Metals In Sediments Research Articles

An Assessment of Metal Pollution in the Surface Sediments of an East Antarctic Lake

ABSTRACT This study discusses the metal concentrations and sedimentological data from Lake L55, a dried, land-locked lake from Schirmacher Oasis, East Antarctica. Toxic metals in sediments are a major threat to the environment. Twenty-five surface sediment samples were analyzed for the presence of fifteen metals. The sedimentological data indicates that the sediments are predominantly sandy with low concentrations of silt and clay. The chemical weathering index for the sediments reflects low degree of weathering. Negligible concentrations of organic content were present in the sediments owing to the cold and dry conditions of the study area. The environmental pollution indices indicate elevated concentrations of Ba, Zn, As and Pb in the sediments. Barium could be supplied by the weathering of the quartzofeldspathic catchment rocks, while Zn, As and Pb could be supplied from the fuel burning for power generation and logistical activities, paint residue, and battery waste. The sediment quality guidelines were calculated for the sediments, and they indicate that the sediments have a 21% risk of being toxic. The pollution load index, potential ecological risk index (PERI) and toxic risk index (TRI) values suggest low toxic risk in the sediments of the lake.

Early Diagenetic Processes in the Sediments of the Krka River Estuary

To study the processes that govern the post-depositional mobility of metals in the estuarine sediment, five sediment cores were sampled in the Krka River estuary (Croatia). The obtained concentration ranges in the pore water were 0.057–49.7 μM for Fe, 0.310–100 μM for Mn, 0.068–26.8 nM for Co, 0.126–153 nM for Cu, 11.5–2793 nM for Zn, 0.222–31.3 nM for Pb, 4.09–59.4 nM for U, 38.8–2228 nM for Mo, and 0.065–2.29 nM for As. The vertical distribution of metals in the dissolved and solid fraction of the sediment, coupled with other diagenetic tracers (e.g., dissolved sulphide), demonstrate the importance of early diagenetic reactions, in particular Fe and Mn oxyhydroxide and sulphate reduction, for the cycling of metals in the sediment. The redox zonation in the sediment was compressed, and the suboxic zone occurs immediately below the sediment–water interface. The estimated benthic fluxes in the estuary were 5220 kg y−1 for Fe, 27,100 kg y−1 for Mn, 6.00 kg y−1 for Co, 20.5 kg y−1 for Cu, 5.16 kg y−1 for Pb, 111 kg y−1 for Mo, and 87.3 kg y−1 for As. The riverine input was more important than the benthic flux, except in the case of Mn and Fe.

Spatiotemporal Distribution and Source Analysis of Heavy Metals in Surface Sediments in Lake Ulansuhai Based on PCA-APCS-MLR Model

To explore the spatial and temporal distribution characteristics of heavy metals in the surface sediments of lakes in cold regions during ice-sealing and non-ice-sealing periods, we analyzed the potential ecological risk degree and the pollution sources. A total of 20 sampling sites in Lake Ulansuhai in cold regions were collected from 2020 to 2021, and 120 surface sediment samples were collected during different periods. The contents of As, Cd, Cr, Cu, Ni, Pb, Zn, and Hg were determined. Correlation analysis, principal component analysis, and the absolute factor score-multiple linear regression (APCS-MLR) receptor model were used to trace the source of heavy metal pollution. The results showed that:① the distribution of heavy metals in lake surface sediments was different between the ice-sealing period and the non-ice-sealing period. The distribution of heavy metals during the ice-sealing period was higher in the north and lower in the south. Cd and Hg were mainly distributed in the central and southern lakes during the non-glacial period. ② Hg, Cd, and As were moderately polluted, and Ni was mildly polluted in the surface sediments of the lake. The overall performance was at a high risk level, and the pollution level during the non-ice-sealing period was higher than that during the ice-sealing period. The main environmental risk factors were Hg and Cd, which showed high risk and moderate risk, respectively. ③ The sources of heavy metals in lake surface sediments were mainly industrial sources from mining and transportation, agricultural sources, and natural sources. As, Ni, Pb, and Hg were mainly affected by industrial sources, with contribution rates of 62.67%, 75.31%, 77.47%, and 80.11%, respectively. The main sources of Cu and Zn were natural sources, and Cd was greatly affected by agricultural sources. The contribution rate was 81.57%. The source of Cr was mainly affected by natural factors, and the influence of human activities and unknown sources require further attention.

