Selective extraction and separation of Fe,Mn oxides and organic materials in river surficial sediments

In order to investigate the adsorption mechanism of trace metals to surficial sediments （SSs）, a selective extraction procedure was improved in the present work. The selective extraction procedure has been proved to selectively remove and separate Fe, Mn oxides and organic materials （OMs） in the non-residual fraction from the SSs collected in Songhua River, China. After screening different kinds of conventional extractants of Fe and Mn oxides and OMs used for separation of heavy metals in the soils and sediments, NH2OH .HCl （0.1 mol/L） ＋ HNO3 （0.1 mol/L）, （NH4）2C2O4 （0.2 mol/L） ＋ H2C2O4 （pH 3.0）, and 30% of H2O2 were respectively applied to selectively extract Mn oxides, Fe/Mn oxides and OMs. After the extraction treatments, the target components were removed with extraction efficiencies between 86.09%--3.36% for the hydroxylamine hydrochloride treatment, 80.63%- 101.09% for the oxalate solution extraction, and 94.76%-102.83% for the hydrogen peroxide digestion, respectively. The results indicate that this selective extraction technology was effective for the extraction and separation ofFe, Mn oxides and OMs in the SSs, and important for further mechanism study of trace metal adsorption onto SSs.

Optimization of Ultrasonic Extraction and Clean-up Protocol for the Determination of Polycyclic Aromatic Hydrocarbons in Marine Sediments by High-performance Liquid Chroma-tography Coupled with Fluorescence Detection

The procedures of ultrasonic extraction and clean-up were optimized for the determination of polycyclic aromatic hydrocarbons (PAHs) in marine sediments. Samples were ultrasonically extracted, and the extracts were purified with a miniaturized silica gel chromatographic column and analyzed with high performance liquid chromatography (HPLC) with a fluorescence detector. Ultrasonication with methanol-dichloromethane (2:1, v/v) mixture gave higher extraction efficiency than that with dichloromethane. Among the three elution solvents used in clean-up step, dichloromethane-hexane (2:3, v/v) mixture was the most satisfactory. Under the optimized conditions, the recoveries in the range of 54.82% to 94.70% with RSDs of 3.02% to 23.22% for a spiked blank, and in the range of 61.20% to 127.08% with RSDs of 7.61% to 26.93% for a spiked matrix, were obtained for the 15 PAHs studied, while the recoveries for a NIST standard reference SRM 1941b were in the range of 50.79% to 83.78% with RSDs of 5.24% to 21.38%. The detection limits were between 0.75 ng L-1 and 10.99 ng L-1for different PAHs. A sample from the Jiaozhou Bay area was examined to test the established methods.

Chemical forms and extractability of iron in sediments of three contrasting lakes of China and UK

Iron is a limiting factor for the eutrophication of lakes, especially those lakes that are enriched with phosphorus. Extractability of iron in sediments of West Lake and Taihu Lake in China and Lower Lough Erne in Northern Ireland of UK was comparatively investigated on the basis of analysing chemical forms of iron using different extractants. It was shown that extractable iron in sediments of the lakes was greatly different using various extractants. Reactive iron or easily released iron such as “active' iron oxides, total free iron oxide and water-soluble iron was not high, only accounting for 0.01%—0.15% of total iron. The efficiency of the extractants for exchangeable iron was decreased in the sequence 0.1 mol/L HCl DTPA+TEA mixed solution > 1 mol/L NH 4OAc > 0.5 mol/L MgCl 2 = 0.5 mol/L CaCl 2. It seems that the complexion of iron by organic matter was not strong because the concentration of organically bound iron was significantly lower than the concentration it was forecasted. Extractable iron is not entirely consistent with or dependent on total iron in lake sediments. To a certain extent, phosphate can inhibit the release of iron in sediments of the lakes. The selection of extractants is thus the first key step to evaluate bioavailability of iron in lake sediments.

