Geochemical forms of trace metals in mangrove sediments—Red Sea (Egypt)

Seven sediment samples from mangrove sediments of the Red Sea were taken in order to evaluate the possible contamination of the sediments by trace metals (iron (Fe), manganese (Mn), zinc (Zn), copper (Cu), lead (Pb) and cadmium (Cd)). Sequential extraction techniques were performed to study the different geochemical forms of these metals. X-ray diffraction analysis has been performed to correlate the mineralogical composition with the geochemical forms of the studied elements. The results of Fe and Mn contents indicate that they are in large part from lithogenous origin. The elevated concentrations are associated with the residual form ranged from 70 to 93% for Fe and 46 to 70% for Mn. The percentage of Zn, Cu, Cd and Pb in the non-residual form was much greater than that of the residual fractions. This reflects the high mobility and bioavailability of these metals in mangrove sediments of the Red Sea. X-ray diffraction analysis revealed the presence of silicate components including quartz, feldspars and clay minerals in some locality. Non-silicate components recorded in the study area as calcite as well as, Mg-calcite. Quantitatively both components i.e. silicate and carbonate varied according to their source material.     

Geochemical forms of trace metals in mangrove sediments—Red Sea (Egypt)

Seven sediment samples from mangrove sediments of the Red Sea were taken in order to evaluate the possible contamination of the sediments by trace metals (iron (Fe), manganese (Mn), zinc (Zn), copper (Cu), lead (Pb) and cadmium (Cd)). Sequential extraction techniques were performed to study the different geochemical forms of these metals. X-ray diffraction analysis has been performed to correlate the mineralogical composition with the geochemical forms of the studied elements. The results of Fe and Mn contents indicate that they are in large part from lithogenous origin. The elevated concentrations are associated with the residual form ranged from 70 to 93% for Fe and 46 to 70% for Mn. The percentage of Zn, Cu, Cd and Pb in the non-residual form was much greater than that of the residual fractions. This reflects the high mobility and bioavailability of these metals in mangrove sediments of the Red Sea. X-ray diffraction analysis revealed the presence of silicate components including quartz, feldspars and clay minerals in some locality. Non-silicate components recorded in the study area as calcite as well as, Mg-calcite. Quantitatively both components i.e. silicate and carbonate varied according to their source material.     

The Influence of Anthropogenic Contamination On Metals Release From Coastal Sediment Suspensions with Aerated Sea Water

The zinc, cadmium, copper and lead release from the uncontaminated and contaminated coastal sediments with aerated sea water was studied. the metals transfer to the dissolved forms was monitored during one-two months by differential pulse anodic voltammetry (DPASV). the sediments with different initial degree of contamination were sampled in the Peter the Great Bay, Sea of Japan around Vladivostok-the biggest city in Russian Far East. Sediment contamination by metals led to increased release to solution of zinc due to sulphide oxidation and cadmium on account of organic matter decomposition. the copper behaviour was complicated by strong binding with organic matter and enhancements of copper release can only be seen in sediment with a low organic matter content. Significant lead transfer to dissolved forms was not observed regardless of sediment contamination. the temperature affected the release of cadmium and copper through enhanced organic matter destruction. the dissolved metal fluxes from the sediment transformation are compared with metal fluxes towards bottom. Such comparisons show that second contamination by dissolved metals of the studied coastal environment may be important for cadmium only.     

The Influence of Anthropogenic Contamination On Metals Release From Coastal Sediment Suspensions with Aerated Sea Water

The zinc, cadmium, copper and lead release from the uncontaminated and contaminated coastal sediments with aerated sea water was studied. the metals transfer to the dissolved forms was monitored during one-two months by differential pulse anodic voltammetry (DPASV). the sediments with different initial degree of contamination were sampled in the Peter the Great Bay, Sea of Japan around Vladivostok-the biggest city in Russian Far East. Sediment contamination by metals led to increased release to solution of zinc due to sulphide oxidation and cadmium on account of organic matter decomposition. the copper behaviour was complicated by strong binding with organic matter and enhancements of copper release can only be seen in sediment with a low organic matter content. Significant lead transfer to dissolved forms was not observed regardless of sediment contamination. the temperature affected the release of cadmium and copper through enhanced organic matter destruction. the dissolved metal fluxes from the sediment transformation are compared with metal fluxes towards bottom. Such comparisons show that second contamination by dissolved metals of the studied coastal environment may be important for cadmium only.     

