Preparation, characterization and application of thiosemicarbazide grafted multiwalled carbon nanotubes for solid-phase extraction of Cd(Ⅱ), Cu(Ⅱ) and Pb(Ⅱ) in environmental samples

Thiosemicarbazide-grafted multi-walled carbon nanotubes were prepared and employed to investigate the pre-concentration of Cd（Ⅱ）, Cu（Ⅱ） and Pb（Ⅱ） from aqueous solution prior to their determination by ICP-OES. The resulting material was characterized by FT-IR, TGA and SEM. Various factors influencing the separation and pre-concentration were investigated. The enrichment factor typically is 60. Under optimized experimental conditions, the maximum adsorption capacities of Cd（Ⅱ）, Cu（Ⅱ） and Pb（Ⅱ） were found to be 1.98, 10.94, 3.69 mg/g, and the relative standard deviations are 〈 3.5% （n = 6）. The new adsorbent shows superior reusability and stability. The procedure was successfully applied to the determination of trace quantities of Cd（Ⅱ）, Cu（Ⅱ） and Pb（Ⅱ） in water samples.     

Phytoremediation potential of charophytes: Bioaccumulation and toxicity studies of cadmium, lead and zinc

The ability for usage of common freshwater charophytes,Chara aculeolata and Nitella opaca in removal of cadmium (Cd),lead (Pb) and zinc (Zn) from wastewater was examined.C.aculeolata and N.opaca were exposed to various concentrations of Cd (0.25 and 0.5 mg/L),Pb (5 and 10 mg/L) and Zn (5 and 10 mg/L) solutions under hydroponic conditions for 6 days.C.aculeolata was more tolerant of Cd and Pb than N.opaca.The relative growth rate of N.opaca was drastically reduced at high concentrations of Cd and Pb although both were tolerant of Zn.Both macroalgae showed a reduction in chloroplast,chlorophyll and carotenoid content after Cd and Pb exposure,while Zn exposure had little effects.The bioaccumulation of both Cd and Pb was higher in N.opaca (1544.3 μg/g at 0.5 mg/L Cd,21657.0 μg/g at 10 mg/L Pb) whereas higher Zn accumulation was observed in C.aculeolata (6703.5 μg/g at 10 mg/L Zn).In addition,high bioconcentration factor values (> 1000) for Cd and Pb were observed in both species.C.aculeolata showed higher percentage of Cd and Pb removal (> 95%) than N.opaca and seemed to be a better choice for Cd and Pb removal from wastewater due to its tolerance to these metals.     

Amino-functionalized core-shell magnetic mesoporous composite microspheres for Pb(II) and Cd(II) removal

Amino-functionalized Fe3O4@mesoporous SiO/ core-shell composite microspheres NH2-MS in created in multiple synthesis steps have been investigated for Pb（Ⅱ） and Cd（Ⅱ） adsorption. The microspheres were characterized by transmission electron microscope （TEM）, scanning electron microscope （SEM）, N2 adsorption-desorption, zeta potential measurements and vibrating sample magnetometer. Batch adsorption tests indicated that NH2-MS exhibited higher adsorption affinity toward Pb（Ⅱ） and Cd（Ⅱ） than MS did. The Langmuir model could fit the adsorption isotherm very well with maximum adsorption capacity of 128.21 and 51.81 mg/g for Pb（Ⅱ） and Cd（Ⅱ）, respectively, implying that adsorption processes involved monolayer adsorption. Pb（Ⅱ） and Cd（Ⅱ） adsorption could be well described by the pseudo second-order kinetics model, and was found to be strongly dependent on pH and humic acid. The Pb（Ⅱ）- and Cd（Ⅱ）-loaded microspheres were effectively desorbed using 0.01 mol/L HC1 or EDTA solution. NH2-MS have promise for use as adsorbents in the removal of Pb（Ⅱ） and Cd（Ⅱ） in wastewater treatment processes.     