土壤和沉积物重金属形态分析研究进展

人类社会的发展进程导致土壤和沉积物中的重金属含量远远超过背景值,具有严重的潜在威胁隐患。然而,由于重金属的流动性、毒性以及生物累积性会对环境造成深远影响,重金属形态分析已然成为环境研究的重要一环。目前最具代表性的形态提取方法为Tessier法和BCR三步法,为标准物质研制、重金属污染评估、生态修复以及生物有效性风险等问题提供了有效解决方案,但也有着各自的局限性。总结目前常用的元素形态提取分析方法,系统对比论证,讨论重金属形态分析方法未来可能出现的问题和发展方向,以期为土壤及沉积物重金属污染研究提供思路与支撑。

胶州湾沉积物的不同相态主量元素含量及铁同位素组成初探

沉积物是物源、沉积环境、生源过程等多因素影响下的产物,不同元素进入沉积物的方式不同导致其赋存在不同的相态中,通过研究不同相态沉积物的元素丰度及同位素组成,可以揭示由于多种过程混合所掩盖的生物、物理及化学信息。本研究通过选择性化学提取法,对胶州湾沉积物进行了分级提取,包括碳酸盐结合态、易还原的氧化物态、可还原的氧化物态、磁铁矿态和残留态。测试结果表明:主量元素主要赋存在残留态中,但在非残留态中不同程度保留有Ca、Fe、Mg、Mn和P。结合胶州湾沉积物中的常见矿物成分,除了之前研究已介绍的不同相态的目标矿物组成,推测易还原的氧化物态的潜在矿物还有独居石和磷灰石;可还原的氧化物态的潜在矿物还有褐铁矿;磁铁矿态的潜在矿物还有钛铁矿;部分硅酸盐矿物也存在于易还原的氧化物态和可还原的氧化物态中。残留态富集了重铁同位素,继承了物源区的特征,并且全组分的铁同位素主要受控于残留态;活性铁组分的铁同位素由于受到了非陆源组分的影响,导致同位素变化。

黄河三角洲海岸线提取及其近期时空变化格局

新入海水沙情势下,黄河三角洲海岸线变迁也相应呈现出新的特征。考虑不同潮位、水体计算指数、涨落潮阶段对海岸线提取效果的影响,利用ArcGIS、ENVI提取了黄河三角洲海岸线,并借助DSAS数字化海岸线分析系统,定量分析了1976-2020年黄河口海岸线变迁特征。研究发现,选择潮位相近、同处落潮阶段且成像质量较好的遥感图,并采用改进的归一化差异水体指数MNDWI计算,黄河三角洲海岸线的提取效果较好。黄河三角洲海岸线变化表现出明显的时空性,神仙沟-刁口河叶瓣1976年以来海岸线基本处于蚀退状态;东营港至孤东油田海岸线自1990年在人工海堤的防护下维持稳定;入海口附近海岸线的蚀退和淤进与陆向来沙量直接相关,陆向来沙充足时呈淤进趋势,反之则冲蚀后退,同时其也受河口改道、海洋动力等其他因素影响。研究可为未来黄河口综合治理规划提供一定参考。

东昆仑东段浪木日地区地球化学异常信息提取方法研究及异常查证

青海沟里地区位于东昆仑造山带东段,根据水系沉积物地球化学测量已发现了多个矿床(点),具有较好的找矿潜力。本文选取沟里地区巴加别里赤尔幅(浪木日地区)1∶5万水系沉积物地球化学测量数据为研究对象,利用统计学方法和趋势面分析法两种方法进行异常信息提取。结果显示,趋势面分析法相较于传统统计法,圈定的异常面积更大、浓集中心更明确、分带特征更明显,且与已知矿床点的吻合度更高,整体上具有强化低背景异常的优势。同时利用趋势面分析法提取了3个元素组合,并对套合性和相关性突出,且与区内浪木日铜镍硫化物矿床相关的Cu-Zn-Cr-Co-Ni组合异常进行异常剖析。结合区内地质特征和浪木日矿区矿体分布情况,圈定了哲扎空龙洼东、龙里、瑙格木东和卡鲁南等找矿远景区,为区内下一步铜镍找矿工作提供了方向。

利比里亚Harper地区水系沉积物地球化学特征及找矿方向

比里姆(Birimian)岩系作为西非地区最重要的Au成矿岩系,在利比里亚东南部的Harper地区广泛分布,Harper图幅1∶25万水系沉积物测量数据的地球化学特征参数表明,区内Au、Hg等元素具有强富集、强分异的分布特征,As具有富集、强分异的分布特征,显示出该地区优异的Au找矿前景。通过元素相关性分析,本次筛选出能够有效指导Au矿勘查的F1因子(Au-Hg-Pb-Sn元素组合)及F2因子(As-Sb-W元素组合),通过对两组主因子中的Au、Hg、As、Sb 4种元素开展异常信息提取,圈定出13处组合异常,有效反映了区内不同类型金矿(点)的异常分布特征。异常区的地质矿产检查工作表明,在具有定向展布特征且异常强度较高的HS1-HS3、HS12-HS13组合异常区内具有明显的Au矿化信息,以此为基础,圈定出Seethum New及Behwan等2处可供开展进一步详细勘查工作的Au重点找矿远景区。

