Trace metal concentrations in selected biological,sediment, and water column samples in a Northern New England river

A baseline ecosystem study was undertaken in a relatively non-industrialized New England river to determine trace metal levels of Cr, Cu, Pb and Zn concentrations in water column, sediment, fish, mollusks and aquatic macrophytes. Additional analyses were completed on fish and mollusks for Hg. Results showed metal concentrations in the study area were in general agreement with literature values. Both mollusks and aquatic macrophytes exhibited the highest levels of accumulated metals.     

Anthropogenic activities drive the microbial community and its function in urban river sediment

Journal of Soils and Sediments - Understanding the dynamics of the structure and function of the microbial community in sediment across freshwater environments will help to predict how these...     

Increase in suspended sediment discharge of the Amazon River assessed by monitoring network and satellite data

This study addresses the quantification of the Amazon River sediment budget which has been assessed by looking at data from a suspended sediment discharge monitoring network and remote sensing estimates derived from MODIS spaceborne sensor. Surface suspended sediment concentration has been sampled every 10 days since 1995 (390 samples available) by the international HYBAM program at the Óbidos station which happens to be the last gauged station of the Amazon River before the Atlantic Ocean. Remote sensing reflectance is derived from continuous time series of 554 MODIS images available since 2000 and calibrated with the HYBAM field measurements. Discharge shows a weak correlation with the suspended sediment concentration during the annual hydrological cycle, preventing us from computing sediment discharge directly from the water discharge. Accordingly, river sediment discharge is assessed by multiplying daily water discharge measurements by the suspended sediment concentration averaged on a monthly basis. Comparisons of annual sediment discharge assessed using both field and satellite datasets show a very good agreement with a mean difference lower than 1%. Both field and satellite-derived estimates of the sediment concentration of the Amazon River are combined to get an uninterrupted monthly average suspended sediment discharge from 1995 to 2007. Unlike the water discharge which exhibits a steady trend over the same period at Óbidos, the 12-year suspended sediment discharge increases by about 20% since 1995, significant at the 99% level. In particular, the inter-annual variability is much more significant in the sediment discharge than in the river discharge.     

开封市城市土壤磁化率空间分布及对重金属污染的指示意义

建立基于土壤磁化率的重金属污染等级标准可为土壤重金属污染评价提供更为简便的磁学方法。采集开封市城市土壤表层样品99个,测定As、Cd、Cr、Cu、Ni、Pb和Zn含量以及低频磁化率(χLF)和高频磁化率(χHF)。采用普通Kriging插值法探讨χLF的空间分布,污染负荷指数(PLI)评价土壤重金属污染程度,并在PLI与χLF相关分析的基础上建立了基于χLF的土壤重金属污染等级标准。结果表明,开封市城市土壤各样点7种重金属的平均PLI为2.53,呈中度污染,Cd是最主要的污染因子。土壤χLF平均值为125.7×10-8m3kg-1,总体上由东南向西北递减,高值区出现在东南部、老城区北部和陇海铁路沿线附近。各样点土壤重金属PLI与其χLF的回归方程为PLI=0.011χLF+0.320(r=0.663),呈极显著正相关(p0.01)。用土壤χLF可以评价开封市城市土壤重金属污染程度:当土壤χLF≤62×10-8m3kg-1时,为无污染;当62×10-8χLF≤153×10-8m3kg-1时,为轻度污染;当153×10-8χLF≤244×10-8m3kg-1时,为中度污染;当χLF244×10-8m3kg-1时,为强度污染。     

Implication of relationships among suspended sediment size, water discharge and suspended sediment concentration: the Yellow River basin, China

According to the yearly maximum suspended sediment concentrations (SSC) in the Yellow River and its tributaries, the rivers are divided into three types of more than 300, 20–300, and less than 20 kg/m³. The middle Yellow River basin is located in the transitional zone from subhumid to semiarid climates, and covered by a thick loess mantle. Neighboring on the desert areas to the northwest, the surface material of the Loess Plateau exhibits some marked areal differentiation in grain size and forms three zones covered by sandy loess, (typical) loess and clayey loess from northwest to southeast. Controlled by these physico-geographical conditions, the grain size of river-transported sediment shows some particular characteristics; at small water discharge or SSC, the grain size of suspended sediment abruptly decreases to a minimum with increasing water discharge or SSC. At water discharge of more than ca. 40 m³/s or at SSC of more than ca. 40 kg/m³, the grain size increases with water discharge or SSC.During the low-stage season, the relatively clear baseflow may scour the coarse bed materials, so the suspended sediment is relatively coarse. In the rainy season, rainstorm runoff washes out fine loess materials to the river, making suspended sediment fine. During relatively strong rainstorms, there often occur hyperconcentrated flows at SSC of more than 300 kg/m³. The relatively coarse grains could then remain suspended in the mixture of water and fine suspended sediment.     