给水厂残泥免烧陶粒对Pb与Cd的吸附特征

针对高效低廉的吸附材料——WTR（water treatment residuals,给水厂残泥）因颗粒细小在水处理工艺中难以应用的问题,利用免烧法制备出WTR陶粒,研究其对Pb和Cd的吸附特征.批量吸附试验结果表明,准二级动力学模型和Langmuir等温吸附模型能较好地描述WTR免烧陶粒对Pb和Cd的吸附动力学（R2>0.995 8）与等温吸附过程（R2>0.994 8）.在溶液pH为5、恒温25℃、振荡24 h下,Langmuir等温吸附模型计算得到的WTR免烧陶粒对Pb和Cd的最大吸附容量分别为13.97和18.60 mg/g.单因素条件试验结果表明,WTR免烧陶粒对Pb和Cd的吸附量均随溶液初始pH的升高而增加,当pH由3升至9时,WTR免烧陶粒对Pb和Cd的吸附量分别增加了1.44和0.95倍;离子强度的增加不利于WTR免烧陶粒对Pb和Cd的吸附.批量等温解吸试验结果表明,在pH为4~8的溶液中,Pb和Cd较难从WTR免烧陶粒中解吸出来,解吸率均在3.5%以内;当溶液pH为3时,Pb和Cd的解吸率分别高达65.88%和45.01%.BCR分级提取结果表明,Pb和Cd均主要以酸提取态形式（占比在68.18%以上）存在于WTR免烧陶粒中;同时,随着初始吸附量的增加,酸提取态比例显著减少,而还原态和残渣态比例显著增加.研究显示,WTR免烧陶粒对Pb和Cd具有较强的吸附能力,可作为一种高效的重金属吸附材料应用于水处理工艺中.      

Adsorption characteristics of copper, lead, zinc and cadmium ions by tourmaline

The adsorption characteristics of heavy metals： Cu（Ⅱ）, Pb（Ⅱ）, Zn（Ⅱ） and Cd（Ⅱ） ions on tourmaline were studied. Adsorption equilibrium was established. The adsorption isotherms of all the four metal ions followed well Langmuir equation. Tourmaline was found to remove heavy metal ions efficiently from aqueous solution with selectivity in the order of Pb（Ⅱ）〉Cu（Ⅱ）〉Cd（Ⅱ）〉Zn（Ⅱ）. The adsorption of metal ions by tourmaline increased with the initial concentration of metal ions increasing in the medium. Tourmaline could also increase pH value of metal solution.The maximum heavy metal ions adsorbed by tourmaline was found to be 78.86, 154.08, 67.25, and 66.67 mg/g for Cu（Ⅱ）, Pb（U）, Zn（Ⅱ） and Cd（U）, respectively. The temperature （25-55℃） had a small effect on the adsorption capacity of tourmaline. Competitive adsorption of Cu（Ⅱ）, Pb（Ⅱ）, Zn（Ⅱ） and Cd（Ⅱ） ions was also studied. The adsorption capacity of tourmaline for single metal decreased in the order of Pb〉Cu〉Zn 〉Cd and inhibition dominance observed in two metal systems was Pb〉Cu, Pb〉Zn, Pb〉Cd, Cu〉Zn, Cu〉Cd, and Cd〉Zn.     

接种丛枝菌根真菌对雌雄美洲黑杨吸收铅镉的影响

以雌雄美洲黑杨(Populus deltoides)为研究对象,砂培条件下,研究接种丛枝菌根真菌(Glomus intraradices)对受Pb污染(200 mg·kg-1)、Cd污染(10 mg·kg-1)及复合污染的雌雄美洲黑杨Pb和Cd的富集与分配特征的影响,关注Pb/Cd复合污染独特的环境效应.结果表明:1未接种丛枝菌根真菌条件下,与单一污染相比,复合污染增加了美洲黑杨雄株叶、粗根、细根Pb和Cd含量;复合污染增加了雌株叶片中Pb和Cd含量,却降低了粗根和细根中Pb和Cd含量;复合污染条件下雄株Pb和Cd向地上部分器官的迁移率分别增加135%和78%,雌株则分别增加52%和18%.2复合污染条件下,接种丛枝菌根真菌引起雄株Pb和Cd富集系数分别增加87%和6%,雌株则分别增加171%和65%;雄株Pb和Cd向地上部分器官的迁移率降低65%和69%,雌株则分别降低59%和53%.3Pb污染条件下,接种丛枝菌根真菌的雌雄之间Pb积累量没有显著差异;Cd污染条件下,接种丛枝菌根真菌的雄株总Cd积累量是雌株的1.7倍;复合污染条件下,接种丛枝菌根真菌的雌株Pb和Cd总积累量分别是雄株的1.3和1.2倍.本研究表明,接种G.intraradices能提高美洲黑杨的Pb和Cd积累能力,对于不同污染条件下,应根据实际情况选择合适的杨树性别进行造林和生态修复.     

