Distribution and their pollution assessment of heavy metals in the sediments of the Yalu River Estuary and its adjacent coastal waters

The present paper deals with the distribution patterns of heavy metals and the associated influenc- ing factors in the Yalu River Estuary and its adjacent coastal waters. Based upon the analysis of the surficial and core sediments measurements, the pollution of heavy metal and potentiM ecological risk were evaluated. The burial flux and contents of heavy metals （except for copper） have been continuously increasing since the 1920s. Therefore, the gross potential ecological risk for the sedi- ments was high or very high, and the study area was endangered by heavy metals contamination. Heavy metals originated mainly from upstream pollutant input, correlation analysis showed that chromium, nickel, zinc~ cadmium, lead, arsenic, and mercury in the sediments of the middle and west channels as well as the sea area of the western Yalu River Estuary concentrations were most probably derived from similar sources. In contrast, the metal of copper most probably originated from sources different from the other metals. Preliminary studies indicate that copper contamina- tion was most likely the result of emission from mining activities situated at the upstream of the river. The contents of heavy metals in the sediments of estuarine turbidity maximum zone of Yalu River were larger than those of any other areas in the middle channel. With large portion of fine sediments, weaker hydrodynamics, and richer sources of heavy metals, the sediments of the west channel, were even more enriched with heavy metals than those of the middle channel.

THE RESEARCH ON THE DISTRIBUTION AND FORMS OF HEAVY METALS IN THE XIANGJIANG RIVER SEDIMENTS

In this paper, the contents and various forms of Cd, Cu, Zn and Pb in the sediments of the Xiangjiang River have been investigated. The presentation of this paper focuses on the various forms and characteristics of the heavy metals in the column sediments at Xiawan Port of Zhuzhou, which has been severely polluted by a metallurgical plant.The forms of the heavy metals discussed in this paper are: The concentration of the exchangeable forms of Cd, Cu, Zn and Pb, in the forms of carbonates and Fe/ Mn oxide in water, the combination of Cu with organic matter and form, and the proportion of the residue form at each section have been studied.

Contamination and Ecological Risk Assessment of Heavy Metal in the Sediment of Turag River, Bangladesh: An Index Analysis Approach

Encroachment, disposal of untreated domestic and industrial wastewater and dumping of solid wastes have degraded the overall quality of the river Turag, which is located in Dhaka—the Capital City of Bangladesh. The present study investigated the extent of pollution of sediments of this river and analyzed the regional variability for the concentrations of Cr, Pb, Zn, Cu and Cd—all of concern because of their potential toxicity, using atomic absorption spectrophotometer. As per US EPA sediment quality guideline, metal concentrations ranged between Cd: 0.00 - 0.80, Cr: 32.00 - 75.50, Cu: 46.30 - 60.00, Pb: 28.30 - 36.40, and Zn: 94.60 - 190.10 mg/kg in the Turag river sediments. Cr, Cu, Zn belongs to moderately to highly polluted, Pb and Cd belongs to not polluted for Turag river. The heavy metals contamination in the sediments were also evaluated by applying Index of geo-accumulation (Igeo), contamination factor (Cf), pollution load index (PLI) etc. Toxicity characteristics leaching procedure (TCLP) test (US EPA 1311) for sediment samples have been performed also for metals (Pb, Cd, Cr, Cu and Zn) to determine the readily toxicity level of heavy metals. Sieve analysis of sediment performed in this study to determine the physical characteristic of sediment samples. The metal concentrations are well below the regulated level as per US EPA. This index can be complemented with the contamination index, which allows more site-specific and accurate information on contaminant levels. If the aim of work on contamination evaluation is to assess the overall contamination of a study area, the indices are highly appropriate.