Heavy metal characterization of river sediment in Hanoi,Vietnam

Abstract

Industrial and municipal waste water is directly discharged to rivers in Hanoi, Vietnam. Sediments were collected from different sites of three rivers in the industrialized and densely‐populated area of Hanoi City and examined for total heavy metals and metal fractions using sequential extraction. Concentration of the total heavy metals ranged from the background levels to over the maximum permissible levels to crop growth. Concentrations of cadmium (Cd), chromium (Cr), copper (Cu), nickel (Ni), lead (Pb), and zinc (Zn) ranged from 0.27 to 4.50,78 to 517, 37 to 309, 37 to 174, 43 to 361, and 93 to 4,950 mg kg^‐1, respectively. Total concentration of heavy metals varied from site to site and tended to be higher in the site where manufacturing companies are located. Heavy metals were accumulated in the site and were not moved away to be redistributed in the whole area. Distribution of heavy metals in different chemical forms in the air‐dry state depended on their total concentration. In the low concentration range, Cr, Cu, Ni, and Zn were for the most part concentrated in the residual fraction. When concentration is equal to or above the maximum permissible level to crop growth, Cr, Ni, and Zn were mostly concentrated in the iron‐manganese (Fe‐Mn) oxides fraction and Cu was in the organic fraction. Irrespective of the total concentration, Cd was highly associated with the exchangeable and carbonate fractions, while the sum of the Fe‐Mn oxides and residual fractions accounted for 80 to 96% of total Pb.     

坝地沉积旋回泥沙养分变化及其对小流域泥沙来源的解释

黄土高原广泛分布的坝地沉积泥沙中赋存了大量小流域侵蚀特征及侵蚀环境变化的信息,泥沙特性的变化则是这些信息的直接体现。该文通过对比分析淤地坝沉积旋回泥沙中和坝控小流域内不同泥沙源地土壤中有机质、全氮、全磷和全钾的含量,发现小流域内土壤养分含量变异性明显大于沉积旋回泥沙中的变异性,沉积旋回泥沙养分含量与沟壁土壤中的相接近,其中与沟壁中的全氮、全磷和全钾无显著差异(p>0.05),但显著小于荒草地和坡耕地中的有机质、全氮和全磷含量(p<0.05),表明淤地坝运行期间小流域泥沙主要来源于沟壁坍塌和沟道扩展,重力侵蚀和沟蚀是主要侵蚀类型;有机质和全氮在坝地沉积旋回中呈明显阶段性变化,分析认为其反映了农村土地联产承包责任制对小流域土地利用和土壤侵蚀的影响。     

Compositional dynamics of suspended sediment in the Rhine River: sources and controls

Journal of Soils and Sediments - Information on the geochemical composition of suspended sediments in rivers is crucial to identify sediment source type or area. In large river basins, however, the...     

Distribution and fractionation of rare earth elements in suspended sediment of the Zhujiang River,Southwest China

Journal of Soils and Sediments - The geochemistry of rare earth elements (REEs, La to Lu) in suspended sediments (SS) is generally controlled by weathering processes and the water environment....     

海南岛河流底泥肥力和重金属污染特征及其风险评价

特征分析及其评价是底泥资源化利用的重要前提,为了解海南岛热带玄武岩地区河流底泥特征及其资源化利用的可能性,选取典型河段塘柳塘为研究对象,采用典型断面布点采样法,对52个底泥样本的重金属和肥力进行检测和评价.结果表明:1)参照第2次全国土壤普查土壤养分分级指标,底泥中全氮质量分数指标达到Ⅰ级水平,全磷、全钾和有机质质量分数均为Ⅱ级水平,阳离子交换量达到Ⅳ级水平;各肥力指标的灰色关联度指数均大于对照区,说明河流底泥养分较为良好.2)采用HJ 332-2006《食用农产品产地环境质量评价标准》,评价底泥重金属污染状况,主要污染物Cd超标率为65.4％,超标幅度为14％;Hg超标率为59.6％,超标幅度为11％.3)地累积指数和内梅罗综合污染指数评价结果显示,该河段底泥中主要污染物为Cd和Hg,河段整体达到中度污染水平.4)潜在生态风险指数评价表明,Hg是最主要的潜在生态风险因子,河段整体达到“轻微生态危害”等级.该研究在海南省南渡江土地整治重大工程中,为疏浚底泥生态改造与土壤资源化利用,提供科学依据和技术支撑.     