组配改良剂对土壤-蔬菜系统铅镉转运调控的场地研究

以组配改良剂LS(石灰石∶海泡石=2∶1)为试验材料,通过对湘南某矿区附近铅镉复合污染旱地土壤进行现场改良钝化,研究施加不同量的LS(0、2、4、8 g·kg-1)对茄子和苋菜植株吸收累积Pb和Cd的影响以及对Pb和Cd在2种蔬菜植株各部位间转运的调控.结果表明:1施加LS能够显著提高土壤p H,降低土壤中交换态Pb和Cd的含量.2施加LS能显著降低2种蔬菜植株各部位中Pb和Cd的含量.LS施加量为2~8 g·kg-1时,茄子果实中Pb和Cd的含量分别降低44.7%~78.6%和36.0%~78.7%;苋菜植株茎叶中Pb和Cd的含量分别降低45.8%~59.1%和40.0%~87.2%.3LS的施加降低了2种蔬菜植株各部位间Pb和Cd的转运系数.2种蔬菜植株在根-茎-果实间或根-茎叶间转运Cd的能力大于Pb,且施加LS各处理下,同种蔬菜相同部位对Pb和Cd的转运能力大小关系保持不变.     

单一与复合胁迫下油菜对镉、铅的吸收效应

以干旱区绿洲灰漠土为供试土壤,油菜(Brassica campestris L.)为供试植物,通过盆栽试验研究了Cd/Pb单一和复合胁迫下其在油菜体内的吸收和富集特征,并解析了油菜条件下Cd、Pb的交互作用.结果表明,Cd/Pb单一和复合胁迫下油菜体内Cd、Pb的含量均随着其胁迫浓度的增大而增大,但复合胁迫下油菜对Cd、Pb的吸收互为拮抗作用(Cd最大胁迫浓度<7mg.kg-1,Pb最大胁迫浓度<1 500 mg.kg-1);Cd单一胁迫下油菜对其富集能力和其在油菜体内的迁移能力均随着其胁迫浓度的增加呈现先增大后减小的趋势,Pb单一胁迫下油菜对其富集能力和其在油菜体内的迁移能力则均随着其胁迫浓度的增加而持续减小;复合胁迫降低了油菜对Cd、Pb的富集能力和Pb在油菜体内的迁移能力,但提高了Cd在油菜体内的迁移能力;油菜对Cd的吸收能力和其在油菜体内的迁移能力均远远大于Pb;油菜对重金属Cd、Pb的吸收和迁移模式均符合二次方程.     

锅炉协同处置危险废物过程中Pb和Cd的挥发特性

为研究危险废物在锅炉协同处置过程中Pb和Cd的挥发特性,通过共燃烧和消解试验,研究了不同化合物形态下Pb、Cd的挥发率(α)、残留率(r)和表观活化能(E). 结果表明:以硫化物、氯化物、硫酸盐和氧化物存在的Pb、Cd的挥发率与温度(T)和停留时间(t)均呈正相关. 当温度低于950 ℃、停留时间为52 min时,不同化合物形态的Pb、Cd挥发率相差较大,PbCl₂在800 ℃下挥发率接近64%,而PbO仅为17%;温度高于1 250 ℃、停留时间为52 min时,不同化合物形态下的Pb、Cd挥发率均大于95%,接近于完全挥发;1 400 ℃时,不同化合物形态的Pb、Cd在燃烧残渣中的残留率均低于0.3%. 结合化学反应动力学理论,对Pb、Cd在锅炉协同处置过程中的挥发特性进行动力学模拟,得到PbS、PbCl₂、PbSO₄、PbO 中Pb的表观活化能分别为23.64、18.44、65.79、61.35 kJ/mol,CdS、CdCl₂、CdSO₄、CdO中Cd的表观活化能分别为53.22、20.87、42.42、28.75 kJ/mol. 由表观活化能数据可以得出不同形态化合物的Pb、Cd挥发率随温度和停留时间变化的动力学方程α=f(T,t),并可预测锅炉协同处置危险废物过程中Pb和Cd的挥发率,确定适合锅炉协同处置的危险废物类别.      