基于文献计量的土壤重金属污染微生物修复研究现状分析

社会经济快速发展带来的土壤重金属污染问题日益严峻,对地球环境和生命健康构成了威胁。微生物修复由于其绿色、经济等优点受到国内外土壤重金属污染修复领域的广泛关注,但针对该领域相关研究的文献还缺乏系统整理。本文以中国知网CNKI全文数据和Web of Science核心合集文献资料为数据源,利用CiteSpace软件对2000—2023年国内外关于微生物修复土壤重金属污染领域的相关文献进行了可视化分析,结果显示：(1)在过去的20多年里,发文数量逐年增多,近年来呈迅速增长趋势。(2)中国在该研究领域具有较大优势,国内(中文文献)和国际(英文文献)分别初步形成了以中国科学院大学和中国科学院等为中心的合作机构;中英文文献作者群体呈大分散小集中的态势,分别形成了以黄巧云、Xu Heng等为主的作者群。(3)该领域研究前沿关键词随时间呈阶段性演变,且研究热点侧重不同,中英文文献分别聚焦微生物菌剂、生物炭、胞外聚合物、酶活以及复合污染、修复机制、微生物-植物联合修复、微生物响应等方向。(4)高被引文献大多属于综述类,系统归纳了土壤重金属污染微生物修复技术和机制。     

Behaviour of trace metals in surface sediments of the Black Sea

Early diagenetic processes control the behavior, and more specifically the dissolved‐solid phase distribution of heavy metals in sediments. The depth distribution of Co, Mn, Cu, Zn, Ni, and Fe in sediment were determined in box cores from the Black Sea. The sequential analyses results of these metals indicate contrasting behavior of Mn and Co during early diagenesis, consistent with their respective chemistries and particle‐associations. The profiles of extractable trace metals in the cores are clearly related to sediment type or depositional environment. Topmost sections of the profiles for these elements are generally similar, i.e. rapid decrease in concentration below the sediment surface.     

基于植物仿生的土壤重金属污染原位自持修复技术

采用基于植物仿生的重金属污染土壤原位自持修复技术,研究该方法对重金属污染土壤的修复能力,同时研究活性炭比例、填料装填方式、装置高度和“叶片”材质等4种因素对植物仿生装置修复效率的影响.结果表明,通过植物仿生修复重金属污染土壤中Cr、Ni、Zn和Fe的降低率分别为12.8%、4.1%、27.6%和16.8%,证明了植物仿生修复技术的可行性.活性炭比例、填料装填方式、装置高度和“叶片”材质等4种因素都对植物仿生装置的修复效率存在一定的影响.其中,管件的高度与修复装置蒸发速率呈负相关性,修复装置越高蒸发速率越慢;增加活性炭的量对装置蒸发速率的影响不明显,模拟“叶片”的材料对蒸发速率大小的影响顺序为：玻璃纤维丝>玻璃纤维布>棉纱,蒸发速率分别为：100.1 g·d-1、64.8 g·d-1和61.6 g·d-1.     

钢铁工业遗留场地土壤重金属洗脱剂筛选研究

土壤重金属污染限制了工业遗留场地再利用,通过振荡试验考察了HCl、HNO3和EDTA对工业遗留场地土壤中超标重金属Pb、Zn、Cd和As的洗脱效果。结果表明：土壤Pb、Zn、Cd、As的脱除效果均随洗脱剂浓度增加而增加;HCl、HNO3和EDTA等3种洗脱剂浓度分别为0.5、0.5和0.1 mol.L-1时,土壤Pb、Cd质量分数可降低至场地安全再利用的控制标准以内（分别为140 mg.kg-1、1mg.kg-1）;洗脱剂浓度分别增至2、2和0.2 mol.L-1时,土壤Pb、Cd质量分数继续降低,Zn、As质量分数有大幅降低但没有达到其相应的场地安全控制标准（分别为200、20 mg.kg-1）;与EDTA相比,HCl在低浓度时的重金属脱除效果较差,但HCl浓度增加对重金属脱除率的提高效果更为明显;洗脱液pH值（7.88~0.15）与重金属脱除率均呈显著负相关且与As的负相关系数最小,说明洗脱液pH值变化对As去除的影响相对较小;与HCl和HNO3相比,EDTA洗脱液pH值与Pb脱除率之间的负相关系数较大,与Zn、Cd、As脱除率之间的负相关系数较较小,说明EDTA洗脱液pH值变化更易对Pb的去除产生影响。     

