Toxic Elements In Sediments Research Articles

Pollution and Ecological Risk Assessment of Potentially Toxic Elements in Sediments Along the Fluvial-to-Marine Transition Zone of the Don River

The quality of sediments in the mixing zone of river freshwater and marine saline water as an important geochemical barrier for potentially toxic elements (PTEs) remains poorly understood. This study aims to analyze the current pollution with PTEs and associated ecological risks in sediments of the Don River delta and the surrounding area of the Taganrog Bay of the Sea of Azov (Russia). The PTE content was determined in fifty-four collected samples using the WDXRF and assessed using geochemical and ecotoxicological indicators. The source of Cr, Mn, Ni and Pb is mainly river runoff, and Cu, Zn and Cd are from a variety of anthropogenic sources. As shown by the assessment of the geoaccumulation index (Igeo), single pollution index (PI) and contamination factor (CF), these elements are the priority pollutants. According to these estimates, high and very high contamination of sediments in the estuarine zone of the Don River with Cd and Pb was detected in 72–94% and 2–57% of samples, respectively. However, environmental risks are determined almost exclusively by the level of Cd. Total contamination as assessed by the Nemerow pollution index (NPI), modified degree of contamination (mCd) and metal pollution index (MPI) is of concern in 83–98% of the samples studied. The most heavily polluted sediments are in the vicinity of residential areas of the Taganrog Bay. Despite the lower average pollution levels of deltaic sediments, freshwater biota are exposed to higher potential toxic risks of adverse effects by PTE, particularly from Ni and Pb. Thus, the complex hydrological regime and uneven anthropogenic impact predetermine the geochemical state of the sediments of the estuarine zone of the Don River.

Human and ecological risk assessments of potentially toxic elements in sediments around a pharmaceutical industry

Potentially toxic elements (PTEs) in sediment can be highly hazardous to the environment and public health. This study aimed to assess the human and ecological risks of PTEs in sediments around a pharmaceutical industry in Ilorin, Nigeria. Physicochemical parameters and the concentrations of lead (Pb), chromium (Cr), cadmium (Cd), cobalt (Co), arsenic (As), and nickel (Ni) were analyzed in sediment samples collected from seven locations in the wet and dry seasons. Standard two-dimensional principal component analysis (PCA) and risk assessments were also conducted. The concentrations of Pb, Co, Ni, Cr, Cd, and As in the sediments ranged from 0.001 to 0.031 mg/kg, 0–0.005 mg/kg, 0.005–0.012 mg/kg, 0.001–0.014 mg/kg, 0.005–0.024 mg/kg, and 0.001–0.012 mg/kg, respectively. The mean concentrations of the total PTEs content were found in decreasing order of concentration: Pb > Cd > Ni > Cr > As > Co. PCA showed that some of the PTEs were highly concentrated in samples obtained at other locations as well as at the discharge point. The Hazard Index was mostly <1 across locations, indicating little to no probable non-cancerous effect. However, the incremental lifetime cancer risk for arsenic and nickel was high and required attention. The ecological risk assessment showed that lead and arsenic were the major PTEs pollutants in all locations. The study identifies PTEs profiles in sediments and emphasises the necessity of continual monitoring and action to stop long-term negative impacts on the local environment and public health.

Spatial Distribution, Risk Assessment, Source Apportionment and Stabilization Performance of Potentially Toxic Elements in Sediments of Dongdagou River, Northwest China

Spatial Distribution, Risk Assessment, Source Apportionment and Stabilization Performance of Potentially Toxic Elements in Sediments of Dongdagou River, Northwest China

Contents of potentially toxic elements in sediments and waters of the Meža river and its tributaries draining mine waste deposits

