城市土壤不同粒径组分PAHs污染特征

利用湿筛法,将采自上海市不同土地利用类型下的表层土壤分成63、63~125、125~250、250~500和500μm 5种粒径组分,测定其16种美国环境保护署优控的多环芳烃(PAHs)含量。∑16PAHs浓度范围为5.2~125.6μg/g,金山石化区污染物浓度最高。不同粒级污染物浓度差别较大,最高值集中在125μm的粗砂粒部分,最低值出现在63μm粒径组分。除商业中心区外,各粒级组分中多环芳烃均以4环及以上多环芳烃为主。低环(2~3环)、中环(4环)、高环(5~6环)PAHs和∑16PAHs与土壤中总有机碳(TOC)、黑碳(BC)均呈显著性正相关(P0.01)。有机碳标准化PAHs浓度表明,有机质结合PAHs能力在125~250μm粒径组分最强,在63μm粒径组分最低。源解析表明样品土壤中PAHs主要来源于燃烧,住宅区虎丘、商业区金茂大厦地区土壤中PAHs部分可能源于石油泄漏。     

长江武汉段不同粒径沉积物中多环芳烃（PAHs）分布特征

将采自长江武汉段的沉积物湿筛分成5个粒径的组分（>200 μm,200～125 μm,125～63 μm,63～25 μm,<25 μm）,分别测定其中多环芳烃(PAHs)的含量.结果表明,不同粒径沉积物中PAHs组成基本相同,均以3环以上PAHs为主,但是∑PAHs浓度相差很大,范围为26.1～7 135.9　ng/g.其中,>200　μm沉积物中∑PAHs浓度最高,为7 135.9 ng/g;63～25　μm沉积物中∑PAHs浓度最低,为26.1　ng/g.占沉积物38.6%质量分数的<25　μm沉积物富集了沉积物中约75%的∑PAHs.总有机碳是影响PAHs在不同粒径沉积物中分布的主要因素,不同粒径沉积物中PAHs与总有机碳呈显著正相关（p<0.01）.此外,有机质类型、结构也是影响PAHs在不同粒径沉积物中分布的重要因素.     

太湖地区几种水稻土团聚体颗粒组中PAHs的分布及其环境意义

以太湖地区代表性的青紫泥、黄泥土、白土等3种水稻土为研究对象,采用低能量分离-分散法提取得到不同粒径的团聚体颗粒组,用HPLC测定了本土和分离得到的团聚体颗粒组中16种PAHs的含量.结果表明,供试水稻土不同粒径的团聚体颗粒组中PAHs含量分布存在差异,PAHs总含量以＜2μm粒径的团聚体颗粒组最高,其次是200～2000μm粒径的团聚体颗粒组,PAHs在这2个团聚体颗粒组有明显富集现象(富集系数为1.25～3.92);而20～200μm和2～20 μm粒径的团聚体颗粒组中PAHs含量小于本土,呈现亏缺现象(富集系数为0.64～0.88).考虑到不同粒径团聚体颗粒组的相对组成,水稻土中PAHs主要分布于20～200μm和200～2000μm 2个团聚体颗粒组中,而在＜2μm粒径的团聚体颗粒组中最少.PAHs在不同粒径的团聚体颗粒组中的含量分布与其总有机碳、腐殖质碳、胡敏酸碳的含量有关,并在很大程度上受芳构化疏水性有机物含量的控制.因此,水稻土不同粒径团聚体颗粒中有机碳及其组分的性质影响着这些团聚体颗粒组分对PAHs的吸持与固定.     

高锰酸钾氧化去除砂壤土中三氯乙烯的试验研究

以环境中常见的污染物三氯乙烯(TCE)为研究对象,利用高锰酸钾(KMnO4)对工业场地土壤中的TCE进行处理,探讨了不同氧化条件、污染物初始浓度、氧化次数等对去除效果的影响.结果表明,采用正交试验获得优化操作条件为:KMnO4浓度125mg/L,pH7,反应时间30min.在此条件下,100mg/kg的TCE去除率达到93.7%.TCE的去除率随污染物浓度的增加而减小,对于污染程度高的土壤,2次处理能有效提高去除率.土柱实验结果表明经过KMnO4溶液淋洗12d后,初始浓度为50mg/kg的TCE氧化率均达到88.1%以上,降低淋洗流速可提高TCE的去除率.     

