Changes in speciation and leaching behaviors of heavy metals in dredged sediment solidified/stabilized with various materials

Solidification/stabilization (S/S) of sediments is frequently used to treat contaminants in dredged sediments. In this study, sediment collected from the Pearl River Delta (China) was solidified/stabilized with three different kinds of functional materials: cement, lime and bentonite. Lime primarily acted via induced increases in pH, while cements stabilization occurred through their silicate-based systems and the main function of bentonite was adsorption. The speciation and leaching behaviors of specific heavy metals before and after S/S were analyzed and the results showed that the residual speciation of Cd, Cr, Ni, Pb and Zn increased in all treatments except for Cu, as the exchangeable speciation, carbonate-bound speciation and Fe-Mn-oxide-bound speciation of Cu (all of which could be stabilized) were less than 2 % of the total amount. Pb leaching only decreased when pH increased, while the mobility of Cr and Ni only decreased in response to the silicate-based systems. The leached portion of the Fe-Mn-oxide-bound speciation followed the order Zn?>?Cu?>?Ni/Cd?>?Pb?>?Cr. The leached portion of organic-matter-bound species was less than 4 % for Cd, Cr, Ni and Pb, but 35.1 % and 20.6 % for Cu and Zn, respectively.     

Trace metals in surface sediments of the Taiwan Strait: geochemical characteristics and environmental indication

The concentration and geochemical fractionation of six trace metals related with environmental quality assessment, namely Cd, Cr, Cu, Ni, Pb, and Zn, in 30 surface sediments from both inshore and offshore areas of the Taiwan Strait were measured to investigate their distribution characteristics, evaluate their potential mobility, and assess their pollution status. The geoaccumulation index results indicated that, on average, the studied metals presented an order of Cd?>?Pb?>?Ni?>?Zn?>?Cu?>?Cr and were practically in uncontaminated status except Cd. The results of the sequential extraction analysis indicated that, on average, the studied metals were mostly accumulated in residual fraction except Cd whose concentration was the highest in the acid soluble fraction presenting a high risk to the environment, and their mobility decreased in the sequence of Cd?>?Pb?>?Ni?>?Cu?>?Zn?>?Cr. Based on the mean probable effect level quotients, the combination of the studied metals had an 8 % probability of being toxic at two sampling sites and had a 21 % probability of being toxic at the rest of sites. The spatial distribution of the studied metals in total concentrations and different geochemical fractions corroborated the previous findings about the possible sediment transportation routes in and around the Taiwan Strait.     

Occurrence, distribution, and ecological risk assessment of DDTs and heavy metals in surface sediments from Lake Awassa—Ethiopian Rift Valley Lake

Dichlorodiphenyltrichloroethanes (DDTs) and heavy metals are ubiquitous contaminants with high bioaccumulation and persistence in the environment, which can have adverse effects on humans and animals. Although applications of DDTs have been banned in many countries, developing countries like Ethiopia are still using these for agricultural and medicinal purposes. In addition, heavy metals are naturally present in the aquatic environment and distributed globally. In this study, the occurrence, distribution, and ecological risk of DDTs and heavy metals in surface sediments from one of the Ethiopian rift valley lakes were studied. Twenty-five surface sediment samples from Lake Awassa, Ethiopia were collected and analyzed for DDTs and heavy metals. Results showed that concentrations of total DDTs ranged from 3.64 to 40.2 ng/g dry weight. High levels of DDTs were observed in the vicinity of inflow river side and coastal areas with agricultural activities. The heavy metals content were followed the order Zn?>?Ni?>?Pb?>?Cu?>?Cr?>?Co?>?As?>?Cd?>?Hg. Correlation analysis and principal components analysis demonstrated that heavy metals were originated from both natural and anthropogenic inputs. The levels of DDE and DDD in surface sediments exceeded the sediment quality guideline values, indicating that adverse effects may occur to the lake. A method based on toxic-response factor for heavy metals revealed that the calculated potential ecological risk indices showed low ecological risk for the water body.     

