腾格里沙漠东南部近地层沙尘水平通量和降尘

沙漠是近地层沙尘物质的重要来源之一,沙漠地区近地层水平输送的沙尘物质随高度的变化特征和不同高度处的沉降量直接影响着沙尘的输送过程. 选择腾格里沙漠东南缘流动沙丘区的风沙科学观测场为研究区,利用沙尘水平通量采集器和降尘测量器对近地层约50 m的不同高度水平运动的沙尘和降尘进行了近2年的观测,对沙漠地区近地层水平运动的沙尘随高度变化特征及不同高度的降尘量进行了讨论. 结果表明:沙尘的水平通量和降尘量均随高度的增加而减小,二者与高度均可表示为指数函数的关系; 同时,沙尘水平通量与降尘量之间存在正相关关系,二者可用线性函数相互转换.      

腾格里沙漠东南部近地层沙尘水平通量和降尘量随高度的变化特征

沙漠是近地层沙尘物质的重要来源之一,沙漠地区近地层水平输送的沙尘物质随高度的变化特征和不同高度处的沉降量直接影响着沙尘的输送过程.选择腾格里沙漠东南缘流动沙丘区的风沙科学观测场为研究区,利用沙尘水平通量采集器和降尘测量器对近地层约50 m的不同高度水平运动的沙尘和降尘进行了近2年的观测,对沙漠地区近地层水平运动的沙尘随高度变化特征及不同高度的降尘量进行了讨论.结果表明:沙尘的水平通量和降尘量均随高度的增加而减小,二者与高度均可表示为指数函数的关系;同时,沙尘水平通量与降尘量之间存在正相关关系,二者可用线性函数相互转换.     

城区与郊区PM2.5污染及传输特征差异性

基于云高仪激光雷达、飞机AMDAR数据和常规站点等多源观测数据,并与数值模拟（CAMx-PSAT模型）相结合,以京津冀典型城市——北京城区与郊区（密云）和石家庄城区与郊区（平山）为案例研究区域,对城区和郊区边界层高度差异（ΔPBLH）、地面PM_2.5浓度差异（ΔSurf_PM_2.5）、高空PM_2.5浓度差异（ΔVert_PM_2.5）和传输通量强度及高度分布特征差异进行分析.结果表明,由于人为热源、短波辐射和热力湍流等因素,导致城区年均边界层高度（PBLH）较郊区高8%~29%,且不同季节下城区PBLH月均较郊区高2%（石家庄4月）~47%（北京7月）.由于人为排放、逆温和大气湍流等共同作用,在0~1260 m之间等高度城区年均ρ（PM_2.5）较郊区高0.1（石家庄）~29.7（北京）μg ·m^-3,随高度增加而减小.城区年均总净通量强度远大于郊区,城区表现为流出,郊区表现为流入,是由于城区低压和郊区高压,形成城郊热力环流.北京城区和郊区与周边的年均总净通量强度之和（44.77 t ·d^-1）大于石家庄（34.44 t ·d^-1）.受风速和PM_2.5浓度的影响,在0~1260 m之间,城区和郊区与周边的净通量随离地高度的增加通量强度呈现明显增大趋势,其中1月城区和4月郊区与周边的传输交换对环境影响最为明显.不同季节下城区和郊区最大净通量的强度差异明显,两者相差2.23~4.48倍;但最大净通量强度的高度特征差异较小,主要位于611~1260 m.     