Soil biological characteristic,nutrient contents and stoichiometry as affected by different types of remediation in a smelter-impacted soil

ABSTRACT

In order to evaluate the ecological risk reductions of copper (Cu) and cadmium (Cd) and the change of nutrient contents and stoichiometry in a smelter-impacted farmland in Guixi, Jiangxi Province, China, with ～ 800?mg Cu kg^?1 soil and 0.8?mg Cd kg^?1 soil, an three years in situ experiment was conducted. The field trial consisted of 4 ×?5?m plots in a completely randomised block design. Hydroxyapatite was added at 10?g kg^?1 soil and Sedum plumbizincicola, Elsholtzia splendens, and Pennisetum sp. were planted. Post-treatment soil and plant samples were collected annually and analysed for Cu and Cd bioaccessibility, soil carbon: nitrogen: phosphorus (C:N:P), and the stoichiometries of soil β-glucosidase (BG), N-acetylglucosaminidase (NAG), and acid phosphatase (AP) activity levels. The results indicated that the hydroxyapatite treatments significantly reduced Cu and Cd bioaccessibility as well as the ratio of C:P and N:P. Moreover, BG, NAG, and AP activity levels all increased relative to those in untreated soil. Plants may also influence soil BG, NAG, and AP activity. This study demonstrated that in situ Cu and Cd stabilisation by hydroxyapatite and phytoextraction is ecologically safe and can alter soil mineral nutrient ecological stoichiometry and enzyme activity.     

农田土壤重金属污染状况及修复技术研究

重金属污染因具有毒性、易通过食物链在植物,动物和人体内累积,对生态环境和人体健康构成严重威胁。随着工业快速发展、农药及化肥的广泛使用,农田土壤重金属污染越来越严重,研究农田土壤重金属污染现状及修复技术对农产品安全具有重要意义。综合国内外农田土壤重金属污染状况,农田土壤重金属污染主要来源于固体废弃物堆放及处置、工业废物大气沉降、污水农灌和农用物质的不合理施用。该文综述了国内外有关农田重金属污染土壤修复技术（物理修复、化学修复、生物修复、农业生态和联合修复）的研究进展,并针对各种修复方法,阐述了其原理、修复条件、应用实例及其优缺点,重点论述了植物修复的机理和应用,提出了草本与木本联合修复可有效提高农田土壤重金属复合污染的修复效率,为农田土壤土壤重金属复合污染修复提出了新的途径。最后在对已有研究分析的基础上,提出了联合修复技术（如生物联合技术、物理化学联合技术和物理化学-生物联合技术）可以在一定程度上克服使用单一修复手段存在的缺点,可提高复合污染的修复效率、降低修复成本,未来应深入探索联合修复技术间的相互作用机理,以期为农田土壤重金属综合治理与污染修复提供科学依据。     

Dissolved trace-metal concentrations along the Mediterranean Sea, to the north of the Nile Delta Region, Egypt

This work focuses on four marine sites of the Mediterranean Sea, north of the Nile Delta, Egypt. Surface-water samples were collected seasonally during 2003. The aim of this study is to assess the levels of some dissolved trace metals (Fe, Mn, Zn, Cu, and Pb) in two environmental conditions. The metal concentrations in the coastal zone were in the following ranges: 11.92-30.45 μg l^-1 for Fe, 5.79-17.36 μg l^-1 for Mn, 0.87-7.80 μg l^-1 for Zn, 0.40-1.87 μg l^-1 for Cu, and 1.53-10.31 μg l^-1 for Pb. In the sites with continental water input (mixing zone), the metals were scattered in the following ranges: Fe (19.72-60.33 μg l^-1), Mn (12.63-35.60 μg l^-1), Zn (2.67-22.00), Cu (0.83-8.10 μg l^-1), and Pb (1.72-29.7 μg l^-1). The results for the metal concentrations showed a remarkable decrease in the levels of the different metals going from the estuaries and outlets into the coastal sea water. Generally, the levels of the metals in the two zones are higher than the background levels of the unpolluted area. A comparison of the trace-metal levels in the coastal zone of the Mediterranean Sea north of Nile Delta with the minimal risk concentration (reported by water-quality criteria, WQC) showed a significantly lower content at the coastal area of the Mediterranean sea of Egypt. The study also indicated that the impact of anthropogenic inputs was limited in the distribution of the metals, except that the Pb content was slightly higher in the area of the mixing zone than that reported for WQC. The relationships between the different trace-metal concentrations and the other parameters (salinity, chlorophyll a and suspended particulate matter) were discussed, and the simple regressions between them were evaluated.     