Developing sediment quality criteria for heavy metal pollution in the Le An River with equilibrium partitioning approach

Equilibrium partitioning(EqP) approach was selected to establish the sediment quality criteria(SQC) in the Le An River near Dexing Copper Mine. Both freshwater quality criteria (WQC) for some heavy metals regulated by USEPA and national quality standards of surface water recommended by CNEPA were used as protective levels of aquatic organisms in this study. Meanwhile, the partitioning coefficients were derived directly from measured data. Comparison between SQC in this region and concentrations of contaminants in situ clearly indicated the distribution characteristics of metal contamination along the river. And the results also illustrated that measures of some metals exceeded their SQC levels in different degree, especially Cu.

Assessment of heavy metals in sediment cores from Xiangjiang River,Chang-Zhu-Tan region,Hunan Province,China

Samples were collected from two core sediments(C1 and C2) of Xiangjiang River,Chang-Zhu-Tan region,Hunan Province,China.The heavy metal contents are relatively higher,especially for the surface or near the surface layers.The calculated anthropogenic factor values indicate that all the heavy metals except for Cr in the core samples are enriched,especially for Cd,with the maximum enriching coefficients of 119.44,and 84.67 in C1 and C2,respectively.The correlation of heavy metals with sulphur indicates that they are precipitated as metal sulphides.Correlation matrix shows significant association between heavy metals and mud.Factor analysis identifies that signified anthropogenic activities affect the region of Xiangjiang River.

Application of face－graph in heavy metal pollution assessment in river sediment

On the basis of sedimentation principles and environmental chemical characteristics of heavymetal, combine international new methods-face graph on heavy metal pollution assessment withmulti-variable graph expression, the article made a synthetical assessment study on state of heavymetal pollution and potential ecological risk of Taizi River sediment in Benxi City reach. The re-sults of the study indicated that the state of heavy metal pollution of Taizi River in Benxi Cityreach is very serious, appropriate counter measures should be taken.

Sediment quality criteria for heavy metal pollution in the Le An River with triad approach

In this study, integrative traid was used to sediment quality in the Le An River, which has been strongly contaminated by large amount of Cu, Pb, Zn,Cd, As and Cr discharging from mining activities. All available data collected from chemical analyses,toxic tests and field survey on benthic macroinvertebrates were transformed into ratio to reference(RTR) and relevant scales.The responses of receiving environment to mining impacts were illustrated by traid graphs. Traid results indicated that a sectional distribution pattern existed from upstream to downstream:(a) relative clean upstream;(b) serious contaminated middle stream;(c) gradual recovery downstream. This situation was closely related with local mining activities, which caused obvious degradation of sediment quality in some sections, therefore, remediation was required urgently.

Assessment of Heavy Metals Pollution in the Sediments of Euphrates River, Iraq

Fourteen bed sediments samples were collected from the Euphrates River in order to determine concentrations, seasonal, spatial and contamination assessment of heavy metals such as Pb, Cd, Zn, Cu, Ni, Co, Fe, Mn and Cr. The mean concentrations are as follows: 2249.47 mg/kg for Fe, 228.18 mg/kg for Mn, 67.08 mg/kg for Ni, 58.4 mg/kg for Cr, 48.00 mg/kg for Zn, 28.16 mg/kg for Co, 22.56 mg/kg for Pb, 18.91 mg/kg for Cu and 1.87 mg/kg for Cd. To assess metal contamination in sediments, sediment quality guidelines were applied. The mean concentration of Cd, Cu, Ni, Fe, Mn, and Cr exceeded the USEPA guideline. The metal contamination in the sediments was also evaluated by appling enrichment factor (EF), contamination factor (CF), geo-accumulation index (Igeo) and pollution load index (PLI). Based on enrichment factor (EF), the Euphrates River sediments have very high enrichment for Pb, extremely high for Cd, moderate for Zn, significant to very high for Ni, very high to extremely high for Co, moderate to significant for Mn and significant to very high for Cr. According to contamination factor (CF), Cd and Cr are responsible for very high contamination. According to Igeo, the Euphrates River sediments are moderately to strongly polluted by Cd. Based on PLI, all sampling sites suggest no overall pollution of site quality.

