Heavy metal pollution in surface water and sediment: A preliminary assessment of an urban river in a developing country

The pollution of river water and sediments by heavy metals has assumed serious problems due to their toxicity and accumulative behavior. The present study has been undertaken to assess the levels of heavy metals and the extent of pollution in the surface water and sediments from the Meghna river. Water and sediment samples were collected by the Standard Methods and, processed and analyzed for heavy metals using Flame Atomic Absorption Spectrophotometer (FAAS). The mean concentrations of heavy metal found in the river water were in the order of: Fe (1.0224 mg L-1) > Zn (0.0364 mg L-1) > Cr (0.0346 mg L-1) > Mn (0.0088 mg L-1) > Cd (0.003 mg L-1) and in the sediments in the order of: Fe (1281.416 mg kg-1) > Mn (442.596 mg kg-1) > Zn (79.021 mg kg-1) > Ni (76.116 mg kg-1) > Cr (31.739 mg kg-1) > Pb (9.4702 mg kg-1) > Cd (0.230 mg kg-1). Pb and Ni were found below detection limit in river water. Based on the findings, the Meghna river water can be considered as unpolluted with respect to Cd, Cr, Mn and Zn, whereas concentration of Fe was above the standard value according to recommended standard guidelines. According to Sediment Quality Guideline (USEPA, 1989), sediments were not polluted for Cd, Pb and Zn; moderately polluted for Cr and Mn and heavily polluted for Ni. The sediment geo-accumulation index (Igeo) values showed no pollution for most of sampling sites for all studied heavy metals. Pollution Load Index (PLI) values showed that all the studied sampling sites were not polluted and on the other hand mean Contamination Factor (CF) values showed low pollution for all measured heavy metals except Ni which indicated moderate pollution. This study can be used as reference to monitor the quality of water and sediments of the Meghna river.

The research was carried out to determine the extent of surface water and sediment pollution using the physicochemical parameters and heavy metal concentrations. The surface water and sediment samples were obtained from 25 sites along the river on March 22 and September 5, 2019 at the main river influenced by the complex tidal regime and aquaculture practices in Ca Mau peninsular in the Vietnamese Mekong Delta. The water quality was compared with international and national standards, while the sediment quality was compared with Vietnamese standards and pollution indices (geo-accumulation index, contamination factor, and pollution load index). Principal component analysis (PCA) was employed to explain the main factors responsible for the observed levels of water pollution. The dependence of water quality parameters and variations in water quality due to tidal regimes and seasonality were also evaluated by statistical comparisons. Based on the logistic regression models, the temporal variability of selected water quality parameters was visualized using QGIS. The Delft 3D model was used to evaluate changes in hydraulic characteristics based on actual fieldwork. The concentrations of nutrients and organic compounds exceeded 2-3 times greater than the standard for surface water quality. The contents of heavy metals were below the standard for sediment quality and consistent with the background levels. The influence of the tidal regime and seasonality caused significant changes in water quality and its association with various flow regimes (P<0.05). Three components based on the PCA accounted for approx. 79.84% of the total variance in water quality characteristics of which the first, second, third component explained for 53.64%, 18.43%, and 7.77% of total variance related to physicochemical properties and organic matter pollution, suspended solids and nutrients, and DO consumption, respectively. Water quality maps indicated pollution hotspots, and the extensive and improved – extensive shrimp culture practices were identified in connection to the changes in water quality. Changes in the river's hydraulic characteristics were influenced remarkably by the tidal regime as well as geomorphological changes. The results of the research addressed the gaps from the previous studies were to identify degradation of surface water quality was associated primarily with extensive and improved extensive shrimp culture. Seasonal factors and tidal regimes influenced significantly changes in water quality parameters. Pollution sources were specified by the principal component analysis. Spatiotemporal distribution maps of selected water quality parameters highlighted pollution hotspot. Changes in the river hydraulic characteristics were caused mainly by the tidal regimes as well as geomorphological changes. The selected water quality parameters responded as well as depended diversely to various flow regimes. The results could be useful not only to local policymakers in developing water management strategies but also to other rivers beyond the geographical regions.
 
