCO₃^-,Ca²⁺是所有水体中的优势阳离子.地表水和矿井水水化学类型以SO₄·HCO₃-Ca·Mg为主.地下水水化学类型主要为HCO₃-Ca·Mg,采煤区的浅层或深层地下水存在HCO₃·SO₄-Ca·Mg型.水体水化学主要受碳酸盐岩风化溶解、采煤活动以及含氟矿物的风化溶解影响,采煤和工农业等人类活动加速了不同水体间水化学转换,尤其是浅层地下水.水体ρ（F^-）介于0.10~1.76 mg·L^-1,其中,42%浅层地下水F^-浓度高于国家饮用水安全限值;时空分布上,西北至东南地下水中F^-浓度平均值呈增加趋势,3月和8月F^-浓度偏高.高氟浅层地下水化学呈现偏碱性和高Na⁺特征.F^-富集主要受采煤活动和含氟矿物风化溶解影响,水体中方解石饱和加速了含氟矿物的风化溶解.     

天津七里海湿地水化学组成及主要离子来源分析

水化学是湿地水环境评价的重要参数.为研究天津七里海湿地的水化学组成和主要离子来源,采集了湿地内的沼泽水、周边的河水和地下水.结果表明：①河水、沼泽水的水化学类型为SO₄·Cl-Na型,地下水水化学类型为HCO₃-Na型和HCO₃-Na·Ca型,沼泽水主要依靠河水补给,浅层地下水与河水交换作用明显;②水体离子组分受大气降水影响小,Na⁺和K⁺来源为盐岩溶解或蒸发浓缩作用,河水、沼泽水中Ca²⁺、Mg²⁺和HCO₃^-主要受蒸发岩溶解作用,地下水中Ca²⁺、Mg²⁺和HCO₃^-主要来源于碳酸盐岩溶解;③河水和地下水的水化学组分受阳离子交换作用明显,而沼泽水阳离子交换作用不明显;各水体的SO₄^2-和NO₃^-受一定人类活动的输入;沼泽水和枯水期河水受蒸发盐岩溶解、蒸发作用及人为输入,丰水期河水主要受碳酸盐溶解及人为活动影响.湿地的水化学组成受到自然因素和人类活动的共同作用.     

长江流域安庆段浅层地下水水化学特征及控制因素

浅层地下水为安庆市居民生活用水和工农业生产用水的主要水源,是维持社会经济可持续发展和区域生态环境的重要基础保障.为深入研究安庆市浅层地下水的水化学特征及控制因素,采集了196组浅层地下水水样,综合运用Piper三线图、Gibbs图、离子比值和数理统计方法对安庆市地下水的水化学特征及控制因素进行研究,定量评估不同来源对地下水水化学组分的贡献.结果表明,安庆市浅层地下水呈弱碱性,pH值在5.84～8.38,均值为7.21; ρ（TDS）介于47～1 620 mg·L^-1,均值为324.21 mg·L^-1,阴阳离子主要以HCO₃^-和Ca²⁺为主,水化学类型为HCO₃-Ca型.地下水水化学组分受岩石风化溶滤作用、阳离子交替吸附作用、矿物溶解和沉淀以及人类活动综合影响.Ca²⁺、Mg²⁺和HCO₃^-主要来源于碳酸盐岩和硅酸盐岩的风化溶解作用,Na⁺、Cl^-和SO₄^2-受工业活动和生活污水的排放、K⁺和NO₃^-受农业活动的影响.APCS-MLR受体模型分析进一步揭示地下水水化学组分主要有地质因子、工业因子、农业因子和未知源这4种来源,其贡献率分别为45.35%、14.19%、25.38%和15.08%.地质因子是浅层地下水水化学组分的重要来源,人类活动则加剧了地下水水化学的演变.     