The results of the monitoring of the contents of potentially toxic elements (PTE) in sediments (2013, 2017, 2020) and waters (2017, 2020) of the Meža River and its tributaries, which drain mining waste deposits, are presented. A total of 13 sample sites were established in a sample scheme that enables long-term observation of the impact of mining waste deposits. In the sediments, the content of PTE, especially Pb, Zn, Cd, Mo and As, is greatly elevated and fluctuates with time. The study area is affected by more than 300 years of mining and ore processing industry. The differences in the contents in various years are most pronounced in the Meža River tributaries, which drain the mining waste dumps. Hydrological conditions have a significant influence on the contents in sediments, as PTE content increases with higher water level and higher water flow. Water erosion of mining waste dumps has a significant impact on the discharge of contaminated material into watercourses. In contrast, in the upper part of the Meža River, we did not observe strong influence of higher water level on the content of PTE in the sediments. Fluctuations in the content between individual years and fluctuations between various hydrological conditions are higher again in the middle part of the the Meža river, downstream from Žerjav. The presented results demonstrate that the contents of Pb, Zn, Cd, Mo and As in the sediments of the Meža River and its tributaries are very high and that they by far exceed the legislative critical value for the soil. PTE contents in the surface water are elevated in some locations and do not change significantly over time. The local concentrations of Pb, Cd and Zn exceed the legislative guidelines. We estimate that the dynamics of the sediment load in the Meža River along the towns of Črna na Koroškem, Žerjav and Mežica is very complex. In addition to mining waste deposits, the content of PTE in sediments and waters is also affected by scattered sources in the environment, such as contaminated soil and floodplains and their varying degrees of pollution, as the environment has been burdened by long-term mining, ore processing and smelting activities. Current industrial activity may also have an additional environmental impact.

Potentially toxic elements in sediments near mines-a comprehensive approach for the assessment of pollution status and associated risk for the surface water environment.

This research is focused on the assessment of the pollution status of river and lake sediments near Pb, Zn, and Cu mines and tailings in the southeastern part of Serbia-Krajište area. The study is based on hypothesis that investigated rivers and lakes in the Krajište area could be polluted by potentially toxic elements (PTEs) and that these elements could pose considerable ecological risk to the studied surface water environment. High PTE contents are detected in studied river sediments (up to 7892mgkg-1 for Zn, 3224mgkg-1 for Cu, 36,790mgkg-1 for Pb, 64.2mgkg-1 for Cd, and 1444mgkg-1 for As). Given that the contents of the studied elements in most of the river sediments exceeded the background values, values prescribed by regulations of the Republic of Serbia, as well as probable effect concentration (PEL), it is possible to conclude that sediments were heavily polluted and that detrimental effects can be expected. Contamination indices including the enrichment factor (EF), contamination factor (CF), index of geoaccumulation (Igeo), potential ecological risk index (Eri), ecological risk index (RI), pollution load index (PLI), and aggregative toxicity index (ATI) were used to assess the degree of pollution by PTEs. The ecological risk assessment revealed that there is a significant risk observed for toxic elements (primarily Pb, Cu, Cd, and As) at this moment. The highest contamination indices (EF, Igeo, CF, PLI, and ATI) are mainly associated with historical and current mining activities. The Monte Carlo analysis based on the risk assessment indices was used to evaluate the uncertainty. The most pronounced toxic risk is found for the Pb, Cu, Cd, and As which assessment was in the range of high and extremely high-risk probabilities. The obtained results suggest that levels of toxic elements pose a significant ecological risk to the surface water environment near Pb, Zn, and Cu mines in the Krajište area. The methodology applied in this paper could be very useful for other researchers dealing with the problem of environmental pollution by toxic elements.

