Determination of heavy metals and other trace elements in lake sediments from a sewage treatment plant by neutron activation analysis

Instrumental neutron activation analysis (INAA) was used to determine metals (Ba, Co, Cr, Cs, Fe, Hf, Rb, Sc, Zn), semi-metals (As, Sb), actinides (U, Th) and rare earth elements (La, Ce, Nd, Sm, Eu, Tb, Yb and Lu) in bottom sediments from one of the ponds of the Sewage Treatment Plant (STP) in São Paulo, Brazil. The results obtained were compared with the concentration determined in a soil profile and in a rock sample, in natura, representing the lithologies of the region, and indicated that only As, Cr and Zn can have their origin associated with the residues disposed around the pond.     

Assessment of trace metals contamination in estuarine sediments using a sequential extraction technique and principal component analysis

Fractionation of the metals Cd, Cr, Cu, Ni, Pb and Zn in sediments was performed for samples collected from eight locations in the Poxim river estuary of Sergipe State, northeast Brazil, using the 3-stage sequential extraction procedure proposed by the European Community Bureau of Reference (BCR). The extraction method was found to be satisfactory for analysis of certified reference material BCR-701, with recovery values ranging from 85% (Cu) to 117% (Cr). The detection limits obtained were 0.001 to 0.305 µg g^− 1. Zn exhibited greatest mobility and bioavailability, indicative of anthropogenic sources, while Cr was mainly found in the residual fraction and could be used as an indicator for the contribution from natural sources. Cd, Cu, Ni and Pb were associated with the oxidizable fraction, and Pb, Cr and Ni with the reducible fraction. Principal component analysis (PCA) clearly separated the metals into three groups: I (Zn); II (Pb); III (Cd, Cu, Cr and Ni). These groupings were mainly due to different distributions of the metals in the various fractions, in sediments from the different locations. Risk assessment code (RAC) analysis indicated that although the metals presented a moderate overall risk to the aquatic environment, nickel showed a low risk (RAC < 10%) at three sites, while zinc presented a high risk (RAC > 30%) at four other sites.     

微波消解-电感耦合等离子体质谱同时测定普里兹湾沉积物中微量元素

以HNO3-H2O2为消解体系,采用微波对沉积物进行消解,建立了普里兹湾沉积物中微量元素的电感耦合等离子体质谱(ICP-MS)测定方法。从样品分析数据可以看出:8个站位10种元素总量变化范围为493.41～1481.02μg/g,总量最大值是最小值的3.00倍。元素Ba、Mn在总量中占了很大比例,V次之,而As、Mo、Ag、Cd的含量很少。大部分元素检出限可达ng/L,仅Co、Mo 2种元素的检出限稍高;各元素线性良好,相关系数r2≥0.9997。方法的RSD<5.0%,适用于普里兹湾沉积物中微量元素的定量分析。     

Distribution of some major and trace elements in Danube Delta lacustrine sediments and soil

Sediment cores collected from lakes Mesteru and Furtuna (eastern part), Sontea channel and soil samples collected from Caraorman bar, all located in the Danube Delta, were analyzed for 42 elements (Ag, Al, As, Be, Na, Mg, P, S, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, As, Se, Br, Rb, Sr, Y, Mo, Ag, Cd, In, Sn, Sb, Cs, Ce, Hf, Hg, Tl. Pb, Bi, Th. U) by instrumental neutron activation analysis (INAA), thick target proton induced X-ray emission (TT-PIXE) and inductively coupled plasma-mass spectrometry (ICP-MS). The INAA and TTPIXE yielded total concentrations whereas the ICP-MS data reflected the fractions soluble in 14M HNO₃. The ICP-MS data exhibited surface enrichment relative to the lower part of the sediment core of Cu, Zn, As, Ag, Cd, In, Sn, Sb, Hg, Tl, Pb, and Bi, most prominently by Cd and Hg. Their vertical distribution in the investigated cores generally reflected the pollution history of recent sediments in Danube delta, showing a steady increase until the end of the 1980s followed by a slow decrease after 1990. The vertical profiles of most remaining elements were characterized by a relatively uniform distribution along the cores. In some cases, the concentrations of As, Cd, Cu, Cr, Mn, Ni and Pb exceeded minimum thresholds of safety, as defined by the Romanian regulations. The elemental composition of the sediment below 20 cm depth (total concentrations) was similar to that of the upper continental crust (UCC) for most elements. Values distinctly higher than UCC were observed for As, Sb (factor ~5) and Cr, Ni, Cu (factor 2 to 3). The nitric acid soluble element concentrations in the soil samples in some cases showed increased values at the surface as compared to 30 cm depth, either due to air pollution or to the action of plants. In no case a large contribution to the topsoil from atmospheric deposition was evident, indicating that the surface contamination of the sediments was mainly by riverine transport. This revised version was published online in July 2006 with corrections to the Cover Date.     