A Comparative Study On the Levels of Trace Metals in Some Mediterranean and Red Sea Fishes

Samples of Mugil cephalus, Liza ramada, Siganus luridus, Siganus rivulatus, Epinephelus alexandrinus, Epinephelus areolatus, Epinephelus fasciatus, Epinephelus chlorostigma, Cephalopholis argus and Cephalopholis sonnerati were collected from the Mediterranean and Red Seas and their muscle and bone analyzed by AAS for some trace metals (Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd, Pb). the results showed that these metals accumulate in the bones to a greater extent than in the muscle. the highest accumulated element is cobalt (4.7-20.8 times), while the lowest is lead (1.1-2.5 times). the accumulation is more pronounced in Red Sea species than in Mediterranean species. the elevated levels of lead in Mugil cephalus (2.6-3.0 mg kg^-1) and Epinephelus alexandrinus (3.0-3.9 mg kg^-1) were attributed to the intake in food in the polluted environment of Alexandria coastal water. the relationship between body size and concentration of trace metals using a standard linear regression technique gives a significant positive correlation for cobalt, manganese, iron and lead in the muscle, as well as for lead in the bones of Mugil species from the Red Sea, while the Mediterranean species showed little correlation.

There is a tendency for increased concentrations of the essential metals manganese, iron and copper with increasing trophic level of the fish, while the opposite is true for the toxic metals chromium and lead. Our results indicate that there is no risk from toxic metal concentrations in muscle of fish from the Mediterranean and Red Seas consumed by man even in contaminated areas.     

Soil washing of As-contaminated stream sediments in the vicinity of an abandoned mine in Korea

A soil washing process was applied to remediate arsenic (As)-contaminated stream sediments around an abandoned mine in Goro, Korea. Laboratory scale soil washing experiments for As-contaminated stream sediments were performed under various washing conditions in order to maximize As removal efficiency. Stream sediments were taken from two sites (S1 and S5) along the main stream connected to an abandoned mine. Stream sediments at the two sites were divided into two groups (≥0.35 and <0.35 mm in diameter), giving four types of sediments, which were thereupon used for soil washing experiments. The results of soil washing experiments involving various pH conditions suggested that As removal efficiency is very high in both strongly acidic and basic solutions (pH 1 and 13), regardless of sediment type. Removal efficiencies for fine sediments from S1 and S5 were >95% after 1 h of washing with 0.2 M citric acid (C₆H₈O₇). When using 0.2 M citric acid mixed with 0.1 M potassium phosphate (KH₂PO₄), the As removal efficiency increased to 100%. When recycled washing solution was applied, As removal efficiency was maintained at a level greater than 70%, even after eight recycling events. This suggests that the recycling of washing solution could be successfully applied as a means of decreasing the cost of the washing process. Results from the experiments suggest that soil washing is a potentially useful process for the remediation of As-contaminated stream sediments around abandoned mines.     

Electro-remediation of tailings from a multi-metal sulphide mine: comparing removal efficiencies of Pb,Zn, Cu and Cd

Sulphidic mine tailings characterised by high concentrations of heavy metals (Pb 3532?±?97?mg/kg, Zn 8450?±?154?mg/kg, Cu 239?±?18?mg/kg and Cd 14.1?±?0.3?mg/kg) and abundant carbonate (17%) were subjected to eight lab-scale electrodialytic remediation (EDR) experiments to investigate the influence of current density, treatment time and particle size on removal efficiency. Pb and Cu removal improved when increasing current density, while Zn and Cd removal did not. In contrast Zn and Cd removal improved by grinding the tailings, while Pb and Cu removal did not. At the highest current density (1.2?mA/cm²), 94%, 75%, 71% and 67% removal of Pb, Zn, Cu and Cd could be achieved, respectively, on grinded tailings in 28 days. Sequential chemical extraction made before and after EDR revealed larger oxidisable fractions of Zn, Cu and Cd, representing large fractions of sulphides, which was likely to be the main barrier to be removed as efficiently as Pb. This was in accordance with acid/base extraction tests in which Pb showed high solubility at both high and low pH (up to 65% and 86% of extraction, respectively), while considerable extraction of Zn (55%) happened only at low pH; and very limited extraction (<20%) of Cu and Cd occurred at any pH.     

