Regional variation of sediment load of Asian rivers flowing into the ocean

Study of Asian major rivers discharge to the ocean reveals variations of their water discharges and sediment loads, and local characteristic of river sediment concentrations. On the basis of this, the Asian rivers can be divided into three regions: Eurasia Arctic, East Asia, Southeast and South Asia Region. The Eurasia Arctic Region is characteristic of the lowest sediment concentration and load, while the East Asia Region is of the highest sediment concentration and higher sediment load, and the Southeast and South Asia Region yields higher sediment concentration and highest sediment load.     

气相色谱法研究有机物在河流沉积物上的吸附

本文提出用有机物在沉积物上的色谱比保留体积值估算沉积物有机碳吸附系数，为此，以河流沉积物作气相色谱固定相，用测定气相色谱固定液相对极性和有机物比保留体积的方法，测定了沉积物相对极性和有机物在其上比保留体积，研究了Ｖｇ与Ｋｏｃ的相关性，结果表明，萘的线性关系式为ｌｏｇＫ＝０．１８＋３．１１（ｒ＝０．９８３１，ｎ＝５）。硝基苯的关系为ｌｏｇＫ＝０．２４ｌｏｇＶｇ＋２．５９（ｒ＝０．９５４４，ｎ＝５）．     

Evaluation of the Potential Release Tendency of Metals and Metalloids from the Estuarine Sediments: Case Study of Raša Bay

Assessing the environmental quality of coastal systems is important not only for the management and protection of such areas, but also for improving the quality of water resources. Since sediment itself can often be a source of certain toxic elements, in addition to information on the distribution of metals in the water column and in the sediment itself, it is useful to determine the bioavailable forms of individual elements, particularly toxic ones. In this study, water and sediment geochemical data were supplemented with oxyanion mobility in sediments estimated by diffusion gradients in thin film (DGTs). The data obtained indicate that the chemical composition of the water in the Raša River estuary primarily reflects the high input of suspended sediment from the catchment, the mixing of freshwater and seawater, and to a lesser extent the effects of anthropogenic activities. Although sediment composition is primarily determined by geological and hydrodynamic conditions in the catchment, it also indicates moderate enrichment in Co, Cr, Mo and Ni. In contrast, the distribution of oxyanions in sediment pore water indicates the influence of sediment as a source of some elements in the bottom water; e.g., sediment contributes to 40% of the arsenic bottom water budget. The obtained depth profiles of the oxyanion distribution in the sediment pore water indicate an early onset of suboxic to anoxic conditions in Raša Bay, which is prone to rapid sedimentation. All this demonstrates the need to consider the bioavailable forms of elements when assessing environmental quality, as the lack of such information can lead to an incomplete assessment, especially in dynamic coastal systems such as estuaries.     

运用测汞仪快速测定水系沉积物中的总汞

建立了采用测汞仪快速测定水系沉积物中总汞的分析方法,并进行标准样品及实际样品测定验证。结果表明,实际样品的加标回收率分别为97.0%~107.2%和98.9%~111.3%,相对标准偏差为1.2%~1.8%。该方法具有无需消解、测定快速、准确度高的特点,是一种测定水系沉积物中总汞的简便快捷方法。     

雨水和表面活性剂的淋溶对河道底泥中多氯联苯迁移的影响

利用雨水和表面活性剂(LAS、AE9和NPE10)淋溶多氯联苯(PCBs)污染的河道底泥柱,初步探讨了它们对表层底泥中PCBs洗脱量的影响,同时也研究了从表层洗脱出的PCBs随着淋洗液在下层底泥中的纵向迁移。淋洗液包括雨水和浓度均为1500mg.L-1的LAS、AE9、NPE10溶液以及浓度都是1500mg.L-1的AE9+NPE10和LAS+NPE10混和溶液。实验发现:雨水和同浓度的表面活性剂溶液对表层底泥中PCBs洗脱量大小依次为:雨水相似文献   

The Influence of the Air-Drying Pretreatment of Sediment Samples for Metallic Element Mobilities

Chemical analysis of sediments provides an efficient tool for water quality management. Ten sediment samples collected in 2008 from two locations situated in the Danube Delta Biosphere were analyzed in a comparative study of mobile metallic elements via two different pre-treatment techniques: air-drying followed by sieving and wet sieving. The experimental data proved that air-drying procedure produces drastic changes in mobility of the metallic elements from the sediments which were studied as an effect of the oxidizing conditions. Wet sediment or oxygen-free dried sediment is recommended to be used in environmental studies regarding determination of mobile fractions from sediment samples.     