水泥窑共处置过程中水泥生料对Pb与Cd的吸附/冷凝特性

为了研究水泥窑共处置过程中水泥生料对Pb、Cd的吸附/冷凝特性,采用氮吸附仪和SEM(场发射扫描电镜)对水泥生料的基本物理性质(比表面积、孔径和微观表面积)进行研究;同时,利用小型试验装置对重金属Pb、Cd的氧化物(PbO、CdO)展开了吸附/冷凝研究. 结果表明:水泥生料的比表面积(2.49 m2/g)较小,微观表面结构致密无孔,因此,在水泥窑共处置过程中水泥生料对重金属的吸附/冷凝作用以冷凝为主. 进入控温立式炉的重金属可分为三部分:①冷凝在管壁上,其中Pb、Cd分别占各自入炉总量的67%～72%、58%～65%;②吸附/冷凝在水泥生料上,其中Pb、Cd分别占各自入炉总量的13%～17%、16%～21%;③随烟气释放到空气中,其中Pb、Cd分别占各自入炉总量的10%～18%、14%～26%. 水泥生料对Pb、Cd的吸附/冷凝特性均可用双常数方程拟合,线性拟合的相关系数均在0.95以上. 动力学方程拟合得到水泥生料对Pb、Cd的吸附/冷凝活化能,二者分别为5.827、6.050 kJ/mol,由此可预测水泥生料对Pb和Cd的吸附/冷凝量.      

曲霉对水中重金属的吸附去除

利用2种曲霉A.sojae M146和A.oryzae M149的菌体，作为吸附剂对水中Pb^2＋和Cd^2 进行去除实验。结果表明，曲霉菌体的最佳培养时间为72h，吸附的最佳pH为5．5、温度为30℃、时间为1h。在最佳实验条件下，A.sojae M146对Pb^2 和Cd^2 的吸附率，分别为69．76％和72．28％；A.oryzae M149对Pb^2 和Cd^2 的吸附率，分别为60．64％和81．34％。使用稀碱溶液对曲霉菌体进行浸泡预处理后，可提高对重金属的吸附去除效果；而使用稀释、乙醇水溶液以及蒸馏水对菌体浸泡后，明显降低了重金属的去除效果。Na2CO3和EDTA溶液，可以有效地将重金属从曲霉体上解吸下来，从而达到重复利用菌体作为吸附剂的目的。     

不同添加剂对铅冶炼污染土壤中铅、镉稳定效果的研究

为了研究铅冶炼形成的重金属复合污染石灰性土壤中重金属的稳定方法,在污染土壤(Pb、Cd含量分别为2337和21.4mg·kg-1)中分别加入磷酸二氢钾、磷酸二氢钙、石灰、盐酸、磷酸,通过盆栽试验探讨了不同添加剂对土壤重金属有效性和黑麦草(Lolium perenne L.cv.Rainbow)性状的影响.结果表明,加入石灰显著降低了土壤中DTPA-Cd含量,但对DTPA-Pb含量无显著影响;加入盐酸显著增加了土壤DTPA-Cd含量,对DTPA-Pb含量无明显影响.磷酸二氢钾、磷酸二氢钾与盐酸配合、磷酸二氢钙和磷酸均显著降低了土壤DTPA-Pb(降低幅度为39.5%～47.8%)和DTPA-Cd含量(降低幅度为10.5%～19.4%)(p<0.05),且磷酸二氢钾和盐酸配合处理与单独加入磷酸二氢钾处理相比,土壤DTPA-Pb含量下降了12.6%(p<0.05).磷酸二氢钾和盐酸配合处理土壤的Olsen-P含量和pH均显著低于单独加入磷酸二氢钾处理.加入石灰和盐酸处理的植物产量显著低于除对照外的其它处理,其余处理地上部产量比对照增加了100%～140%.加入盐酸显著增加了植物地上部镉含量,各处理均显著降低了植物地上部铅含量(p<0.05).     

