Planting woody crops on dredged contaminated sediment provides both positive and negative effects in terms of remediation

There is currently a requirement for studies focusing on the long-term sustainability of phytoremediation technologies. Trace element uptake by Salix, Populus and Alnus species planted in dredged contaminated canal sediment and concentrations in sediment and pore waters were investigated, eight years after a phytoremediation trial was initiated in NW England. Soil biological activity was also measured using invertebrate and microbial assays to determine soil quality improvements. Zinc was the dominant trace metal in foliage and woody stems, and the most mobile trace element in sediment pore water (∼14 mg l⁻¹). Biological activity had improved; earthworm numbers had increased from 5 to 24, and the QBS index (an index of microarthropod groups in soil) had increased from 70 to 88. It is concluded that biological conditions had improved and natural processes appear to be enhancing soil quality, but there remains a potential risk of trace element transfer to the wider environment.     

土壤原位覆盖对底泥的修复作用研究

在高度厌氧底泥和富营养化水体构成的模拟生态系统中,采用土壤和硅藻土进行原位覆盖,研究了覆盖技术对水．沉积物界面微环境的改善作用和不同覆盖材料对苦草生长的影响。这2种底质覆盖后,表层底泥氧化还原电位（Eh）分别提高了48．37％和46．77％,底层水体的溶解氧消耗降低,水体中的总氮（TN）和总磷（TP）含量降低;与对照箱体的苦草死亡相比,经过土壤和硅藻土覆盖的箱体中苦草正常萌发、定植和生长;硅藻土箱体苦草的生物量、叶绿素和根茎比均高于土壤覆盖箱体。因此,原位覆盖能有效改善底层水体和表层底泥的氧化还原环境,隔绝污染底泥和延缓营养盐释放,为沉水植物种子萌发和幼苗生长提供有利的生境条件。     

电动联合法对复合重金属污染底泥的修复

河流与湖泊底泥中重金属污染物的清除是实现水体彻底净化及底泥工程利用的关键。以增加了电解液循环的电动联合装置为修复设备,以Cu、Zn、Pb、Cr、Ni污染底泥为研究对象,结合小试模拟和中试模拟实验,明确修复装置对复合污染底泥的净化修复效果,并优化污染物回收的技术参数。结果表明,增设电解液循环有助于增强复合污染底泥中重金属离子的迁出,在小试模拟和中试模型实验中,底泥污染物的去除率分别达到了74%~84%和52%~60%;中试模型实验修复后底泥中的Cr、Cu、Ni和Zn含量分别为140.31、314.47、250.93、464.17 mg·kg⁻¹,低于《土壤环境质量-建设用地土壤污染风险管控标准》(GB 36600-2018) 的筛选值。在两极电解液增设pH调节装置和斜板沉淀池有助于以Cr(OH)₃、Cu(OH)₂、Ni(OH)₂和Zn(OH)₂沉淀物的方式对重金属离子进行回收,阳极电解液pH控制在5.0~6.5,阴极电解液pH控制在10时,阴阳极两侧电解液中重金属沉淀回收率均达99%。增加了电解液循环的电动联合修复技术可同步实现底泥污染物的净化及回收。     

A field study on phytoremediation of dredged sediment contaminated by heavy metals and nutrients: the impacts of sediment aeration