北京2019年冬季一次典型霾污染特征与成因分析

为研究北京冬季霾污染过程的污染特征和成因,以北京2019年12月一次典型PM_2.5污染过程为分析对象,利用气溶胶垂直探测资料、边界层气象场和近地湍流资料,对霾不同污染阶段的特征与边界层理化特性的演变进行综合分析.结果表明：①观测期间北京共经历两次污染生消,历时5 d,PM_2.5小时浓度最高220 μg·m^-3,超过重度污染标准的时次占比53%.②高空稳定形势和地面均压场配置下,来自北京西南城市群地表的气溶胶和水汽传输（占比48%）,在近地层偏南弱风（风速1~2 m·s^-1）,贴地强逆温［0.8 K·（100 m）^-1］和高湿（相对湿度80%以上）等不利扩散的气象条件下不断吸湿增长,加之本地污染排放,成为霾日维持的主要原因.且随污染加重,气溶胶球形特征逐步显著（退偏比从0.05降至0.02）.③各湍流统计量（湍流强度、摩擦速度和湍流动能）在重污染发生与结束前提前出现规律性异常突降（小时波动率77%）与激增（超过一个量级的峰值）现象,表明湍流统计量可作为重污染过程发生和结束的预报指标,其中湍流强度响应提前的时长与其峰值后的持续湍流强弱有关.污染累积阶段摩擦速度（0.04~0.21 m·s^-1）、湍流强度（均值0.678）和湍流动能（均值0.643 m²·s^-2）等均维持在较低水平,底层大气混合扩散能力较差,对污染持续累积起重要作用.另外晴天和霾天感热通量均由地面向大气输送,且呈明显的日单峰变化特征,霾天感热通量（20W·m^-2）较晴天小（60W·m^-2）;潜热通量则全程在0值附近.     

基于综合观测的中国中东部地区一次严重污染过程分析

利用寿县国家气候观象台GRIMM80颗粒物监测仪、Aurora3000浊度计等探测的气溶胶浓度、大气散射系数分析了2018年1月中国中东部地区发生的一次严重污染过程.利用Airda微波辐射计探测的近地层温湿廓线数据,结合地面常规气象观测资料及EC再分析资料,探讨了此次污染过程形成、短时消散及清除的气象原因.结果表明：与历史同期相比,500 hPa极涡较浅、经向环流减弱;850 hPa西南气流强盛,中低层水汽充足加剧污染.污染发生于冷空气间歇期.在此污染过程中,地面平均风速为1.5 m·s^-1,日均日照时数为0.1 h,相对湿度为91.2%,高湿、小风、多云寡照不利于污染水平扩散.1月18-22日边界层持续存在多层逆温,第一逆温层基本多为贴地逆温,逆温高度低于200 m,近地层大气比湿超过5 g·kg^-1,最大值高于7 g·kg^-1.在此期间出现两次空气质量短时段好转,这主要源于对流层中低层转为西北风,900 hPa以下聚集相当位温（Q_e）低于288 K的浅薄冷空气堆,导致贴地逆温层消失地面污染被稀释.但两次弱冷空气没有打破边界层内有利于污染聚集的逆温、高湿结构,地面气团温度露点差无明显变化.23日较强冷空气使高空干洁大气入侵近地层,850 hPa以下Q_e<284 K,表明地面污染气团被置换,污染过程结束.     

水深和扰动对北运河沉积物释放的模拟研究

结合汛期河道水位上涨现状,以河流沉积物为研究对象,通过实验室水槽模拟河道的方式,分别在静置和扰动两种工况下,探索汛期降雨导致河道水位上涨对河道沉积物中污染物释放的影响.研究结果表明,在静置条件下,水深正向影响沉积物中COD_Cr的释放通量（R²=0.945）,负向影响NH₃-N释放通量（R²=0.967）.在扰动条件下,水深负向影响沉积物中硝酸盐氮的释放通量（R²=0.892）,正向影响其他污染物的释放通量.与水位0.3 m相比,水位在0.9 m时,扰动条件下沉积物中COD_Cr、TN、TP以及活性磷的平均释放通量分别提高约150.09%、63.59%、400.84%和352.28%.水位上涨会明显提升沉积物中污染物释放通量,水深对扰动条件下污染物释放更敏感.     