Assessing heavy metal pollution in the surface soils of a region that had undergone three decades of intense industrialization and urbanization

Heavy metals in the surface soils from lands of six different use types in one of the world’s most densely populated regions, which is also a major global manufacturing base, were analyzed to assess the impact of urbanization and industrialization on soil pollution. A total of 227 surface soil samples were collected and analyzed for major heavy metals (As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, and Zn) by using microwave-assisted acid digestion and inductively coupled plasma–mass spectrometry (ICP-MS). Multivariate analysis combined with enrichment factors showed that surface soils from the region (>7.2?×?10⁴ km²) had mean Cd, Cu, Zn, and As concentrations that were over two times higher than the background values, with Cd, Cu, and Zn clearly contributed by anthropogenic sources. Soil pollution by Pb was more widespread than the other heavy metals, which was contributed mostly by anthropogenic sources. The results also indicate that Mn, Co, Fe, Cr, and Ni in the surface soils were primarily derived from lithogenic sources, while Hg and As contents in the surface soils were controlled by both natural and anthropogenic sources. The pollution level and potential ecological risk of the surface soils both decreased in the order of: urban areas?>?waste disposal/treatment sites?～?industrial areas?>?agricultural lands?～?forest lands?>?water source protection areas. These results indicate the significant need for the development of pollution prevention and reduction strategies to reduce heavy metal pollution for regions undergoing fast industrialization and urbanization.     

巢湖表层沉积物中重金属的分布特征及其污染评价

以巢湖表层沉积物为研究对象,利用BCR连续提取法研究了沉积物中Cr、Co、Ni、Cu、Cd、Zn、V和Pb等8种重金属元素的分布特征,同时运用潜在风险指数法和地累积指数法综合评价了巢湖沉积物中重金属的生态风险。结果表明,巢湖沉积物中的重金属含量在空间上表现出东西高、中间低的分布特征。巢湖表层沉积物中Cr、Co、Ni、V和Cu 5种重金属都主要以残渣态为主,Zn和Cd主要以弱酸提取态为主,Pb以可还原态为主,同时,Co和Cu 2种元素的可交换态及可还原态含量占有较高比例,具有潜在危害性。相关性分析显示,Cr、Cu、Pb、Ni、Zn和Cd 6种重金属元素的来源和分布可能具有相似性,Co和V 2种重金属元素具有相似的地球化学行为且其主要来源可能与其他几种重金属不同。潜在生态风险指数评价结果表明,巢湖表层沉积物中8种重金属元素构成的生态危害顺序为:Cd>Pb>Co>Cu>Ni>Zn>V>Cr,Cd具有高的生态危害等级,其他7种重金属元素均为低生态危害等级。地累积指数法评价结果表明:巢湖沉积物重金属元素的富集程度为Cd>Zn>Pb>Co>Cu>V>Ni>Cr,Cr属于清洁级别,Co、Cu、V和Ni处于轻度污染水平,Zn和Pb处于偏中度污染,Cd达到了重污染水平。     

Health risk assessment for consumption of fish originating from ponds near Dabaoshan mine, South China

Mining effluents are a potential source of toxic metals in the surrounding aquatic ecosystem and pose a potential health risk to humans from fish consumption. The objective of this paper is to assess the impact of the long-term Dabaoshan mining operation on heavy metal accumulation in different fish species. Heavy metal accumulation (lead (Pb), cadmium (Cd), zinc (Zn), and copper (Cu)) in four tissues (liver, muscle, intestine, and gills) of five carp species (Hypophthalmichthys molitrix, Ctenopharyngodon idellus, Megalobrama amblycephala, Aristichthys nobilis, and Carassius auratus auratus) from two fishponds exposed to effluent waters from Dabaoshan mine, South China. The bioaccumulation factor (BAF) and target hazard quotients were calculated to assess potential health risks to local residents through fish consumption. Levels of heavy metals varied depending on the analyzed tissues. C. auratus auratus accumulated the higher Pb, Cd, Zn, and Cu in the intestine compared with other fish species. Liver of all five species contained high concentrations of Pb, Cd, Zn, and Cu. The BAF for the studied metals showed a descending order of Cd?>?Zn?>?Cu?>?Pb for fishpond 1 and Zn?>?Cd?>?Cu?>?Pb for fishpond 2. Risk assessments suggested that potential human health risk may be present due to high Pb and Cd concentration in the muscle of some fish species exceeding the national and international limits, although the target hazard quotients were less than one.     