会仙岩溶湿地地下水主要离子特征及成因分析

以我国最大的低海拔岩溶湿地会仙岩溶湿地为研究区,对该区丰水期、平水期和枯水期共采集的27组地下水样品中常规离子进行检测和分析,在分析会仙岩溶湿地地下水主要离子化学特征和不同时期变化基础上,运用单指标污染标准指数法对不同时期地下水进行污染评价,利用多元统计、Gibbs模型和离子比例关系识别地下水主要离子成因.结果表明,研究区内岩溶地下水主要为弱碱性淡水,Ca²⁺和HCO₃^-为优势离子.不同时期地下水主要离子总浓度顺序为：平水期 > 丰水期 > 枯水期,枯水期水质优于丰水期和平水期.地下水中K⁺和NO₃^-主要受含水层空间分布差异影响,Mg²⁺、SO₄^2-、NO₂^-、NH₄⁺和TDS受时空尺度综合作用,Na⁺、Ca²⁺、HCO₃^-和Cl^-为水体中较稳定离子.受碳酸盐岩控制,丰水期、平水期和枯水期地下水化学类型具有高度一致性,HCO₃-Ca水占比分别为77.78%、77.78%和88.89%.地下水主要受SO₄^2-、NO₃^-和NO₂^-污染,NO₃^-出现极严重程度污染样点,SO₄^2-在丰水期和平水期出现较重污染样点.地下水化学组分主要受水岩作用控制,Ca²⁺和HCO₃^-主要来源于方解石风化溶解,少量水点受白云岩、白云质灰岩及硫铁矿控制导致Mg²⁺和SO₄^2-浓度偏高,K⁺、Na⁺、SO₄^2-、NO₃^-和Cl^-部分来源于大气降水,Na⁺和Cl^-部分来源于当地居民生活,K⁺与种植施用的钾肥相关,NO₃^-主要来源是化学肥料.     

珠穆朗玛峰绒布河源区河水化学特征

为了研究绒布河源区夏季河水的基本化学特征 ,野外采集水样 117份 ,采用 PE-2380型原子吸收光谱仪测定样品的阳离子 ,Dionex-100型离子色谱仪测定阴离子 .结果表明 :①绒布河源区河水为 HCO₃,SO₄^- Ca型 .其离子浓度顺序为 :Ca²⁺>K⁺>Na⁺>Mg²⁺,SO^2-₄>Cl^->NO^-₃ .②河水中离子 Ca²⁺、Mg²⁺、SO^2-₄ 之间 ,以及 K⁺和 Na⁺之间有很好的正相关关系 ,河水化学组成大部分来源于当地岩石的风化分解 .③整个夏季河水各月离子平均浓度和流量有良好的正相关关系 ,流量大的月份 ,各离子平均浓度也大 ,反之亦然 .     

涡河流域中部地区地下水化学特征及其成因分析

地下水是涡河流域中部地区重要的供水水源,但普遍面临着污染及水质异常等问题.本文在调查采样的基础上,综合运用数理统计、Piper三线图、Gibbs图和离子比值等方法对不同深度地下水的水化学特征及其形成机制进行分析和探讨.结果表明：①研究区地下水总体为弱碱性水,不同深度地下水中的优势阴、阳离子均为HCO₃^-和Na⁺.浅层地下水的水化学类型以HCO₃-Ca·Mg和HCO₃-Na·Mg型水为主,中层和深层均以HCO₃·SO₄·Cl-Na型水为主.②基于含水层沉积环境差异及水-岩作用强度不同,地下水化学成分出现明显的垂向差异.随着深度的增加,地下水中TDS、Na⁺、Mg²⁺、Cl^-、SO₄^2-和HCO₃^-平均质量浓度均呈现先增大后减小的趋势,Ca²⁺平均质量浓度呈逐渐降低趋势.③地下水水化学特征的形成受水-岩相互作用、阳离子交换作用和人类活动的共同影响,以水-岩作用为主.水-岩作用以含钠硅酸盐溶解作用为主.人类活动普遍对浅层地下水影响较大,对中层和深层地下水影响较小.④区内深层地下水水质明显优于浅层和中层地下水,为避免增加地面沉降及中层微咸水向深层淡水越流的风险,建议合理布局深层地下水开采井,并合理调控取水量.     