超声提取-高效液相色谱法测定沉积物中6种邻苯二甲酸酯

拟建立超声提取,采用高效液相色谱技术,实现对河道沉积物中6种邻苯二甲酸酯的快速测定方法。经验证,6种邻苯二甲酸酯组分在浓度范围0~5μg/mL内均表现出优异的线性关系(相关系数r>0.999)。在取样量为5.00 g的条件下,该方法的6种邻苯二甲酸酯组分检出限被确定为0.0129~0.0387 mg/kg。使用该方法测定标准物质(RMU001a),结果均在标准值范围内;实际样品加标回收率在83.3%~107.8%。结果表明:使用超声提取联合高效液相色谱法可有效提高检测效率,适用于推广用于沉积物中6种邻苯二甲酸酯批量化快速测定。

超声提取-紫外分光光度法测定海洋沉积物中油类的研究

利用超声提取和离心分离方法替代手工振荡提取和分液漏斗洗涤分离方法提取海洋沉积物中的油类,研究最佳试验条件,并与标准方法开展比对。试验结果表明,超声提取法总体较手工振荡法回收率高10个百分点,且工作流程简单、操作方便快速,减少了提取液多次转移的误差,在提高工作效率的同时提升了分析方法的精密度和正确度。

富硫型水库沉积物AVS和SEM空间分布特征及重金属风险评价

随着湖库外源性污染的有效控制,沉积物污染特征成为影响湖库水环境质量的关键因素。本文以富硫型水库——汤河水库为研究对象,分析探讨水库沉积物的理化性质、重金属总量、酸可挥发性硫化物(acid volatile sulfide,AVS)和同步提取重金属(simultaneously extracted metals,SEM)的空间分布特征,采用沉积物基准法(sediment quality guidelines,SQGs)和AVS与SEM关系法对重金属可能诱发的生态风险和毒性效应进行评估。结果表明:汤河水库沉积物中AVS含量在0.03~51.75μmol/g之间,并呈现坝前深水区>东支流库区>西支流库区的空间分布特征。根据Pearson相关性分析可知,汤河水库沉积物AVS含量与间隙水中SO^(2-)_(4)浓度、沉积物烧失量(LOI)含量呈显著正相关,与沉积物间隙水中NO^(-)_(3)浓度和沉积物pH呈现显著负相关。间隙水中SO^(2-)_(4)浓度和沉积物LOI含量是控制AVS产量的重要因素。水库沉积物中ΣSEM变化范围为0.52~2.75μmol/g,呈现出东支流库区>坝前深水区>西支流库区的分布规律。水库沉积物中ΣSEM/AVS和ΣSEM-AVS的变化范围分别为0.06~22.73和-49.18~2.44μmol/g,显示出水库坝前深水区表层0~10 cm沉积物不具有生态风险,而东、西支流库区沉积物中的SEM因为不能完全被AVS所固定而存在潜在生态风险。就单一重金属而言,汤河水库坝前深水区和东西支流中部区域沉积物Ni、Cu、Pb和Zn含量均介于临界效应含量(threshold effects level,TEL)值和可能效应含量(probable effect level,PEL)值之间,可产生低级风险毒性效应,但Ni的毒性效应风险接近中级,今后应予以重点关注。富硫型水库沉积物中容易出现高含量AVS,沉积物间隙水中SO^(2-)_(4)和NO^(-)_(3)的浓度是决定沉积物AVS净产量的重要因素。流域内重金属土壤背景值以及工业、采矿产业排放的废水类型直接影响着诱发生态风险的重金属种类。

Heavy metals partitioning in the sediments of Izmir Inner Bay

Izmir Bay is known to be polluted by high concentrations of heavy metals and organic pollutants. Sediment samples taken from 7 different stations in Izmir Inner Bay were analyzed for their total organic matter content and, Cu, Cr, Pb and Zn. In addition, the chemical distribution of the metals were determined by means of the BCR （Community Bureau of Reference） Extraction Procedure （developed by European Commission for Standards, Measurement and Testing） which allows the determination of metals bound as four fractions; exchangeable and acid soluble, reducible （bound to iron-manganese oxides）, oxidizable （bound to organics） and residual. The results show that Izmir Inner Bay contains sediments with high metal concentrations. According to the chemical distribution of metals, Cr and Cu tend to accumulate mostly on the organic fraction of the sediment. Pb is mostly found in the reducible fraction where Zn is mobile in the sediment, and it is distributed evenly on each fraction.