Determination of trace elements and heavy metals in a lake sediment by neutron activation analysis

Twenty trace elements and heavy metals of Dalat lake sediment were analyzed by neutron-activation analysis at the ASTRAREACTOR. The elaborated method was also controlled by analyzing the reference material for lake sediment SL-1 of IAEA. It showed a good agreement with the certified values for most of the elements. The relative errors ranged from 1% to 25%.     

Ultrasound energy focused in a glass probe: An approach to the simultaneous and fast extraction of trace elements from sediments

The 3051 USEPA method (or alternatively, the 3051A) can be considered nowadays as a reference method to extract metals from sediments. However, after microwave heating, the sample must be allowed to cool down, which results in a considerable lengthening of the whole analytical process. Microwave ovens and their maintenance are, in addition, expensive, and its use is relatively dangerous. The use of ultrasound focused energy to assist the extraction of chemicals from solid samples is a safe and relatively cheap technique. In this work we propose a new method to extract simultaneously several elements from sediments using ultrasound energy focused in a glass probe to accelerate the process, and check its possibilities to become an alternative to the EPA3051(A) approach. The optimised procedure allows extracting 13 elements in only 6 min, with similar recoveries and, in general, better repetitivities than the EPA3051. In addition, the suspension is only slightly heated during the leaching process.     

湖泊沉积物中镉的测定及环境意义研究

建立了氢化物发生-原子荧光光谱法测定湖泊沉积物中镉的分析方法.优化了沉积物中镉的提取条件和测定条件,研究了Cu元素对测定镉的干扰及消除方法.以武汉市涨渡湖为例,通过对总镉和有效态镉的测定揭示了涨渡湖近百年来镉的各形态垂直分布特征.结果表明:自上世纪50年代以来,涨渡湖沉积物中的总镉由深层到表层呈上升趋势,有效态镉变化不大但其含量维持在较高水平.镉的潜在风险性较大.     

Biogenic substances in sediments and fossils

Most sedimentary rocks contain small concentrations of finely divided organic material. With the aid of modern analytical methods, samples of such rocks can be examined in detail, and conclusions can be drawn concerning the origin of the organic substances. Intact or modified biogenic compounds such as paraffins, isoprenoids, alcohols, ketones, carboxylic acids, steroids, triterpenes, and porphyrins have been isolated from the soluble fractions of the organic material of many sediments and from identified fossils of various geological ages. Even Precambrian rocks contain biogenic substances, so that life forms must have existed more than three billion years ago. The main component of the organic material is “kerogen”, the complicated polymeric structure of which has not yet been established.     

微波消解-GFAAS测定浅水湖泊底泥中重金属元素

探讨了采用微波消解作为底泥样品的前处理方法,运用石墨炉原子吸收法测定浅水湖泊底泥中Cu,Pb,Zn,Cd,Cr含量的实验条件.方法的RSD为2.0％～4.1％,平均回收率为97.4％～101.5％,Cu,Pb,Zn,Cd,Cr的检出限分别为0.4,5,2.8,0.25,2.5ng.该法适合于浅水湖泊底泥中重金属含量的测定.     