污泥基活性炭去除水中重金属离子效能与动力学研究

以城市污泥为主要原料制备了污泥基活性炭(SAC),考察了其对重金属离子的吸附去除效能和吸附动力学规律.并选择了2种商品活性炭(煤质炭,MAC和椰壳炭,YAC)作为对比,以初始浓度为50mg/L的Cu(II),Pb(II),Cd(II),Cr(VI)4种重金属离子为去除对象,分别进行了3种活性炭的表面理化性质分析及其对4种重金属离子的吸附试验.结果表明,SAC的比表面积和微孔容积仅为YAC和MAC的1/3~1/2,吸附速率也相对较慢,但其对Cu(II),Pb(II),Cr(VI),Cd(II)的平衡吸附量却远大于2种商品活性炭,分别为9.9,8.9,8.2,5.4mg/g,说明SAC表面的高酸性基团含量对重金属离子的吸附起到了关键作用;Langmuir与Freundlich吸附等温模型均能较好地拟合SAC对Cu(II)和Pb(II)的吸附,SAC对Cr(VI)的吸附过程更符合Langmuir模型,而SAC对于Cd(II)的吸附过程用Langmuir与Freundlich两个模型均不能较好地拟合,说明SAC表面缺少能够与Cd(II)发生反应的结合位点.     

污泥堆肥施用对土壤及地下水影响研究

为探究北京市污泥堆肥产品施用对土壤和地下水的影响,采用原状土柱模拟降雨试验方法,研究了在污泥堆肥产品年施用量为3、6、12kg/m²的条件下,Cu、Cr、Ni、Zn、Pb、Cd、As、Hg 8种重金属元素的迁移和淋溶特征.结果表明,Cd淋溶后残留最少（6.1%~11.9%）,进入淋溶水最多（4.5%~7.3%）;Hg淋溶残留最多（16.0%~22.1%）,进入淋溶水最少（<0.1%）.Hg、Pb、Ni、Cd、Cu在0~20cm土壤层积累最多（52.0%~78.7%）;Cr、Zn、As则在20~40cm层积累最多（42.7%~53.2%）.8种元素在土壤中的含量均符合《土壤环境质量农用地土壤污染风险管控标准（试行）》（GB 15618-2018）限值.淋溶水中测得的6种重金属浓度由大至小依次为Zn > As > Cd > Cu > Pb > Cr,受堆肥施用量及降雨量共同影响.淋溶水中Cu、Cr、Ni、Zn、Pb 5种元素的浓度始终在《地下水质量标准》（GB/T 14848-2017）Ⅰ类水质范围内,Cd、As、Hg在Ⅲ类范围内.     