Concentrations and chemical forms of potentially toxic metals in road-deposited sediments from different zones of Hangzhou, China

The 25 road-deposited sediments were collected from five different land-use zones （industrial, residential, commercial, park, and countryside） in Hangzhou, China. The concentrations of metals （Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn） in these samples were determined using ICP-AES after digestion with the mixture of HNO3-HF-HC1 （aqua regia）, and chemically fractionated according to the modified BCR （the European Community Bureau of Reference） sequential extraction procedure. The high metal concentration levels were detected in the sample from industrial zone and commercial zone having heavy traffic. While the low metal levels were noted in the street dust sample from residential zone, park, and countryside zone. The mobility sequence based on the sum of the BCR sequential extraction stages was： Zn （80.28%）, Pb （78.68%）, Cd （77.66%） 〉 Cu （73.34%） 〉 Mn （67.92%） 〉 Co （41.66%） 〉 Ni （30.36%） 〉 Cr （21.56%）, Fe （20.86%）. Correlation analysis and principal component analysis were applied to the data matrix to evaluate the analytical results and to identify the possible pollution sources of metals. Factor analysis showed that these areas were mainly contaminated by three sources, namely lithology, traffic, and industry.

Speciation of heavy metals in surface sediments from Suzhou Creek

Nine elements （As, Cd, Cr, Cu, Fe, Mn, Ni, Pb, Zn） in sediment samples at 7 sites （Site 1-7） from Suzhou Creek in Shanghai were analyzed with the Community Bareau of Reference （BCR） （sequential extraction （SE）） protocol and simultaneously extracted metals （SEM）/acid volatile sulfide （AVS） procedure to assess the metal bioavailability and toxicology in this area. The results showed that the BCR extraction can be utilized as an additional tool with the AVS method for assessing the potential bioavailability and toxicity of metals in sediments. Pollution from S5 （Site 5） was more severe than from other sites, especially Pb, Cu and Zn. Among all the sites, more than 80% of the total concentration of Fe existed in the residual fraction, As, Cr, Mn also dominated in the residual fraction （more than 50%）. While Cd, Ni and Zn （more than 35%） were mainly in the non-stable phase. Cu had a strong affinity with oxidizable phase and Pb varied from site to site. The SEM/AVS ratio was less than one in these sediments and results implied that the majority of Zn and Ni （〉 40%） were bound to AVS. In contrast, Pb, Cu and Cd were little bound to AVS due to their low ration of SEM-Pb, Cu, Cd to corresponding total concentration and relatively high Dorewater concentration.

苦荞复合饮料配方优化及贮藏品质研究

以苦荞粒为原料,以浸提率为指标,考查料液比、浸提时间和浸提温度对浸提效果的影响,优化提取工艺;以苦荞浸提液为原料制作复合饮料,对其配方进行优化;以感官评价为指标,通过检测可溶性固形物含量、饮料沉淀率、菌落总数、大肠菌群、色泽等指标,考查复合饮料于25℃条件下贮藏28 d品质的变化。结果表明,苦荞最佳浸提工艺为料液比1∶10(g∶mL),浸提时间15 min,浸提温度60℃时,苦荞浸提率19.77%;苦荞陈皮复合饮料的最佳配方为苦荞浸提液用量80 mL,陈皮汁用量60 mL,白砂糖用量20 g,柠檬酸用量0.2 g时,所得的苦荞陈皮复合饮料无杂质,色泽清亮,具有苦荞陈皮的香气,口感较好;产品于25℃条件下贮藏28 d可溶性固形物和沉淀率变化平稳,可溶性固形物含量约为14.3%,沉淀率约为0.65%,菌落总数小于100 CFU/mL,大肠菌群小于3 MPN/mL,随着贮藏时间的延长,L*值、b*值呈下降趋势,a*值、ΔE呈上升趋势。

Phosphorus fractions and its release in the sediments of Haihe River,China

The amounts and forms of phosphorus （P） in surface sediments of Haihe River, Tianjin, North China, were examined using a sequential chemical extraction procedure. Five fractions of sedimentary P, including loosely sorbed P （NH4Cl-P）, redox-sensitive P （BD-P）, metal oxide bound P （NaOH-P）, calcium bound P （HCI-P）, and residual P （Res-P） （organic and refractory P）, were separately quantified. The results indicated that the contents of different P fractions in the sediments varied greatly. The total P （TP） contents ranged from 968 to 2017 mg/kg. Phosphorus contents in NH4Cl-P, BD-P, NaOH-P, and HCl-P ranged from 6.7 to 26.6 mg/kg, 54.5 to 90.2 mg/kg, 185.2 to 382.5 mg/kg, and 252.3 to 425.5 mg/kg, respectively, which represented 1.2%-3.2%, 7.7%-13%, 33.3%-48.9%, and 36.2%-54.2% of the sedimentary inorganic P, respectively. For all the sediment samples, the rank order of P-fractions was Res-P 〉 HCl-P 〉 NaOH-P 〉 BD-P 〉 NH4Cl-P. The highly positive relationship between the amounts of P released from the sediments and those in the NH4Cl-P and BD-P fractions, indicated that NH4Cl-P and BD-P were the main fractions that can release P easily.