适用异位淋洗修复技术的铬污染土壤条件探究

土壤理化特性、污染物分布情况、污染物存在形态和淋洗剂类型均为影响异位淋洗技术的关键因素。针对两种类型的铬污染土壤开展了异位淋洗对比试验,结果表明:当污染土壤中粗颗粒物料(砾石、砂砾、粗砂和中粗砂)质量分数超过70%,总铬和六价铬在细颗粒物料(细砂和粉土)中含量大于其总含量的60%,且水溶态和弱酸提取态铬占比超过50%时,仅以去离子水作为淋洗剂,粗颗粒物料的六价铬去除率即可达到70%。     

天津某住宅区降雨径流颗粒粒径分布及污染物赋存形态

为考察城市不同下垫面降雨径流中颗粒粒径分布及与污染物的关系,2020年7—8月在相同降雨条件下对天津市某居民区油毡屋面、塑钢屋面、水泥瓦屋面和沥青路面的6场降雨事件进行采样,分析降雨径流污染特征及颗粒物分布. 结果表明:①沥青路面降雨径流中悬浮颗粒物（suspended solids, SS）浓度最高,与油毡屋面、塑钢屋面和水泥瓦屋面径流SS浓度在统计上有显著差异(P<0.05);②不同下垫面降雨径流中颗粒物粒径主要分布在10~200 μm之间,4种下垫面中值粒径（D₅₀）浓度在计量上均有显著差异(P<0.05);③粒径在10~50 μm的颗粒物占比最大,在油毡屋面、塑钢屋面、水泥瓦屋面和沥青路面径流中占比分别为30.95%、25.53%、30.41%和50.47%,粒径大于300 μm的颗粒物体积分数占比最小;④降雨径流中颗粒物是污染物的主要载体,径流中化学需氧量（COD）和总磷（TP）主要以颗粒态形式存在,而总氮（TN）主要以溶解态形式存在. 通过对降雨径流中颗粒物粒径分布和污染物赋存形态的研究,以期为城市径流污染控制及雨水净化方法的选取提供数据支撑.      

城市不同下垫面降雨径流多环芳烃（PAHs）分布及源解析

以上海市不透水下垫面降雨径流为研究对象,分析了交通道路、校园、小区路面和小区屋面径流样品中16种溶解相、颗粒相PAHs质量浓度和场次降雨事件平均浓度(EMC).研究了不同下垫面降雨径流PAHs冲刷过程.通过对不同样点降雨径流初始冲刷散点进行幂函数拟合,定量表征了降雨径流PAHs和悬浮颗粒物(TSS)的初始冲刷强度.对径流样品中PAHs来源进行了分析.结果表明,径流样品Σ16PAHs(包括溶解相和颗粒相)质量浓度变化范围为317.21~10364.32 ng·L-1,其中龙吴路Σ16PAHs质量浓度(均值)最大,而校园最小.污染物的EMC值在不同样点具有很大的差异.不同样点PAHs含量在径流过程中皆呈现出明显的衰减特征,并显示出不同程度的初始冲刷效应.运用因子分析方法解析PAHs来源发现,降雨径流PAHs来自化石燃料的不完全燃烧、石油泄漏、炼焦等,且各源的贡献率在不同下垫面降雨径流中有差异.     

典型污染区农业土壤中PAHs的分布、来源及生态风险

采用同位素稀释气相色谱-质谱（GC/MS）分析了路桥农业表层土壤中16种优控PAHs的含量,并对其分布、来源及生态风险进行了分析.结果表明,土壤中16种PAHs的检出率达到100%,其总含量范围为52.3~991 μg·kg-1,与土壤有机碳显著相关（p < 0.01）.PAHs组成特征表明,路桥土壤中以高环PAHs为主.PAHs（除Nap、Acy和Fl）间呈显著相关（r > 0.7,p < 0.01）,表明采样区PAHs污染来源具有一定的相似性.同分异构体比值和因子分析表明,路桥农业土壤中PAHs主要来源于煤和生物质的燃烧.土样中16 PAHs的毒性当量浓度（TEQBaP）介于4.61~164 μg·kg-1之间,7种致癌性PAHs对总TEQBaP的贡献达99%.在35%的土样中,10种PAHs的总TEQBaP超过荷兰土壤目标参考值,表明路桥部分农业土壤存在潜在的生态风险.     