滨州市浅层地下水化学时空变化及成因分析

随着海平面升高和全球气候变化,沿海城市地下水化学的长期演变规律研究变得尤为重要。通过采集2010～2020年滨州市浅层地下水样(250个),运用数理统计、ArcGIS空间插值、相关性分析、Piper三线图、Gibbs图及离子比等方法系统地分析了近10年来地下水化学时空演变规律及成因,结果表明:(1)研究区水体整体呈弱碱性,以微咸水为主,地下水阳离子以Na⁺为主,阴离子以Cl^-为主;由陆向海,水化学类型由Ca-SO₄·HCO₃型过渡到Na·Mg-HCO₃·SO₄、Na·Mg-Cl·HCO₃型,近海迅速转化为Na·Mg-Cl及Na-Cl型;(2)水化学组分年际变化表现为:TDS、Na⁺、Cl^-、SO₄^2-和NO₃^-在2012～2013年显著升高,2013～2020年波动降低,2013年区域TDS突增主要受海水入侵影响;水化学组分空间分布为:TDS、Na⁺、K⁺、Mg²⁺、Ca²⁺、Cl^-和SO₄^2-浓度空间变异不大,由陆向海浓度增高,并在博兴县北部沿黄河区域出现极大值,主要受河道补给状况影响;NO₃^-浓度空间变异较大,10年间在小清河流域浓度显著增高,增幅为15.81mg/(L·a);(3)由陆向海,水化学控制因素由岩石风化控制型过渡至蒸发浓缩控制型;(4)Ⅰ区Na⁺、Cl^-主要来源于岩盐及钠长石,Ⅱ区Na⁺来源受到上游生活污水影响,Ⅲ、Ⅳ区部分水体受海水影响较重,Na⁺、Cl^-可能来源于海水,SO₄^2-、Ca²⁺则主要来源于石膏。     

青藏高原纳木错流域河水主要离子化学特征及来源

2006年6～10月对青藏高原纳木错流域你亚曲、曲嘎切、昂曲3条河流进行了连续采样,同时在2005年9月和2006年9月2次环纳木错考察中采集了其他河水的样品.河水中主要阴离子（Ca²⁺、 Mg²⁺、 Na⁺、 K⁺）和阳离子（Cl^-、 NO^-₃、 HCO^-₃、 SO^2-₄）的分析结果表明,你亚曲、曲嘎切和昂曲的离子总量（TDS）分别为79.48、 23.44和111 mg/L.离子总量明显低于青藏高原及我国其他河流,且相互之间存在较为明显的差距. 3条河流中,曲嘎切为重碳酸盐钙型水,昂曲介于重碳酸盐钠型和重碳酸盐钙型之间,你亚曲的化学类型介于两者之间.河流水化学的时间变化显著,而且与流量成一定的反相关关系.利用主成分分析和相关分析得出：你亚曲河水主要化学成分来源于碳酸盐中的Ca²⁺和HCO^-₃;曲嘎切来源于冰川融水以及碳酸盐中的Ca²⁺、HCO^-₃和Na⁺;昂曲则来源于蒸发岩中的Na⁺、Mg²⁺和Cl^-.     

北京市丰台区永定河以东浅层地下水水化学演变规律及成因分析

为更好支撑北京市丰台区地下水资源开发利用、污染管控与防治工作,以丰台区永定河以东区域枯水期浅层地下水长序列监测数据为基础,综合运用数理统计、Gibbs图和离子比例分析等方法探究了丰台区地下水水化学演变规律、形成机制及污染来源,结果表明：①研究区现状地下水质量整体较差,地下水中各指标平均浓度自1976年至今呈先升高后降低趋势,Cl^-、SO₄^2-和总硬度（TH）污染范围总体呈扩大趋势,溶解性总固体（TDS）和硝酸盐氮（NO₃^-）污染范围以2005年为拐点呈先扩大后缩小趋势;②各年份地下水中优势阴、阳离子均为HCO₃^-和Ca²⁺,1976年和2021年地下水水化学类型数依次为8和17种,其主要水型依次为HCO₃·SO₄-Ca·Mg·Na（40%）和HCO₃·Cl·SO₄-Ca·Na·Mg（23.88%）,各年份区域范围内与沿地下水流向上地下水水化学类型均呈现复杂化趋势,地下水水文地球化学演变过程中水化学组分受人为活动影响显著;③地下水受岩石风化和蒸发结晶双重作用,且以蒸发作用为主,地下水阳离子交替作用较弱,碳酸盐矿物的溶解为Ca²⁺和Mg²⁺的主要来源;④离子比例分析得出,外源输入的NO₃^-和Cl^-主要来源于农业活动、城市污水,且2005年前农业活动污染影响较大,与研究区历史上大量渗坑、渗井、工业和生活污水灌溉直排关系密切.     