Application of Pollution Indices in the Assessment of Heavy Metal Contamination of Surface Sediments of River Bonsa, Ghana

Heavy metal contamination of sediments is a major risk to ecological systems and human health. Not only do sediments influence the quality of the water column, but can be transferred to micro biota and fishes, ultimately ending up at higher trophic levels in the food chain though biomagnification. This study was carried out to assess the contamination levels of heavy metals in the sediments of river Bonsa. Ten sediment samples were taken along the river and analyzed for Copper (Cu), Lead (Pb), Manganese (Mn), Iron (Fe), Zinc (Zn), Cadmium (Cd), Chromium (Cr), Cobalt (Co), and Nickel (Ni) using Atomic Absorption Spectroscopy (AAS). Data analysis was accomplished by comparing the measured heavy metal concentrations to Australian and New Zealand Environment and Conservation Council (ANZECC) and National Oceanic and Atmospheric Administration (NOAA) fresh water sediment quality guidelines and by the computation of geo-accumulation indices and enrichment factors. The results show that apart from Ni which had two of its sample concentrations (at BS1 21.167 mg/kg and at BS2 29.374 mg/kg) exceeding the ANZECC lower limit (21 mg/kg) guideline for fresh water sediment, all other heavy metals recorded concentrations below the lower limits of their respective ANZECC standards. Out of the 10 samples analyzed, 7 recorded Mn concentrations above the NOAA ARC TEL. A one-sample t-test also showed that the mean concentrations of Cu, Pb, Cd, Zn, Ni, and Cr were significantly lower than their respective ANZECC threshold values and Fe concentration was also significantly lower than the NOAA threshold;however, there was no significant difference between Mn mean value and the corresponding NOAA guideline value. The assessment of heavy metal pollution was derived using the Enrichment Factor (EF) and geo-accumulation indices (I-geo). The computed enrichment factors indicated that all the heavy metals except Ni are from natural sources (i.e., EF < 1.5) signifying a degree of heavy metal depletion rather than enrichment. The sources of Ni were attributed to domestic waste disposal into the river at sampling points BS1 and BS2 as well as run offs from a nearby auto mechanic workshop. All the metals had I-geo values between 0 and 1 (0 < I-geo < 1) denoting unpolluted to moderately polluted sediments. Thus, in terms of heavy metals, the river is unpolluted. These findings are very important as it shows that river Bonsa has not yet been impacted as far as heavy metals are concerned and the data gathered may serve as baseline for future studies.

Water Quality and Heavy Metal Monitoring in Water, Sediments, and Tissues of the African Catfish Clarias gariepinus (Burchell, 1822) from the River Nile, Egypt

Water quality of the river Nile and trace elements of the water, sediments and fish tissues were investigated in the current work. Eighteen different sampling points were selected along the whole course of the River Nile from its spring at Aswan to its estuaries at Rosetta and Damietta. Higher mean value of conductivity, alkalinity, chemical oxygen demand (COD), total organic carbon (TOC), ammonia (NH3), nitrate (NO3), total solid (TS), sulphate (SO4), chloride (Cl), orthophosphate were recorded in the water of Damietta and Rosetta branches comparing to other sites. Also trace metals in the water, sediments and tissues of Clarias gariepinus increased significantly (P Fe > Cu > Pb > Mn > Cr> Cd > Hg. In the gill tissues theses metals were accumulated in the following order Fe > Zn > Mn > Pb > Cr > Cu > Cd> Hg. The low accumulation of metals in muscle may be due to lack of binding affinity of these metals with the proteins of muscle. This is particularly important because muscles contribute the greatest mass of the flesh that is consumed as food.