Heavy metals and polycyclic aromatic hydrocarbons in sediments from the Shenzhen River,South China

With the analysis of eight heavy metals (As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn) and sixteen polycyclic aromatic hydrocarbons (PAHs) in sediments from the Shenzhen River, South China, the ecological risks associated were evaluated using Hakanson’s method (for the metals) and the Effect Range Low/Effect Range Median (ERL/ERM) method (for the PAHs). The result shows concentrations of heavy metal in the order Zn?>?Cu?>?Cr?>?Ni?>?Pb?>?As?>?Cd?>?Hg, and among which the Zn, Cu, Ni, and Pb are exceeding the maximum contaminant level for sediments while those of PAHs are far below. The potential ecological risk index value for the heavy metals in the sediment samples was 261.90, which is in the moderate risk category. Total PAH concentrations in the sediments ranged from 1,028 to 1,120 ng/g, which are all far lower than the sediment guideline concentration of 4,022 ng/g, indicating that the risks of biological impacts caused by PAHs in Shenzhen River sediments are, therefore, relatively low. Besides, the fluorene concentration was above the ERL, and would potentially cause negative biological effects in the Shenzhen River. Heavy metals risks are suggested among the most important concerns that the environmental recover measures pay attention to.     

Concentrations,spatial distribution,and pollution assessment of heavy metals in surficial sediments from upstream of Yellow River,China

Surface sediments were collected from 122 sites in the upstream of the Yellow River, China. The concentration of Fe, Mn, Cu, Ni, Zn, Cr, Pb, and Cd in sediments was investigated to explore the spatial distribution based on statistics and interpolation method. The results suggested that the concentrations of heavy metals were lower than potential effect levels (PEL). The samples above threshold effect level (TEL) for Pb and Zn were less than 10%, while almost 50% of samples for Ni exceeded PEL. Pb and Zn in sediments performed little or no adverse effects on the aquatic ecosystems. Higher concentrations of all heavy metals occurred in Qinghai and Gansu sections; the concentrations of Cu, Ni, and Zn were significantly higher than the Inner Mongolia section. Lower concentration of Fe, Mn, Cu, Ni, and Zn appeared in Qinghai section; the concentrations of Fe, Mn, Cr, and Pb manifested relatively steady and similar distributions and approximately decreasing tendency along the upstream of Yellow River.

     

Distribution coefficients of potentially toxic elements in soils from the eastern Amazon

The solid-solution distribution or partition coefficient (Kd) is a measure of affinity of potentially toxic elements (PTE) for soil colloids. Kd plays a key role in several models for defining PTE guideline values in soils and for assessing environmental risks, and its value depends on edaphic and climatic conditions of the sites where the soils occur. This study quantified Kd values for Cd, Co, Cr, Cu, Hg, Ni, Pb, and Zn from representative soil samples from Brazil’s eastern Amazon region, which measures 1.2 million km². The Kd values obtained were lower than those set by both international and Brazilian environmental agencies and were correlated with the pH, Fe and Mn oxide content, and cationic exchange capacity of the soils. The following order of decreasing affinity was observed: Pb?>?Cu?>?Hg?>?Cr?>?Cd?≈?Co?>?Ni?>?Zn.     