镇江城市径流颗粒粒径分布及其与污染物的关系

为了解城市中不同粒径颗粒物对于径流中污染物的影响,2006年3月在镇江城市不同功能区地表采集了沉积物样品和径流样品,分析了颗粒物的粒径分布和污染物浓度.结果表明,晴天条件下道路沉积物主要由粒径＜250μm的颗粒组成;降雨初期主要为＜5μm的颗粒物随径流迁移,随降雨历时的延长较大颗粒开始随径流迁移,降雨期间随地表径流迁移主要为小于150μm的颗粒物,特别是5～40μm粒径段的颗粒要特别予以关注;同时污染物浓度也由降雨初期的高浓度逐渐下降并趋于稳定.明确了径流中污染物的主要输出形态,并通过分析不同降雨历时污染物与固体悬浮物和颗粒粒径的相关性探明了径流污染物形态输出的原因,从而为城市非点源污染的管理以及控制方法的选择提供科学依据.     

低山丘陵区焦化厂土壤中PAHs空间分布特征

为了解低山丘陵区焦化厂多环芳烃类污染物空间分布特征,对山西省低山丘陵区某106667m²焦化厂土壤中的16种多环芳烃浓度进行分析,分别从平面和垂向研究污染物迁移扩散规律,结果表明：首先,表层土壤的16种多环芳烃多分布于化产车间,在表层0~0.5m深度范围内土壤中污染物ΣPAHs浓度由高到低顺序为蒸氨洗苯区（991.33mg/kg） > 冷鼓脱硫区（406.50mg/kg） > 污水处理区（97.69mg/kg）;为说明PAHs来源,用高低环比例法进行多环芳烃单体分类计算统计,结果显示该场地的PAHs以M202,M228和M252的组合占优势,但M178仍占一定比例,因此污染源并非单一源,而是以油料燃烧释放的生成物即焦油的跑冒滴漏为主的石油源和燃烧源的混合源;其次,PAHs在不同车间的垂向分布存在差异.其中冷鼓脱硫区污染主要集中于3.0~4.0m,蒸氨洗苯区PAHs集中于地表0~0.5m,污水处理区PAHs集中于地表及深度1.0~2.0m处,这与污染区原工程工艺以及地层结构特点密切相关.     

芘在土壤不同粒径组分中的形态分布

以芘为PAHs代表物,采用土壤粒径分级和PAHs连续提取方法,研究了老化4周污染黄棕壤中芘在不同粒径组分中的形态分布.结果表明,供试土壤中芘主要以有机溶剂提取态和可脱附态存在,结合态残留量所占比例甚小;细砂粒、粉粒、粗黏粒和细黏粒中芘残留占原土总残留的比例分别为6.00%、4.66%、34.68%和40.88%.各粒径组分中各形态芘含量大小顺序为有机溶剂提取态>可脱附态>结合态,有机溶剂提取态和可脱附态是各粒径组分中芘残留的主要存在形态(占比98.82%以上),芘结合态残留量占比<1.18%.土壤中黏粒(包括细黏粒和粗黏粒)是芘可脱附态、有机溶剂提取态、结合态和可提取态残留储存的主要粒径组分.     