Compared to traditional chemical or physical treatments, phytoremediation has proved to be a cost-effective and environmentally sound alternative for remediation of contaminated dredged sediment. A field study was conducted in a sediment disposal site predominantly colonized by Typha angustifolia under different sediment moisture conditions to estimate the phytoremediation effects of dredged sediment. The moisture content was 37.30 % and 48.27 % in aerated and waterlogged sediment, respectively. Total nitrogen (TN) content was higher in the waterlogged sediment than in the aerated sediment. The total Cd contents were lower in aerated sediment, which was mainly resulted from the lower exchangeable fraction of Cd. The bioaccumulation of P, Cu and Pb in T. angustifolia was promoted by waterlogging, and the belowground tissue concentrations and accumulation factors (AFs) of Cu were higher than that of other metals, which can be explained by that Cu is an essential micronutrient for plants. Consistent with many previous studies, T. angustifolia showed higher metal levels in roots than in above-ground tissues at both the sediment conditions. Due to the improved biomass produced in the aerated sediment, the removals of nutrients and the metals by plant harvest were higher from aerated sediment than from waterlogged sediment. It was indicated that maintaining the dredged sediment aerated can avoid release risk and plant uptake of metals, while the opposite management option can promote phytoextraction of these contaminants.     

Availability of heavy metals for uptake by Salix viminalis on a moderately contaminated dredged sediment disposal site

Extractability of Cd, Cr, Cu, Ni, Pb, and Zn in a dredged sediment disposal site was assessed using single extraction procedures (H2O; 0.01 M CaCl2; 1 M NH4OAc; NH4OAc-EDTA; CaCl2-TEA-DTPA). Only Cd and Zn were found to exceed statutory threshold values for total content. The field was planted with Salix viminalis "Orm" and accumulation of heavy metals in bark, leaves, roots, and wood was evaluated at seven sampling locations along an observed gradient in texture and pollution. Biomass production was high, ranging from 13.2 to 17.8 t ha(-1) y(-1) dry weight. Metal accumulation in aboveground plant parts was low, amounting to the following annually extracted mass of metals per ha: 5034 g Zn, 83 g Cd, 145 g Cu, 83 g Pb, 12 g Ni and 6 g Cr. The use of accumulating clones and the use of soil amendments might enhance extraction efficiency in future research.     

疏浚底泥免烧陶粒的制备及其净水效果

以疏浚底泥为原料,采用免烧法制得疏浚底泥免烧陶粒（DSUC）,同时对DSUC磁改性制得磁改性免烧陶粒（MUC）,并将其作为陶粒过滤器滤料,与商品烧结陶粒（CSC）进行净水实验对比,探究了不同滤料对原水的处理效果,并调节循环水温度探究最佳运行温度。在净水实验中,控制原水流速0.07 mL·s-1,进水方式为连续进水。结果表明,运行温度为30 ℃时效果最优,此条件下COD、NH3-N、SS和TP的去除率在22 d后稳定,平均去除率分别为55%、65%、78%和50%。DSUC对原水处理效果与CSC相近,MUC效果更佳,MUC对COD、NH3-N、SS及TP去除率在22 d后分别稳定在65%、69%、79%和51%左右,说明弱磁性可能能够增加微生物活性,促进其在陶粒表面生长,提高处理原水的效果。     

Metal solubility as a function of pH in a contaminated, dredged sediment affected by oxidation

The solubility as a function of pH for metals in a reduced dredged sediment, subjected to different redox conditions, was studied in a laboratory experiment. The redox conditions imposed simulated (i) the undisturbed sediment (flooded), (ii) a dredged material stored in a confined pond (aerated once and then flooded), (iii) an upland stored dredged material (drained and dried), and (iv) an upland stored sediment subjected to tillage (drained, dried and mixed). Minor differences in the solubility as a function of pH were observed between the treatments after two weeks. After three months, the solubility of Cd, Cu, Pb and Zn increased strongly in the oxidized sediments. Leachability of Fe decreased, while Mn, Ni and Co were mostly unaffected. Both short- and long-term mobility of metals (except Fe) is expected to be lowest when a reduced sediment remains in reduced conditions. Studying the solubility as a function of pH may provide additional information on the chemical association of metals in sediments.     