Evaluation of concentrations and contamination factors of potentially toxic elements in sediments of Egi communities, Rivers State, Nigeria

Potential toxic elements in sediments and water are harmful to humans and other organisms even at low concentration. Therefore, the objective of this paper was employed to evaluate the concentrations and contamination factors of potential toxic elements (PTE) in sediments of selected areas in Egi communities (Obagi, Oboburu and Ogbogu) in Ogba/Egbema/Ndoni LGA of Rivers State, Nigeria using AAS (GBC XplorAA) after mixed-acid wet digestion of the sediment. The result of the levels of PTEs reveals that the highest mean were iron (6983±123 mg/Kg), manganese (19.42±6.87 mg/Kg), zinc (11.73±2.10 mg/Kg) copper (7.057±1.08 mg/Kg), and lead (5.871±2.76 mg/Kg). The result also showed that the most toxic metals had values as follows: cadmium: Obagi (1.244±0.01 mg/Kg), Oboburu (0.411±0.01 mg/Kg) and (0.051±0.01 mg/Kg); arsenic; Ogbogu (2.481±0.31 mg/Kg), Obagi (1.452±0.02 mg/Kg), and Oboburu (0.991±0.02 mg/Kg), copper Oboburu (5.333±0.010 mg/Kg), Obagi (6.800±0.07 mg/Kg), and Ogbogu (9.037±0.12 mg/Kg). The geo-accumulation (Igeo) values indicated uncontaminated for all the PTEs. The contamination factor shows that all samples had low contamination. The enrichment factor for Obagi; Pb (1.011), As (0.675), Cr (0.467), Cu (1.052), Zn (0.650), Ni (0.493), and Co (0.767) were of biogenic, while Cd (45.42) was of anthropogenic origin. For Oboburu; biogenic origin were As (0.321), Cr (0.188), Mn (0.003), Cu (0.574), Zn (0.709), Ni (0.313), and Co (0.454) while Pb (2.100), Cd (5.756) were of anthropogenic origin. Ogbogu; Cr (0.845) and Mn (0.807) were of biogenic while Pb (5.079), Cd (4.241), As (4.770), Cu (5.780), Zn (2.339), Ni (2.135) and Co (5.586) were of anthropogenic sources. The order of toxicity was Fe&gt;Mn&gt;Zn&gt;Cu&gt;Cr&gt;Pb&gt;Ni&gt;Co&gt;Cd&gt;As&gt;Hg. The order of impact were Ogbogu&gt;Obagi&gt;Oboburu.

Assessment of contamination level of watercourses and streambed sediments downstream the Capillitas Mine, Catamarca, Argentina

The present study constrain the degree of contamination by heavy metals and metalloids of streams impacted by mining activities in Capillitas Mine (Catamarca, Argentina), an epithermal precious- and base-metal vein deposit previously mined for copper along with gold and silver; and subsequently for rodhochrosite. Geochemical analyses of water of three streams (Ortíz, Acid and Capillitas) and a small pond depicting a very thin layer of turquoise-colored precipitates in its bottom were performed and the environmental risk factor was calculated. Moreover, the concentrations of potential toxic elements in sediments from the Ortíz and Capillitas streams were determined by ICP-OES and the Index of geoacumulation (Igeo) for As, Cd, Zn, Cu, Mn and Pb was computed.&#x0D; According to their major ions concentration the four water samples correspond to calcium SO4 waters. The Acid and Ortíz streams and the turquoise pond show concentrations of Al, Mn, Cd, Zn, Cu, Cr, Ni and Pb that largely exceed the limiting concentrations for protection of aquatic life, as well as for irrigation waters. The Capillitas stream has a lower content of heavy metal but shows concentrations of Mn, Zn, Cu and Pb exceeding the limiting values for protection of aquatic life. &#x0D; According to the obtained Igeo the three streambed sediments from the Ortíz creek are extremely polluted for Cd, Zn and Pb, whereas they range from strongly to extremely polluted for Cu, As and Mn. The sediments from Capillitas creek depict lower contents of metals and metalloids; though it is strongly polluted for Cd, moderately polluted for Cu and unpolluted to moderately polluted for Pb and Zn.