Assessment of metals and trace elements in sediments from Rio Grande Reservoir,Brazil, by neutron activation analysis

The Rio Grande Reservoir, Southeast of the São Paulo Metropolitan Area, supplies water for four counties (about 1.6 million people). It has been seriously affected by urban expansion due to chaotic urban occupation and improper use of the surrounding areas. In this study bottom sediment samples were collected during the dry season and rainy season. Four sampling points were defined and located at the mouth of the Rio Grande and Ribeirão Pires Rivers (points 1 and 2), in the middle of the reservoir (point 3) and near the catchment point of the water supply (point 4). Samples were submitted to instrumental neutron activation analysis and some metals, trace and rare earth elements were determined. The methodology validation according to precision and accuracy was carried out by reference material analyses. The results obtained were compared to earth crust values and also with results already published in the literature. The enrichment factor in relation to earth crust values using Sc as reference element was calculated and a strong enrichment was found for the elements As, Br, Sb, Th, U and Zn. A strong anthropogenic influence was observed for some elements, mainly in the points located in the entrance of the reservoir that receives domestic and industrial effluents from the rivers that reach the reservoir.     

Amazon estuary — assessment of trace elements in seabed sediments

The interactive processes operating on the continental shelf adjacent to the river mouth control the amount and the characteristics of the Amazon discharge reaching the Atlantic Ocean. In this study, the distribution of trace elemental concentrations, with emphasis to the rare-earth elements, in sediment cores collected at several stations from the Amazon continental shelf during the falling water period was investigated by instrumental neutron activation analysis. Cores from the terrigenous and blue water zones have relatively uniform REE concentrations throughout the profile. Cerium anomalies for samples of the upper section of the eight stations are consistently positive and of high values (normally >2). Similar variation in the elemental concentration ratios between the seabed sediments and Amazon River suspended sediments was seen for stations located in the biogenic and blue water zones, with an enrichment for Ce, Sm, Fe, Th, and Sc and a depletion for the La, Eu, Tb, Yb, Co, Cr, Cs, Hf, Ta, and Zn. The shale-normalized REE patterns from shelf sediments are enriched in LREE relative to HREE, with enrichment factors varying from 1.5 for stations near the river mouth (terrigenous zone) to 1.9 for stations located far in the blue water zone. Published data for the Amazon River suspended sediment agree remarkably well with this observation of LREE-enrichment.     

In situ voltammetric measurement of trace elements in lakes and oceans

A submersible probe with a flow-through cell allowing in situ voltammetric measurements by means of either a mercury film or a mercury drop electrode has been developed. The various possibilities of voltammetric measurements in the presence of dissolved oxygen have been reviewed and tested. Optimum conditions for the determination of trace metals in oxygenated waters have been found. In situ determinations of Mn(II) in anoxic lake water and of trace metals (Cu²⁺, Pb²⁺, Cd²⁺, Zn²⁺) in oxygen-saturated sea water are reported.     

Determination of elemental selenium and pyrite-selenium in sediments

A method is described for the selective determination of concentrations of elemental selenium and pyrite-selenium in sediments. A 1 M sodium sulfite solution is used to solubilize elemental selenium and a Cr(II) solution releases selenium in pyrite. The accuracy of the methods was evaluated by using various selenium compounds. The detection limits for the elemental and pyrite-selenium procedures are 0.001 and 0.025 μg Se per gram of sediment, respectively. The relative standard deviationis < 10% for elemental selenium and < 16% for pyrite-selenium. These and other procedures were used for selenium speciation in marine and freshwater sediments.     

Inductively coupled plasma optical emission spectrometric determination of trace elements in sediments after sequential selective extraction: effects of reagents and major elements on the analytical signal

The interfering effects due to the reagents and matrix elements associated with a four step sequential extraction procedure on ICPOES determination of trace elements were investigated in a systematic way. The emission lines were selected in order to include the most interesting elements for environmental studies (Zn, Pb, Ni, Cr, V and Cu) and the concentrations ranged according with the values occurring in the real samples. In order to distinguish between chemical and physical interfering effects, the Mg 280.270–Mg 285.213 line intensity ratio was measured, in each condition. Both pneumatic and ultrasonic nebulization were considered for comparison. It was found that both the elements which constitute the sample and the reagents which are added during the sample preparation steps significantly influence the emission intensity of all the analytes, depending on the analytical concentration and the nebulization system. Generally, the signal variations were higher with ultrasonic nebulization. Concerning the interference mechanism, it was found that the effect of the major elements (Na, K, Mg, Ca, Al and Fe) is essentially related to a change of the aerosol generation and transport processes. Differently, acetic acid, ammonium acetate and hydroxylamine hydrochloride significantly improved the plasma excitation conditions, depending on their concentration. A change of the sample introduction efficiency due to the presence of these reagents was also evident. On the contrary, the effect of hydrochloric and nitric acid emerged to be related only to the processes occurring in the sample introduction system.     