The stability of butyltin compounds in a dredged heavily-contaminated sediment

A treatment process for marine sediment heavily contaminated with tributyltin (TBT) was designed that included dehydrating, sunlight drying and dumping processes. The time course in butyltin (BTs) compounds, TBT, dibutyltin (DBT) and monobutyltin concentrations were investigated in the sediment treated under various conditions (light (UV, sunlight and light exclusion), moisture (air-drying and water saturation) and wetting and drying cycles). Significant changes in all the BT compound concentrations with time were not found regardless of the sediment conditions for light and moisture. The results indicated the high stabilities of TBT and DBT in the sediments versus light and moisture condition changes, probably taking place in the treatment process. It is also estimated that the BTs in the sediment are resistant to photo-degradation and biochemical degradation and their half lives are relatively long. In contrast, the decreases in the TBT and DBT were observed during the wetting and drying cycle treatment for the water saturated sediment both during exposure to sunlight and under a dark condition. This result suggested the hypothesis that the TBT degradation could be accelerated by the high microbial activity induced by the moisture changing treatments.     

多环芳烃污染土壤的植物与微生物修复研究进展

概括介绍了多环芳烃污染土壤的植物修复、微生物修复和植物 微生物联合修复的原理、优缺点、影响因素及国内外研究进展 ,并对生物修复的未来发展进行了展望     

生物强化修复石油污染土壤

筛选高效石油降解菌,考察菌株的降解性能及降解机理,进行花盆模拟高效外源菌强化修复石油污染土壤实验,在降解后期添加激活剂H2O2以及木屑来试图改善微生物的修复环境,减缓微生物的衰亡,并考察修复效果。结果表明,菌株L-1的降解效果较好,其对pH和温度有较大范围的适应性,能分泌较多的表面活性物质,细胞疏水性较强。将其应用于土壤修复中,经过50 d的修复,石油残留率达到50.6%左右,生物强化比自然修复残留率降低了8%左右。在第45天添加激活剂能有效改善修复效果,70 d时添加外源菌的土样最小石油残留率达到37.9%。     

污染土壤化学修复技术研究与进展

污染土壤修复环境工程近年来发展迅猛，欧美等发达国家在其技术创新和设备改进2个层面都取得了长足进展。本文概述了化学淋洗修复技术（原位化学修复技术和异位化学修复技术）、化学还原与还原脱氯修复技术、化学氧化修复技术、溶剂浸提技术和土壤性能化学改良修复技术等污染土壤的化学修复技术原理、进展与适用性以及有关关键技术参数，并对其发展前景进行了展望。     

表面活性剂增效修复土壤有机污染研究进展

系统评述了表面活性剂增效修复土壤有机污染的原理、研究现状及存在的问题。     

汞污染土壤的电动力学修复试验研究

利用电动力学修复汞污染土壤,并考察电动力学修复对土壤部分理化指标的影响。结果表明,常规的电动力学修复方法不能有效去除土壤中的汞污染物,需要一些强化措施,在阴极电解液中引入KI,KI的引入提高了修复过程中的电流,且KI会与汞化合物生成HgI2-4,提高了汞的迁移效率,从而改善了电动力学修复效果。同时,添加0.50mol/L的KI溶液的试验组具有最佳的修复效果,在此试验条件下,污染土壤中的汞总去除率为81.7%。电动力学修复后,土壤pH有明显改变,阳极区土壤酸化,阴极区土壤碱化;土壤有效氮在阳极区出现明显增加,在阴极区降低,而土壤有机质则没有明显变化。     

污染土壤化学修复技术研究与进展

污染土壤修复环境工程近年来发展迅猛,欧美等发达国家在其技术创新和设备改进2个层面都取得了长足进展。本文概述了化学淋洗修复技术(原位化学修复技术和异位化学修复技术)、化学还原与还原脱氯修复技术、化学氧化修复技术、溶剂浸提技术和土壤性能化学改良修复技术等污染土壤的化学修复技术原理、进展与适用性以及有关关键技术参数,并对其发展前景进行了展望。     

表面活性剂增效修复土壤有机污染研究进展

系统评述了表面活性剂增效修复土壤有机污染的原理、研究现状及存在的问题.     