Behavior of some macroelements,trace elments and RE in the water-sediment system

The aim of this work was to estimate the processes of sorption or desorption which take place when water of slightly higher temperature and elevated concentrations of some elements, compared to groundwater, comes into contact with aquifer sediments under aerobic conditions. The behavior of some macro-elements, trace elements and RE in the water/sediment systems, prepared as five different granulometric fractions of the sediment, was followed by INAA, AAS and titrimetric methods, under simulated natural conditions. It was found that, for the majority of elements, desorption takes place. Opposite to this, Mg and Zn are sorbed from water on all sediment granulometric fractions. The concentration of Ca as a major cation is lingering about its initial value. Na, K, Ba, Sr, Fe, Hg, Au, Sc, Sb, U, La and Ce are desorbed from all sediment fractions. The desorption from finer sediment phase was less pronounced for Fe, Hg, Au, Sc, Sb and Ce. Sorption of some elements (like Co, Cr and Zr) on smallest sediment fraction (<90 m) appears. Sorption-desorption processes, as well as water pH changes, are time dependent, continuing for some weeks, especially in the coarse sediment system. The extents of sorption and desorption for most of the determined elements indicate that the specific surface area is not a key parameter     

Apparatus for the investigation of microbial reaction rates in sediment suspensions

An apparatus is described for the determination of microbe-induced reaction rates in stirred sediment/water suspensions and material fluxes across the sediment/water interface of undisturbed sediment cores. The system consists of a closed gas loop coupled to a reaction vessel, thus maintaining an equilibrium between water and gasphase. The vessel is equipped with sensors for oxygen, pH and redox potential and with facilities for sampling. On-line gas analysis is done by gas chromatography with a sensitive helium-ionization detector. The oxygen concentration in the system is regulated by computer-controlled injection of oxygen into the gas loop. As an example, flux measurements of an undisturbed sediment core are presented and discussed.     

Extraction and speciation of arsenic in lacustrine sediments

Arsenic was partially extracted with 4.OM hydrochloric acid, from samples collected at 25-cm intervals in a 350-cm column of sediment at Milltown Reservoir, Montana and from a 60-cm core of sediment collected at the Cheyenne River Embayment of Lake Oahe, South Dakota. The sediment in both reservoirs is highly contaminated with arsenic. The extracted arsenic was separated into As(III) and As(V) on acetate form Dowex 1-X8 ion-exchange resin with 0.12M HCl eluent. Residual arsenic was sequentially extracted with KClO(3) and HCl. Arsenic was determined by graphite-furnace atomic-absorption spectrometry. The analytical results define oxidized and reduced zones in the sediment columns.     

沱江流域Pb、Cd的环境污染化学行为研究

对沱江流域金堂、简阳、内江三地河流沉积物中重金属Pb和Cd含量及其时空分布特征进行了研究,并结合与沉积物中Fe、Mn和LOI等参数的相关性对河流沉积物中Pb和Cd地球化学性质进行了初步的分析和讨论。结果表明,沱江三地沉积物中Cd、Pb含量不高,平均含量按上、中、下游次序逐渐降低;从垂向分布行为看,Cd在上游金堂地区上部含量高于下部,而中、下游两地则相反,而Pb均随着深度的增加而减少,反映了近年来人类活动所产生Pb污染的加剧;TOC、沉积物性状和上覆水体中的物化性质对于其垂向分布有着较大影响。对于深入揭示水环境中重金属的环境地球化学循环有着重要的指导意义。     

Improvement of extraction recovery for the monobutyltin species from sediment

An improvement of the extraction recovery of the MBT species from sediment has been achieved by using a more polar solvent, toluene, and tropolone as chelating agent. A recovery of 84.7 ± 6.3% from spiked sediment has been achieved, which is the highest recovery of MBT species from sediment so far reported using solvent extraction techniques. The relative detection limit for organotin compounds in general in sediment (2 g) is 0.5 ng g⁻¹ when gas chromatography with atomic emission spectrometric detection is used for the analysis. Relative standard deviations (%) for recovery of MBT, DBT and TBT in spiked sediment range from 2.5 to 6.3% (at 0.5 μg g⁻¹ level). The extraction solution also recovers satisfactorily 7 other commonly used organotin compounds. Analyses of selected environmental samples and the Reference Sediment PACS-1 are given.     

