Ecological risk assessment of heavy metals sampled in sediments and water of the Houjing River, Taiwan

The coastal waters of Palu Bay are vulnerable to pollution from various activities of the surrounding population. This study aimed to determine the content of heavy metals Pb, Cd, and Cu in the water and sediment of the coastal waters of Palu Bay. The analysis of heavy metal content (Pb, Cd, and Cu) in water and sediment was conducted using an Atomic Absorption Spectrophotometer (AAS). Based on the research, the results showed that the heavy metal content in the water ranged from undetected to 0.04 mg/L for Pb, undetected for Cd and Cu. The heavy metals content in the sediment ranged from 2.17 to 13.8 mg/kg for Pb, undetected to 0.17 mg/kg for Cd, and 5.02 to 37.67 mg/kg for Cu. The Pb content in the water has significantly exceeded the quality standard as stipulated in the Minister of Environment Decree No. 51 of 2004. The Pb content in the sediment is still within safe limits according to Canadian quality standards. The Cd content in the sediment exceeded the quality standard at station 6, while for the other 9 stations, it was not detected. The Cu content in the sediment at 5 stations (2, 3, 4, 5, and 10) has exceeded the Canadian quality standard of 18.7 mg/kg.

The heavy metal concentration in water and sediment, Choba segment of New Calabar River, Port Harcourt was investigated between February and April, 2020. Samples collected from the three locations were analysed in the laboratory for heavy metals using Atomic Absorption Spectrophotometer (AAS) following standard method of APHA. The mean values of heavy metal in water (mg/l) were: Cr (2.29±1.29), Ni (2.32±0.28), Pb (2.46±0.38), Cd (0.04±0.02), Fe (52.18±7.26) while that of sediment were: Cr (7.18±0.43), Ni (5.57±0.29), Pb (8.09±0.39), Cd(0.30±0.15), Fe (123.64±5.17). The heavy metal values showed variations across the stations at P<0.05. The order of concentration of heavy metal in water was: Fe>Pb>Ni>Cr>Cd while that of sediment is Fe>Pb>Cr>Ni > Cd with heavy metal concentration in sediment higher than that of water while Fe and Cd concentrations were highest and lowest in both water and sediment respectively. All the heavy metals in water except Ni exceeded the permissible limits of World Health Organisation (WHO), Federal Environmental Protection Agency (FEPA) while that of sediment were below the permissible limits except Fe. It was concluded from the results that Choba segment of the New Calabar River is under stress since the heavy metals apart from Nickel (Ni) present were above the permissible limit. This implies that the quality of the water is unsafe for use especially for domestic purpose if untreated owing to the on-going anthropogenic activities in the area. Therefore, regulatory standards for discharges from anthropogenic activities should be strictly controlled

The Chironomidae family, known as "non-biting midges" in their adult stage and "bloodworms" in their larval stage, consists of diverse dipteran insects inhabiting various global aquatic environments. Despite extensive global research, data on Chironomidae in the polluted Nyanza Gulf of Lake Victoria, Kenya, is scarce, and molecular identification methods have not been explored. This study aimed to quantify heavy metal concentrations in water, sediment, and insect samples and assess their impact on Chironomid species identified using mitochondrial DNA barcoding of the cytochrome oxidase subunit 1 (COI) gene. Analysis of Variance was used to determine if there were any statistically significant differences in heavy metal concentrations across different sample types or locations along the pollution gradient. Chironomids were collected from Nyanza Gulf, focusing on a pollution gradient. Results showed that concentrations of arsenic (As), lead (Pb), and cadmium (Cd) in insect, water, and sediment samples exceeded standard limits, while mercury (Hg) concentrations were within limits. Significant variations (p ≤ 0.05) in Pb levels were observed in water samples, and heavy metal concentrations in sediment samples varied significantly (p ≤ 0.05), with Pb showing the highest variation (p ≤ 0.0001). Insect samples exhibited significant differences (p ≤ 0.0001) in As and Hg contents. Genetic analysis identified two known species: Chironomus transvaalensis at the heavily polluted Kisumu station and Chironomus pseudothummi at the moderately polluted Kendu Bay and Homa Bay stations. Additionally, a unique Chironomus species was found on Ndere Island, a relatively clean site with restricted human activities. Sequence comparisons indicated proximity to global data but also highlighted the evolutionary significance and uniqueness of the identified species. This study demonstrated the potential use of genetic methods in determining Chironomid species diversity, community structure, and abundance in relation to heavy metal concentration. It suggests that heavy metal pollution may act as a selective pressure, driving the evolution of Chironomid species. The study recommends combining genetic approaches with other pollution sources for a comprehensive understanding of using this species in monitoring pollution