Occurrence,speciation, and risks of trace metals in soils of greenhouse vegetable production from the vicinity of industrial areas in the Yangtze River Delta,China

The effect of industrial activities on trace metals in farmland of rapidly industrializing regions in developing countries has increasingly been a concern to the public. Here, soils were collected from 13 greenhouse vegetable production (GVP) farms or bases near industrial areas in the Yangtze River Delta of China to investigate the occurrence, speciation, and risks of Cr, Cu, Zn, Cd, Ni, and Pb in GVP soil. The results revealed that the main metal elements causing GVP soil pollution were Cd, Zn, Ni, and Cu, of which contamination levels were generally unpolluted to moderately polluted. Zinc pollution was mainly attributed to heavy fertilization, while Cd, Ni, and Cu pollution may be greatly ascribed to industrial effluents and coal combustion. Metal speciation studies showed that most of Cr, Ni, Cu, and Zn was present in residual fraction while more than half of Cd and Pb was present in non-residual fractions. Additionally, pollution of Cd, Cu, Ni, and Zn in GVP soil increased their corresponding mobile fractions. Risk assessment using potential ecological risk index and risk assessment code showed that Cd was the major risk contributor. Specifically, Cd generally posed moderate or considerable ecological risk as well as displayed medium or high mobility risk in GVP soil. Thus, great attention should be paid to the contribution of both industrial discharges and intensive farming to soil pollution by trace metals, especially Cd, because of its high mobility risk.

     

Spatial distribution and ecological risk assessment of sediment metals in a highly industrialized coastal zone southwestern Taiwan

Spatial variations of Cr, Cu, Hg, Ni, Pb, and Zn in the surface sediments from 34 stations of the Kaohsiung coastal zone southwestern Taiwan were studied to address the current pollution status, sediment quality, and potential ecological risk. The study revealed that the concentrations of sediment metals in Kaohsiung Harbor were alarmingly high compared to the other region of Kaohsiung coast. The concentrations of Cr, Cu, Hg, Ni, Pb, and Zn in the harbor sediments were as high as 351, 247, 1.93, 61.8, 60.9, and 940 mg kg⁻¹, respectively. The current situation of metal pollution was assessed by different pollution indices and results showed moderate to severe enrichment of Cu, Hg, and Zn in the harbor sediments. According to the degree of contamination, pollution load index, and contamination severity index, the sediments from the inner Kaohsiung Harbor show high degree and high severity of metal contamination, while the rest of Kaohsiung coastal areas show uncontaminated or low-level pollution. Results of mean ERM quotient and potential ecological risk index also indicated that the harbor sediments posed a 49% probability of biological toxicity and very high ecological risk. The toxic units indicated that the negative biological effects of the six metals in the harbor sediments were Zn > Cu > Cr > Ni > Hg > Pb. In contrast to Kaohsiung Harbor as a trap where considerable amount of anthropogenic metal loadings accumulated in sediments, low metal concentrations were observed in most Kaohsiung coastal sediments. It probably resulted from the limited fine-grained sediment deposition. In the wave-dominated Kaohsiung coastal zone, fine-grained sediments associated with polluted metals tend to be easily resuspended and transported offshore via waves and wave-induced currents. The results of this study can provide valuable information for river and coastal zone management.

     

Heavy metals in coastal wetland sediments of the Pearl River Estuary, China

Sediment quality in coastal wetlands of the Pearl River Estuary was concerned since the wetlands were used for land reclamation, aquaculture and wildlife protection, and meanwhile served as one of the main ultimate sinks for large amount of heavy metals discharged from the rapidly developing Pearl River Delta. Total concentrations of heavy metal, such as Zn, Ni, Cr, Cu, Pb, and Cd, and their chemical speciation were investigated. Results showed that the sediments were significantly contaminated by Cd, Zn and Ni with concentration ranges of 2.79-4.65, 239.4-345.7 and 24.8-122.1mg/kg, respectively. A major portion (34.6-46.8%) of Pb, Cd, and Zn was strongly associated with exchangeable fractions, while Cu, Ni and Cr were predominantly associated with organic fractions, residual, and Fe-Mn oxide. Cd and Zn would be the main potential risk and the sediment quality is no longer meeting the demand of the current wetland utilization strategies.     