Assessment of potential ecological risk based on the vertical characteristics of potential toxic elements in sediments from a high-density cage culture reservoir in China

The pollution of sediments around Lu Ban Island is a serious environmental issue that is threatening human health. The concentration of As, Cd, Cu, Cr, Hg, Ni, Pb, and Zn at 73 layer points were investigated, vertical distribution characteristics, correlation among potential toxic elements and potential ecological risks of sediments at different depth were analyzed. The following results were obtained, (1) the hypothesis that there was a linear relationship between concentration of potential toxic elements and the reciprocal of deep was reasonable. Based on hypothesis, the ultimate value of concentration by making depth go to infinity was regarded as the background concentration. The background concentration of As, Cd, Cu, Cr, Hg, Ni, Pb, and Zn are respectively 4.94 mg/kg, 0.20 mg/kg, 15.48 mg/kg, 58.41 mg/kg, 0.062 mg/kg, 26.96 mg/kg, 20.29 mg/kg, and 53.31 mg/kg. (2) But correlation between Ni and As was relatively weak, high degree of correlation among other potential toxic elements were found. Based on their correlation, eight potential toxic elements were classified into three groups. First group included Ni and Cr, mainly releasing by coal burning; Cu, Pb, Zn, Hg, and Cd were grouped together, possibly due to their shared source of fish cage culture; Arsenic with relatively weak correlation with other potential toxic elements was classified as a separate class, which was usually one important mineral resource associated with phosphate. (3) Potential ecological risk index (PERI) of sediment above − 0.40 m belonged to moderate risk, the PERI of sediment in − 0.10 m, − 0.20 m, and − 0.40 m were 289.06, 254.33, and 201.44, respectively. Sediment below − 0.40 m belonged to low risk with average PERI value 112.82, with no significant changes in PERI values. The order of contribution to PERI was Hg > Cd > As > Cu > Pb > Ni > Cr > Zn. (4) According to result of cluster analysis and potential ecological risk, the potential ecological risk of sediment above − 0.40 m mainly contributed by potential toxic elements of Cu, Cd, Hg, Pb, and Zn sharing source of fish cage culture.

Radionuclides and Potentially Toxic Elements in Sediments from the Northern Bulgarian Black Sea Coast

This paper presents data on the content of toxic elements (Mn, Ni, Zn, Cu, Pb, As, Cr, Cd and Co), technogenic (137Cs, 134Cs) and natural radionuclides of the 238U and 232Th series (234Th, 226Ra, 210Pb, 232Th) and 40K in sediments collected from ten sampling stations along the northern Bulgarian Black Sea coast for a period of more than twenty years. Measurements were made by Gamma Spectrometry and Inductively Coupled Plasma Mass Spectrometry. The results show that the nuclides and toxic elements concentration in sediments strongly depend on the sediments nature. The obtained data create a database on the concentrations of radionuclides and toxic elements in sediments from the Northern Bulgarian Black Sea coast and can be used for assessment of the ecological status of the marine environment along the whole northern coastal zone.

Toxic Elements in Sediment and Water of the Crocodile River (West) System, South Africa, Following Acid Mine Drainage

The upper reaches of the Crocodile River (West) system are located in the western basin of the Witwatersrand mountain chain, an area heavily influenced by gold mining. After the spill of highly acidic and contaminated mining-influenced water into the river system in 2002, chemical water treatment was implemented to compensate for the consequences of acid mine drainage. Some studies thereafter have shown metal concentrations of concern in the system, but never considered longer periods of time. For this study, we investigated water and sediments over a period of 13 months from 7 sampling sites in the system. In addition to physico-chemical parameters such as temperature, pH, and electrical conductivity, a multi-element analysis was conducted. We used various versions of atomic-absorption-spectroscopy, total reflection x-ray fluorescence spectroscopy, and inductively coupled plasma mass spectrometry in filtered and acidified water samples as well as sediment leachates. Concentrations of Ni, Zn, As, Pb, and U in the sediment were clearly elevated at the site closest to the mine as well as further downstream, some of them far exceeding quality guidelines. Moreover, dissolved Mn, Fe, Ni, Zn and U occurred irregularly in concentrations of concern at the site of mining-influenced water inflow. Our findings clearly indicate a risk of further and chronic mobilization of toxic elements from this site and a possible threat to the connected river system.

