有机质官能团及微孔特性对疏水性有机污染物吸附的影响机制

作为重要的地质吸附剂,土壤/沉积物中的有机质是环境中疏水性有机污染物主要的汇.由于有机质的结构异质性,疏水性有机污染物一旦进入其中,会被吸附在不同的位点上,反应活性和生态风险进而会发生变化.对疏水性有机污染物在有机质上的吸附进行研究有助于了解其在环境中的分布,传输及生物有效性.本文就疏水性有机污染物在土壤/沉积物中的有机质上吸附的国内外研究进展进行了综述,讨论了重要有机质组分(腐殖质和碳黑)的结构和吸附作用差异性,重点分析了有机质的微孔特性和官能团对吸附的影响机制.     

超临界流体萃取在研究土壤和沉积物结合态残留中的应用

许多有机污染物在土壤和沉积物中形成持久稳定的结合态残留；结合态残留对土壤和沉积物的解毒过程、污染物长期分配行为、生物可用性和生物毒性都具有重要影响。为了揭示结合态残留的形成机制及其对污染物环境行为和毒理学参数的影响，从土壤或沉积物中提取出不同结合状态的有机污染物就显得非常重要。超临界流体萃取(SFE)可以实现选择性萃取，从而得到有关污染物一基体间相互作用的信息。文章介绍了SFE应用类型、超临界流体种类以及影响SFE萃取率的因素，对SFE模拟有机污染物长期吸附／解吸行为和生物可用性研究进行了论述，并认为SFE势必发展成为土壤或沉积物中结合态残留形成机理研究、土壤修复和生态风险评价的一种强有力的技术。     

土壤和沉积物中疏水性有机污染物的锁定及其环境效应

大量研究表明,吸附到土壤和沉积物中的疏水性有机物只有部分能够较容易地解吸出来,而残留的部分很难解吸.这种现象常被称为"解吸滞后","不可逆吸附",或者"锁定".锁定会导致受污染土壤和沉积物修复效率的降低;但与此同时,锁定也会降低受污染土壤和沉积物的环境风险.本文综述了土壤和沉积物中疏水性有机污染物锁定的典型热力学和动力...     

菲在不同地质吸附剂上吸附/解吸的研究

研究了菲在不同土壤和沉积物等天然地质吸附剂上的吸附/解吸行为.结果表明,菲在四种天然地质吸附剂上的吸附和解吸都能较快达到稳态.菲的吸附符合线性吸附等温线,说明菲的吸附是分配作用占主导,吸附系数Kd在24.1-187.5 L·kg-1之间.连续解吸实验表明,菲在天然地质吸附剂上的解吸存在不同程度的滞后现象,吸附剂的有机碳含量和菲的加入浓度是影响菲解吸率和滞后程度的重要因素.当菲加入浓度分别为1mg·1-1和2mg·1-1时,在有机碳含量为2.82%的榆林县土壤上的解吸滞后系数为1.61和0.67;而2mg·1-1的菲在有机碳含量为0.69%的泰达河岸土上的滞后系数为-0.06,吸附几乎完全可逆.     

Fenton氧化处理对土壤中芘的生物可利用性的影响

研究发现蚯蚓吸收土壤中污染物芘的速率很快,10 d后蚯蚓体内富集污染物浓度基本达到稳定态;土壤中的有机质是影响污染物迁移的重要因素,土壤有机质的含量越高对芘滞留(吸附)能力越强,蚯蚓富集芘的量越低,蚯蚓富集到体内污染物的浓度越低.这也说明土壤对污染物的吸附/解吸行为决定了土壤中污染物的生态风险;氧化处理降低了土壤中的有机质含量,改变土壤有机质的组成,氧化处理也降低了土壤中被吸附污染物芘对蚯蚓的生物有效性.     