Metal uptake capability of <Emphasis Type="Italic">Cyperus articulatus</Emphasis> L. and its role in mitigating heavy metals from contaminated wetlands

Wetland plants are biological filters that play an important role in maintaining aquatic ecosystem and can take up toxic metals from sediments and water. The present study investigated the seasonal variation in the accumulation potential of heavy metals by Cyperus articulatus in contaminated watercourses. Forty quadrats, distributed equally in 8 sites (six contaminated sites along Ismailia canal and two uncontaminated sites along the River Nile), were selected seasonally for sediment, water, and plant investigations. Autumn was the flourishing season of C. articulatus with the highest shoot density, length, and diameter as well as aboveground biomass, while summer showed the least growth performance. The photosynthetic pigments were markedly reduced under contamination stress. C. articulatus plants accumulated concentrations of most heavy metals, except Pb, in their roots higher than the shoots. The plant tissues accumulated the highest concentrations of Fe, Cd, Ni, and Zn during autumn, while Cu and Mn during spring, and Cr and Co during winter. It was found that Cd, Cu, Ni, Zn, Pb, and Co had seasonal bioaccumulation factor (BF) > 1 with the highest BF for Cd, Ni, and Zn during autumn, Co, Cu, and Pb in winter, spring, and summer, respectively. The translocation factor of most heavy metals, except Pb in spring, was <1 indicating potential phytostabilization of these metals. In conclusion, autumn is an ideal season for harvesting C. articulatus in order to monitor pollution in contaminated wetlands.     

Assessment of trace element pollution and ecological risks in a river basin impacted by mining in Colombia

Trace element pollution in rivers by anthropogenic activities is an increasing problem worldwide. In this study, the contamination and ecological risk by several trace elements were evaluated along a 100-km stretch of the San Jorge River in Colombia, impacted by different mining activities. The increase of average concentration levels and range of trace elements in sediments (in μg/g) was as follows: Cu 6656 (454–69,702) > Cd 1159 (0.061–16,227) > Zn 1064 (102–13,483) > Ni 105 (31–686) > Pb 7.2 (5.1–11.7) > As 1.8 (1.0–3.2) > Hg 0.31 (0.12–1.37). Results showed that surface sediments could be classified as very high ecological risk index (RI > 600), associated with high contamination of Hg, Cd, and Cu, in stations close mining activities. Values for pollution load index indicate an environmental deterioration (PLI > 1), and sediment quality guidelines (SQGs) suggested that Cu, Ni, Zn, and Hg caused adverse biological effects. We further used pollution indices such as contamination factor (CF), enrichment factor (EF), and geoaccumulation index (Igeo) to assess the extent of contamination. According to these indices, discharges of hazardous chemicals over many years have resulted in a high degree of pollution for Cu, Pb, and Cd, with critical values in stations receiving wastes from mining activities. Multivariate statistical analysis suggested that Hg, Cd, Cu, and Zn derived from gold and coal mining, Ni and As were related from the mining of ferronickel and coal, respectively, whereas the high Pb load was attributed to diffuse source of pollution. In sum, our study provided the first detailed database on metal concentration and ecological risks to organisms in sediments of the San Jorge River Basin, and the current results also suggested future research for public health action.

     

Mobility of heavy metals from polluted sediments of a semi-enclosed basin: in situ benthic chamber experiments in Taranto’s Mar Piccolo (Ionian Sea,Southern Italy)