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Water and sediment samples have been collected from five different stations, located along Djendjen River between February and June, 2016 so that the concentrations of Cd, Ni, Zn, and Cu could be determined. The extent of the sediment pollution has been assessed, using the multiple pollution indices, namely Contamination Factor (CF), Pollution Load Index (PLI), and the geoaccumulation index (Igeo).The distribution of trace elements in water and sediment follows Ni>Zn>Cd>Cu and Zn>Ni>Cu>Cd, respectively. The water sample analysis from Djendjen River shows that the total concentrations of Cu, Ni, Cd, and Zn have been lower according to the references. In comparison, sediment mean metal concentrations with several environmental contamination parameters, like probable effect level (PEC) and background levels, indicates that the concentrations of all investigated elements are lesser than PEC, except for Ni, but higher than the background levels. The Igeo values reveal that Cd has been the most accumulated compared to the other metals. Contamination Factor (CF) confirms that the sediment samples have been moderate in terms of all studied metals contamination. The Pollution Load Index (PLI) values have been above one (>1), indicating an advanced decline of the sediment quality.

The objective of the study was to evaluate the role of brick kilns in contaminating water bodies with heavy metals in Punjab, India. The energy-dispersive x-ray spectroscopy (EDS/EDX) machine effectively tested heavy metals in water samples. The research revealed that the surface water near the brick kilns was extensively polluted with heavy metals. Their Pollution Load Index (PLI) values varied between 2.83 and 52.98, and their degree of contamination was “Progressive deterioration”. The PLI values for groundwater ranged between 0.089 and 3.68, and the degree of contamination varied from “Baseline levels of pollutants” to “Progressive deterioration”. In general, the groundwater of the studied area had a PLI value of 0.477 (Baseline levels of pollutants), whereas the surface water had a PLI value of 11.453 (Progressive deterioration). The Water Quality Index (WQI) of groundwater was highly influenced by heavy metals, notably Arsenic (As) from lithologic origins, and Lead (Pb) from the burning of fuels in the brick kilns. In descending order, Pb>Zn>As>Cr>Ni metals were influencing the PLI, and the correlation matrixes demonstrated that the presence of heavy metals was associated with the PLI and WQI values. Therefore, there is evidence that brick kilns are polluting water bodies with heavy metals. EDS proved to be one of the instruments to evaluate the chemical elements in water. It was recommended to enforce the law governing the use of biomass to reduce vast quantities of coal used in baking bricks.

It is a well–known fact that heavy metal pollution in sediments causes serious problems not only in the Danube basin, but also in the large and small adjacent river streams. A suitable method for assessing the level of heavy metals and their toxicity in sediments is the calculation of pollution indices. The present research aims to assess heavy metal pollution in the Lower Danube surface sediments collected along the Danube course (between 180 and 60 km) up to the point where the Danube River flows into the Danube Delta Biosphere Reserve (a United Nations Educational, Scientific and Cultural Organization—UNESCO, protected area). In addition, this monitored area is one of the largest European hydrographic basins. Five heavy metals (Cd, Ni, Zn, Pb, Cu) were analyzed in two different seasons, i.e., the autumn of 2018 and the spring of 2019, using the Inductively Coupled Plasma Mass Spectrometry (ICP– MS) technique. Our assessment of heavy metal pollution revealed two correlated aspects: 1. a determination of the potential risks of heavy metals in sediments by calculating the Potential Ecological Risk Index (RI), and 2. an evaluation of the influence of anthropogenic activities on the level of heavy metal contamination in the surface sediments, using three specific pollution indices, namely, the Geo–Accumulation Index (Igeo), the Contamination Factor (CF), and the Pollution Load Index (PLI). The results of this pioneering research activity in the region highlighted the presence of moderate metal (Ni and Cd) pollution and a low potential ecological risk for the aquatic environment.

Anthropogenic activities have significantly contributed to soil and sediment pollution. Heavy metals are among the most common soil/sediment pollutants, owing to the fact that they easily get adsorbed on sediment surfaces and get carried from one ecosystem to another. This study examines the pollution effect of heavy metals in sediments from River Ndambuk, Busia County, Kenya. A total of eight heavy metals (Co, Cu, Fe, Cr, Ni, Cd, Pb and Zn) were examined during dry and wet seasons. The levels of Cd, Ni and Pb were above the World Health Organization (WHO) recommended limits for heavy metals in sediments. However, Pb levels were only above the WHO limit during the dry season, with the wet season registering concentrations way below WHO limits. Co, Cu, Fe, Cr and Zn recorded concentrations below WHO limits during the dry and wet seasons. Pollution indices were used to determine the extent of sediment pollution. Geoaccumulation index, pollution load index, contamination factor and enrichment factor were calculated from the heavy metal concentrations in sediments. Fe, Cr and Zn recorded negative I geo values during both seasons, signifying no pollution by these metals. Ni recorded moderately polluted to strongly polluted status whereas Pb recorded strongly polluted status only during the dry season. Points 1 – 4 recorded lack of pollution due to anthropogenic activities, while points 5 – 7 recorded pollution due to anthropogenic activities as per the PLI values. The study recommends proper land use and dumping of wastes and controlled mining activities to keep soil pollution at bay. Pollution by heavy metals can be controlled by embracing circular economy, which advocates for the reuse and reduction of waste to a minimum. Waste reduction will go a long way in reducing water and sediment pollution as the volume of pollutants discharged into water bodies will significantly reduce. The other principles of circular economy that will aid in mitigating water and sediment pollution include: regeneration of reagents, close water loops, integration of materials and waste flows, safe disposal of harmful elements, use of benign chemicals (which are less harmful to the environment) and reduction of chemical diversity.