季节非对称升温对喀斯特土壤CO2释放的影响

全球变暖呈现季节非对称升温特征,若在研究全球变化对生态系统的影响时未充分考虑该特征,很可能导致研究结果失真.基于红外线辐射增温法,野外模拟不同升温情景下喀斯特土壤CO₂释放的短期（4 a）特征.升温情景包括不升温（对照）、对称升温（全年同步升温2.0℃）和非对称升温（冬春/夏秋季升温幅度为2.5℃/1.5℃、3.0℃/1.0℃、3.5℃/0.5℃和4.0℃/0℃）.结果表明,与对照相比,升温样地土壤CO₂通量显著提高,增加了0.26 μmol·（m²·s）^-1,增幅为17.41%,其中冬春季通量增加了0.23 μmol·（m²·s）^-1.在平均升温2.0℃情景下,土壤CO₂释放的温度系数（Q₁₀）变幅为1.53~3.24之间,平均值为2.23.对称升温处理中夏秋季土壤CO₂通量升温贡献率（80%）远高于冬春季（20%）;非对称升温处理夏秋季和冬春季平均升温贡献率相当（46%和54%）.5个升温情景下CO₂通量和Q₁₀呈现随升温的非对称性增加而降低的趋势,其中对称升温处理CO₂通量显著高于中度、高度和极端非对称升温处理.各处理中,夏秋季Q₁₀均大于冬春季,这可能与土壤含水量、土壤微生物、可溶性无机碳和植被生长等有关.研究揭示,基于对称升温情景可能会高估全球变暖对喀斯特土壤CO₂释放的影响.     

黄土丘陵区柠条人工林不同深度土壤呼吸速率对土壤温湿度的响应

明确气候变化背景下生态脆弱区土壤呼吸速率特征和土壤温湿度对其影响,对准确评估和预知该区碳收支具有重要意义.以陕北黄土丘陵区自然撂荒地22 a柠条人工纯林为研究对象,通过CO₂分析仪和温湿度传感器测定不同土层（10、50和100 cm） CO₂浓度平均值和土壤温湿度,采用Fick第一扩散系数法计算土壤呼吸速率,探究不同土层土壤温度、土壤湿度和土壤呼吸速率的动态变化特征,并进一步分析不同土层土壤呼吸速率对土壤温湿度的响应.结果表明,土壤呼吸速率日变化随土层深度增加显著降低（P<0.05）,峰值出现时间存在滞后现象,相邻土层间（10、50和100 cm）土壤呼吸速率由上至下均滞后1 h;6~9月土壤呼吸速率月变化为多峰曲线,其中10、50和100 cm土层土壤呼吸速率最大值分别在7月25日、8月6日和8月10日,达13.96、2.96和1.47 μmol ·（m² ·s）^-1;土壤温度对土壤呼吸速率影响随土层深度增加而减弱,50 cm及以下土层土壤温度对土壤呼吸速率无显著影响（P>0.05）,10 cm土层指数拟合最优,R²=0.96,50 cm和100 cm土层拟合较差,R²分别为0.00和0.01,温度敏感系数Q₁₀随土层深度增加而减小;不同土层土壤湿度对土壤呼吸速率影响均显著（P<0.05）,二次拟合表现为50 cm （R²=0.35）>10 cm （R²=0.22）>100 cm （R²=0.31）;10、50和100 cm土层土壤温度与土壤湿度的综合作用可解释土壤呼吸速率的96%、6%~50%和22%~24%.综上所述,黄土丘陵区柠条人工纯林不同深度土壤温湿度对土壤呼吸速率影响存在差异,10 cm土层土壤呼吸速率受土壤温湿度的综合影响,但土壤温度的相对贡献更高,50 cm土层及以下土壤湿度为关键因子.研究结果有助于更好地预测未来气候变化对该区陆地生态系统碳循环影响,为温室气体调控提供理论依据.     

