Geoaccumulation and distribution of heavy metals in the urban river sediment

Current study presents the application of chemometric techniques to comprehend the interrelations among sediment variables whilst identifying the possible pollution source at Langat River,Malaysia.Surface sediment samples（0-10 cm）were collected at 22 sampling stations and analyzed for total metals（~（48）Cd,~（29）Cu,~（30）Zn,~（82）Pb）,pH,redox potential（Eh）,salinity,electrical conductivity（EC）,loss on ignition（LOI）and cation exchange capacity（CEC）.The principal component analysis（PCA）scrutinized the origin of environmental pollution by various anthropogenic and natural activities：four principal components were obtained with 86.34%（5 cm）and88.34%（10 cm）.Standard,forward and backward stepwise discriminant analysis effectively discriminate 2variables（84.06%）indicating high variation of heavy metals accumulation at both depth.The cluster analysis accounted for high input of Zn and Pb at LA8,LA 10,LA 11 and LA 12 that mergers three（5 cm）and four（10cm）into clusters.This is consistent with the contamination factor（C_1）that shows high Cd（LA 1）and Pb（LA 7,LA 8,LA 10,LA 11 and LA 12）contaminations at 5cm.These indicate that Pb and Zn are the most bioavailable metals in the sediment with significant positive linear relationship at both sediment depths.Therefore,this approach is a good indication of environmental pollution status that transfers new findings on the assessment of heavy metals by interpreting large complex datasets and predicting the fate of heavy metals in the sediment.     

Comparison of the role of two Spartina species in terms of phytostabilization and bioaccumulation of metals in the estuarine sediment

In the joint estuary of the Odiel and Tinto rivers (SW Spain), the invasive Spartina densiflora Brongn. and the native Spartina maritima (Curtis) Fernald are growing over sediments with extreme concentrations of heavy metals. The contents of As, Cu, Fe, Mn, Pb and Zn were determined in sediments, rhizosediments and different tissues of both species, from Odiel and Tinto marshes. S. densiflora showed a higher capability to retain metals around their roots and to control the uptake or transport of metals, mediated by a higher formation of plaques of Fe/Mn (hydro) oxides on the roots. At the Tinto marsh, there were no differences between the metal concentrations of the sediment and those of the rhizosediment, a fact that could be explained by the extremely high concentrations of metals which can pass over a threshold value, altering the properties of root cells and preventing roots from acting as a ‘barrier’ to the uptake or transport of metals.     

Geomorphic controls on floodplain sediment and soil organic carbon storage in a Scottish mountain river

River floodplains constitute an important element in the terrestrial sediment and organic carbon cycle and store variable amounts of carbon and sediment depending on a complex interplay of internal and external driving forces. Quantifying the storage in floodplains is crucial to understand their role in the sediment and carbon cascades. Unfortunately, quantitative data on floodplain storage are limited, especially at larger spatial scales. Rivers in the Scottish Highlands can provide a special case to study alluvial sediment and carbon dynamics because of the dominance of peatlands throughout the landscape, but the alluvial history of the region remains poorly understood. In this study, the floodplain sediment and soil organic carbon storage is quantified for the mountainous headwaters of the River Dee in eastern Scotland (663 km²), based on a coring dataset of 78 floodplain cross-sections. Whereas the mineral sediment storage is dominated by wandering gravel-bed river sections, most of the soil organic carbon storage can be found in anastomosing and meandering sections. The total storage for the Upper Dee catchment can be estimated at 5.2 Mt or 2306.5 Mg ha^-1 of mineral sediment and 0.7 Mt or 323.3 Mg C ha^-1 of soil organic carbon, which is in line with other studies on temperate river systems. Statistical analysis indicates that the storage is mostly related to the floodplain slope and the geomorphic floodplain type, which incorporates the characteristic stream power, channel morphology and the deposit type. Mapping of the geomorphic floodplain type using a simple classification scheme shows to be a powerful tool in studying the total storage and local variability of mineral sediment and soil organic carbon in floodplains. © 2019 John Wiley & Sons, Ltd.     

Heavy metals in surface sediment and epibenthic macroinvertebrates from the coastal zone and continental slope of Kenya

In surface sediments, a statistically significant increase was measured in the concentration of copper and cadmium along all transects, and of zinc along only the most southern (Gazi) transect, radiating into the Indian Ocean perpendicular to the Kenyan coast. Mean copper and cadmium increased from 5 to 30 μg g⁻¹ dry wt and from 0.01 to 0.34 μg g⁻¹ dry wt in shallow coastal (±20 m depth) to deep-sea stations (±2000 m depth), respectively. These gradients were found both during the south-east monsoon and north-east monsoon period. The shallow estuarine zone of the Sabaki river mouth showed significantly enhanced levels of total organic carbon and nitrogen and all metals analysed, except cadmium.In crustaceans, the concentration of copper and particularly cadmium was significantly above baseline levels, varying from 45 to 90 μg g⁻¹ dry wt and 1.0 to 8.5 μg g⁻¹ dry wt, respectively. Zinc levels (49–102 μg g⁻¹ dry wt) were at about baseline levels or a little elevated. On the contrary, lead showed very low concentrations, varying from 0.1 to 0.6 μg g⁻¹ dry wt. Other species generally showed the same pattern.     