Relationship between suspended sediment load, channel geometry and land area increment in the Yellow River Delta

The annual river discharges and suspended sediment loads into the Yellow River Delta show a declining tendency with some distinct fluctuations over the last 50 years. The decrease of river discharge and suspended sediment load and the change in the river channel must influence the evolution of the Yellow River Delta. During this period several new river mouths formed via channel switch at the river delta, and the old watercourse was gradually abandoned. Recently, in years with very low annual suspended load, erosion of land area has been recorded for the delta. The aims of this work are (1) to determine what is the critical suspended sediment load needed in order to maintain the land balance of the Yellow River Delta for two periods before and after 1976 (the last time the channel shifted), and (2) to examine the variation in the channel geometry and gradient in response to changes in suspended sediment load and delta area at the river mouth. In order to estimate these critical values, we used statistical method to analyze the relationships between land area increment, and suspended sediment load and channel geometry. In order to examine the variation in the channel geometry, the channel cross-sections of the Q1 and Q6 were compared. The results show that to maintain the land area balance between 1953 and 1973, when the river mouth was the Diaokouhe, the critical annual suspended sediment load entering the delta was 4.21  10⁸ tonnes/a. After the main channel switched to Qingshuigou in 1976, the critical value to maintain the Qingshuigou mouth between 1976 and 1997 was 1.51  10⁸ tonnes/a. To maintain the land area balance for the entire Yellow River Delta between 1976 and 1997 the critical suspended sediment load was 3.18  10⁸ tonnes/a. The annual mean channel thalweg elevation and channel gradient at the river delta increase with increasing land area increment at the Qingshuigou mouth. The critical channel gradient at the channel reach between cross sections Q1 and Q6 is 0.000095. The channel has narrowed during the time period from 1976 to 1997. Also, lateral channel migration has decreased remarkably, resulting in enhanced hydraulic efficiency of the deltaic channel and artificial levees. This channel geometry evolution was influenced by river adjustment and human activities. These results are of importance for the management of the lower Yellow River channel and the delta. Future water diversion or river damming should consider the balance between suspended sediment delivery and delta growth.     

Trace metal composition and speciation in street sediment: Sault Ste. Marie,Canada

Street sediment collected in Sault Ste. Marie, Ontario was examined for trace element composition (As, Cd, Cr, Cu, Fe, Pb, Hg, Ni and Zn) and the metal partitioning to various sediment properties was determined by sequential extraction. Total Ni, Cu, Zn and Pb concentrations exceeded the lowest effect levels specified in the Ontario Provincial Sediment Quality Guidelines for Metals (Environment Ontario, 1992) and derived from bioassay studies. According to these Guidelines, the disposal of such sediment has to be guided by environmental considerations. A significant fraction of these metals was extractable in 0.5 N HCl over a 12-hour period and considered as potentially bioavailable. The major accumulative phases of toxic metals in this sediment are exchangeable, carbonate, Fe/Mn oxides and organic matter but the relative importance of each phase varied for individual metals. Approximately 20% of the total extractable Cd is found in each of these four fractions. Pb, Zn and Mn are predominantly bound to carbonates, Fe/Mn oxides and organic matter. Cu shows a high affinity for organic matter and to a lesser extent for carbonates. Elevated levels of Cd, Pb, Cu, Zn, Mn and Cr in the exchangeable and/or soluble phase suggest that sediment associated metals, mobilised from streets in Sault Ste. Marie during runoff and snowmelt, would adversely impact water quality in the receiving waters. However, large fractions of the total metal load are associated with coarser particles which are unlikely to be transported through the drainage system into receiving waters.     

Urbanization effects on sediment and trace metals distribution in an urban winter pond (Netanya,Israel)

Purpose

This paper aims to elucidate urban development-induced processes affecting the sediment and the distribution of contaminating metals in a seasonal pond located in the highly populated Israeli Coastal Plain. The paper demonstrates how an integrated approach, including geochemical, sedimentological, geochronological, mathematical, historical, and geographical analyses, may decipher a complicated and dynamic metal pollution history in a sedimentary environment controlled by anthropogenic activity.