生物扰动对沉积物中污染物环境行为与生物可利用性的影响

疏水性有机污染物进入环境水体后易于与沉积物结合,对沉积物中的底栖动物造成危害。底栖动物引起的生物扰动作用可以通过改变沉积物的地球化学性质,对其中污染物的赋存形态、迁移转化和生物可利用性产生重要影响。在综述了国内外生物扰动影响沉积物中污染物环境行为和生物可利用性的最新研究进展基础上,重点讨论了沉积物颗粒交换、水体环境条件改变、疏水有机污染物解吸释放过程以及对生物扰动影响的定量化表征。最后对该研究方向进行了展望,指出应重点研究多种污染物及不同生物共存条件下的生态效应,以及造成沉积物扰动的影响因素的定量化表征等。     

不同粒径沉积物对1,2,4,5-四氯苯的吸附/解吸特性

采用静态吸附实验,研究不同粒径沉积物的基本性质及其对1,2,4,5-四氯苯吸附/解吸性能的影响.结果表明,不同粒径沉积物所含天然有机质(NOM)质和量的不同,导致其对1,2,4,5-四氯苯吸附性能的不同.颗粒最细的沉积物因其主要结合聚合度较低的无定型腐殖物质,导致1,2,4,5-四氯苯吸附等温线的非线性程度最低,在沉积物上的吸附亲和力和吸附.解吸滞后现象也最弱.而颗粒最粗的沉积物因为含有一些煤炭和木炭等高比表面积的碳黑类物质,NOM聚合度较高,导致1,2,4,5-四氯苯吸附等温线的非线性程度最高,在沉积物上的吸附亲和力和吸附-解吸滞后现象也最强.而粒径中等的沉积物本身的性质和吸附性能介于颗粒最粗和最细的两种组分之间.     

芘在不同粒径红树林沉积物团聚体上的吸附/解吸行为

采用海藻酸钙凝胶包覆的方法,研究了芘在九龙江河口红树林区不同粒径沉积物团聚体上的吸附/解吸行为.结果表明,海藻酸钙凝胶包覆可有效减少沉积物团聚体粒径的改变,其等温吸附、吸附/解吸速率情况与未包覆沉积物团聚体存在明显差异.包覆后等温吸附曲线中吸附容量Kf值取决于总有机碳(TOC)的含量,非线性吸附常数n不仅与其硬碳和软碳的比值有关,还与团聚体复杂的孔隙结构存在着一定的关系.包覆后沉积物团聚体的快吸附速率常数值与沉积物团聚体的比表面积值正相关(krap=0.041S-0.0146,R2=0.9923).小粒径沉积物团聚体的"老化"现象较大粒径更为显著,使得其解吸量较小.     

疏水性有机污染物在草甸土中的吸附和解吸行为

研究5种有机污染物在草甸土中的吸附和解吸行为.结果表明,污染物在土壤中的吸附主要受疏水性作用的影响,吸附数据基本符合传统的线性模型.解吸行为则表现出明显的滞后现象,解吸实验结果与"双元平衡解吸(DED)模型"的预测值相吻合.DED模型能够更加准确地定量描述疏水性有机污染物的解吸行为.     

pH对宁夏引黄灌区盐碱化土壤重金属吸附-解吸过程的影响

高pH值是宁夏引黄灌区盐碱化土壤的显著特征,研究盐碱化土壤的高pH值对不同重金属元素的富集和释放规律,可为宁夏引黄灌区盐碱化土壤重金属污染的控制及治理提供科学依据。通过调节pH值,采用土柱淋溶的方法,模拟盐碱化土壤的Cd和Pb的吸附-解吸过程,研究pH对盐碱化土壤重金属Cd、Pb吸附-解吸特征、形态和生物活性的影响。结果表明:在试验设定的pH范围内,盐碱化土壤对Cd的吸附量随着pH值的升高而呈升高趋势,在pH值为8时达到峰值,对Pb的吸附量随pH的升高呈波动状变化状态,在pH值为10时达到峰值;同时,Cd的解吸量随吸附量增加而线性增大,解吸量随pH升高而增加,但解吸量随吸附量变化而变化的幅度随pH值的升高而减小,Pb的解吸量随吸附量增加而呈选择性增加。随着pH的升高,Cd可交换态和碳酸盐结合态的含量变化趋势相反,生物活性基本不变,其Fe/Mn氧化物结合态、有机结合态和残渣态的含量不变;Pb可交换态和碳酸盐结合态的含量随着pH的升高而升高,生物活性增强,有机结合态的含量减少,Fe/Mn氧化物结合态和残渣态的含量不变。宁夏引黄灌区盐碱化土壤的高pH值可以降低土壤对重金属Cd、Pb的吸附,缓解重金属污染引起的生态、粮食及其食品安全压力。     