Effects of two sludge application on fractionation and phytotoxicity of zinc and copper in the soil

The potential harm of heavy metals is a primary concern in application of sludge to the agricultural land. A pot experiment was conducted to evaluate the effect of two sludges on fractionation of Zn and Cu in soil and their phytotoxicity to pakchoi. The loamy soil was mixed with 0%, 20%, 40%, 60% and 80% (by weight) of digested sewage sludge (SS) and composted sludge (SC). The additions of both sludges caused a significant raise in all fractions, resulting in that exchangeable (EXCH) and organic bound (OM) became predominance of Zn and organic bound Cu occupied the largest portion. There was more available amount of Zn and Cu in SS treatments than SC treatments. During the pot experiment, the concentration of Zn in EXCH, carbonate (CAR) and OM and Cu in EXCH and OM fractions decreased in all treatments, so their bioavailability reduced. Germination rate and plant biomass decreased when the addition rate was high and the best yield appeared in 20% mixtures at the harvest of pakchoi. The two sludges increased tissue contents of Zn and Cu especially in the SS treatments. Zn in pakchoi was not only in relationship to ΔEXCH and ΔCAR forms but also in ΔOM forms in the sludge-soil mixtures. Tissue content of Cu in pakchoi grown on SC-soils could not be predicted by ΔEXCH. These correlation rates between Zn and Cu accumulation in pakchoi and variation of different fractions increased with time, which might indicate that sludges represented stronger impacts on the plant in long-term land application.     

Intraspecific differences in effects of co-contamination of cadmium and

A hydroponic experiment was carried out to study intraspecific differences in the effects of different concentrations of cadmium (Cd)(0-10 mg/L) and arsenate (As(V)) (0-8 mg/L) on the growth parameters and accumulation of Cd and As in six wheat varieties Jing-9428, Duokang-1, Jingdong-11, Jing-411, Jingdong-8 and Zhongmai-8. The endpoints of wheat seedlings, including seed germination,biomass, root length and shoot height, decreased with increasing the Cd and As concentrations. Significant differences in seed germination, biomass, root length, shoot height and the accumulation of Cd and As were observed between the treatments and among the varieties (p ＜ 0.05). The lethal dosage 50% were about 20, 80, 60, 60, 80 and 20 mg As/L for Jing-9428, Duokang-1, Jingdong-11,Jing-411, Jingdong-8 and Zhongmai-8, respectively, and the corresponding values for Cd were about 30, 80, 20, 40, 60 and 10 mg Cd/L, respectively. Among the six varieties, Duokang-1 was found to be the most resistant to Cd and As toxicity, and Zhongmai-8 was the most sensitive to Cd and As co-contamination. The resistance of the six varieties was found dependant on the seedling uptake of Cd and As. Duokang-1 was the most suitable for cultivation in Cd and As co-contaminated soils.     

Toxic effects of acetochlor, methamidophos and their combination on nifH gene in soil

Toxic effects of two agrochemicals on nifH gene in agricultural black soil were investigated using denaturing gradient gel electrophoresis （DGGE） and sequencing approaches in a microcosm experiment. Changes of soil nifH gene diversity and composition were examined following the application of acetochlor, methamidophos and their combination. Acetochlor reduced the nifH gene diversity （both in gene richness and diversity index values） and caused changes in the nifH gene composition. The effects of acetochlor on nifH gene were strengthened as the concentration of acetochlor increased. Cluster analysis of DGGE banding patterns showed that nifH gene composition which had been affected by low concentration of acetochlor （50 mg/kg） recovered firstly. Methamidophos reduced nifH gene richness that except at 4 weeks. The medium concentration of methamidophos （150 mg/kg） caused the most apparent changes in nifH gene diversity at the first week while the high concentration of methamidophos （250 mg/kg） produced prominent effects on nifH gene diversity in the following weeks. Cluster analysis showed that minimal changes of nifH gene composition were found at 1 week and maximal changes at 4 weeks. Toxic effects of acetochlor and methamidophos combination on nifH gene were also apparent. Different nifH genes （bands） responded differently to the impact of agrochemicals： four individual bands were eliminated by the application of the agrochemicals, five bands became predominant by the stimulation of the agrochemicals, and four bands showed strong resistance to the influence of the agrochemicals. Fifteen prominent bands were partially sequenced, yielding 15 different nifH sequences, which were used for phylogenetic reconstructions. All sequences were affiliated with the alpha- and beta-proteobacteria, showing higher similarity to eight different diazotrophic genera.     