Materials and methods

Three short sediment cores were collected from the margins and center of a small urban pond (Dora, Netanya), located within the Israeli Coastal Plain. Profiles of grain size, organic matter (OM), trace metals (Pb, Zn, V, Ni, Cu, Cr and Co), Pb isotopic ratios, and ²¹⁰Pb activities (center and southern cores) were determined and a geochemical mixing model was employed (southern core). The watershed contour was calculated, and aerial photos and satellite images were examined.

Results and discussion

Construction activities in the watershed were chronologically associated with coarse sediment transport and deposition in the margins of the pond. The upper sandy layers were superimposed on layers rich in fine particles and OM, high concentrations of trace metals, and with Pb isotopic composition of more recent petrol. In the ²¹⁰Pb-dated southern core, deep metal-rich layers with petrol-related Pb isotopic ratios were inconsistent with metal emissions history. These findings point to mobility and migration of recent contamination metals through the coarse upper sediment layers and into deeper denser layers, confirmed also by a geochemical mixing model. Conversely, in the center of the pond, homogeneous fine particles were deposited with metal profiles consistent with regional emissions.

Conclusions

A small urban pond was found to provide an important case study for understanding heavy metal pollution records in highly populated regions. The margins of the pond depicted the surrounding urban development and the induced coarse sediment erosion, accompanied with post-depositional metal mobility. Due to the proximate developing residential areas, high metal concentrations accumulated in the margins, overshadowing regional atmospheric pollution levels recorded by sediment at the center of the pond.

     

Geochemical tracing and spatial evolution of the sediment bed load of the Romaine River,Québec,Canada

A four-reservoir hydroelectric complex which is projected on the Romaine River, in eastern Québec, Canada, will likely lead to the complete settling of the sand-size bed load of the river. In order to characterise the present river bed load sources, sediment transport and sedimentary connectivity, a study was conducted to document the compositional continuum of the lower 300 km portion of the river. Bed load samples were collected during the late summer low water period and ICP-MS geochemical analyses of the light and heavy mineral portions were conducted. Principal component analysis of the results successfully identified a series of distinctive geochemical domains. Multivariate Euclidean distance coefficients were also calculated between consecutive samples along the river revealing major bed load compositional breaks. These results indicate a longitudinal fractionation of the bed load along the 300 km course of the river. This is further supported by the sedimentary budget calculated from the annual sedimentary input derived from erosion rates of the river banks, from sediment bed load measurements at three gauging stations and from calculated bed load transport capacity at these three locations. It appears that significant sediment accommodation space is available on the upper course (250 km) of the Romaine River, in spite of the fact that this river has drained highly sediment-laden meltwaters from the receding Laurentide Ice Sheet, some 10 ka ago. This accommodation space leads to the renewal of the bed load due to recurrent partial to complete sedimentation. The major part of the bed load reaching the Romaine River mouth originates from the lower 50 km of the river course.     

Multiple‐scale soil moisture distribution and its implications for ecosystem restoration in an arid river valley,China

The spatial distribution of soil moisture and its multiple‐scale correlations to other environmental factors were examined along the Upper Minjiang River valley, China, a landscape subject to severe land degradation of soil and water erosion but also under investigation for potential ecosystem restoration. Results showed that: (1) Soil moisture was highest in the headwaters, and lowest in the arid valley, while moderate values characterized outside the arid valley. The polynomial model of soil moisture distribution on slopes was concave in the lightly disturbed headwaters, convex in the highly damaged arid valley, while convex on south facing slopes and concave on north facing slopes in highly damaged areas in better environmental condition. (2) Soil moisture was correlated with environmental factors at different scales, where elevation and air humidity were only correlated at the sample plot scale, light intensity and wind speed were found to be significant at both slope and site scales and slope and sample plot scales; while slope angle was correlated at all the three scales. From this we conclude that it is possible to improve soil moisture conditions in the arid valley by lowering slope angle and adding low‐cost irrigation systems. (3) The practical threshold of soil moisture for growing meadows, shrubs, and forests were 11ċ800 per cent, 3ċ925 per cent, and 16ċ078 per cent respectively; the arid valley displayed soil‐moisture conditions unfavourable to forest growth. The planned reforestation project is not ecologically reasonable. Reducing human disturbance and revegetating with natural shrubs and meadows may produce more effective results. Copyright © 2004 John Wiley & Sons, Ltd.     