In situ benthic flux experiments were conducted at two stations in the Mar Piccolo of Taranto (Italy), one of the most industrialised and contaminated coastal areas of the Mediterranean. Sediments of the two stations are notably different in their trace metal content, with a station closer to a Navy harbour showing higher mean concentrations of almost all investigated metals (Al, As, Cd, Cr, Cu, Fe, Hg, Mn, Ni, Pb, V and Zn). Conversely, both stations are characterised by significant Hg contamination, compared to the local baseline. Results of a sequential extraction scheme on surface sediments suggest a relatively scarce mobility of the examined metals (Zn > Ni > Cr > As > Cu > Pb). A Hg-specific extraction procedure showed that most of the element (93.1 %) occurs in a fraction comprising Hg bound to Fe/Mn oxi-hydroxides. Reduction of these oxides may affect Hg remobilisation and redistribution. Porewater profiles of dissolved trace metals were quite similar in the two sites, although significant differences could be observed for Al, Cu, Fe and Hg. The highest diffusive fluxes were observed for As, Fe and Mn. Mobility rates of several trace elements (Al, As, Cd, Cr, Cu, Fe, Hg, Mn, Ni, Pb, V and Zn) were directly measured at the sediment–water interface. Results from benthic in situ incubation experiments showed increasing dissolved metal concentrations with time, resulting in higher fluxes for Cu, Fe, Hg, V and Zn in the most contaminated site. Conversely, fluxes of Mn, Ni and Pb were comparable between the two stations. The estimated flux of Hg (97 μg m^?2 day^?1) was the highest observed among similar experiments conducted in other highly contaminated Mediterranean coastal environments. Benthic fluxes could be partially explained by considering rates of organic matter remineralisation, dissolution of Fe/Mn oxy-hydroxides and metal speciation in sediments. Seasonal and spatial variation of biogeochemical parameters can influence metal remobilisation in the Mar Piccolo area. In particular, metals could be promptly remobilised as a consequence of oxygen depletion, posing a serious concern for the widespread fishing and mussel farming activities in the area.     

天津市典型河网区沉积物中重金属分布及生态风险评价

选择天津市典型河网区为研究对象,分析了沉积物中6种重金属(Cr、Cu、Mn、Ni、Pb和Zn)的分布特征,并采用富集系数法和潜在生态危害指数法分析了重金属的来源,进而评价了其生态风险。结果表明,表层沉积物中Cr、Cu、Mn、Ni、Pb和Zn的平均含量分别是58.18、23.52、524.60、22.93、25.24和49.51 mg/kg,其中Cr、Mn和Ni含量均低于天津市土壤背景值,而Cu、Pb和Zn含量在部分样点高于背景值;在垂直分布上,沉积物中Cr和Ni的含量相对稳定,而Cu、Mn、Pb和Zn的含量从底层到表层均先增加后降低。重金属富集系数(EF)分析显示,河网区表层沉积物中Cu和Zn在个别样点以及Pb在近一半样点存在人为输入过程(EF1.5),与接纳上游及区域的生活污水、农田退水有关,而Cr、Mn和Ni均来自自然源。重金属综合潜在生态危害指数(RI)评价表明,整个河网区表层沉积物为轻微生态危害水平,对区域的水环境质量不构成威胁。     

Spatial distribution and ecotoxicological risk assessment of heavy metals in surface sediments of the southern Bohai Bay, China

The concentrations of heavy metals (Cd, Cr, Cu, Ni, Pb, and Zn) and organic carbon in surface sediments, collected from the southern Bohai Bay, were determined to assess the potential contamination and determine the environmental risks associated with heavy metals. Results showed that heavy metal concentrations in the sediments generally met the China Marine Sediment Quality criteria. Both the ecotoxicological index and the potential ecological risk index suggest that the combined ecological risk of the six studied metals may be low, with the highest ecotoxicological potential zones located in the offshore area. The methods of enrichment factor and geoaccumulation index suggested that elevated concentrations of Cd, Cr, and Ni are presented in the region. Multivariate analysis also indicated that the lithogenic factor dominates the distribution of most part of the considered metals in the study area, whereas Cd and Cr are clearly influenced by anthropogenic inputs. The results of this study are likely to be a useful tool to authorities in charge of sustainable marine management.     