Arsenic uptake by arbuscular mycorrhizal maize （Zea mays L.） grown in an arsenic-contaminated soil with added phosphorus

The effects of arbuscular mycorrhizal (AM) fungus (Glomus mosseae) and phosphorus (P) addition (100 mg/kg soil) on arsenic (As) uptake by maize plants (Zea mays L.) from an As-contaminated soil were examined in a glasshouse experiment.Non-mycorrhizal and zero-P addition controls were included.Plant biomass and concentrations and uptake of As,P,and other nutrients,AM colonization,root lengths,and hyphal length densities were determined.The results indicated that addition of P significantly inhibited root colonization and development of extraradical mycelium.Root length and dry weight both increased markedly with mycorrhizal colonization under the zero-P treatments,but shoot and root biomass of AM plants was depressed by P application.AM fungal inoculation decreased shoot As concentrations when no P was added,and shoot and root As concentrations of AM plants increased 2.6 and 1.4 times with P addition,respectively.Shoot and root uptake of P,Mn,Cu,and Zn increased,but shoot Fe uptake decreased by 44.6%,with inoculation, when P was added.P addition reduced shoot P,Fe,Mn,Cu,and Zn uptake of AM plants,but increased root Fe and Mn uptake of the nonmycorrhizal ones.AM colonization therefore appeared to enhance plant tolerance to As in low P soil,and have some potential for the phytostabilization of As-contaminated soil,however,P application may introduce additional environmental risk by increasing soil As mobility.     

Degradation of metabolites accumulated of benzo[a]pyrene by coupling Penicillium Chrysogenum with KMnO4

Several main metabolites of benzo[a]pyrene （BaP） formed by Penicillium chrysogenum, Benzo[a]pyrene-1,6-quinone （BP 1,6- quinone）, trans-7,8-dihydroxy-7,8-dihydrobenzo[a]pyrene （BP 7,8-diol）, 3-hydroxybenzo[a]pyrene （3-OHBP）, were identified by high-performance liquid chromatography （HPLC）. The three metabolites were liable to be accumulated and were hardly further metabolized because of their toxicity to microorganisms. However, their further degradation was essential for the complete degradation of BaP. To enhance their degradation, two methods, degradation by coupling Penicillium chrysogenum with KMnO4 and degradation only by Penicillium chrysogenum, were compared; Meanwhile, the parameters of degradation in the superior method were optimized. The results showed that （1） the method of coupling Penicillium chrysogenum with KMnO4 was better and was the first method to be used in the degradation of BaP and its metabolites; （2） the metabolite, BP 1,6-quinone was the most liable to be accumulated in pure cultures; （3） the effect of degradation was the best when the concentration of KMnO4 in the cultures was 0.01% （w/v）, concentration of the three compounds was 5 mg/L and pH was 6.2. Based on the experimental results, a novel concept with regard to the bioremediation of BaP-contaminated environment was discussed, considering the influence on environmental toxicity of the accumulated metabolites.     

Impact of atrazine and nitrogen fertilizers on the sorption of chlorotoluron in soil and model sorbents

Sorption of chlorotoluron in ammonium sulfate, urea and atrazine multi-solutes system was investigated by batch experiments. The results showed application of nitrogen fertilizers to the soil could affect the behavior of chlorotoluron. At the same concentration of N, sorption of chlorotoluron decreased as the concentration of atrazine increased on the day 0 and 6 in soil, respectively. The sorption of chlorotoluron increased from 0 to 6 d when soils were preincubated with deionized water, ammonium sulfate and urea solution for 6 d. That indicated incubation time was one of the most important factors for the sorption of chlorotoluron in nitrogen fertilizers treatments. The individual sorption isotherms of chlorotoluron in rubbery polymer and silica were strictly linear in single solute system, but there were competition sorption between pesticides or between pesticides and nitrogen fertilizers. That indicated the sorption taken place by concurrent solid-phase dissolution mechanism and sorption on the interface of water-organic matter or water-mineral matter.     