Characteristics of bacterial community in the water and surface sediment of the Yellow River,China, the largest turbid river in the world

Purpose

Few studies have described the bacterial community structures of turbid rivers. In this paper, the characteristics of the bacterial community in the water and surface sediment of the Yellow River, China, the largest turbid river in the world, were studied.

Materials and methods

Water and sediment samples were collected from six sites along the river. Bacterial community composition was determined using the 16S ribosomal RNA (rRNA) gene clone library technique. The relationship between environmental parameters and bacterial diversity was analyzed.

Results and discussion

A total of 1,131 gene sequences were obtained and clustered into 639 operational taxonomic units (at the 97 % identity level), with Proteobacteria as the predominant phylum. The Shannon index for water samples ranged from 3.39 to 4.40 and was generally higher than that in other rivers; this was probably due to the high suspended particulate sediment (SPS) concentration in the Yellow River, which can provide more habitats for both aerobic and anaerobic bacteria. Also, the bacterial diversity of the water samples was slightly higher than that of the surface sediment samples. The bacterial diversity of water increased along the river in the downstream direction, while there was no trend for the sediment. Redundancy analysis indicated that pH, dissolved organic carbon (DOC), and SPS were the main factors controlling the water bacterial community in the Yellow River, and pH, nitrate–nitrogen, and water content were the main factors for the surface sediment bacterial community.

Conclusions

This study indicated that the bacterial diversity of the Yellow River is generally higher than that in other rivers, suggesting that SPS plays an important role in regulating bacterial diversity and community structure in aquatic environments.     

Importance of bank erosion for sediment input, storage and export at the catchment scale

Purpose

The importance of bank erosion was quantified during three periods (October 2006–April 2007, May 2007–April 2008 and May 2008–April 2009) in the 486 km² catchment area of River Odense, Denmark. A catchment sediment budget was established including other sediment sources such as tile drains and surface runoff, in-channel and overbank sinks and storage and the resulting bed load and suspended sediment load exported from the catchment.

Material and methods

Bank erosion and sedimentation were measured using ca. 3,000 erosion pins established in 180 pin plots, each consisting of three vertical lines of pins. Thirty-six representative reaches, each with a length of 100 m, were selected by a stratified random procedure in GIS. Bed load and suspended sediment export from the catchment were measured using a bed load sampler and from continuous measurements of turbidity at the outlet gauging station.

Results and discussion

The gross sediment input from bank erosion during the three study periods amounted to 21,100–25,200 t in the River Odense catchment, which is considerably higher than the estimated input of sediment from tile drains and surface runoff, which amounted to 220–500 t and 0–100 t, respectively. The measured bed load (20–490 t) was five to 60 times lower than the suspended sediment export from the catchment (1,240–2,620 t) during the three study periods, with the largest difference occurring in the driest year. Sediment sinks and storage were of high importance for the catchment sediment budget as the measured in-channel storage of sediment on stream banks was as high as 16,200–20,100 t, and the overbank sediment sink was estimated at 360–3,100 t.

Conclusions

Bank erosion was the dominant sediment source (90–94 %) in the River Odense catchment during the three study years. In-channel and overbank sediment sinks and storage dominated the sediment budget as 79–94 % of the sediment input from all sources was not exported from the catchment during the three study years. Such a large attenuation of sediment in river channels and on floodplains is extremely important for fluvial habitats and ecology. Moreover, it has strong implications for attempts to document changes in sediment export following implementation of mitigation measures.     

Mercury and methylmercury in sediments and suspended particles from the river Elbe,North Germany

Total Hg and McHg concentrations have been determined in sediments and suspended particulate matter from one of the most Hg-polluted rivers of the world, the Elbe river in Northern Germany. Results of total Hg and McHg are presented. Total Hg concentrations in suspended particulate matter (SPM) are 30 mg kg^?1 in the average and up to 150 mg kg^?1 as the maximum value. Total Hg-fluxes ^?1 calculated from measurements of an automatically operating station upstream Hamburg as about 17 ta?1 in suspended particles. A new McHg determination by HPLC chromatography and photometric detection was developed and verified. Methylmercury concentrations were up to 10% of the total Hg, i. e. 2.7 mg kg^?1 (dw).