Book Reviews

A gas chromatography/ion trap mass spectrometry method was used for the trace analysis of atrazine and its deethylated degradation product deethylatrazine in environmental water and sediment samples. The isotope dilution technique was applied for the quantitative analysis of atrazine at parts-per-trillion levels. Water samples were pre-concentrated by solid-phase extraction using a C18 cartridge while the sediment samples were extracted by sonication with methanol. The concentrated extracts were analysed by a GC/ion trap MS operated in the MS/MS method. The extraction recoveries for the analytes were better than 83% when 1 L of water or 10 g of sediment was analysed. The method detection limits were 0.75 ng/L and 0.13 ng/g for atrazine and deethylatrazine detected in water and sediment, respectively. The precisions of the method represented by the relative standard deviation were in the range of 3.2-16.1%. The method was successfully applied to analyse surface water and sediment samples collected from Beijing Guanting reservoir. Trace levels of atrazine at 35.9-217.3 ng/L and 2.4-8.4 ng/g were detected in the water and sediment samples, respectively. The levels of deethylatrazine were five to 20 times lower that those of atrazine.     

Field measurements of bottom boundary layer processes and sediment resuspension in the Changjiang Estuary

A field observation of the hydrodynamics and the sediment resuspension in a bottom boundary layer was carried out in the Changjiang Estuary, during July-August 1997. Using bottom field research facilities, detailed measurements of near-bottom currents and suspended sediment concentration distribution within 1.0 m above bed have been obtained in the Changjiang Estuary——a high concentration estuary. An Acoustic Suspended Sediment Monitor (ASSM) wasused to observe near bed sediment resuspension processes. In addition, the log-profile method was applied to estimating hydraulic roughness Z0 and bottom shear stress values (or friction velocities u). Further understanding of sediment suspension mechanics and hydrodynamic characteristics will require the long-term measurements of near bed processes.     

Online molecularly imprinted solid‐phase extraction coupled to liquid chromatography‐tandem mass spectrometry for the determination of hormones in water and sediment samples

The molecularly imprinted SPE directly coupled to RP LC‐MS/MS method has been developed and successfully validated for the determination of six hormones in water and sediment samples. The method is based on the use the home‐made column filled with a molecularly imprinted sorbent (imprinted against estrogens) that was used under nonaqueous conditions. Thus, its high selectivity could be utilized resulting in low matrix components’ coextraction. The method showed excellent recovery (92–105%) and satisfactory sensitivity (LOQs water: 1.9–4.0 ng/L; LOQs sediment: 0.2–0.5 ng/g). The intra‐ and interprecision for water and sediment was in the range of 4.0–6.0% and 4.4–7.6%, respectively. Finally, 20 water and sediment samples collected from the Svratka river were analyzed. Only estrone was quantified in eight water samples (4.4–7.1 ng/L); no analytes were found in sediment samples.     

Washing of sediment on filtering devices

Problems of filtration washing of sediment are considered; the brief overview of the most common filtering devices is made; the particularities of the course of the washing process on these devices are considered. It is stated that the optimal conditions for the effective and economic washing are provided by filter presses with vertical plates. The mechanism of the flow of the washing liquid through the sediment on these filters for two versions, chamber and membrane filter presses, is illustrated. The method of the objective control of the change in the concentration of agent washed out from the sediment during the process of washing of sediment on mentioned filters with the help of the industrial conductivity meter is described.     