铬渣污染土壤清洗剂筛选研究

以3种不同质地的铬渣污染土壤(A土,B土和C土)为研究对象,探讨了4种清洗剂对污染土壤中Cr的清洗效果,并采用欧盟BCR三步顺序提取法,研究了不同清洗剂对土壤中各形态Cr的去除效果. 结果表明:同一污染土壤上4种清洗剂对总Cr的去除效果差别不大;低浓度清洗剂对Cr(Ⅵ)和Cr(Ⅲ)的去除效果与去离子水相当;高浓度清洗剂效果优于低浓度清洗剂,且高浓度清洗剂洗出的总Cr主要以Cr(Ⅲ)为主. 同一清洗剂对3种污染土壤的清洗效果为C土>B土>A土. 去离子水主要去除酸可提取态Cr;EDTA-Na₂对酸可提取态和可还原态Cr去除效果较好;柠檬酸去除的是酸可提取态、可还原态和可氧化态Cr;而HCl对各形态Cr都有所去除. 因此,对于酸可提取态和可氧化态Cr含量较高的A土,柠檬酸是最佳清洗剂;而对于酸可提取态Cr占优势的B土和C土,去离子水是最佳清洗剂.      

Removal of polycyclic aromatic hydrocarbons from different soil fractions by persulfate oxidation

Removal of polycyclic aromatic hydrocarbons (PAHs) from different soil fractions of contaminated soil was investigated by using activated persulfate oxidation remediation in our research. The results showed that the light fraction, which accounted for only 10% of the soil, contained 30% of the PAHs at a concentration of 4352?mg/kg. The heavy fraction contained more high-molecular-weight PAHs, and the total PAH concentration was 625?mg/kg. After being oxidized, the removal rate of PAHs was 39% in the light fraction and nearly 90% in the heavy fraction. Among the different fractions of the heavy fraction, humic acid contained the highest concentration of PAHs, and consequently, the highest removal efficiency of PAHs was also in humic acid. Compared with the light fraction, the heavy fraction has more aromatic compounds and those compounds were broken down during the oxidation process, which may be the removal mechanism involved in the oxidation of high-ring PAHs. Similarly, the enhancement of C = C bonds after oxidation can also explain the poor removal of high-ring PAHs in the light fraction. These results imply that different fractions of soil vary in composition and structure, leading to differences in the distribution and oxidation efficiencies of PAHs.     

Removal of heavy metals and arsenic from a co-contaminated soil by sieving combined with washing process

Batch experiments were conducted with a heavy metals and arsenic co-contaminated soil from an abandoned mine to evaluate the feasibility of a remediation technology that combines sieving with soil washing.Leaching of the arsenic and heavy metals from the different particle size fractions was found to decrease in the order: 0.1,2–0.1,and 2 mm.With increased contact time,the concentration of heavy metals in the leachate was significantly decreased for small particles,probably because of adsorption by the clay soil component.For the different particle sizes,the removal efficiencies for Pb and Cd were75%–87%,and 61%–77% for Zn and Cu,although the extent of removal was decreased for As and Cr at 45%.The highest efficiency by washing for Pb,Cd,Zn,and As was from the soil particles 2 mm,although good metal removal efficiencies were also achieved in the small particle size fractions.Through SEM-EDS observations and correlation analysis,the leaching regularity of the heavy metals and arsenic was found to be closely related to Fe,Mn,and Ca contents of the soil fractions.The remediation of heavy metal-contaminated soil by sieving combined with soil washing was proven to be efficient,and practical remediation parameters were also recommended.     

六氯苯在土壤不同粒径级份上的吸附行为研究

研究比较了HCB在湖北水稻土和山东褐土不同粒径级份上的吸附特性,探讨不同粒径级份中有机质线性分配过程、慢吸附过程和小孔扩散过程的相对贡献.结果表明,Freundlich方程、DMM吸附模型和Polanyi-Manes方程都对实验数据进行了较好的拟合(R2＞0.91),其中DMM吸附模型能更好地反映土壤有机质溶解相线性分...     