In the environment, heavy metal contamination is a well known problem due to its persistence and toxicity. Heavy metal pollution has significantly affected soil properties and functions, resulting in significantly increased land degradation as a result of anthropogenic interventions that include mining and various industrial and agriculture activities. While heavy metals pollution in soil have been studied very rarely in this District, this paper explores the current status of agricultural soil pollution by heavy metals in Raebareli. This study identifies heavy metals as well as their quantities in the soil and their spatial distribution; our study employed various pollutant indices and geographical information system (GIS) techniques. This research work evaluated the physiochemical properties, the pollution load index (PLI), contamination factor (CF) and the degree of contamination and geoaccumulation (Igeo) in sodic soils of the Raebareli District, Uttar Pradesh, India. Uchahaar site (US) has the most polluted soil, while the Bacharawa site (BS) has the least contaminated soil. The soil quality has degraded due to anthropogenic interventions at most sites. There is slight to moderate contamination by heavy metals at all sites. The Igeo values in subSites US1, US2 and US3 included high levels of Cu, Zn, Pb, Mn and Sr. SubSites BS2 and BS3 have high Sr levels and US1 has a high As level all these Subsites have high anthropogenic influences. The PLI values indicate that most of the study subSites come under a slightly polluted class, except US1 where the PLl was > 3 indicating severe heavy metal pollution at this site. All the pollution indices have then been utilized for building maps using the IDW method of interpolation. The spatial projection of PLI and ecological risk index (Er) values suggest that the northern part of Raebareli has a high pollution load and ecological risk in terms of heavy metal pollution. This study provide valuable information that policymakers could use to develop an appropriate plan to control pollution within the agricultural sector.

The Dhaleswari river is considered as one of the most important rivers of Bangladesh due to its geographical location and ecological services. The present study attempts to evaluate the degree of heavy metal pollution, contamination, and accumulative behavior in the sediment of the Dhaleswari river. The sediment samples were collected from fifteen different locations of the Dhaleswari river. Heavy metals were analyzed using the Flame Atomic Spectrophotometer (FAAS). The mean concentrations of Zn, Cu, Cr, Pb and Cd were 131.9, 48.89, 43.16, 33.23 and 0.37 mgkg-1, respectively. According to the United States Environmental Protection Agency (USEPA) Sediment Quality Guideline, the sediment of most of the locations were not polluted for Pb and Cd. But S-11 location for Cd (0.8 mg kg-1) was highly polluted. For Cr, Cu and Zn, maximum locations were moderately polluted. Although the geo-accumulation index (Igeo) values of Dhaleswari river sediments showed almost no severe contamination for most of the sampling locations, the pollution load index (PLI) values showed that most of the sampling sites were contaminated for all heavy metals tested. Moreover, for all measured heavy metals, the mean Contamination Factor (CF) values indicated moderate pollution, except for Cr, which suggested low pollution. The Pearson’s correlation coefficient matrix among the selected heavy metals of Dhaleswari river sediment showed no significant correlation among each other. Therefore, regular monitoring of the heavy metal concentration of the Dhaleshwari river sediment from different location is necessary to identify the sources of pollution so that proper initiative could be taken to prevent heavy metal pollution.