Assessment of heavy metals in sediment in a heavily polluted urban river in the Chaohu Basin, China

The Nanfei River （Anhui Province, China） is a severely polluted urban river that flows into Chaohu Lake. In the present study, sediments were collected from the river and analyzed for their heavy metal contents. Multivariate statistics and the fuzzy comprehensive assessment method were used to determine the sources of pollution, the current pollution status, and spatial and temporal variations in heavy metal pollution in sediments. The concentrations of arsenic （As）, cadmium （Cd）, chromium （Cr）, copper （Cu）, mercury （Hg）, nickel （Ni）, lead （Pb）, and zinc （Zn） in sediments ranged from 5.67-113, 0.08-40.2, 41.6-524, 15.5-460, 0.03-4.84, 13.5-180, 18.8-250, and 47.9-1 996 mg/kg, and the average concentrations of each metal were 1.7, 38.7, 1.8, 5.5, l 8.8, 1.3, 2.5, and 11.1 times greater than the background values, respectively. Multivariate statistical analysis demonstrated that Hg, Cu, Cr, Cd, and Ni may have originated from industrial activities, whereas As and Pb came from agricultural activities. The fuzzy comprehensive assessment method, based on the fuzzy mathematics theory, was used to obtain a detailed assessment of the sediment quality in the Nanfei River watershed. The results indicated that the pollution was moderate in the downstream tributaries of the Nianbu and Dianbu Rivers, but was severe in the main channel of the Nanfei River and in the upstream tributaries of the Sill and Banqiao Rivers. Therefore, sediments in the Nanfei River watershed are heavily polluted and urgent measures should be taken to remedy the status.

Geochemical Characteristics of Heavy Metals in Riparian Sediment Pore Water of Songhua River, Northeast China

This study reports the geochemical characteristics of zinc (Zn), copper (Cu), lead (Pb), nickel (Ni), mercury (Hg), iron (Fe), and manganese (Mn) in the riparian sediment pore water of the Songhua River, Northeast China. In total, 36 pore water samples and 18 surface water samples from three typical sections were collected and analyzed in June 2009. Cluster analysis of heavy metals was performed to analyze the pollution sources of the metals. Results showed that Hg concentrations in the pore water were greater than those in the surface water, indicating a potential ability of Hg release from riparian sediment system to river water. However, concentrations of Fe and Mn in the surface water were greater than those in the pore water, demonstrating that the microenvironments of riparian and riverbed sediment systems were quite different. Variations of Zn, Cu, Pb and Ni between the surface and the pore water were different in each section. Most metals had similar horizontal and profile distribution characteristics in the three sections except for Zn and Ni. Hg, Fe and Mn concentrations in the pore water increased gradually with the increase in horizontal distance from water body, in contrast to this, Cu decreased, and Pb presented a fluctuating trend. With the increase in depth, Pb and Fe, Cu and Mn showed the same trends, and Hg showed a variable trend. The above distribution characteristics could mainly be attributed to the properties and the interactions of metals, pH and oxidation-reduction conditions, and the complex pollution sources and hydrologic regime in history. The probable sources of metals include the historical and ongoing discharge of industrial wastewater, mining activities, sewage irrigation for agricultural production, and atmospheric deposition from coal-fired plants.

Source analysis and risk evaluation of heavy metal in the river sediment of polymetallic mining area:Taking the Tonglüshan skarn type Cu-Fe-Au deposit as an example,Hubei section of the Yangtze River Basin,China