Contamination level and ecological risk assessment of selected heavy metals in surface water and sediments from Mudi River, Blantyre, Malawi

Contamination level and ecological risk assessment of selected heavy metals in surface water and sediments from Mudi River, Blantyre, Malawi

Bibliometric and visual analysis of heavy metal health risk assessment: development, hotspots and trends

Due to the widespread presence and harmfulness of heavy metals in the environment, scholars around the world have evaluated the exposure characteristics and health risks of heavy metals. To understand the status, hotspots, and development treads of heavy metal health risk assessment research, we used bibliometric analysis tools to conduct scientometric analysis of the literature related to the health risk assessment of heavy metals in the Web of Science database from 2000 to 2022. The analysis results indicate that research related to heavy metal health risk assessment is rapidly developing in both developed and developing countries. China’s significant international influence in this field is worth noting, as there are many publications and highly cited documents related to China. France and other developed countries also play an important role in this field due to their high centrality and strong bursts. The results of co-citation cluster analysis and keyword co-occurrence analysis indicate that in the past two decades, the primary research domains and hotspots of heavy metal health risk assessment have been the study of heavy metals in soil, dust, drinking water, vegetables, fish, and sediment. There is a specific focus on bioaccumulation, bioavailability, source apportionment, and spatial distribution of heavy metals. The main types of heavy metals studied are lead, cadmium, mercury, and zinc. The results of the bursts keywords analysis suggest that future research trends may focus more on the health risks of heavy metals in different functional areas of cities.

Controlling factors and sources-specific ecological risks associated with toxic metals in core sediments from cascade reservoirs in Southwest China

Toxic metals (TMs) in reservoir sediments pose significant risks to ecosystem security and human safety, yet their presence in the cascade reservoirs of the Lancang River remains understudied. This research examined TMs in core sediments from the Manwan (MW) and Dachaoshan (DCS) cascade reservoirs, aiming to elucidate contamination characteristics, controlling factors, and source-specific ecological risks. The study revealed that the concentrations of As, Cd, Cr, Cu, Hg, Ni, and Zn in the MW Reservoir (37.3, 0.54, 95.1, 44.0, 0.09, 44.8, and 135.7 mg/kg) were notably higher compared to the DCS Reservoir (14.6, 0.30, 82.6, 31.0, 0.08, 36.6, and 108.7 mg/kg). While both reservoirs demonstrated elevated contamination levels of Cd and Hg, the MW Reservoir also exhibited high levels of As, whereas the DCS Reservoir showed relatively high levels of Pb. Mining activities in upstream metal deposits significantly correlated Cd, Hg, and Zn in the MW Reservoir with sulfur. In both reservoir sediments, Cr and Ni displayed a greater affinity for iron oxides, while As, Cd, Cu, Hg, and Zn showed more affinity with manganese oxides. Ecological risk index (RI) values in half of the sediments from the MW Reservoir ranged from 300 to 600, denoting a significant ecological risk. Conversely, in the DCS Reservoir, 93.3 % of the sediments exhibited RI values between 150 and 300, signifying a moderate ecological risk. Source-oriented ecological risks highlighted the need for particular attention to Cd from anthropogenic sources in the MW Reservoir. These findings underscore the importance of implementing measures for TM contamination prevention and control, contributing to strategic planning for sustainable water resource management in the Lancang-Mekong River.