Spatiotemporal assessment of potentially toxic elements in sediments and roadside soil samples and associated ecological risk in Ropar wetland and its environs.

Sediments from banks of the Sutlej River and roadside soils from vicinity of Ropar wetland (collected during pre- and post-monsoon seasons, 2013) were analysed to determine the spatiotemporal distribution of potentially toxic elements (PTEs, viz. arsenic, cadmium, cobalt, chromium,copper, iron, manganese, lead and zinc), which when present in high concentrations may pose health hazards and ecological risk. Contamination factor, degree of contamination, modified degree of contamination, metal pollution index, pollution load index, enrichment factor, geoaccumulation index and ecological risk index were also determined for these PTEs in the study area. Sediment and soil samples were found to be alkaline and non-saline (pH > 7.0; EC < 4500 μS cm-1) with sodium and potassium as major ions. Iron (mg kg-1) was found to be most abundant in sediments (1477.59-6512.45) and soils (922.64-12,455.00). Cadmium content in sediments exceeded the threshold value (0.99mgkg-1) at 2 (pre-monsoon) and 3 (post-monsoon) sampling sites. In both seasons, cadmium (0.10-2.05) and cobalt (11.40-17.52) contents (mg kg-1) exceeded the threshold limits (0.06 and 8.00 respectively) in all roadside soils. Significant spatiotemporal variation (p ≤ 0.05) was observed for pH; EC; and calcium, magnesium, copper, iron and zinc contents. Low to moderate potential ecological risk was observed for both roadside soils (31.80-213.82) and sediments (41.47-236.73). Contamination factor, enrichment factor and geoaccumulation index for cadmium were highest in roadside soils (6.84, 46.91 and 2.19, respectively) and sediments (7.64, 167.46 and 2.35, respectively) due to settlement of coal fly ash released from the industrial setups, on sediments/soils of the study area.

Distribution of Heavy Metals in Sediments and Soft Tissues of the &lt;i&gt;Cerithidea obtusa&lt;/i&gt; from Sepang River, Malaysia

The main purpose of the research was to analyze the distribution of Arsenic (As), Cadmium (Cd), Copper (Cu), Iron (Fe), Nickel (Ni), Cobalt (Co), Mangan (Mn), and Zinc (Zn) in soft tissues, shells, and associated surface sediments of Cerithidea obtusa (C. obtusa) mangrove snails collected from Sungai Besar Sepang. The concentration of iron (Fe) was found to be the highest in relation to other toxic elements in sediments, soft tissues, and shells of C. obtusa. The concentrations of Cu and Zn in soft tissues of C. obtusa were found to exceed the concentrations in sediments, indicating bioaccumulation of these metals. Metal pollution was assessed with the Enrichment Factor (EF), Geoaccumulation Index (Igeo), and Pollution Factor (CF). EF, Igeo, and CF were 0.34 to 22.41, -3.37 to 2.65, and 0.14 to 9.42, respectively. The results indicate that sediments in Sungai Besar Sepang are contaminated with As and Zn. According to the bivalve bioaccumulation results, the soft tissues of C. obtusa act as a macro-concentrator for Cu and Zn. As a result, it is suggested that ongoing monitoring of releases of heavy metals from anthropogenic sources and stricter environmental protection measures should be implemented.

Environmental and Human Health Risk Assessment of Potential Toxic Elements in Sediments from Ebrié Lagoon, Côte d’Ivoire