电动修复不同形态铬污染土壤的研究

研究了土壤中铬的价态对电动修复效率的影响以及电动修复前后土壤中铬形态的变化.结果表明,电动修复对于土壤中1 000 mg Cr(Ⅵ)/kg的去除效果明显,总铬去除率达59.7%;而对1 000 mg Cr(Ⅲ)/kg的去除效率较低,仅为6.2%;Cr(Ⅲ)和Cr(Ⅵ)(各500 mg/kg)同时污染的土壤,铬的去除率介于中间,为18.7%.电动修复前后,土壤中铬的形态也发生了明显的变化.其中,电动修复对土壤中Cr(Ⅵ)的提取形态影响最大,而对Cr(Ⅲ)提取形态并无太大的影响.总体上,电动修复后对于生物有效的弱酸可提取态铬的浓度都保持在较低水平,预期铬的环境风险(物理流动性和生态风险)将大大降低.     

铜污染土壤电动修复研究

应用实验方法研究了土壤重金属污染的电动力学修复方法,分析了土壤重金属污染物的迁移和变化特征。实验结果表明,在电场作用下土壤中重金属的浓度分布发生明显变化,使得大部分重金属能在电极附近富集而被去除。当实验的电场强度为0.5 V/cm时,在阳极附近土壤中铜的去除效率达到71.1%。阳极附近的pH值由开始时的6.8逐渐变小到4.4,而阴极附近则相反,由开始时的6.6逐渐增大到9.1,此外电动修复过程中电极附近的温度会发生相应的变化。     

铜污染土壤电动修复研究

应用实验方法研究了土壤重金属污染的电动力学修复方法,分析了土壤重金属污染物的迁移和变化特征。实验结果表明,在电场作用下土壤中重金属的浓度分布发生明显变化,使得大部分重金属能在电极附近富集而被去除。当实验的电场强度为0.5 V/cm时,在阳极附近土壤中铜的去除效率达到71.1%。阳极附近的pH值由开始时的6.8逐渐变小到4.4,而阴极附近则相反,由开始时的6.6逐渐增大到9.1,此外电动修复过程中电极附近的温度会发生相应的变化。     

污染土壤修复技术预测

土壤污染已成为世界性环境问题,我国土壤污染现状更为严峻。污染土壤修复技术已成为全球科技的研究重点。本研究基于该领域国内外的相关研究论文与专利,采用文献计量学的统计方法,结合国内外相关项目、计划和法规等信息,对比分析了国内外论文/专利发文量阶段变化、技术研究的首篇报道年、专利景观图等。研究结果表明,我国污染土壤修复技术研发起步较晚,与发达国家总体水平存在10~15年的差距,在产业化领域更为突出。提出了在兼顾系统集成与技术原创的条件下,我国污染土壤修复的重点研发技术,为我国土壤修复技术的发展布局与政策制定提供决策依据。     

鼠李糖脂协助下的土壤中镉电动修复

实验研究了重金属Cd在生物表面活性剂鼠李糖脂协助下的电动修复过程,通过不同方式、不同浓度、不同酸碱度的鼠李糖脂溶液的添加与空白处理对比,探讨了鼠李糖脂协助下电动修复过程中的Cd在土壤介质中的迁移转化和机理,分析了鼠李糖脂溶液作为电动修复添加剂的可行性。结果表明,中等浓度酸性的鼠李糖脂溶液(pH=4.78,浓度为0.5、1和2 g/L)能对土壤中的重金属Cd进行有效的富集,富集量均在初始值的4倍以上,且其可交换态比重均大于42.07%,非常有利于土壤进行二次修复。此外,以pH=4.78,浓度为0.5 g/L的鼠李糖脂溶液作为预处理剂的Ex-08中的重金属Cd并未出现富集现象,但其对重金属的Cd的总去除效率达到了49.27%。表明利用鼠李糖脂溶液作为电动修复添加剂进行土壤重金属修复是可行的。