固相微萃取和固相萃取评价多环芳烃降解过程中的生物有效性变化

为了揭示多环芳烃(PAHs)降解过程中的生物有效性变化规律,应用PAHs降解菌剂对PAHs污染焦化厂土壤进行微生物修复,采用固相微萃取及固相萃取方法提取评价PAHs的生物有效性,分析降解率和生物有效性变化的差异及相关关系.结果表明,该焦化厂土壤中PAHs总量以低环PAH为主,微生物菌剂对土壤总PAHs降解率为68.3%;微生物作用后,孔隙水中PAHs的降低以3、4环为主,孔隙水中PAHs变化率普遍低于土壤中的降解率;Tenax-TA提取降解前后土壤中的PAHs,降解后3、4环PAHs的快速解吸组分降低,5、6环的快速解吸组分变化不大;土壤中PAHs降解量分别与PAHs孔隙水浓度和Tenax-TA快速提取量存在相关关系.以上结果表明可用PAHs孔隙水浓度以及Tenax-TA快速提取量预测微生物对土壤PAHs的降解,这为焦化厂土壤PAHs污染的修复提供了理论依据.     

Distribution of Cu and Pb in particle size fractions of urban soils from different city zones of Nanjing, China

Soil samples from 4 defined city zones of Nanjing were randomly collected at 0-5 cm and 5-20 cm intervals and size fractions of soil particles were separated from undisturbed bulk soils by low energy dispersion procedure. The total contents of Cu and Pb in the different particle size fractions of the urban soils were analyzed by HNO3-HF-HClO4 digestion and flame atomic absorption spectrophotometer determination. The total content of Cu and Pb in soil particle size fractions varied with their size and with city zones as well. Both the content and variation with the size fractions of Pb was bigger than of Cu supporting our previous finding that there was Pb pollution to different degrees in the urban soils although the two elements were generally enriched in clay-sized fraction. Contaminated Pb tended to be preferentially enriched in the size fraction of 2000-250 μm and clay-sized fraction. While the size fractions of the soils from newly developed and preserved area contained smaller amount of Cu and Pb, the partitioning of them in coarse and fine particle size fractions were insignificant compared to that from inner residence and commercial area. The very high Pb level over 150 mg/kg of the fine particle fractions from the soils of the inner city could be a cause of high blood Pb level reported of children from the city as acute exposure to Pb of fine particles of the urban soil might occur by soil ingestion and inhalation by young children. Thus, much attention should be paid to the partitioning of toxic metals in fine soil particles of the urban soils and countermeasures against high health risk of Pb exposure by soil ingestion and dust inhalation should be practiced against the health problem of blood Pb for young children from the cities.     

Sorption of pyrene on two paddy soils and their particle-size fractions

In the present study, the sorption of pyrene on two kinds of bulk paddy soils, Gleyic Stagnic Anthrosols, and Ferric accumulic Stagnic Anthrosols as well as their particle-size fractions was investigated. The sorption isotherms fitted well with Freundlich equation. For both soils, the clay fraction（ 〈 2μm） and coarse sand fraction（2000-250μm） had higher sorption capacity than fine sand fraction（250-20 μm） and silt fraction（20-2 μm）. The IogKoc values obtained of each soil and its particle-size fractions were similar, proving that SOM content was a key factor affecting pyrene sorption. The Kd values showed a significant correlation with contents of dithionite-extractable Fe in both paddy soils and a good relationship with CEC in Gleyic Stagnic Anthrosols, indicating possible effects of surface properties of particle-size fractions on the sorption of pyrene.     

生物堆修复城市多环芳烃污染土壤的调控研究

土壤多环芳烃(PAHs)污染已成为一种严重的全球性城市环境问题。以通风时间、绿肥、无机营养剂和疏松剂含量为调控因素,利用现场规模的正交试验进行了生物堆修复城市多环芳烃污染土壤的调控研究。结果表明,所有生物堆处理对土壤PAHs的去除均有一定促进作用,75 d时平均降解率为30.63%~80.41%,且深层土壤降解率比表层土壤高8.55%;运行期间各调控因素对不同深度土壤PAHs降解的影响程度和作用规律各不相同,其中通风时间始终是主导因素,且通风时间越长,降解效果越好;生物堆的最佳运行条件总体上为通风时间3 h、绿肥3.5%、营养剂0.2%、疏松剂18%(表层土壤)或14%(深层土壤)。因此,利用生物堆修复城市PAHs污染土壤是有效的,且增加通风时间是提高其修复效率的优先调控方式。