The unscientific disposal of waste is a main source of soil pollution. In order to mitigate heavy metal exposure strategies, the main purpose of the present study was to provide background data to understand the effect of municipal solid waste dumping on topsoil and the health risk assessment of soil heavy metals. Health risk assessment provides information for the reduction of environmental pollution and for reducing its effects. Soil samples were taken at three sampling points (10, 20 and 30 m) away from the dumping waste at depths of 15, 30 and 45cm. Heavy metals, including Cu, Pb, Zn, Ni and Cd, were analysed using standard methods. The level of contamination of heavy metals in a dumpsite soil was assessed by contamination indices, including contamination factor (CF), degree of contamination (CD), pollution load index (PLI) and geo-accumulation index (I-geo). The health risks via the three pathways were detected. The carcinogenic and non-carcinogenic health risks and lifetime cancer risk were evaluated based on inhalation, ingestion, and dermal routes of exposure to metals. CF showed low environmental risk potential as CF values were less than one (CF < 1) Geo-accumulation index (1-geo) presents uncontaminated to moderately contaminated as I-geo values less than one (I - geo < 1). The degree of contamination was low with the CD values ranging within Cd < 5. PLI of this study suggests that there was no heavy metal pollution risk with PLI values less than one (PLI < 1). The order of overall contamination at the three sampling depths for CD was 15 > 30 > 45cm while that of the PLI was still 15 > 30 > 45cm. No major risk was contributed for adults and children in the dumping site as the risk index (HI), which is the summation of hazard quotients of individual metals, posed no harmful effect to both adults and children's health as HI < 1. Overall, LCR for adults was in the range of 1 × 10-7 – 10-8, whereas LCR for children was in the range 1 × 10 – 10-8, which is regarded as negligible for the three pathways via ingestion, inhalation and dermal contact.

Heavy-metal pollution of surface water, sediment and fish have been seen as a major global problem, with a significant proportion of developing countries like Bangladesh. This study assessed the intensity of alarming six toxic substances (Cr, Zn, Fe, Cu, Pb and Ni) throughout the River water, sediments as well as soft tissues of three widely consumed fishes (Heteropneustes fossilis, Channa punctatus and Channa striata) obtained from two urban streams of the Buriganga and Turag in the Dhaka metropolitan. For evaluating the comparative seasonal variation of heavy-metal concentration, water and sediment samples were collected from five selected sites for two different seasons (viz. 10 from winter seasons and 10 from summer seasons). Finally, a total of 20 water samples, 20 sediment and 12 fish samples were investigated by flame atomic absorption spectroscopy (FAAS) and graphite furnace atomic absorption spectrometer (GFAAS) corrected with the Zeeman effect background correction system. The hierarchy of mean concentration of selected heavy metals in Buriganga water is found to be Fe > Cr > Ni > Zn > Cu > Pb in the winter season whereas during the summer season the order is Fe > Cr > Zn > Ni > Cu > Pb. For the River Turag, the order is Fe > Zn > Cu > Ni > Cr > Pb and Fe > Zn > Ni > Cu > Cr > Pb during winter and summer season, respectively. The level of metals studied surpassed the acceptable level of drinkable water, implying the ineptitude of drinking and cooking water from these Rivers. However, this hierarchy of heavy metals for sediments of Buriganga River changed to Fe > Cr > Ni > Zn > Cu > Pb for the winter season and Fe > Cr > Ni > Cu > Zn > Pb for the summer season. Whereas, for the Turag River, the decreasing trend of metal concentration found in sediment was Fe > Zn > Cr > Ni > Cu > Pb for both seasons. For probable human health hazard implications, contamination factor (CF) and pollution load index (PLI) were studied. The CF values revealed the low-to-moderate pollution of sediment. The PLI value above one shows the degradation of the consistency of the sediments. Fe, Ni, Pb, Cr, Zn and Cu concentrations in fish species were found to be 19.66–45.1, 0.07–12.18, 1.2–10.18, 20.18–187.07, 11.08–68.25, 2.07–10.4 mg/kg, respectively. The metals studied differed considerably among organisms and seasons. Bioconcentration factor (BCF), the daily average consumption of metal (EDI), as well as target threat quotients (THQs) for specific metal indicated that Cr and Pb are harmful in fish muscles and possible risks remain for fish consumers. The obtained concentrations of some metals are higher than the WHO/FAO’s permissible limit, suggesting that the water and fish found in these Rivers are like to be harmful to the human being. This study shows that attention should be given to the risk assessment for heavy metals in these Rivers.