Impact of a catastrophic flood on the heavy metal pollution status and the concurrent responses of the bentho-pelagic community in a tropical monsoonal estuary

Low-, middle- and high-income countries, exhibit indications of risks associated with water quality. The study investigated heavy metal concentrations in surface water and sediments within the Ngerengere River and its tributaries (Kikundi, Bigwa, and Morogoro) drain within in the Morogoro Municipality of Tanzania, an Urban Catchment Area (UCA) with limited available data mainly because of inadequate monitoring and reporting capabilities. Analysis of health and ecological risks associated with heavy metal pollution was also carried out using health risk assessments models, pollution indices, and multivariate analysis techniques. Between the dry and wet seasons of 2023, water and sediment samples from (13) sampling stations strategically established along the Ngerengere river and its tributaries were analyzed for six heavy metals (Pb, Cr, Ni, Cd, Cu and Zn) using the Atomic Absorption Spectrophotometer Model Perking Elmer 850 Graphite Furnace and Perking Elmer AS 800 Auto-sampler coupled with a computer interface for operational, displaying and reading the results. The calculated degree of water contamination (Cd) values in river water in both dry and wet seasons ranged from 0 to 6.803 indicating low and high degrees of contamination respectively. Heavy metal concentration in sediment decreases in the order of Zn>Ni>Cr>Cu>Cd>Pb. The non-cancer risk index (HI) via ingestion and dermal pathways in dry and wet seasons for both children and adult groups was <1 hence no non-cancer risk, However, cumulative dermal and ingestion exposure in both children and adults indicated potential cancer risk in dry and wet season. The analysis of ecological risks associated with heavy metal enrichment in the sediment indicated high enrichment of sediments with Cd, Ni and Zn. Conclusively, in wet months, risk indices tend to be low, while in dry months, they typically remain high.

The pollution levels of lakes vary in quantity and type of contaminants accumulated in their sediment and water. The second Chinese capital city will be built around Baiyangdian Lake in the near future, and thus, it is important to monitor pollution status of Baiyangdian Lake. This study mainly focused on the accumulated heavy metal concentrations in the surface sediment and in variety of fish bodies. Sediment pollution status and ecological risk were evaluated through geo-accumulation (I-geo), contamination factor (CF), pollution load index (PLI), potential ecological risk ([Formula: see text]), and mean probable effect concentration quotient (mPEC-Q). In addition, human health risks via fish consumption were also evaluated. Based on the results, the average sediment trace As, Cd, Cr, Cu, Mn, Ni, Pb, and Zn concentrations were 9.53, 0.35, 56.37, 32.33, 617.05, 30.18, 19.17, and 84.24mg/kg dry wt, respectively. Both I-geo and [Formula: see text] inferred low pollution levels and low ecological risks from all assessed trace metals except Cd. Cd posed moderate to high ecological risks. Based on sediment quality guidelines (SQGs), average Ni and Cr concentrations exceeded the threshold effect concentrations (TEC), but their [Formula: see text] are low as their average concentrations is below Hebei province pre-contaminations (30.8mg/kg for Ni and 68.3mg/kg for Cr). There is no cumulative toxicity from all the metals through mPEC-Q. Omnivorous fish accumulated statistically insignificantly higher amounts of metals than carnivorous fish, except for Hg. The intake of 12.22g/person/day fish muscle for the entire life is safe from noncarcinogenic human health problems.