Characterization and composition of heavy metals and persistent organic pollutants in water and estuarine sediments from Gao-ping River, Taiwan

The objective of this study was to determine the concentrations and possible sources of heavy metals and persistent organic pollutants (POPs) in water and estuarine sediments from Gao-ping River in order to evaluate the environmental quality of aquatic system in southern Taiwan. High concentrations of heavy metals including Cr, Zn, Ni, Cu and As, ranging from 10.7 to 180 mg/kg-dry weight (dw), were detected in sediments from Gao-ping River. When normalized to the principal component analysis (PCA), swinery and electroplating wastewaters were found to be the most important pollution sources for heavy metals. Of various organochlorine pesticide (OCP) residues detected, aldrin and total-hexachlorocyclohexane (HCH) were frequently found in sediments. The total concentrations of OCPs were in the range 0.47-47.4 ng/g-dw. Also, the total-HCH, total-cyclodiene, and total-dichlorodiphenyltrichloroethane (DDT) were in the range 0.37-36.3, 0.21-19.0, and 0.44-1.88 ng/g-dw, respectively. The polychlorinated biphenyl (PCB) concentrations in sediments from Gao-ping River ranged between 0.37 and 5.89 ng/g-dw. The PCB concentrations are positively correlated to the organic contents of the sediment particles. alpha-HCH was found to be the dominant compound of HCH in the sediments, showing that long-range transport may be the possible source for the contamination of HCH in sediments from Gao-ping River. In summary, trace amounts of POPs in estuarine sediments from Gao-ping River were detected, showing that there still exist a wide variety of POP residues in the river sediments in Taiwan. These POP residues may be mainly from long-range transport and weathered agricultural soils, while heavy metal contamination is primarily from the swinery and industrial wastewaters.     

Characterization and composition of heavy metals and persistent organic pollutants in water and estuarine sediments from Gao-ping River,Taiwan

The objective of this study was to determine the concentrations and possible sources of heavy metals and persistent organic pollutants (POPs) in water and estuarine sediments from Gao-ping River in order to evaluate the environmental quality of aquatic system in southern Taiwan. High concentrations of heavy metals including Cr, Zn, Ni, Cu and As, ranging from 10.7 to 180 mg/kg-dry weight (dw), were detected in sediments from Gao-ping River. When normalized to the principal component analysis (PCA), swinery and electroplating wastewaters were found to be the most important pollution sources for heavy metals. Of various organochlorine pesticide (OCP) residues detected, aldrin and total-hexachlorocyclohexane (HCH) were frequently found in sediments. The total concentrations of OCPs were in the range 0.47–47.4 ng/g-dw. Also, the total-HCH, total-cyclodiene, and total-dichlorodiphenyltrichloroethane (DDT) were in the range 0.37–36.3, 0.21–19.0, and 0.44–1.88 ng/g-dw, respectively. The polychlorinated biphenyl (PCB) concentrations in sediments from Gao-ping River ranged between 0.37 and 5.89 ng/g-dw. The PCB concentrations are positively correlated to the organic contents of the sediment particles. α-HCH was found to be the dominant compound of HCH in the sediments, showing that long-range transport may be the possible source for the contamination of HCH in sediments from Gao-ping River. In summary, trace amounts of POPs in estuarine sediments from Gao-ping River were detected, showing that there still exist a wide variety of POP residues in the river sediments in Taiwan. These POP residues may be mainly from long-range transport and weathered agricultural soils, while heavy metal contamination is primarily from the swinery and industrial wastewaters.     

河口海域水流挟沙能力分析

水流挟沙力是反映河床处于冲淤平衡状态下水流挟带泥沙能力的综台性指标。作者通过对众多挟沙力公式的分析比较,基于量纲和谐的考虑,建立了新的挟沙力公式形式。本文以长江口的泥沙输运为例,利用长江口泥沙实测资料,研究了新建立的挟沙力公式在长江口的适用性。计算结果表明,本文作者建立的公式在长江口具有一定的适用性,与刘家驹公式相比较,计算精度差不多,计算结果尚令人满意,但还存在一定的误差,说明将本文建立的挟沙力公式进行率定后,可以将其推广到近岸河口海域,为工程实践提供有益的参考价值。     