Ebrie lagoon is one of the largest in the West Africa lagoon system and contributes to the social and economic well-being of the habitants. Whereas, the sectors IV and V of Ebrié lagoon are increasingly threatened by potential toxic elements (PTEs) pollution due to urban growth, and industrial and agricultural activities, but few studies have focused on the contamination of sediments by PTEs and the human health risks. In the present study, surface sediments from sectors IV and V of Ebrié lagoon were sampled for the geochemical, human risk and ecological risks assessment of four potential toxic elements (PTEs) (As, Cd, Hg and Pb). Results indicate that particle of grain size of > 63 µm (sand) were the most abundant in the surface sediments with relative high TOC content. However, particle size did not affect metals distribution in sediments. PTE mean concentrations did not exceed the UCC values. The geoaccumulation index and enrichiment factor values indicate that no Cd and Pb contamination has occured on the whole, but sediments have been polluted by As and Hg and suggest that Cd and Pb were influenced by from natural weathering processes, whereas As and Hg derived from anthropogenic inputs. The concentrations of Hg higher than PEC, which suggest that it may pose adverse effects to organisms. The results of this study indicated that As, Hg and Pb increase health risks via sediment ingestion for both chidren and adults. With regard to concentrations and level of risk, Hg is the most toxic metal that requires special attention including monitoring of pollution level, wastewater treatment for better environmental management in sectors IV and V of Ebrié lagoon.

Assessment of Potentially Toxic Elements in Egbetua Stream Sediments, South-Western Nigeria

The study area is located in Egbetua area in Akoko Edo Local Government Area of Edo State, southwestern Nigeria. the aim of the study is to assess the concentrations of potentially toxic elements in sediments from the study area. Ten samples collected from various locations in Egbetua stream were subjected to standard geochemical analysis using energy dispersive x-ray fluorescence spectrometer model “Minipal 4”. The average concentrations of six elements are V (26.89 ppm), Cr (32.33 ppm), Co (6.13 ppm), Ni (16.10 ppm), Au (21.13 ppm), and Zr (1,285.20 ppm) and they were compared to those of upper continental crust baseline values. V, Cr, Co, and Ni have extremely low concentrations, while Au and Zr have very high concentrations. Moreover, V, Cr, Co, and Ni have average enrichment ratios of 0.28, 0.35, 0.35 and 0.34, respectively, which are &lt; 1 implying their depletion in relation to their average crustal baseline concentrations. On the other hand, Au and Zr are highly enriched in the study area. Au has average geoaccumulation index (Igeo) values of 4.40 indicative of strongly to extremely polluted, while Cr, Co, Ni and Zr have average Igeo values of 10.95, 6.14, 9.98 and 17.34, respectively, indicative of sediments that are extremely polluted. The potentially toxic elements pose very serious environmental geochemical pollution threat in the study area. It is recommended that urgent action should be taken to mitigate and clean the study area of these potentially toxic elements.

Pollution, ecological risk, and source identification of potentially toxic elements in sediments of a landscape urban lagoon, China

Given the great importance of Yundang lagoon (China), a detailed evaluation and source identification of multiple potentially toxic elements (PTEs) is required. Low concentrations of the PTEs were found in the Diversion canal, while high in the Main canal, Inner lagoon, and Outer lagoon. Evaluation results indicated that the pollution of PTEs was widespread, and that the extremely high eco-risks and evident toxicity were owing to the great contributions of Hg and Cd. Positive matrix factorization model demonstrated that the PTEs were from both natural and different types of anthropogenic sources. TOC played a critical role in the PTEs. It was also found that the limited environmental carrying capacity and the poor hydrological condition of the lagoon may still accumulate the pollution in a progressive fashion. These findings provide a detailed information on making effective strategies of new directions for long-term prevention of PTEs pollution in the landscape urban lagoon.

A comprehensive assessment of anthropogenic impacts, contamination, and ecological risks of toxic elements in sediments of urban rivers: A case study in Qingdao, East China