Heavy metal distribution and ecological pollution assessments in water bodies and sediments in rural areas of Bangladesh

Pollution in rural waterbodies, sediments, and aquatic species due to long-range transportation and mobilization of heavy and toxic metals contaminants is a growing concern in many developing countries nowadays. Environmental components in rural areas are usually considered as safe and information on metals toxicities in rural natural resources are very limited. Herein, accumulation, mobilization, and distribution of eight different elements (Fe, Ni, Mn, Pb, Cr, Cu, Cd, As) in water bodies and sediments in rural areas of Bangladesh have been investigated successfully. Different metals contents found in water and sediment were compared with standard threshold levels reported by WHO, USEPA, China, and the results revealed the occurrence of pollution in respective environmental resources with the excessive presence of some heavy metals. Pollution characteristics analyses with trace metal pollution index (TPI), heavy metal evaluation index (HEI), contamination index (Cd), and comprehensive pollution index (CPI) indicated that water bodies in rural areas are contaminated with Pb, Mn, Fe, and different metals contents were varied in the order of Fe > Mn > Cu > Pb > Cr > As > Cd > Ni (mg/L). Contamination analyses in sediments with potential ecological risk index (PERI), pollution load index (PLI), metal enrichment (EF), and geo-accumulation index (Igeo) assessments revealed the occurrence of pollution in sediments with Ni, Cr, Cu, and the translocations of different heavy metals in rural sediments were varied in the order Fe > Mn > Cr > Ni > Cu > Cr > Cu > Pb > As > Cd (mg/Kg). PLI data of metals showed higher than one and the magnitudes of Igeo were greater than zero which indicated inordinate accumulation of Ni, Cr, and Cu in sediments. The present research findings offer significant information on how the pollutants from point sources impact the environmental ecosystems in rural areas of Bangladesh due to the long-range pollution with flood and other natural disasters that occur frequently in the region. These results may be useful for making necessary environmental policies in developing countries regarding long-range pollution.

Identification of toxic metal contamination in surface sediments of the Xiaoqing River under a long-term perspective (1996–2020): Risks, sources and driving factors

The contamination of sediments by toxic metals poses a significant threat to both river ecosystems and human health. In this study, the geo-accumulation index (Igeo), biotoxicity evaluation method, and potential ecological risk index (RI) were employed to analyze the contamination level, biotoxicity risk, and potential ecological risk of toxic metals in surface sediments of the Xiaoqing River. To identify toxic metal sources, Spearman correlation and principal component analysis with multiple linear regression analysis (PCA−MLR) were employed. Additionally, redundancy analysis (RDA) was utilized to investigate potential driving factors affecting toxic metal accumulation in sediments. The results revealed that the levels of the five investigated metals (Cr, Pb, As, Hg, and Cd) showed constant fluctuations during the period 1996–2020. The midstream was found to be more polluted than the upstream and downstream. In the research area, Hg was identified as the primary contaminant with high levels of contamination, posing a biotoxicity risk and potential ecological risk. Pollution sources were identified for two periods: A (1996–2010) and B (2011–2020), with industrial, agricultural, traffic, and natural sources being the main contributors. During period A, industrial sources accounted for the highest proportion (40.8%), followed by agricultural sources (36.6%), and geological natural sources (22.6%). During period B, agricultural sources accounted for the highest proportion (42%), followed by industrial and traffic sources (32.4%), and geological natural sources (25.6%). The distribution of toxic metals in the basin was significantly influenced by water pH, sediment organic matter, population density, and per capita GDP. The study results provide fundamental data for preventing pollution and managing water resources contaminated with toxic metals in the sediments of the Xiaoqing River in Jinan. Additionally, it serves as a reference for analyzing related ecological and environmental issues in the basin.

Characteristics of heavy metals in surface sediments of the Van Don-Tra Co coast, northeast Vietnam

Eighteen surface sediment samples were collected from the Van Don-Tra Co coast, northwestern Gulf of Tonkin, for analyzing the concentration of heavy metals (Zn, Cr, As, Cu, Ni, Pb, Co, and Cd) and grain size. The statistical and contamination indices of heavy metals were calculated to evaluate the extent of pollution caused due to heavy metals and their potential harm to the environment. According to the analysis results, the contamination of heavy metals in the study area were higher than the background concentrations, except for Pb. The heavy metal concentrations in the study area followed the descending order of Zn > Cr > As > Cu > Ni > Pb > Co > Cd. The concentrations of heavy metals do not correlate with clay content, and almost heavy metals were non-correlated with silt and sand contents, except for Cr, implying that the grain size does not control heavy metals concentration in surface sediments in the region. The results of pollution indices imply that the contamination in the environment was due to excess accumulation of Cd, in contrast to that of Zn. The ecological pollution risk shows an increased risk of heavy metal pollution. According to the statistical index, the contamination of heavy metals in surface sediments in the study area could come from the same sources under the same environmental conditions and is related to the source of sedimentary material from the mainland near the study area.