Investigation on Fe,Mn,Zn,Cu,Pb and Cd fractions in the natural surface coating samples and surficial sediments in the Songhua River,China

Natural surface coating samples （NSCSs） from the surface of shingles and surficial sediments （SSs） in the Songhua River, China were employed to investigate the relationship between NSCSs and SSs in fractions of heavy metals （Fe, Mn, Zn, Cu, Pb, and Cd） using the modified sequential extraction procedure （MSEP）. The results show that the differences between NSCSs and SSs in Fe fi＇actions were insignificant and Fe was dominantly present as residual phase （76.22% for NSCSs and 80.88% for SSs） and Fe-oxides phase （20.33% for NSCSs and 16.15% for SSs）. Significant variation of Mn distribution patterns between NSCSs and SSs was observed with Mn in NSCSs mainly present in Mn-oxides phase （48.27%） and that in SSs present as residual phase （45.44%）. Zn, Cu, Pb and Cd were found dominantly in residual fractions （〉48%）, and next in solid oxides/hydroxides for Zn, Pb and Cd and in easily oxidizable solids/compounds form for Cu, respectively. The heavy metal distribution patterns implied that Fe/Mn oxides both in NSCSs and SSs were more important sinks for binding and adsorption of Zn, Pb and Cd than organic matter （OM）, and inversely, higher affinity of Cu to OM than Fe/Mn oxides in NSCSs and SSs was obtained. Meanwhile, it was found that the distributions of heavy metals in NSCSs and SSs were similar to each other and the pseudo-total concentrations of Zn, Cu, Pb and Cd in NSCSs were greater than those in SSs, highlighting the more importance for NSCSs than SSs in controlling behaviours of heavy metals in aquatic environments.

Vertical variation of phosphorus forms in surface sediments from Wuli Bay,Taihu Lake,China

In order to investigate the cycling of phosphorus in the Taihu Lake, a sequential extraction technique was used to separate different phosphorus forms in surficial sediments from the Wuli Bay of the Taihu Lake. The concentrations of total P are high in the sediments, with an average of {2.80} mg·g+{-1}, and a variation range between {4.02} and {2.05} mg·g+{-1}. Total P is composed mainly of inorganic P (70%-90%), a large portion (75%-85%) of which lies in the CDB-extractable iron oxide phase. The low Fe/P atomic ratios ({2.0}-{5.3}) indicate that the Fe compounds extracted with CDB have a lower proportion of relatively crystalline phases in all samples, and that the absorption between iron and phosphorus has probably reached certain equilibrium. Organic C/N atomic ratios ({8.8}-{10.6}) for most of the samples are lower, which suggests a lacustrine authigenic source of organic matter in the sediments. Moreover, organic C/P atomic ratios (135-320) are usually higher than the Redfield ratio (106∶1), showing that the organic phosphorus had been preferentially released via organic matter degradation during the early diagenesis process.

Experimental Study on Mechanical Properties of Gas Hydrate-Bearing Sediments Using Kaolin Clay

A triaxial system is designed with a temperature range from -20 ℃ to 25℃ and a pressure range from 0 MPa to 30 MPa in order to improve the understanding of the mechanical properties of gas hydrate-bearing sediments. The mechanical properties of synthetic gas hydrate-bearing sediments （gas hydrate-kaolin clay mixture） were measured by using current experimental apparatus. The results indicate that： （1） the failure strength of gas hydrate-bearing sediments strongly depends on the temperature. The sediment＇s strength increases with the decreases of temperature. （2） The maximum deviator stress increases linearly with the confining pressure at a low-pressure stage. However, it fluctuates at a high-pressure stage. （3） Maximum deviator stress increases with increasing strain rate, whereas the strain-stress curve has no tremendous change until the axial strain reaches approximately 0.5%. （4） The internal friction angles of gas hydrate-bearing sediments are not sensitive to kaolin volume ratio. The cohesion shows a high kaolin volume ratio dependency.