In this paper,25 sampling points of overlying deposits in Tonglushan mining area,Daye City,Hubei Province,China were tested for heavy metal content to explore pollution characteristics,pollution sources and ecological risks of heavy metals in sediments.A geo-accumulation index method was used to evaluate the degree of heavy metal pollution in the sediment.The mean sediment quality guideline quotient was used for evaluating the ecological risk level of heavy metal in the sediment.And a method of correlation analysis,clustering analysis,and principal component analysis was used for preliminary analysis on the source of heavy metal in the sediment.It was indicated that there was extremely heavy metal pollution in the sediment,among which Cd was extremely polluted,Cu strongly contaminated,Zn,As,and Hg moderately contaminated,and Pb,Cr,and Ni were slightly contaminated.It was also indicated by the mean sediment quality guideline-quotient result that there was a high ecological risk of heavy metals in the sediment,and 64%of the sample sites had extremely high hidden biotoxic effects.For distribution,the contamination of branches was worse than that of the main channel of Daye Dagang,and the deposition of each heavy metal was mainly influenced by the distance from this sample site to the sewage draining exit of a tailings pond.The source analysis showed that the heavy metals in the sediment come from pollution discharging of mining and beneficiation companies,tailings ponds,smelting companies,and transport vehicles.In the study area,due to the influence of heavy metal discharging from these sources,the ecotoxicity of heavy metals in the sediment was extremely high,and Cd was the most toxic pollutant.The research figured out the key restoration area and elements for ecological restoration in the sediment of the Tonglüshan mining area,which could be referenced by monitoring and governance of heavy metal pollution in the sediment of the polymetallic mining area.

Water Quality and Some Heavy Metals in Water and Sediments of Euphrates River, Iraq

Water samples, sediments from three stations in Euphrates River, lraq were analyzed quantitatively for some physical and chemical characters and six heavy metals （Co, Cu, Fe, Mn, Ni and Pb） using flam atomic absorption spectrophotpmeter in period Sept. 2009-Oct. 2010. The physical and chemical characters included temperature, pH, water flow, salinity, dissolved oxygen, BOD5, alkalinity total hardness, calcium and nutrients （nitrite, nitrate reactive phosphate and silicate）. The results showed variation in water flow 0.05-0.40 m/sec., according to the values of salinity 0.40%-0.60% values of the BOD5 were ranged between 0.2-4.3 mg/L. The mean concentration of the heavy metals （Pb, Ni, Mn, Co, Cu and Fe） of the dissolved phase in water were 0.13 μg/L, 0.021 μg/L, 0.31 μg/L, 4.29 μg/L, 7.78 μg/L, 6.46 μg/L and 79.04 μg/L, respectively, while their concentration in the particulate phase were 0.59 μg/g, 0.06 μg/g, 0.42 μg/g, 50.06 μg/g, 6.61 μg/g, 7.17 vg/g and 149.42 μg/g dry weight, respectively. Also the mean concentrations of heavy metals in sediment （exchangeable phase） were 0.51 vg/g,0.18 vg/g, 0.08 μg/g, 61.39 μg/g, 5.40 μg/g, 14.06 vg/g and 130.05 μg/g dry weight respectively, and 0.40 μg/g, 0.17 μg/g, 0.10 μg/g, 63.01 μg/g, 4.64 μg/g, 18.44 μg/g and 126.26 μg/g D.W. respectively in residual phase of sediment.

Distribution of Heavy Metals and Rare Earth Elements in the Surface Sediments of Penang River Estuary, Malaysia

Geochemical sediment of the tropical Pinang River, Malaysia was carried out with the aim at documenting elemental concentrations and pollution level assessment. Concentration of selected heavy metals (Cu, Cd, Cr, Pb, Zn and Mn), rare earth elements, TOC and grain size distribution of sediments were determined at 100 m sampling interval along the river. Sediment size showed a positive correlation with ∑REE and Mn and medium correlations with TOC, Zn, Cu, Cr and Pb contents showing enrichment in the clay size fraction. Results of enrichment factor and geoaccumulation index showed that most of the elemental sources were natural (especially REE) and mostly likely represented background values. However, pollution load index revealed the higher levels of Cr, Cd, Zn and Pb, and, therefore, indicating to the anthropogenic sources (i.e. fishing activities) especially in the downstream locations. Thus, the Pinang River is classified as moderately to highly polluted.