施用海泡石对铅、镉在土壤-水稻系统中迁移与再分配的影响

以浙江省绍兴市某铅(Pb)、镉(Cd)复合重污染地区土壤(全Pb含量为2 028.22 mg·kg~(-1),全Cd含量为2.36 mg·kg~(-1))及具有低Pb、Cd积累特性的浙江省典型晚粳稻品种嘉33为对象,通过土培盆栽试验,研究了海泡石的施用对铅、镉复合污染土壤中有效态Pb、Cd的含量以及水稻植株对Pb、Cd的吸收和分配关系的影响.结果表明:供试土壤中有效态Pb、Cd的含量与添加的海泡石量呈显著负相关,其相关系数分别为-0.940、-0.952,均达到显著水平(P0.01).随着海泡石添加量的增加,水稻根、茎、叶和精米中Pb、Cd的含量有不同程度地降低,水稻根、茎、叶及精米对Pb、Cd的富集系数显著下降,同时茎对根系吸收的Pb、Cd以及精米对茎中Pb、Cd的转运系数也显著下降.当海泡石的添加量为9.00 g·kg~(-1)土时,嘉33精米中的Pb、Cd含量分别为(0.14±0.02)mg·kg~(-1)、(0.03±0.01)mg·kg~(-1),均低于国家的限量指标(GB 2762-2012);相比于对照组而言,水稻根、茎、叶及精米对Pb的富集系数分别下降了8.83%、29.96%、49.20%、79.41%,对Cd的富集系数分别下降了23.08%、63.22%、44.00%、82.35%;另外,茎对根吸收的Pb、Cd的转运系数分别下降了23.18%、52.19%,精米对茎转运的Pb、Cd的转运系数分别下降了70.83%、52.00%,意味着在铅、镉复合重污染土壤上,海泡石同时对重金属Pb、Cd在土壤-水稻系统的迁移与再分配具有较好的阻控作用,合理施用海泡石与低重金属积累品种相结合可以实现污染浓度相对较高的重金属Pb、Cd复合污染土壤的农业安全利用.     

Cd、Cu和Pb复合污染对蚯蚓抗氧化酶活性的影响

采用蚯蚓毒性试验和均匀组合设计(Cd:0~15 mg·kg-1,Cu:0~175 mg·kg-1,Pb:0~600 mg·kg-1)方法,以赤子爱胜蚓(Eisenia foetida)为试验蚓种,研究了土壤中重金属Cd、Cu、Pb复合污染对蚯蚓体内超氧化物歧化酶(SOD)、谷胱甘肽硫转移酶(GST)和酸性磷酸酶(AP)活性的影响,为重金属污染土壤的生物学诊断和风险评价提供科学依据.结果表明,Cd、Cu、Pb复合胁迫对蚯蚓SOD、GST和AP活性产生显著的诱导效应,酶活性与重金属含量及其持续时间密切相关:蚯蚓SOD活性在暴露前8 d因受重金属胁迫比第0 d增加了7.4%~240.5%,之后因胁迫过强被抑制,比第8 d下降了19.4%~69.7%.GST活性则在暴露前16 d持续增加了104.3%~217.3%,之后受抑制比第16 d下降了1.2%~40.3%.AP活性随时间呈"促进-抑制-促进-抑制"变化,在第8 d受胁迫比第0 d下降了9.2%~37.8%,至第16 d产生适应比第8 d增加了37.2%~117.2%,但最终因胁迫过强比第16 d下降了24.3%~34.0%.回归分析表明,Pb和Cd-Cu-Pb对SOD活性的产生影响最为显著,Cd和Cu则显著影响了GST和AP活性.     

Identification of rice cultivars with low brown rice mixed cadmium and lead contents and their interactions with the micronutrients iron, zinc, nickel and manganese

Paddy fields in mining areas are usually co-contaminated by a cocktail of mixed toxic heavy metals (e.g., Cd and Pb in Pb/Zn mines). However, previous studies on rice cultivars screened for effective metal exclusion have mostly focused on individual metals, and have been conducted under pot-trial or hydroponic solution conditions. This study identified rice cultivars with both low Cd and Pb accumulation under Cd-and Pb-contaminated field conditions, and the interactions of the toxic elements Cd and Pb with the micronutrient elements Fe, Zn, Mn and Ni were also studied. Among 32 rice cultivars tested, there were significant differences in Cd (0.06-0.59 mg/kg) and Pb (0.25-3.15 mg/kg) levels in their brown rice, and similar results were also found for the micronutrient elements. Significant decreases in concentrations of Fe and Mn were detected with increasing Cd concentrations and a significant elevation in Fe, Mn and Ni with increasing Pb concentrations. A similar result was also shown by Cd and Ni. Three cultivars were identified with a combination of low brown rice Cd and Pb, high micronutrient and grain yield (Wufengyou 2168, Tianyou 196 and Guinongzhan). Present results suggest that it is possible to breed rice cultivars with low mixed toxic element (Cd, Pb) and high micronutrient contents along with high grain yields, thus ensuring food safety and quality.     