Distribution and ecological effect of mercury in Laogang landfill, Shanghai, China

Laogang landfill near Shanghai is the largest landfill in China, and receives about 10000 t of daily garbage per day, Samples of topsoil and plants were analyzed to evaluate mercury pollution from the landfill. For topsoil samples, there were significant correlations among total mercury （HgT）, combinative mercury （Hgc） and gaseous mercury （HgG）, and content of total organic carbon （TOC）, but, no significantly relationship was found between Hg content and filling time. Hg content changes in vertical profiles with time showed that the average Hgv of profiles 1992, 1996, and 2000 was similar, but their average HgG was quite different. HgT was significantly correlated with Hgc in profile 1992 and 2000, and Hgv was significantly correlated with Hg6 in profile 1996. HgG/Hgv ratio in profile samples decreased in the order of （HgG,/HgT）1992〉（HgG/HgT）1996〉〉（HgG/HgT）2000. A simple outline of Hg release in landfill could be drawn： with increasing of filling time, degradation undergoes different biodegradation, accordingly, gaseous mercury goes through small, more, and small proportion to total mercury. Distribution of Hg in plants was inhomogeneous, following the order of leaf〉root〉stem. The highest value of leaf may be associated with higher atmospheric Hg from landfill. Ligneous plants （e.g. Phyllostachys glanca, Prunus salicina and Ligustrum lucidum） are capable of enriching more Hg than herbaceous plants.     

EDTA-enhanced phytoremediation of lead contaminated soil by Bidens maximowicziana

Phytoremediation is a potential cleanup technology for the removal of heavy metals from contaminated soils.Bidens maximowicziana is a new Pb hyperaccumulator,which not only has remarkable tolerance to Pb but also extraordinary accumulation capacity for Pb.The maximum Pb concentration was 1509.3 mg/kg in roots and 2164.7 mg/kg in overground tissues.The Pb distribution order in the B. maximowicziana was:leaf>stem>root.The effect of amendments on phytoremediation was also studied.The mobility of soil Pb and the Pb concentrations in plants were both increased by EDTA application.Compared with CK(control check),EDTA application promoted translocation of Pb to overground parts of the plant.The Pb concentrations in overground parts of plants was increased from 24.23-680.56 mg/kg to 29.07-1905.57 mg/kg.This research demonstrated that B.maximowicziana appeared to be suitable for phytoremediation of Pb contaminated soil,especially,combination with EDTA.     

Decomposition of alachlor by ozonation and its mechanism

Decomposition and corresponding mechanism of alachlor, an endocrine disruptor in water by ozonation were investigated. Results showed that alachlor could not be completely mineralized by ozone alone. Many intermediates and final products were formed during the process, including aromatic compounds, aliphatic carboxylic acids, and inorganic ions. In evoluting these products, some of them with weak polarity were qualitatively identified by GC-MS. The information of inorganic ions suggested that the dechlorination was the first and the fastest step in the ozonation of alachlor.     

Enzymatic oxidation of aqueous pentachlorophenol

The influence of the nonionic surfactant Tween 80 on pentachlorophenol （PCP） oxidation catalyzed by horseradish peroxidase was studied. The surfactant was tested at concentrations below and above its critical micelle concentration （CMC）. Enhancement of PCP removal was observed at sub-CMCs. The presence of Tween 80 in the reaction mixture reduced enzyme inactivation which occurred through a combination of free radical attack and sorption by precipitated products. A simple first-order model was able to simulate time profiles for enzyme inactivation in the presence or absence of Tween 80. At supra-CMCs, the surfactant caused noticeable reductions in PCP removal, presumably through micelle partitioning of PCP which precluded the hydrophobic PCP molecule from interacting with the enzyme.