Rapid urbanization and industrialization have aggravated heavy metal contamination in river sediments of the riverine ecosystem in developing countries like Bangladesh owing to their toxicity and persistence. Sediments are dynamic components and useful indicators to understand the level of contamination and their associated ecological risks in the aquatic environment. The study was conducted to investigate the heavy metal contamination in sediments for assessing the ecological risks of an urban river of Bangladesh using principal component analysis (PCA), Pearson’s correlation matrix, geo-accumulation index (Igeo), contamination factor (CF), contamination degree (CD), pollution load index (PLI), enrichment factors (EF), and potential ecological risk factor (RI). The ranges of Zn, Cr, Cu, Pb, and Cd in sediments were 42.22–99.55, 11.12–57.83, 7.98–53.31, 6.76–22.41, and 0.38–0.87 mg/kg, respectively. In the present study, heavy metal concentration in sediments followed the descending order of Zn > Cr > Cu > Pb > Cd, while the concentrations of Cu, Cr, and Cd were higher and the concentrations of Pb and Zn were lower than the toxicity reference value (TRV). Geoaccumulation index (Igeo) demonstrated that most of the sediment samples were unpolluted to moderately polluted. The PLI ranged from 0.334 to 1.209 that stated that sediments were moderately polluted by studied metals. The multivariate statistical analysis revealed that heavy metal contamination was influenced by multiple pollution sources. The extent of heavy metal pollution in the Shitalakhya River implies that the condition is much frightening to both the aquatic biota and inhabitants in the vicinity of the river.

Concentrations of heavy metals (Cd, Cr, Cu, Ni, Pb, and Zn) were measured in water, sediments, Ceratophyllum (hornwort), and Bellamya sp. (edible snail) from residential, mixed (industrial and commercial), and agricultural areas with rural rivers in the Taihu Lake region, China. Zn concentrations were the highest, whereas Cd concentrations were the lowest among the six metals in water, sediments, and aquatic organisms. Cd was mainly present in the acid-soluble fraction, Cr in the residual fraction, and Pb in the reducible fraction of sediments. Heavy metal concentrations in water, sediments, and aquatic organisms in the three areas followed the order of the mixed area > residential area > agricultural area. Heavy metal concentrations in aquatic organisms were not only related to total metal concentrations in water and sediments but also to metal speciation concentrations in sediments. In addition, the bio-concentration factor (BCF) values of Cr, Cu, Pb, and Zn for Bellamya sp. were higher than those for Ceratophyllum, whereas the BCF values of Cd and Ni for Bellamya sp. were lower than those for Ceratophyllum. An ecological risk assessment of heavy metals in sediments showed that Cd posed the highest ecological risk to the environment. A health risk assessment showed that consuming Bellamya sp. from the mixed area could cause a potential health risk.

Heavy metals distribution in the bottom sediments of Nizampatnam Bay -Lankevanidibba Coast, East Coast of India

Occurrence, source identification and potential risk evaluation of heavy metals in sediments of the Hunza River and its tributaries, Gilgit-Baltistan

Heavy metal concentrations in water, fish, and sediments from Bangladesh's haor region were investigated. Fish and sediment samples were taken once a season and evaluated using standard methods, while water samples were collected monthly. Results showed that metals in water (mg/L) were found in order of Mn (0.1694) > Cu (0.0189) > Zn (0.0045) > Pb (0.0040) > Cd (0.0028) within the maximum permissible level of Environment Conservation Rules (ECR). Mean concentrations of metal in fish (mg/kg–dry wt.) found in order of Zn (56.16) > Cu (25.47) > Mn (4.36) > Pb (2.19) > Cd (1.27) that were higher than maximum allowable level of Food and Agricultural Organization (FAO) except Cu. Metal in sediments (mg/kg) found in order of Mn (127.61) > Zn (32.51) > Pb (10.09) > Cu (5.40) > Cd (0.43), and except Cu all metal concentrations were lower than the Environmental Protection Agency's (EPA) probable effect concentrations. In water and sediments, pollution indices revealed a critical pollution threshold for water, and a range of unpolluted to highly polluted for sediments. Sampling sites had low potential ecological risk, despite the fact that metals were showing signs of a negative impact on people' health. Furthermore, bio-concentration factor for fish and water was low to extremely high, but for fish and sediment was low. The level of heavy metal contamination in haor shows the situation is alarming for biota and residents of the region. The relevant authority should control and monitor the aquatic ecology in order to protect it.