Relationship between heavy metals concentrations in egret species,their environment and food chain differences from two Headworks of Pakistan

Concentration of ten metals (Cd, Cr, Co, Cu, Fe, Li, Mn, Ni, Pb and Zn) were analyzed in the egg contents, prey and soil samples of little egret (Egretta garzetta) and cattle egret (Bubulcus ibis) from two Headworks to determine habitat and species-specific differences; to assess the importance of prey and habitat contamination as an exposure source for heavy metals. Concentration of Cu, Mn, Cr and Pb in egg contents, Fe, Co, Cu, Mn, Zn in prey and Fe, Co, Cu, Ni, Li in surface soils were significantly different (P < 0.05). Mean metal concentrations of Cr, Pb and Cd were relatively higher in little egret whereas Cu and Mn were higher in the egg contents of cattle egret. The mean concentrations of Cu, Mn and Zn were higher in prey samples of cattle egrets and Cr, Cd and Pb in prey samples of little egrets. In soil samples collected from little egret heronries metal concentrations were higher except Cu and Ni. Correlation Analysis and Hierarchical Agglomerative Cluster Analysis (HACA) identified relatively similar associations of metals and their source identification. Metals such as Fe, Cu, Mn, and Li were related with geochemical origin from parent rock material as well as anthropogenic input whereas Cr, Cd, Pb, Ni, Co and Zn were associated mostly with anthropogenic activities. The study suggested that eggs are useful bio-monitor of local heavy metal contamination.     

Assessment of heavy metal contamination in Hindon River sediments: a chemometric and geochemical approach

The aim of this study was to assess the level of heavy metals (Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) in the surface sediments of the Hindon River, India that receives both treated and untreated municipal and industrial discharges generated in and around Ghaziabad, India. Mean metals concentrations (mg kg⁻¹) were in the range of; Cu: 21.70-280.33, Cd: 0.29-6.29, Fe: 4151.75-17318.75, Zn: 22.22.50-288.29, Ni: 13.90-57.66, Mn: 49.55-516.97, Cr: 17.48-33.70 and Pb: 27.56-313.57 respectively. Chemometric analysis was applied to identify contribution sources by heavy metals while geochemical approaches (enrichment factor and geo-accumulation index) were exploited for the assessment of the enrichment and contamination level of heavy metals in the river sediments. Chemometric analysis suggested anthropic origin of Cu, Cd, Pb, Zn, and Ni while Fe showed lithogenic origin. Mn and Cr was associated and controlled by mixed origin. Geochemical approach confirms the anthropogenic influence of heavy metal pollution in the river sediments. The study suggests that a complementary approach that integrates chemometric analysis, sediment quality criteria, and geochemical investigation should be considered in order to provide a more accurate appraisal of the heavy metal pollution in river sediments. Consequently, it may serve to undertake and design effective strategies and remedial measures to prevent further deterioration of the river ecosystem in future.     

Metals in a northern Nile Delta lake: water,suspended particulates,sediments, and biota

Lake Edku is one of the important fishing areas in the Nile Delta. It is exposed to different quantities of serious pollutants in particular metals. To overall appraise the risk and status of metals in the lake, a comprehensive study of total concentrations of cadmium (Cd), chromium (Cr), copper (Cu), iron (Fe), manganese (Mn), nickel (Ni), and zinc (Zn) in sediments and spatial-temporal variations of these metals in the dissolved and suspended particulates, and some tissues of Tilapias niloticus, was conducted from ten sampling sites during 2016. Results showed that none of the investigated metals exceeded the limits considered as hazardous for aquatic life in water. The highest concentrations of Cd, Cu, Ni, and Zn were observed in suspended particulate matter, which may precipitate on the surface of the sediments. Potential ecological risk analysis of the majority of the investigated metals in the sediment indicated that Lake Edku posed a low ecological risk. The estimated values of all metals in tissues of Tilapia niloticus were below the international permissible limits. Moreover, the potential risk of metals to human via the consumption of Tilapia niloticus was estimated using the weekly intake levels, which was lower than the WHO’s safe provisional tolerant weekly intake levels. These results prove the importance of performing measurements of contaminants in various compartments of Lake Ecosystem including sediment, biota, and suspended particulate matter for proper management.