Study of heavy metal in sediment of The Klagison River, Sorong City

The Klagison River is one of the rivers located in the North Sorong District to the Sorong Manoi District. The flow of the Klagison River is used by the sand mining industry to dispose of liquid waste products from mining sites. Mining activities are in the middle of the Klagison River so that it can affect the quality of river water and experience a decrease in carrying capacity due to the high level of turbidity in river water caused by sedimentation. The purpose of this research is to provide knowledge about the content of metal elements in sediments by identifying the constituent elements of the Klagison River sediments, Sorong City, West Papua. Determination of the sampling point using the purposive sampling method and the sediment collection tool using the Ekman grab. The method of analyzing the constituent elements of the sediment uses the XRF (X-Ray Fluorescence) method. Based on the research results, there are various types of metal elements contained in the sediments of the Klagison River, namely the elements Al, Si, P, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Rb, Sr, Zr and Re where the dominant concentration of metal elements from 5 observation stations is Fe>Si>K>Cl>Al>Ca. At the 5 observation stations, the element Fe>Si>K>Cl>Al>Ca was the highest compared to the other 4 observation stations. This is because station 5 is the mouth of the Klagison River so that it becomes a place for liquid waste deposits to coalesce.

Risk assessment and strontium isotopic tracing of potentially toxic metals in creek sediments around a uranium mine, China

The contamination of creek sediments near industrially nuclear dominated site presents significant environmental challenges, particularly in identifying and quantifying potentially toxic metal (loid)s (PTMs). This study aims to measure the extent of contamination and apportion related sources for nine PTMs in alpine creek sediments near a typical uranium tailing dam from China, including strontium (Sr), rubidium (Rb), manganese (Mn), lithium (Li), nickel (Ni), copper (Cu), vanadium (V), cadmium (Cd), zinc (Zn), using multivariate statistical approach and Sr isotopic compositions. The results show varying degrees of contamination in the sediments for some PTMs, i.e., Sr (16.1–39.6 mg/kg), Rb (171–675 mg/kg), Mn (224–2520 mg/kg), Li (11.6–78.8 mg/kg), Cd (0.31–1.38 mg/kg), and Zn (37.1–176 mg/kg). Multivariate statistical analyses indicate that Sr, Rb, Li, and Mn originated from the uranium tailing dam, while Cd and Zn were associated with abandoned agricultural activities, and Ni, Cu, and V were primarily linked to natural bedrock weathering. The Sr isotope fingerprint technique further suggests that 48.22–73.84% of Sr and associated PTMs in the sediments potentially derived from the uranium tailing dam. The combined use of multivariate statistical analysis and Sr isotopic fingerprint technique in alpine creek sediments enables more reliable insights into PTMs-induced pollution scenarios. The findings also offer unique perspectives for understanding and managing aqueous environments impacted by nuclear activities.

Univariate and Multivariate Analyses of Metals in Water, Sediment, and Shrimp (Penaeus aztecus) from a Fishing Zone in Laguna Madre, Mexico

Univariate and Multivariate Analyses of Metals in Water, Sediment, and Shrimp (Penaeus aztecus) from a Fishing Zone in Laguna Madre, Mexico

The predictive model of hydrobiological diversity in the Asana-Tumilaca basin, Peru based on water physicochemical parameters and sediment metal content