外源盐对盐碱土壤无机碳淋溶特征的影响

为探究干旱盐碱区高风化土壤-地下水无机碳的固存机制,利用室内土柱淋溶模拟实验结合相关与回归分析,设置5个土壤电导率（EC=0.899、10、20、40、80 mS·cm^-1）处理,依次编号为S₀、S₁、S₂、S₃、S₄,每个处理重复2次,共计10个土柱（内径7.5 cm,高120 cm）,研究无机碳在不同盐碱程度土壤及淋出液中的分布、运移转化及其影响因素.结果表明：①土壤及淋出液无机碳含量均随土壤电导率的增加呈先增后降的变化趋势,其中,淋出液溶解性无机碳（DIC）和土壤难溶性无机碳（SIC）含量在电导率为10 mS·cm^-1处理下最高（淋溶后分别可达431.58 mg·L^-1和128.91 g·kg^-1）,且该处理下淋出液DIC含量随淋溶时间延长持续增加;土壤可溶性无机碳（SDIC）含量在电导率为20 mS·cm^-1处理下高于其他处理,在表层（0~30 cm）有最高值（淋溶后可达0.66 g·kg^-1）,随深度增加而降低.电导率为0~20 mS·cm^-1处理下,表层土壤SIC含量低于深层（60~100 cm）土壤;电导率为40和80 mS·cm^-1处理下,土壤及淋出液无机碳含量均降低,土壤SIC在表层聚积,随深度增加而降低.②淋出液DIC与EC呈显著负相关（r=-0.928,p<0.01）,与pH呈显著正相关（r=0.958,p<0.01）;土壤SDIC与土壤EC呈显著负相关（r=-0.582,p<0.05）,与土壤pH呈显著正相关（r=0.899,p<0.01）;土壤SIC与土壤EC呈显著负相关（r=-0.58,p<0.05）,与土壤pH无明显相关性（r=0.236,p>0.05）.pH和EC都是影响土壤及淋出液中无机碳含量的重要因素,pH对溶解性无机碳的影响高于EC,土壤难溶性无机碳主要受EC影响.总而言之,在干旱盐碱区高风化土壤的淋溶过程中,无机碳一部分以DIC的形式随淋溶液淋出到地下水中,另一部分以SDIC和SIC的形式存在于土壤中.     

外源碳和氮输入对降水变化下土壤呼吸的短期影响

利用野外原位小区控制试验,模拟研究了降水变化下草地生态系统土壤呼吸对外源碳和氮输入的响应.在2014年,以内蒙古锡林河流域温带典型草原为研究对象,测定了增加降水处理（CK）、增加降水配施氮肥处理[CN,2.5 g·（m²·a）^-1]、增加降水配施碳源处理[CG,24 g·（m²·a）^-1]和增加降水配施氮肥和碳源处理[CNG,2.5 g·（m²·a）^-1+24 g·（m²·a）^-1]下土壤呼吸的变化,并分析了土壤呼吸与土壤温度、土壤水分、土壤可溶性有机碳（DOC）、土壤微生物量碳（MBC）之间的关系.结果表明,在自然降水较多的第一次增加降水（FWE）阶段,CG处理和CNG处理168 h土壤CO₂累积通量显著增加,而CN处理168 h土壤CO₂累积通量无显著变化,并且CG处理和CNG处理土壤MBC含量显著高于CK处理和CN处理,同时,该阶段平均CO₂释放速率与土壤MBC含量正相关（P<0.05）.与FWE阶段相比,无自然降水的第二次增加降水（SWE）阶段各处理168 h土壤CO₂累积释放量显著降低,并且各处理MBC含量也显著降低（P<0.05）,仅有土壤DOC含量显著增加（P<0.05）,CG处理和CN处理168 h土壤CO₂累积通量显著降低（P<0.05）.两个降水阶段土壤呼吸速率与土壤温度或土壤体积含水量均有显著的正相关性（P<0.05）.因此,自然降水的分布对土壤水分的影响调控着外源氮和碳对半干旱草地生态系统土壤呼吸的作用效应.     

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.