Urban river sediments usually serve as a sink for potentially toxic elements (PTEs) during the process of urbanization. A systematic evaluation of human influence, contamination, and risk assessment of PTEs in urban river sediments is essential for sustaining river health. In this study, 24 sediment samples were collected from 5 rivers in Qingdao, a coastal urbanized city in East China. Zinc had the highest concentration (141 ± 134 mg/kg), followed by Cr, Cu, Pb, Ni, Co, As, and Cd. Generally, the PTE concentrations were higher in eastern rivers than those in western rivers affected by intensive industrialization and urbanization. The principal component analysis identified three principal components: natural origins (As, Co, Cr, and Ni), urban activities (Cd, Cu, Pb, and Zn), and atmospheric deposition (Pb), respectively. The excessive concentrations of Cd and Pb were frequently appeared in the sampling sites, with the anthropogenic contribution rates of 8.4%–77% and 6.6%–87%, respectively. Additionally, the river sediments experienced moderate contamination of As, Cd, Cu, Pb, and Zn. Among the PTEs, Cd had moderate ecological risk and others had low risk. The results of Monte Carlo simulation were generally in accordance with the detected contamination and risk levels, except for several elements (Cu and Zn) with huge spatial heterogeneity. According to the Monte Carlo simulation, the river sediments could undergo extremely high contamination and high ecological risk of the PTEs in the worst situation. Thus, it becomes essential that PTEs in the urban rivers should not be overlooked before their discharge into the sea.

Potential toxic elements in sediment and fishes of an important fish breeding river in Bangladesh: a preliminary study for ecological and health risks assessment

Indexical appraisal of potentially toxic elements (PTEs) in sediment and fish of riverine ecosystem give valuable information for environmental management. In this research, PTEs were measured in sediment and soft tissues of six fish species from an important fish breeding river (Halda) of Bangladesh to assess sediment quality and human health risks. The abundance of PTEs in sediments varied in the decreasing order of Fe > K > Ca > Ti > Zr > Sr > Rb > Mn > Zn > Cu > Ni > Pb > Co. The ranges of mean PTEs concentrations in fish species were as follows: Ca, 138.54–366.68; Cr, 8.86–11.34; Mn, 6.20–7.44; Fe, 52.98–871; Co, 2.0–3.06; Cu, 17.82–26.45; Zn, 48.27–115.75; Se, 5.16–6.79; Sr, 35.56–69.57; Hg, 0.42–2.15, and Pb, 0.26–0.64 mg/kg. The outcomes of the enrichment factor, geo-accumulation index, and contamination factor of PTEs in sediments varied spatially and most of the sediment samples were moderately polluted by PTEs. Biota-sediment accumulation factor indicated that Zn, Cu, and Co were more concentrated in fish species than other elements. Target hazard quotient (THQ) for the individual element was below 1, suggesting that people would not experience significant health hazards if they ingest a single metal from fish species.

Cytogenetic, Serum Liver Enzymes and Liver Cell Pathology of the Hampala Barb Fish (Hampala macrolepidota) Affected by Toxic Elements in the Contaminated Nam Kok River Near the Sepon Gold-Copper Mine, Lao PDR.

This study aimed to determine toxic element concentrations in aquatic environments, including water and sediment, and in the Hampala macrolepidota fish, and to evaluate chromosome abnormalities, serum liver enzyme changes and liver histopathological alterations in H. macrolepidota from the Nam Kok River near the Sepon gold-copper mine, Lao People’s Democratic Republic, as compared with a control area without mining activity. The results revealed significant differences (p < 0.05) in As, Ba, Cu, Fe, Mn, Ni, Se and Zn in water, in all of the studied potentially toxic elements in sediment, and in As, Ba, Cd, Cr, Cu, Mn, Ni, Se, and Zn in the fish between the study and control areas. A chromosome assessment demonstrated 6 types of chromosome abnormalities, among which centric gap had the highest total number of chromosome abnormalities. Percentage of chromosome abnormalities, percentage of cells with chromosome abnormalities and serum liver enzymes in H. macrolepidota were significantly different (p < 0.05) between the two studied areas and were higher in the contaminated fish than in the control fish. The observation of liver histopathological changes revealed cellular degeneration, such as nuclear damage, abnormal cytoplasmic mitochondria and the disintegration of rough endoplasmic reticulum. The results indicate that the contamination of potentially toxic elements in the Nam Kok River near the Sepon gold-copper mine area negatively affected chromosomes, serum liver enzymes and liver cell structures in H. macrolepidota.