The hydrobiological diversity in the basin depends on biotic and abiotic factors. A predictive model of hydrobiological diversity for periphyton and macrobenthos was developed through multiple linear regression analysis (MLRA) based on the physicochemical parameters of water (PPW) and metal content in sediments (MCS) from eight monitoring stations in the Asana-Tumilaca Basin during the dry and wet seasons. The electrical conductivity presented values between 47.9 and 3617 μS/cm, showing the highest value in the Capillune River due to the influence of geothermal waters. According to Piper's diagram, the water in the basin had a composition of calcium sulfate and calcium bicarbonate-sulfate. According to the Wilcox diagram, the water was found to be between good and very good quality, except for in the Capillune River. The Shannon–Wiener diversity indices (H′) were 2.62 and 2.88 for periphyton, and 2.10 and 2.44 for macrobenthos, indicating moderate diversity; for the Pielou's evenness index (J′), they were 0.68 and 0.70 for periphyton, and 0.68 and 0.59 for macrobenthos, indicating similar equity, in the dry and wet seasons, respectively, for both indices. In the model there were three cases, where the first two cases only worked with PPW or MCS, and case 3 worked with PPW and MCS. For case 3, the predicted values for H′ and J′ of periphyton and macrobenthos concerning those observed presented correlation coefficients of 0.7437 and 0.6523 for periphyton and 0.9321 and 0.8570 for macrobenthos, respectively, which were better than those of cases 1 and 2. In addition, principal component analysis revealed that the As, Pb, and Zn contents in the sediments negatively influenced the diversity, uniformity, and richness of the macrobenthos. In contrast, Cu and Cr had positive impacts because of the adaptation processes.

Content of heavy metals in bottom sediments of drained Kakhovka Reservoir

The article highlights the ecological danger of the destruction of the Kakhovka HPP dam and the draining of the Kakhovka Reservoir. The results of experimental studies of the content of mobile compounds and gross forms of heavy metals in five samples of bottom sediments taken from the bottom of drained reservoirs taken on the territory of the Kushugum community of the Zaporizhia district of the Zaporizhia region. Two samples were taken from the bottom of the former flood zone (Balabyne village), 2 samples — from the bottom of the former limestone quarry, which was connected to the floodplain of the Dnipro (Kushugum village) and 1 sample taken from the open area of the Kakhovka Reservoir (Malokaterynivka village). Based on the results of the research, it was established that the maximum permissible limit (for soil) of mobile compounds of lead (from 2.0 to 4.1 times), zinc (from 2.4 to 5.4 times), cadmium (from 1.9 to 2.5 times) was exceeded. and nickel (from 1.04 to 2.2 times) in all investigated bottom sediment samples. Exceeding the MPC (soil) for the content of gross forms of lead was found in five bottom sediment samples (from 1.1 to 1.5 times). Exceedings of the MPC of the soil by the content of gross forms of cadmium and manganese and mobile compounds of copper, nickel, cobalt and manganese were not detected. The maximum limit for the content of mobile compounds of iron and gross forms of zinc, copper, nickel, cobalt and iron is not regulated. The highest degree of contamination of bottom sediments by the content of: mobile compounds and gross forms of lead and nickel was found in samples taken from the bottom of a former limestone quarry (Kushugum village, Zaporizhzhia region); zinc — in a sample taken from the bottom of the former flood zone in the territory of the town of Balabyne and a sample taken from the open area of the Kakhovka Reservoir in the territory of the town of Malokaterynivka; cadmium — in the samples taken from the bottom of the former limestone quarry in the territory of the town of Balabyne and the sample taken from the open area of the Kakhovka Reservoir in the territory of the town of Malokaterynivka. According to the results of the correlation analysis, an extremely strong dependence was established between the content of mobile compounds of heavy metals and their gross forms — for cobalt (r=0.96), cadmium (r=0.92), nickel (r=0.91), lead (r=0.88) and zinc (r=0.84).