Heavy metal concentrations in the surface sediments of specially managed Ulsan Bay were investigated to determine metal distribution, pollution status and its ecological risk using pollution indices (enrichment factor and geo-accumulation index), potential ecological risk index and sediment quality guidelines (SQGs). The order of mean concentration (mg/kg) of metals was Zn (361.9) > Cu (95.6) > Pb (90.7) > Cr (64.7) > Ni (32.2) > Co (16.6) > As (15.8) > Cd (0.40) > Hg (0.16) in sediments of Ulsan Bay. Spatial distribution of metals in sediments showed a significantly higher concentration near industrial complexes, indicating that metal pollution is caused by anthropogenic sources. The results of enrichment factor (EF) and geo-accumulation index (Igeo) showed that sediments were significantly accumulated with Cu, Zn, As, Cd, Pb and Hg, indicating moderate to very severe enrichment (pollution) by these metals. Based on the potential ecological risk index, Hg and Cd posed a very high and a considerable potential ecological risk. Cu and As posed a moderate potential ecological risk, while, other metals (Cr, Co, Ni, Zn and Pb) rarely posed any potential ecological risk to the coastal environments. The sediments in Ulsan Bay showed a very high level of ecological risk, dominated by Hg and Cd. Metal concentrations in sediments were 80% for Cu, 96.7% for Zn, 50% for As, 70% for Pb and 50% for Hg above the threshold effects level (TEL), respectively.

Heavy metal concentrations in surface waters of Hurghada and environs, Red Sea Coast, Egypt, and their correlation with sediment distribution

Heavy metals impair water and sediment quality and thus, can cause adverse impacts on aquatic organisms especially when they exceed the recommended threshold levels. Heavy metal concentrations in water and sediments are a reflection of the anthropogenic activities on the watershed as well as the geology of the area. Metal concentrations and subsequently their bioavailability are influenced by the sediment characteristics including particle size and total organic carbon among others. This study determined the concentration of heavy metals - cadmium (Cd), copper (Cu) mercury (Hg) and lead (Pb) in the sediments in relation to grain size and total organic carbon in Lake Baringo. Samples were collected from five sites using a grab sampler and analyzed for total heavy metals using AAS. Particle size classification was done using the sieve method, while organic carbon (OC) was estimated using the Loss on Ignition (L.O.I) method. One way ANOVA revealed significant difference in mean Cu concentrations amongst the sampling sites at P<0.05 (F (4, 14) =6.945 p=0.01). However, there was no significant differences in the levels of Cd and Hg, that is, F (4, 14) =0.03, p= 1.0 and F (4, 14) = 0.36 p=0.83 respectively. However, there was no significant difference in the levels of Cd and Hg. Sites with higher percentages of silt and clay recorded a higher concentration of Cd and Cu as well as percentage of TOC. The results indicated the pollution of the lake by heavy metals presented an ecological and a human health concern requiring monitoring. Key words: Sediment quality, heavy metals, particle size, total organic carbon.

Heavy metals concentration in water and sediment was investigated at the Motor Park Area and New Bridge Site of lower River Benue, Ibi, Taraba State. The heavy metals levels were examined using atomic absorption spectrophotometer (AAS) Buck Scientific model 210 VGP using spectrophotometry techniques. The highest mean concentration of Zn recorded in the sediment at the Motor Park Area was 0.55 mg/kg while the lowest value of 0.004 mg/kg was recorded for Cr at the Motor Park Area. The highest mean concentration of Mn recorded in the water was 0.375 mg/l at New Bridge Site while the lowest value of 0.00 mg/l was recorded for Cu. Values for Cu, Cd, Cr. Cu were generally low throughout the study period. There was no significant difference (p&gt;0.005) in Zn concentrations in sediment at the sampled locations (Motor Park Area and New Bridge Site) throughout the study periods. However, Cr, Cd and Pb show variations (p&lt;0.005) at the sampled locations. The concentration of Mn (0.375 mg/l) was not significantly different (p&gt;0.05) from Mn (0.325 mg/l) in water between the two location, Pb value (0.343 mg/l) of water in December at the New Bridge Site exceeded the WHO recommended safe limit. However, all other metals were within the WHO and FMENV safe limit for portable drinking water. Since Pb value (0.343 mg/l) exceeded the WHO and FMENV safe limit for December. It shows that there is need for continuous monitoring of Lower River Benue waters at Ibi, Taraba State.