The assessment of heavy metal pollution in river sands of Jalingo,Nigeria using magnetic proxy parameters,pollution,and ecotoxicological indices

The measurement of environmental magnetic properties and metal contents of sands from Nukkai(NKR),Mayo-Gwoi(RMYG)and Lamurde(LR)rivers located in Jalingo,Nigeria are reported.We seek to determine the extent of anthropogenic impact on the river sands using magnetic-proxy-parameters,pollution and ecotoxicological indices and multivariate statistics.Measurements of magnetic susceptibilityχ,frequency-dependentsusceptibilityχfd%,anhystericremanent magnetization,isothernal remanent magnetization and X-ray fluorescence were undertaken.The average values of theχ(in×10^(-8)m^(3)kg^(-1))were 24.53,12.76 and 39.27 for NKR,RMYG and LR sites respectively,implying that the magnetic minerals in the sands were mostly ferrimagnetic.The meanχfd%value of 2.64%,4.85%and 3.53%for NKR,RMYG and LR respectively suggest that the study area was dominated by multi-domain magnetic grain sizes.The value of the S-ratio is~1 in all river samples,suggesting that low coercivity magnetic minerals(e.g.,magnetite)dominated the samples.The mean concentrations of Ti,Zr,Sn,Ba and Pb were higher than the background values in the studied samples.All the estimated pollution indices puts the level of pollution of the river sands between low and moderate pollution with Sn,Ba and Pb as the elements of concern.Multiple sources of metal contents such as fertilizers,pesticides,waste dumps and vehicular sources etc.were found.Significant positive correlations between magnetic parameters(particularly,SIRM)and some heavy metals and pollution/ecotoxicological indices were obtained,showing that magnetic methods could be used as a geochemical proxy for pollution assessment.

Assessment of Heavy Metal Contaminants Using Pollution Indices in Ankobra River at Prestea Huni-Valley District, Ghana

The reliance of communities on River Ankobra as the source of drinking water makes the assessment of its quality very imperative to human health and environmental management. The objective of this work was to investigate the concentration of heavy metal in the Ankobra River sediments at the Prestea Huni-Valley District using pollution indices. Sediments were collected randomly from the bottom of the Ankobra River at four different communities namely: Awodua, Heman, Ankobra and Tarkwa Breman. The presence of a set of heavy metals Fe, Mn, Cd, Pb, Zn, Cu, and Hg in the sediments was determined using Atomic Absorption Spectroscopy (AAS). The results showed that the concentration of Fe, As, and Hg did not differ significantly (p > 0.05) amongst the four communities but significant variation in the levels of Cu, Mn, Cd, Pb, and Zn was found (p < 0.05) amongst the sampling areas. The geo-accumulation index revealed that the communities were not polluted with Cu, Mn, Fe, Pb and Zn. However, all communities except Tarkwa Breman were found to have exceptionally high levels of Cd. The contamination factor results were consistent with the I-geo results. The pollution load index (PLI) showed that the four communities were not polluted with heavy metals. Strong statistical positive relationship were found between Mn and Cu;Cd and Cu;Pb and Mn;Hg and Mn;Zn and Cu;Zn and Mn;Zn and Pb;Zn and Hg whilst As and Fe showed strong negative correlation.

Assessment of Heavy Metal Contamination in Sea Bed Sediment of the Bight of Bonny, Southern Atlantic Coast of Nigeria Using Index Model Analysis

The heavy metal contamination status of Bight of Bonny sea bed sediment was investigated. Sediment samples were collected from eleven locations grouped into three stations. The samples were analyzed to determine the heavy metals (Fe, Pb, Ni, Zn, Mn, Co, Cd, Cu, Cr) concentration using atomic absorption spectrophotometer. Index model analyses, such as geo-accumulation index (I-geo), Enrichment factor (EF), and Pollution load index (PLI) were used for pollution assessment of sea bed sediment. The most predominant heavy metals in the upstream sediment were Fe;13.57 ± 1.838 mg/kg, cobalt;7.987 ± 3.550 mg/kg, and Ni;1.020 ± 0.802 mg/kg, midstream sediment were Fe;8.554 ± 3.010 mg/kg, Co;8.520 ± 4.00 mg/kg, and Ni;1.140 ± 0.879 mg/kg, while the downstream sediment result had Fe;11.12 ± 3.825 mg/kg, Co;7.275 ± 1.700 mg/kg, and Cd;1.025 ± 0.159 /kg. The I-geo results indicate that Cu, Mn, Pb, Cr, Fe, Zn, Ni, and Co were in their background concentrations while Cd had I-geo > 3 which implies a moderately or heavily polluted environment. The EF indicates metal enrichment from anthropogenic sources for Co, Ni, Pb, Cd, Cu, and Cr while Fe and Mn predicate biogenic origin. The PLI of the heavy metals in the three sample stations of sea bed sediment was found to be generally low (<1). The Enrichment Factor and geo-accumulation index strongly suggest the Bight of Bonny sea bed sediment contamination by Cd from anthropogenic sources.