Elemental geochemical evidence for the river-derived sources of trace metals in surface sediments from Hangzhou Bay, East China Sea

Coastal estuaries are often heavily subject to riverine influences by the inputs of sediment from terrestrial sources. Hangzhou Bay (HZB) is threatened by the riverine derived trace metals from two large rivers of Qiantang River (QTR) and Yangtze River (YZR). However, previous studies mainly focused on the incidental transport from the largest river in China (YZR) and failed to simultaneously evaluate the contributions of these two rivers, especially the directly flowing river of QTR, by their trace elemental geochemical composition and distribution. Herein, a comprehensive study identified the river-derived sources of multiple trace metals in surface sediments which transported from both of the rivers. The sampling stations were separated into three regions of YZR, HZB, and QTR based on their spatial distributions of sediment grain size and components. The significant variations for most of the trace metals concentrations, except for Cd, Th, and U, were found among three regions (χ2 ≥ 8.22, p ≤ 0.016). The highest concentrations in HZB were mainly resulted from the grain size effect (68.82% of the total variance), while the highest concentrations of Sr, Cd, and Ba in YZR and Zr and Hf in QTR were attributed to the anthropogenic source (11.90%) and mineral composition (6.21%) of river basins. After normalized the diversity of multiple trace metals concentrations and the influence of grain size by ratios of Igeo and EFLi, three regions were effectively distinguished. It was indicated that As, Cd, and Sb were enriched in the sediments of rivers by anthropogenic source (EFLi > 1.5 and/or Igeo > 1). The results evidenced that, after removing the influence of grain size, elemental geochemical composition of the surface sediments confidently identified the river-derived anthropogenic sources of the enriched trace metals from two major rivers, and largely from YZR.

Risk Assessment and Distribution of Heavy Metals in Water and Sediments along Ibelebiri Axis of Kolo Creek, Ogbia Local Government Area, Niger Delta Region of Nigeria

Pollution arising from uncontrollable combustion processes, including artisanal refineries are common in communities through which Kolo Creek traverses. Previous studies have centered on the effect of oil and gas production on Kolo Creek at shell flow station at Imiringi. Therefore, the aim of this study is to investigate the risk and distribution of heavy metals (Zn, Ni, Cr, Cu, Pb, Co, and Cd) in water and sediments along Ibelebiri axis of Kolo creek in Ogbia L.G.A., Niger Delta region of Nigeria. Water and sediment samples were collected at locations upstream, within and downstream at Ibelebiri community, and also from a control site. Generally, heavy metal concentrations showed a decreasing trend of Cu˃Zn˃Pb˃Cr˃Cd˃Co˃Ni for water samples. The mean concentration of these metals: Ni, Cr, Zn and Cu recorded in this study was below international recommended limits. But, Pb, Cd levels in locations LC1, LC3 and LC4 are above the international recommended limits. The heavy metals in the sediments showed a decreasing trend of Zn˃Pb˃Cu˃Co˃Cr˃Ni˃Cd. The concentrations of these metals Cd, Pb, Ni, Cr, Cu and Zn are below the permissible limit set by Department of Petroleum Resources (DPR). However, Co values at locations LC3 and LC4 are slightly above the DPR target value of 20 mg/kg for sediments. Using the geoaccumulation index (Igeo) classification, the sediments across the four locations are uncontaminated with Cd, Cr, Cu, Zn, Co and Ni. But, the sediments in locations LC1, LC3 and LC4 are moderately contaminated with Pb. Similarly, the contamination factor (CF) classification, revealed low contamination of Cd, Cr, Cu, Zn, Ni and Co across the four locations; moderate contamination of Pb in the four locations. Finally, principal component analysis (PCA) identified two major factors.

Metal contamination, their ecological risk, and relationship with other variables in surface sediments of urban rivers in a big city in Asia: case study of Hanoi, Vietnam.