水分条件对生物炭钝化水稻土铅镉复合污染的影响

采用培养试验,探究30% WHC、淹水和干湿交替等3种水分条件下,向Pb和Cd污染水稻土以1%添加量施入水稻秸秆生物炭后重金属的形态变化,为生物炭修复重金属复合污染稻田的水分管理提供科学依据.结果表明,添加生物炭后,淹水和干湿交替可显著提高土壤pH值、可溶性有机碳（DOC）和无定形氧化铁含量（Fe_o）.培养结束后,在添加生物炭的处理中,相较于30% WHC,淹水和干湿交替条件下TCLP提取态Pb含量分别下降31.87%和20.33%,TCLP提取态Cd含量分别下降25.29%和16.07%.淹水条件下弱酸提取态Pb和Cd下降幅度分别为24.78%和20.14%,且弱酸提取态Cd含量随时间逐渐降低.在3种水分条件下,Pb和Cd有效性降低顺序为：淹水 > 干湿交替 > 30% WHC.相关分析结果显示,土壤pH和无定形氧化铁含量均与有效态Pb和Cd呈显著负相关,表明淹水条件下添加生物炭可通过提高土壤pH和无定型氧化铁含量来有效钝化Pb和Cd,具有促进复合重金属污染酸性水稻土中重金属向稳定态转化的协同机制.     

Physiological responses and detoxific mechanisms to Pb, Zn, Cu and Cd in young seedlings of Paulownia fortunei

Paulownia fortunei has been successfully used in the phytoremediation of many Pb/Zn mine tailings. However, seed germination and young seedlings of P. fortunei rarely occurred in these mine tailings. The physiological responses and detoxific mechanisms of P. fortunei young seedling to Pb, Zn, Cu and Cd stress were investigated. The germinated rate, shoot length, chlorophyll and carotenoid contents in leaves of young seedlings had a great reduction under Zn and Cu treatments, but had little decrease under Pb and Cd treatments. The production rate of O₂^•−, H₂O₂ and malondialdehyde (MDA) contents significantly increased in response to added Zn and Cu indicating great oxidative stress for young seedlings, but they had no significant change to added Pb and Cd. Young seedlings had effective detoxific mechanism to Pb and Cd, as antioxidant enzymes activities, phytochelatins (PCs-SH) and proline contents increased with increasing rates of added Pb and Cd. However, young seedlings had un-effective detoxific mechanisms to Zn and Cu stress. Results revealed the heavy metals (such as Cu) that present at low concentrations in mine tailings may be major constraint for the survival of young seedlings.     

北京市不同区位耕作土壤中重金属总量与形态分布特征

采集北京市不同区位(中心城区、近郊平原、远郊平原)的代表性耕作土壤-麦粒匹配样品23组,分析不同人类活动强度影响下耕作土壤中重金属(Cd、Cu、Zn、Pb)全量、赋存形态以及生物有效性,并探讨其来源差异与健康风险.结果表明:①频繁的交通活动与工业释放致使中心城区(Pb平均含量为35.59 mg·kg-1)土壤呈现出较为明显的Pb富集特征,而长期污水灌溉等农业活动导致了近郊平原局部土壤重金属的明显积累.②土壤中Cu、Zn和Pb主要以残余态(35%～75%)与有机结合态(23%～53%)形式存在,其次是铁锰氧化态(1%～19%),而碳酸盐结合态(n.d.～5%)与离子交换态(n.d.～2%)含量非常少.Pb、Zn和Cu的生物可利用性从中心城区到近郊平原、远郊平原逐渐下降,Cd则呈相反的趋势.近远郊土壤中Cd的离子交换态(13%～31%)与碳酸盐结合态(11%～27%)占有相当高的比例,在4种重金属中生物可利用性最高.③Cd与Zn在麦粒中的含量与土壤中金属的铁锰氧化态含量正相关(P<0.05,r为0.43～0.57);④种植于中心城区与近郊土壤上的小麦籽粒中部分Zn、Pb含量超出了WHO限值,对当地居民健康构成潜在风险.