A Pilot Study on the Concentration of Heavy Metals in Sediments from the Lower Orange River, //Karas Region, Namibia

Global water shortage is caused not just by the physical scarcity of water, but also by gradual deterioration of the quality of water resources such as lakes, streams and rivers with heavy metals. This present study evaluated the status of Mn, Fe, Cr, Cu, Ni, As, Zn, Pb and Cd in sediments from the lower Orange River by Inductively Coupled Plasma Atomic Emission Spectrometry technique by collecting a total of eleven samples, each weighing 1 - 2 kg at the depth of 15 - 20 cm from two observations sites along the lower Orange River and applying pollution indicators such as contamination factor(CF), pollution load index(PLI), index of geo-accumulation(Igeo) and enrichment factor(EF) to assay the nature and extent of heavy metals contamination in sediments. The sequence of the total heavy metal content in descending order was Fe > Mn > Cr > As > Zn > Ni > Cu > Pb > Cd. The results of CF and Igeo showed Mn, Cd, Ni, Zn and Pb were minor sources of sediment contamination since most of the samples were unpolluted and moderately polluted by these metals. However, most sediments were moderate to considerably polluted with Cr, As and Fe suggesting that these were the major pollution sources. The value of PLI at one of the two observation sites was equivalent to the value of baseline level, while the next site indicted quality deterioration of the sediments. The EF revealed that Cr was moderately enriched and arsenic (As) significantly enriched in all the sediments, which suggested contamination due to anthropogenic intervention. Hence, it is recommended that sediment quality be evaluated on a regular basis to avoid further deterioration of the Orange River’s health, which might have detrimental repercussions for both aquatic life and local communities along the river.

Heavy Metal Dispersion in Stream Sediments in River Iyiudene, Abakaliki South-Eastern Nigeria: Source, Distribution Pattern, and Contamination Assessment

River Iyiudene is a vital distributary resource in Abakaliki, southeastern Nigeria and conveys an abundant amount of sediments to provincial and residual ecosystems. Although the importance of the river cannot be overemphasized, the geochemistry of its stream sediments is less investigated. Twenty (20) stream sediment samples were taken at the centre of the river channels to represent the entire drainage area well and avoid collapsed bank materials. The stream sediment samples were used to determine the dispersion, contamination status and sources of heavy metal concentrations. Total elemental digestion accompanied this with the use of aqua regia, an admixture of Hydrochloric acid (HCl) and Nitric acid (HNO3) in the ratio of 3:1 using the atomic absorption spectrometer (AAS). The heavy metal concentration levels in River Iyiudene were low compared with sediments from Imo River, Gulf of California, Upper continental crust, Average shale and surface horizons, excluding Cd, which showed high concentration levels than the other reference studies. The results delineated a wide contrast in the concentration levels of the heavy metals, with the mean contents in the order Zn > Cu > Pb > Cd > Ni > As. The pollution evaluation utilizing the Effect range low (ERL), Effect range median (ERM), single pollution index, and geo-accumulation index revealed Cd contamination. This study indicates that the heavy metals were sourced from the natural geological background of the river basin and possibly from agricultural runoff and atmospheric pollutants.