Heavy metals,organochlorine pesticides and PCBs in green mussels,mullets and sediments of river mouths in Thailand

This investigation was undertaken to determine the levels of lead, zinc, copper, cadmium, and mercury and certain organochlorines including DDT and PCBs in green mussels, mullets, and bottom sediments of the mouths of the river Mae Klong, Ta Chin, Chao Phraya, and Ban Pakong. The four river mouths are contaminated by the five heavy metals to some extent. The contamination of lead in mussels, mullets and sediments was quite obvious, at values significantly higher than those previously reported. Contamination of the other four metals in mussels and mullets was still within acceptable limits, except for mercury in the Chao Phraya river mouth which was approaching the limit. Organochlorines, especially DDT and its metabolites, are detectable in some samples of mussels, mullet, and sediments. PCBs were detectable in some samples of mussels and mullets, but none were detected in the sediments. The levels of these organochlorines are considered to be comparable to baseline levels.     

The fate of suspended sediment and particulate organic carbon in transit through the channels of a river catchment

Particulate organic matter (POM) transiting through rivers could be lost to overbank storage, stored in‐channel, added to by erosion or autochthonous production, or turned over to release greenhouse gases to the atmosphere (either while in the water column or while stored in the channel). In the UK, a net loss of POM across catchments has been recorded, and the aim here was to investigate the balances of processes acting on the POM. This study considered records of suspended sediment and POM flux in comparison to stream flow, velocity, stream power, and residence time for the River Trent (English Midlands, 8,231 km²). We show that for the lower two thirds (106 km) of the River Trent, 2% is lost to overbank storage; 10% is lost to the atmosphere in the water column; and 31% is turned over while in temporary storage. Permanent in‐channel storage is negligible, and for the lower course of the river, material stored in‐channel will have a residence time of the order of hundreds of days between the last flood hydrograph of one winter and the first winter storm of the next winter (usually in the same calendar year). When considered at the scale of the UK, 1% POM in transit would be lost to overbank sedimentation; 5% turned over in the water column, and 14% turned over while in temporary storage. In the upper third of the study river channel, there is insufficient stream power to transport sediment and so in‐channel storage or in‐channel turnover over to the atmosphere dominate. The in‐channel processes of the River Trent do not conform to that expected for river channels as the headwaters are not eroding or transporting sediment. Therefore, the source of sediment must be lower down the channel network.     

Small river basin and estuarine sediment fluxes: The magnitude necessary for coastal dispersion and siltation effects on a coral reef

Increasing continental suspended sediment influx to coral reefs is an example of land-sea coupling that requires the identification of sources, magnitude of transport, and controlling processes. In Brazil, a small coastal basin (Macaé River) was identified as a source of suspended sediment to a coral reef on the coast of Cape Armação dos Búzios. Biannual suspended sediment loads were measured at the basin as were fluxes within the estuary and towards the coast during eight tidal cycles. Particle load and yield from this basin were typical of small coastal basins, showing high to moderate slopes and transitional land management. However, the magnitude of the river loads was lower than the sediment transport within the estuary, indicating that the estuary amplifies river fluxes and sustains the transference of suspended sediment alongshore to the coral reef. Nonetheless, the estuary displays both suspended particle retention and export capacity and, therefore, fluxes to the coast and the coral reef occur as episodic events.     

Distribution of heavy metals in water and sediment of an urban river in a developing country: A probabilistic risk assessment

River water and sediment embody environmental characteristics that give valuable eco-environmental information.Due to rapid industrialization,the aquatic environment of any urban river can be seriously polluted by heavy metals（HMs）.The global concern is caused by heavy metal pollution because of its potential harm to aquatic ecosystems and human health.In the Bhairab River,Bangladesh,surface sediment concentrations of globally alarming toxic metals such as arsenic（As）,chromium（Cr）,cadmium（Cd）,an...     

Heavy metals in Baltic herring and cod

The monitoring programme of harmful substances in selected species in the Baltic Sea was started in 1979. In the present study, three-year averages of Zn, Cu, Cd and Pb in cod liver (Hg in cod muscle) and herring muscle are reported. The concentrations of heavy metals in cod show areal differences roughly in accordance with the concentrations of heavy metals in sea water. No significant differences between heavy metal concentrations in North Atlantic and Baltic Sea species were found, except for mercury, for which values in the Baltic Sea species are lower than in those from the North Atlantic.     