Environmental mobility of trace metals in sediments collected in the Lake Balaton

In environmental pollution studies on solid materials sequential extraction techniques are used for the identification of the main binding sites of trace metals. A four-step sequential extraction procedure was applied to the determination of the distribution of elements like Cd, Cu, As, Pb, Cr, Ni, Zn, Al, Fe, and Mn in sediment samples collected in the Lake Balaton. The fractions were (1) exchangeable and bound to carbonate, (2) bound to Fe/Mn oxide, (3) bound to organic matter and sulfides, and (4) acid-soluble. Elements were mainly accumulated in the stable, acid-soluble fractions. Arsenic and Cd-ions were found in low concentration (1.2–13 mg/kg and < 1 mg/kg, respectively) in the samples. Based on the results determined at 15 sampling points it can be stated that the Lake Balaton has not yet been polluted by the elements investigated.     

Neutron activation analysis of major and trace elements in crude petroleum

We have determined the concentration of 25 trace elements in crude petroleum from seven Libyan oil fields by instrumental neutron activation analysis. Crude oil samples were irradiated with a thermal neutron dose rate of 10¹² and 10¹³ n·cm^–2·s^–1 in the Tajoura research reactor. The concentration of U, Br, Mg, Cu, Na, V, Cl, Al, Mn and Ca is in a range of 0.015 to 84 ppm and that of sulphur of 0.12 to 1.8%. The elements Sc, Cr, Ni, Fe, Co, Zn, Ag, Se, Sb, Ba, Cs, Yb, Hf and Hg have a concentration range of 0.009 to 8747 ppb. The coefficients of variation are within 10%. The elements V and Ni occur as both porphyrin and non-porphyrin and the ratio of these two forms varies over a wide range. The V/Ni ratios are located between 0.17 and 6.67, which are comparable to the reported values for the crude oils from other countries.     

Investigation of the vertical distribution of major and trace elements in Matita Lake (Danube Delta) sediments by activation analysis

The vertical profiles of two major elements (Na and Ca) and 24 trace elements (Rb, Cs, Sr, Ba, Sc, La, Ce, Sm, Eu, Tb, Yb, Lu, Th, U, Hf, Nb, Ta, Cr, Fe, Co, Zn, As, Sb and Br) have been investigated by neutron activation analysis in a 2.5 m core collected from the Danube Delta, Matita Lake. The data have been correlated with the concentrations of five major minerals (calcite, dolomite, feldspar, clay and quartz) as determined by X-ray diffration. This study revealed the presence of As, Sb and Br as pollutant microelements.     

Role of mineralogical structure of sediments in accumulation of radionuclides and trace elements

Similar distributions for ²³⁸U, ²³²Th, ²²⁶Ra, ²¹⁰Po, ^238,239,240Pu, ¹³⁷Cs and trace elements were obtained in sediment samples collected along the Romanian sector of the Danube River and the Black Sea coast during 1994. The radionuclide and trace element accumulation in the investigated samples is discussed with respect to their geochemical behavior and the mineralogical structure of the samples. The latter, investigated by X-ray diffraction and cation exchange capacity of the same samples, proves to be an important factor in the selection of sampling sites for monitoring the pollution of river basins and the sea.     

Major and trace elements in sediments of the upper course of Lerma river

Summary The Lerma is one of the most important rivers of Mexico, where it drains highly populated and industrialized regions. The concentration of six major and trace elements: titanium, manganese, iron, zinc, copper and lead in the surface sediments of the upper course of Lerma river was investigated, in order to identify its distribution along the river and to recognize the principal sites of pollution. The surface sediment samples were collected at 8 sites distributed following the stream flow direction of the river. Major and trace elements concentrations were determined by energy dispersive X-ray spectrometry. The results show that the metal concentrations in the sediments decrease in the sequence: Fe > Ti > Mn > Zn > Cu > Pb. Concentration of Fe, Mn and Ti were significantly higher than the other metals in site 8,200 meters downstream the Alzate Dam. The high concentrations and spatial variations of Zn, Cu and Pb in the middle sites of the upper course of the Lerma River indicate that the river pollution is probably associated with urban and industrial discharges.