Heavy metals (HMs) in dust act as potential indicators of air pollution and pose significant risks to both human health and the environment. This study investigates the concentrations and pollution characteristics of six heavy metals (Cd, Cr, Cu, Ni, Pb, and Zn) in rooftop dust collected from three types of concrete buildings of varying heights: low-rise buildings (LRB), medium-rise buildings (MRB), and high-rise buildings (HRB) in the Kathmandu metropolitan area. A total of 36 dust samples were collected from the buildings during the dry season (March–April 2024) and analyzed for HMs content using flame atomic absorption spectrophotometry (FAAS). Pollution assessment was conducted using four indices: contamination factor (Cf), degree of contamination (Cdeg), pollution load index (PLI), and geo-accumulation index (Igeo). Results indicated that the mean HM concentrations were highest in dust from low-rise buildings, with all measured values exceeding background levels. The overall abundance of metals (mg/kg) in rooftop dust followed the order: Zn (372.0) > Cu (85.9) > Cr (69.3) > Ni (65.8) > Pb (56.2) > Cd (0.65). Pollution assessment using the contamination factor (Cf) and degree of contamination (Cdeg) revealed values ranging from 0.42 to 5.06 and 7.83 to 15.72, respectively, indicating low to considerable and considerable levels of contamination across all building types, with zinc (Zn) identified as the predominant pollutant. Pollution load index (PLI) values greater than 1.0 in this study confirmed that rooftop dust was polluted in all cases. Meanwhile, geo-accumulation index (Igeo) values ranging from 0.11 to 1.03 indicated a contamination level from unpolluted to moderately polluted. These findings suggest that vehicular emissions, industrial activities, construction and demolition, and other anthropogenic sources are the primary contributors to rooftop dust contamination in the metropolitan area.

The study aimed to determine eight hazardous heavy metals in surface water and sediment samples collected from the Naf River, Shah Porir Dwip (estuary), and mostly around Saint Martin's Island in the Bay of Bengal. The results of heavy metals in water samples were ranged as Pb 14.7-313.0, Cd 33.0-70.0, Cr < 11.0-37.0, Cu 38.0-57.0, Zn 26.8-69.2, Ni 102.0-285.0, and Hg 0.3-1.6μgL-1. The concentrations of metals in sediment samples were ranged as Pb < 10.0-37.5, Cd 0.2-1.0, Cr < 5.0-30.1, Cu < 3.0-30.9, Zn 24.1-88.0, Ni < 4.0-48.3, As 0.1-7.3, and Hg < 0.01-0.08mgkg-1 dw. Ni and Cr were strongly correlated, suggesting that this pair of metals might diffuse from a common origin. The contamination factor (Cif) demonstrated that sediment samples were mostly contaminated by Cd and slightly contaminated by Pb and Zn. The geoaccumulation index (Igeo) revealed considerable values for Cd on Saint Martin's Island. Cd as a single regulator posed moderate to considerable risk frequently among the sampling stations. Pollution load index (PLI) values remained below 1 (< 1), which indicated a decrease from baseline pollution value among all stations. However, potential ecological risk (PER) was graded for two stations (St1 and St13) with a moderate-risk zone due to the Cd contribution. However, shipping emission and lithogenic sources were the most predominant for heavy metals in the sediment, which were determined by applying the principal component analysis-absolute principal component score (PCA-APCS). Graphical abstract.

This study presents a review of available data on heavy metal contents in sediments collected along the Montenegrin coast, starting from 2005 to recent years. The aim was to evaluate the pollution level of Montenegrin coastal sediments by determining the concentrations of heavy metals (Fe, Mn, Zn, Cu, Ni, Pb, Cr, Cd, As, and Hg). The pollution status was evaluated using the contamination factor, pollution load index, and geo-accumulation index, as well as the statistical methods, such as cluster analysis (CA). This study showed that concentrations of individual metals at some locations were extremely high. Mean metal concentrations (mg/kg) in sediment samples during whole investigated period were in the following order: Fe > Mn > Zn > Cr > Ni > Pb > Cu > As > Hg > Cd. The calculated contamination factor and pollution load index values indicated enrichment by either natural processes or anthropogenic influences. According to contamination factor (CF), the contents of Zn, Pb, Ni, Cr, and Hg are responsible for very high contamination. Extreme Igeo values were found for Zn, Cu, Pb, and Cd (strongly or strongly to extremely polluted) for the sediment samples from the location Port of Bar in 2011. Also, the location Ada Bojana was characterized as strongly to extremely polluted with Ni in 2019, and Porto Montenegro was extremely polluted with Hg during 2016 and 2019 with the Igeo values of 6.18 and 6.28, respectively. Locations with the highest PLI values in surface sediments were Porto Montenegro (2018–2019) and Port of Bar (2011, 2014). Cluster analysis grouped the examined metals into two main clusters, indicating possible similar origins of the elements within the same cluster.

Distribution, source identification, and contamination level of trace metals in the sediment of the Shari-Goyain River in Bangladesh: Implications for ecological health risks

Ecological risk assessment of heavy metals in sediments and water from the coastal areas of the Bohai Sea and the Yellow Sea