Simulation of relationship between river discharge and sediment yield in the semi-arid river watersheds

Complex and variable nature of the river sediment yield caused many problems in estimating the long-term sediment yield and problems input into the reservoirs. Sediment Rating Curves (SRCs) are generally used to estimate the suspended sediment load of the rivers and drainage watersheds. Since the regression equations of the SRCs are obtained by logarithmic retransformation and have a little independent variable in this equation, they also overestimate or underestimate the true sediment load of the rivers. To evaluate the bias correction factors in Kalshor and Kashafroud watersheds, seven hydrometric stations of this region with suitable upstream watershed and spatial distribution were selected. Investigation of the accuracy index (ratio of estimated sediment yield to observed sediment yield) and the precision index of different bias correction factors of FAO, Quasi-Maximum Likelihood Estimator (QMLE), Smearing, and Minimum-Variance Unbiased Estimator (MVUE) with LSD test showed that FAO coefficient increases the estimated error in all of the stations. Application of MVUE in linear and mean load rating curves has not statistically meaningful effects. QMLE and smearing factors increased the estimated error in mean load rating curve, but that does not have any effect on linear rating curve estimation.     

Wood and sediment storage and dynamics in river corridors

Large wood along rivers influences entrainment, transport, and storage of mineral sediment and particulate organic matter. We review how wood alters sediment dynamics and explore patterns among volumes of in‐stream wood, sediment storage, and residual pools for dispersed pieces of wood, logjams, and beaver dams. We hypothesized that: volume of sediment per unit area of channel stored in association with wood is inversely proportional to drainage area; the form of sediment storage changes downstream; sediment storage correlates with wood load; the residual volume of pools created in association with wood correlates inversely with drainage area; and volume of sediment stored behind beaver dams correlates with pond area. Lack of data from larger drainage areas limits tests of these hypotheses, but the analyses suggest that sediment volume correlates positively with drainage area and wood volume. The form of sediment storage in relation to wood appears to change downstream, with wedges of sediment upstream from jammed steps most prevalent in small, steep channels and more dispersed sediment storage in lower gradient channels. Pool volume correlates positively with wood volume and negatively with channel gradient. Sediment volume correlates well with beaver pond area. More abundant in‐stream wood and beaver populations present historically equated to greater sediment storage within river corridors and greater residual pool volume. One implication of these changes is that protecting and re‐introducing wood and beavers can be used to restore rivers. This review of the existing literature on wood and sediment dynamics highlights the lack of studies on larger rivers. Copyright © 2016 John Wiley & Sons, Ltd.     

Bed morphology in vegetated estuarine river with mild-curved meander bend

ABSTRACT

In this study, the effect of single and double row piles for reducing scouring in a mild-curved river meander was studied experimentally. The experimental study focused on the effect of vegetation on bed topography in a mild-curved meander bend. The experimental tests were conducted in a laboratory flume under clear water flow conditions. A series of experimental tests were carried out with a fixed bed and non-vegetated and vegetated moveable beds with different vegetation patterns. Analysis of the flow characteristics indicated that when the bed was mobile with vegetation on the inner bank, the core of maximum streamwise velocity shifted towards the centreline of the bend. Additionally, the cross-sectional kinetic energy increased from 0.05% for the fixed-bed test to 4.30% for the test with a double row of vegetation. Furthermore, the presence of vegetation was found to increase the uniformity of the distribution of turbulence intensity and to reduce the Reynolds shear stress along the test section. Also, the mass fluxes increased from the outer bank to the inner bank and from the upstream towards the downstream of the bend. Finally, comparison of bed topography in vegetated and non-vegetated channels showed that the maximum scour depth at the bend apex was reduced by 77% and 62% for the cases with one row and two rows of vegetation, respectively. The results of this study were compared with previously proposed models for predicting the vertical distribution of the streamwise velocity at the bend apex. It was found that Johannesson and Parker’s model (JPM) gave the lowest value of standard error. The above findings are useful in river training works and, in particular, for restoration of meandering rivers.

Editor D. M.C. Acreman; Associate editor C. Cudennec     

Erodibility study of sediment in a fast-flowing river

Determination of sediment stability in the field is challenging because bed shear stress (BSS), a determining factor of sediment erosion, can’t easily be directly measured. To tackle this challenge and reliably assess sediment erodibility in a fast flowing river, a standalone underwater camera system and a new insitu flume (ISF) were developed and applied in this study. The camera system was used to record sediment movement and the new ISF was used for measuring critical bottom shear stress (CBSS). The camera can be deployed alone in water to record videos or take pictures with light emitting diode (LED) lighting and flexible schedule settings. The ISF is based on the concept that the amount of force needed to erode the same particle under different flow conditions should be similar. Two high resolution Acoustic Doppler Current Profilers (ADCP) also were deployed in the field to collect velocity-depth profiles which are used by conventional methods to calculate BSS with the law of the wall. The sediment erodibility was then assessed based on the comparison between the obtained CBSS and BSS and then further verified with the recorded observations from the deployed camera. The results reveal that the widely used conventional method can produce large uncertainties and is not adequate to provide meaningful conclusion under these conditions.