Spatial distribution and level of contamination of potentially toxic elements in sediments and soils of a biological reserve wetland, northern Amazon region of Ecuador

This study quantifies the degree of pollution and assess the ecological risk of As, Ba, Cd, Co, Cr, Cu, Mo, Ni, Pb, V and Zn in sediments and soils of the Limoncocha Biological Reserve (Ecuador), identified as a Ramsar site with high ecological and socioeconomic value. The hydrologic system of the Reserve is mainly formed by two rivers that drain into the Limoncocha lagoon, which occupies only five percent of the protected area but support a high anthropic influence. Local statistical baseline of studied potentially toxic elements is established using cumulative frequency method, and Al is selected as reference element due to the good correlation with the studied elements. The grade of pollution and the potential ecological risk are evaluated applying three individual (Contamination Factor, Geo-accumulation Index and Enrichment Factor) and six integrated (Degree and modified degree of contamination, Pollution Load Index, Nemerow and modified Nemerow pollution indexes and potential ecological risk index) indices. Results analysis are based on the combined application of traditional statistics, multivariate data analysis and self organizing maps. Outcomes suggest to classify sediments and soils as “moderate contamination and enrichment” due mainly to the concentrations of Cu (66.4–110 mg/kg) and Cd (0.0262–0.808 mg/kg), derived from domestic wastewaters and agricultural activities, and in a lesser extent due to Mo (0.822–4.37 mg/kg), Ni (10.3–25.8 mg/kg), Co (7.27–24.8 mg/kg) and V (60.3–178 mg/kg), derived from oil field drilling activities. The distributions of As (0.328–8.83 mg/kg), Ba (143–1100 mg/kg), Pb (7.20–26.5 mg/kg), Zn (60.1–276 mg/kg) and Cr (10.1–48.6 mg/kg) are heterogeneous in the studied sampling sites. Sediments located next to the pier and at the central area of the Limoncocha lagoon, show moderate potential risk and according to sediment quality guidelines, the calculated mean Effect Range Median quotient (mERMq) classify the sites as medium-low priority risk level. A three-level classification of a mean quotient based on soil quality and soil potential uses is proposed. Soil sites with high anthropogenic activities show low to moderate potential ecological risk being classified as poor soil quality sites but with all potential soil uses allowed according to the legal limits for land uses in Ecuador.

Mobility and Sequential Extraction of Potentially Toxic Elements in Sediment of Lagos Lagoon

The continuous discharge of metallic waste into the Lagos lagoon in various forms could have adverse impact on the harbor and it’s environ. This work was carried out to determine the distribution, concentration and mobility of potentially toxic elements in sediment of Lagos harbor. The sediments were sampled from six different locations between November 2016 and July 2018, modified sequential Tessier’s procedure was used for the metal extraction. The extracted samples were analyzed by using inductively coupled plasma—optical emission spectroscopy (ICP-OES) technique. The ranges of the mean fractions for all the elements are: 235.54–3075.14 mg/kg for aluminum (Al), 0.16–1.09 mg/kg for cadmium (Cd), 3.83–16.77 mg/kg for chromium (Cr), 2.89–40.50 mg/kg for copper (Cu),1499.52–5900.93 mg/kg for iron (Fe), 2.28–13.49 mg/kg for nickel (Ni), 8.21–23.19 mg/kg for lead (Pb), 1.50–5.49 mg/kg for tin (Sn), and 4.72–24.03 mg/kg for silicon (Si). The distribution of the metals across the four phases followed the decreasing order: metals in organic fraction > metals in reduced form > Exchangeable and carbonate fraction > metals in residue form. The pollution load index revealed that contamination ranged from low to high level. The geochemical assessment carried out with the aid of FTIR and XRD showed that quartz is the major mineral phase across the locations while the results of enrichment factor (EF) revealed that the metals are majorly from non-crustal origin. Furthermore, the risk assessment codes showed that there is tendency for these metals to move from low to high risk which could pose a threat to aquatic environment. Hence, there is need for close monitoring and preventive measures against the discharge of untreated waste.