Urban rivers are significantly impacted by anthropogenic pressure. This study presents the updated assessment of the concentrations of 11 metals and other variables (pH, total organic carbon (TOC) and nutrients (total nitrogen, total phosphorus, and total silica)) in the sediments of four urban rivers in inner Hanoi city, Vietnam, during the period 2020-2022. The mean concentrations of Fe, Zn, As, and Cr were higher than the permissible values of the Vietnam National technical regulation on the surface sediment quality. Moreover, Zn and Cr were at the severe effect level of the US EPA guidelines for sediment quality. The calculation of pollution indices (Igeo and EF) demonstrated that Mn, Ni, and Fe were from natural sources whereas other metals were from both anthropogenic and natural sources. The ecological risk index revealed that metals in Hanoi riverine sediments were classified at considerable ecological risk. High values of metals, TOC, and nutrients in the sediments of these urban rivers mostly originate from the accumulation of untreated urban wastewater that is enhanced by low river discharge. Our results may provide scientific base for better management decisions to ensure environmental protection and sustainable development of Hanoi city.

The variations of heavy metals sources varied their aggregated concentration and health risk in sediments of karst rivers – A case study in Liujiang River Basin, Southwest China

The sources and health risk variation of heavy metals (HMs) in sediments of Liujiang River Basin were investigated seasonally to clear the control of HMs contamination in karst rivers. The results revealed the exogenous input of HMs should be more prominent in wet season, due to the higher concentration and EF values. PMF identified HMs were mainly from natural, mining and industrial sources. The input of exogenous HMs were influenced by mining and industrial sources in wet season, but primarily by industrial sources in dry season. HI values were overall below 1, suggesting the relatively low non-carcinogenic risk. The TCR values of HMs were generally beyond 10−6, particularly those of As and Cr even exceeded 10−4 for children, which expressed a high carcinogenic risk. The sources components of As and Cr suggested preventing the migration of mining contaminants and limiting industrial emission should be essential to Liujiang River Basin.

Spatial Distribution, Ecological Risk Assessment, and Source Identification of Metals in Sediments of the Krka River Estuary (Croatia)

To evaluate the level of contamination and predict the potential toxicity risk, selected metal concentrations (Cd, Pb, Cr, Mn, Co, Ni, Cu, Zn, and As) were determined in 40 surface sediment samples from the stratified karstic Krka River estuary (Croatia). In addition, diffusive gradients in thin films (DGT) probes were deployed in situ to understand the mobilization mechanisms and bioavailability of metals in the sediment. The results show significant spatial differences between the upper and lower estuary, with the latter being more affected by anthropogenic pollution. The pollution assessment using the enrichment factor (EF), the geoaccumulation index (Igeo), and the pollution load index (PLI) showed a strong enrichment of metals in the lower part of the estuary, especially of Mn, Cu, Zn, Pb, and As. The statistical analysis (PCA) revealed the former ferromanganese factory and the port as major sources of pollution in the area. Nickel, Co, and Cr, although slightly elevated, may be attributed to the natural origin. The metal mobility in the estuarine sediment was primarily governed by early diagenetic processes (aerobic organic matter mineralization, Fe and Mn oxyhydroxide reduction), which caused the release of metals from the sediment into the pore water and subsequently into the overlying water column.

Insights on trace metal enrichments in tourists beaches of Santa Elena Province, Ecuador

Metal concentrations in beaches of major coastal cities is directly identified based on the enrichment pattern of bioavailable metals in sediments. The main objective of the study is to know the present level of metal enrichments in beach sediments of Santa Elena Province in Ecuador. Sediment beach quality was assessed in five tourist beach zones (n = 52) by analyzing the bioavailable trace metal concentration. Distribution pattern of trace metals indicates Cd, Co, Pb is on higher side exceeding the UCC. Geochemical indices calculations (Geoaccumulation index, Enrichment factor, Degree of contamination) and ecological risk indices (Hazard quotient, potential risk index, pollution load index) indicates that Cd has the high degree of enrichment level (Cd ≥ 32) followed by Co, Pb and As posing adverse ecological risk (RI > 600). Sediment quality assessment results reveals that the sediments were very unsafe in nature with a probability level of 11–21% being toxic. Statistical correlation suggests that carbonates vs Cu, Ni, Co, Pb, Cd (r2 = 0.51–0.98) were the main controlling factor for the metal behavior in sediments. Overall results reveals that the toxic elements were derived locally accompanied by anthropogenic influences enriching the geochemical elements affecting the beach quality in the Santa Elena coast region and for future coastal management programs.