Sorption of DDTs on biofilms, suspended particles and river sediments: effects of heavy metals

The sorption by solid materials is one of the most important processes that affect the fate of hydrophobic organic pollutants in aquatic systems. Current studies focus on the sorption of hydrophobic pollutants by single natural solid material, whereas few studies compared the sorption behaviors of different solids. Furthermore, natural aquatic environment is a complex system where hydrophobic pollutants coexist with many other pollutants, but only limited studies reported the effects of coexisting components on the sorption. Here we studied the sorption of dichlorodiphenyltrichloroethanes (DDTs) by three common solids in natural water, i.e., biofilms, suspended particles and sediments. The effects of typical coexisting heavy metals on the sorption were also examined. The results show that the sorption is described by a dual-mode sorption model. Compared with sediments, more DDTs were sorbed by biofilms and suspended particles. Coexisting Pb, Cd and Cu increased the sorption of DDTs on sediments while decreasing the sorption on biofilms slightly, with little effect on the sorption on suspended particles. The different sorption behaviors of the solids were mainly determined by the composition of the solids: more organics were observed in biofilms and suspended particles.     

Evidence for a mutual effect of biofilms, suspended particles and sediments on DDT sorption

This report shows that biofilms and suspended particles double DDT sorption capacity on surface sediments. Sorption of pollutants by solid materials, such as biofilms, suspended particles and sediments, is a major process controlling the fate of hydrophobic pollutants in natural waters. Most previous studies focused on the sorption of hydrophobic pollutants by single-solid material, whereas few studies considered the mutual effect of different solids on the sorption. Various solid materials often interact with each other when they coexist in the same system. Therefore, pollutants sorption could be different from that in the single-solid sorption system. Here we studied the mutual effect of biofilms, suspended particles and surface sediments on the sorption of dichlorodiphenyltrichloroethane (DDT). Results showed that biofilms and suspended particles double DDT sorption capacity on surface sediments. The different effects were mainly determined by distinct components and structures of the three solid materials, particularly by organic components. Here we show the mutual effect of biofilms, suspended particles and sediments on DDT sorption.     

沉积物对菲和五氯酚的吸附性能

研究了菲和五氯酚（PCP）在五种沉积物的吸附解吸行为，菲和PCP在各沉积物上的吸附和解吸都是较快的过程。均能在8h内达到平衡，吸附和解吸结果表明，高有机质含量的沉积物对菲和PCP的吸附和持留能力都较强，菲和PCP在各沉积物中的吸附系数跟沉积物的有机质含量呈线性正相关。等温吸附结果表明，低有机质含量的三种沉积物比有机质含量较高的两种沉积物呈更好的线性关系。不同沉积物对菲和PCP的吸附性能差异跟沉积物的有机质含量密切相关。     

Sorption of 1,1,1-trichloro-2,2-bis(p-chlorophenyl) ethane (DDT) by clays and organoclays

This study focused on the sorption isotherms of 1,1,1-trichloro-2,2-bis(p-chlorophenyl) ethane (p,p'-DDT) and 1,1-dichloro-2,2-bis(p-chlorophenyl) ethylene (p,p'-DDE) on different original clays (i.e., zeolite, montmorillonite and attapulgite) and organoclay complexes. Sorption of organic pollutants was determined using gas chromatographic (GC) techniques to investigate the sorption behavior, and characterize the effect of, different organic cations. The original clays only sorbed low amounts of p,p'-DDT and p,p'-DDE, and the sorptive curves can be classified as L-shaped. Organoclays exhibited higher amounts of p,p'-DDT and p,p'-DDE sorption. The p,p'-DDT and p,p'-DDE sorption increased with increasing total organic carbon (OC) content of the organoclays. For hexadecyltrimethylammonium (HDTMA)-modified organoclays, the dominant adsorptive medium showed the partitioning sorption of hydrophobic-hydrophobic interaction, indicating no competitive sorption. The sorptive curves can be classified as C-shaped of constant partition (CP). However, benzyltrimethylammonium (BTMA)-modified organoclays exhibited competitive sorption. The sorption isotherm curves can be classified as S-shaped. The sorptive capacity of the HDTMA-modified organoclays for p,p'-DDT were higher than those for p,p'-DDE, but the BTMA-modified organoclays showed a reverse trend. This can be attributed to the different structures and shapes of organic cations, giving different sorptive mechanisms. The p,p'-DDT and p,p'-DDE sorption onto HDTMA-modified organoclays were caused by chemical interaction, with the BTMA modified organoclays occuring due to physical sorption.     