Quantitative Speciation of Arsenic in Water and Sediment Samples from the Mokolo River in Limpopo Province,South Africa

The Mokolo River is disposed to environmental contaminants such as arsenic (As) due to its proximity to several anthropogenic activities. Speciation of As in water and sediment samples from Mokolo River is crucial to evaluate the level and distribution of As in the river and underlying sediment since toxicity depends on its chemical forms. In this study, As species in water and sediment were determined by developing a new method for sediment extraction. Effective microwave-assisted extraction of As species in sediment samples was achieved using 0.3?M (NH₄)₂HPO₄ and 50?mM EDTA, which showed no species interconversion during extraction. The chromatographic separation and detection of As(III), dimethylarsinic acid (DMA), monomethylarsonic acid, and As(V) in water and sediment samples were achieved by coupling to high-performance liquid chromatography to inductively coupled plasma mass spectrometry. Baseline separation of four As species was achieved in 12?min using gradient elution with 10 and 60?mM NH₄NO₃ at pH 8.7 as the mobile phase. The analytical figures of merit and validation of analytical procedures were assessed and adequate performance and percentage recoveries ranging from 81.1 to 102% for water samples and 73.0–92.0% for sediments were achieved. The As species concentration in water and sediment samples was found to be in the range of 0.304–4.99?µg?L^?1 and 74.0–92.0?ng?g^?1, respectively. DMA was not detected in both water and sediment samples.     

Pyrite Genesis During Early Diagenesis in Yellow Sea and East China Sea

The content and isotopic compositions of different sulphur species in pore-water and solid phases have been examined on five sediment cores taken from muddy sediment region in the Yellow Sea and the East China Sea. Relationships among these data have been investigated with the combination of morphology of mineral pyrite and organic matter so as to role out the diagenetic behaviour of sulphur species at the early stage of diagenesis in modern marine sediment and the origin of pyrite formation.     

210Pb and 137Cs based techniques for the estimation of sediment chronologies and sediment rates in the Anzali Lagoon,Caspian Sea

Journal of Radioanalytical and Nuclear Chemistry - 137Cs and 210Pb based sediment chronology methods, along with an HPGe gamma-ray spectrometry system, were applied to estimating of sediment...     

Use of solid-phase microextraction/gas chromatography-electron capture detection for the determination of energetic chemicals in marine samples

Gas chromatography with electron capture detection (GC-ECD) is a highly explosive-sensitive analytical technique. However, its application to the analysis of sediment extracts is hampered by the presence of numerous endogenous interferences. In the present study, solid-phase microextraction (SPME) was used both as a purification technique for sediment extracts and as an extraction technique for water samples prior to analysis by GC-ECD. SPME/GC-ECD coupling was optimized and applied to the trace analysis of nine explosives including nitroaromatics and RDX in real seawater and marine sediment samples. Addition of a high concentration of salt (30%, w/v) in the aqueous medium and use of a carbowax/divinylbenzene (CW/DVB) coating led to optimal extraction efficiencies. Method detection limits (MDLs) ranged from 0.05 to 0.81 microg/L in water and from 1 to 9 microg/kg in dry sediment. Except for RDX, spike recoveries in seawater were satisfactory (89-147%) when samples were fortified at 2 microg/L of each analyte. Spike recoveries from dry sediment fortified at 10 microg/kg of each analyte gave lower recoveries but these could also be due to degradation in the matrix. With a smaller volume of aqueous sample required compared to solid-phase extraction (SPE), SPME is an attractive method for the analysis of limited volumes of sediment pore-water. Moreover, the use of SPME eliminated interferences present in sediment extracts thus allowing the detection of the target analytes that were otherwise difficult to detect by direct injection.     

Winter evolution of DMS and DMSP in Venice lagoon water and sediment

The evolution of dimethylsulphide (DMS) and dimethylsulphoniopropionate (DMSP) concentrations in the water and sediment of the Venice lagoon were studied together with the concentration of chlorophyll a, temperature and the composition and density of phytoplankton to understand the role of the sediment as a source of DMS during the winter period. The temporal trend of water DMS concentration in this period showed a maximum concentration in February (75.7 nmol S l-1) related to low DMSP and chlorophyll a concentrations but to high phytoplanktonic abundance. The DMS and DMSP concentrations were greater in the sediment than in the water. The temporal trend of DMS concentration in sediment showed a maximum in February (1155 nmol S l-1) related to the maximum of DMS concentration in surface water. These observations suggested that in the winter period DMS could be produced by the conversion of the DMSP present in the bulk water but principally by that present in the sediment (microbiological degradation of DMSP or other sulphur-containing compounds) that subsequently diffuse in water.