阴极pH控制对电动去除电镀污泥重金属的影响

采用电动修复装置,选用电镀污泥作为试验材料,试验设计了3个不同pH值的阴极缓冲液处理,施加直流电压32 V,运行7 d,研究了不同pH值阴极缓冲液对电镀污泥电动修复过程的影响.结果表明,阴极缓冲液pH值的变化,影响了电动过程中电流大小,pH较低时,电流较大;pH较高时,电流较小.电动修复后,各处理电镀污泥重金属的电动修复效果不同,其中,pH值控制为3时,Ni、Cu、Zn和Cr的去除率分别达到70%、59%、30%和29%,而Pb的去除率在pH值控制为5时去除率达46%.各处理截面重金属浓度较实验前都有不同程度的降低,其中Cu、Pb和Ni在不同污泥截面分布较均匀,而Cr和Zn在各截面分布波动较大.电动修复对各种形态的重金属都有不同程度的去除,对可交换态和铁锰氧化物态的去除效果较差,对碳酸盐结合态和残渣态有明显去除,有机硫化物态去除效果一般.     

Trace metal distribution in different chemical fractions of marine sediments along the eastern Aegean shelf

The major objective of this study was to carry out sequential chemical extraction for the partitioning of particulate trace metals in sediment samples, collected along the eastern Aegean shelf during cruises July‐August 1994, in the framework of a National Marine Measurement and Monitoring Programme for the Aegean Sea.

Five metals, Cd, Pb, Cu, Zn and Cr were examined in each of sediment samples. Three chemical fractions of the sediments were separated and concentrations of the trace metals were determined by AAS techniques. The three different leaches used were hydroxylamine hydrochloride‐acetic acid, hydrogen peroxide and nitric‐perchloric acids.

Metals were concentrated mainly in the fraction extracted by nitric‐perchloric acids. Lead in the first fraction were found in the sediments of Northern part of Aegean, where the concentration of organic material was high.

The total concentrations of Cd, Cu, Zn, Cr were higher in Izmir Bay than the other sampling points. The distribution of Pb concentrations was the highest in Edremit Bay and Izmir Bay.     

杨树、落叶松对土壤重金属的吸收及修复研究

在沈阳生态实验站开展了木本植物对土壤重金属的吸收积累及修复效应的研究,实验结果表明,重金属污染物已影响了杨树(Populus canadensis)的正常生长,Cd、Cu、Zn复合污染处理杨树总生物量比对照下降了26%。Cd、Cu、Zn处理杨树和落叶松重金属吸收量多于对照,杨树叶Cd、根Cu重金属吸收量分别比对照增加了2.09倍、2.2倍。落叶松(Larix koreana)根Cd、Cu、Zn的吸收量比对照分别增加了2.17、1.95和1.42倍。树木体内重金属元素迁移能力的大小分别为Cd>Zn>Cu,重金属吸收系数大小依次为杨树>落叶松,重金属在杨树体内的迁移能力及地上部吸收能力要大于落叶松。土壤一旦遭受重金属污染(Cd、Cu、Zn),通过木本植物杨树、落叶松修复净化的时间相当漫长。     

Soil remediation using in situ immobilisation techniques

The main objective of this study was to investigate the efficiency of different substrates to reduce the extraction of heavy metals concentration in a heavily contaminated soil. Two contaminated soils by Cu and Zn were used to evaluate the effectiveness of eight substrates (calcium carbonate, bentonite, kaolinite, charcoal, manganese oxide, iron oxide, zeolite, phosphate) to reduce metal availability and to study the change of metals speciation in different forms using sequential extraction technique (single step). Sequential extraction technique (single step, 0.11 M acetic acid, HONH₃Cl, H₂O₂+NH₄OAc, Aqua regia) was applied on contaminated soils after and before treatment to evaluate metals speciation. Results indicate that the most effective treatments in decreasing available metal concentrations were calcium carbonate, zeolite and manganese or iron oxide. Metal sequential fractionations indicate that the exchangeable fraction of Cu and Zn in contaminated soils can be transformed into unavailable forms after chemical remediation.