除草剂苯噻草胺在土壤中的吸附

对除草剂苯噻草胺在6种不同土壤中的吸附行为进行了研究。结果表明,土壤对苯噻草胺有较强的吸附性。在试验浓度范围内,苯噻草胺的土壤吸附行为可用线性吸附模型表征。土壤有机质是影响苯噻草胺吸附行为的重要因素,其吸附系数有随土壤有机质含量增高而增大的趋势。通过在线性吸附系数（Kd)和土壤有机质含量（OM％）之间构建的回归方程：Kd=2.6120 OM% 1.0746,可以预测苯噻草胺的Kd值,其预测的可靠性通过蒙特卡洛模拟得以检验。     

Metal speciation in sediments of polluted and non‐polluted lakes

A five‐step extraction procedure for metal speciation studies (copper, lead, nickel, manganese and zinc) was applied to the analysis of lake sediments characterised by different environmental features. A different partition of metals into the several metal forms was observed. Both the metal fraction sorbed or co‐precipitated on hydrous Mn‐oxides (especially lead and zinc) and that bound to organic matter (especially copper) are high in some samples. A prevalently anthropogenic origin of these metals may be hypothesised on the basis of existing knowledge of the equilibrium and change phenomena occurring among water, particulate and sediments. Conversely, the non‐solubilised forms of metals are abundant in the sediments of lakes that are certainly not polluted. The concentration of manganese is very high in the sediments of Antarctic lakes; sequential extractions show its lithogenic origin. In conclusion, a knowledge of the different types of metal associations in sediments and their percentage can facilitate understanding of both natural and anthropogenic metal enrichment of aquatic systems.     

Effects of different sediment fractions on sorption of galaxolide

Sorption isotherms of galaxolide (HHCB) of different fractions from two sediments with different mineral and organic carbon contents were determined to compare HHCB sorption behavior and contribution to the total sorption. The HHCB sorption isotherms that used the batch equilibration method were studied on different sediments of different fractions. The sorption isotherms of 600°C heating fractions were detailed using the linear model, while the other fractions were nonlinear and fitted well with the Freundlich model. The dissolved organic carbon (DOC) removed, NaOH extracted, and 375°C heating fractions showed more nonlinear sorption than the original sediments, which suggested more heterogeneous sorption sites in these fractions. Compared to the original sediments, the 375°C heating fractions had higher carbonnormalized distribution coefficient (K _oc) values, indicating a higher sorption affinity for HHCB. Among the different sediment fractions, the contribution of the 600°C heating fractions to the overall sorption were the lowest (< 20%), while the 375°C heating fractions were the highest (up to 85%).     

对硝基苯酚在沉积物上的吸附特性1

研究了沉积物吸附对硝基苯酚的作用机理及影响因素.结果表明,对硝基苯酚在沉积物上的吸附由其中的有机质含量和结构决定,体系的pH值对对硝基苯酚的吸附有较大的影响,其主要原因是体系的pH值控制着沉积物中有机质的溶出量.在实验浓度范围内,分配作用在沉积物吸附对硝基苯酚中占主导地位.     

生物修复中有机污染物的生物可利用性

论述了土壤和地下水生物修复中有机污染物的生物可利用性。污染物的可利用性对生物修复速率和生物强化效率有重要影响。生物可利用性是指土壤和地下水中的微生物或其胞外酶对有机污染物的可接近性，它受土壤理化性质、污染物和微生物性质、污染接触时问等许多因素的综合影响。污染物的介质吸附、多相分配、老化和形成非水相基质，以及土壤微生物的吸附、过滤和沉降作用降低了污染物的可利用性。促进土壤中污染物和微生物的解吸附，增强非水相基质的溶解，加速土壤污染物与微生物之间的质量传递，可以增强污染物的可利用性和生物降解的速率。施用表面活性剂和电动力学方法可有效地增强污染物的生物可利用性。