Accumulation Of Metals In Sediments Research Articles

Distribution and geochemical speciation of metals in the sediments of marine aquaculture areas in Japan.

Metal contamination is a crucial environmental issue because of its persistence and toxicity, which can have deleterious effects on aquatic ecosystems. Coastal sediments serve as reservoirs for metals. Aquaculture is an important human activity in coastal areas; however, the actual status of metal distribution in these areas has not been well characterized. We investigated the distribution and geochemical speciation of metals in the sediments of the Japanese aquaculture areas of Shidugawa and Furue Bays. Total metals were generally in the order Zn > Cu > Ni > Cd > Pb and occurred at high levels at the sites in the inner parts and near the fish cages in the sampling areas. Pearson's correlations and principal component analysis results suggested that the metals in these aquaculture areas might originate from several sources, such as fish feces, fish feeds, corrosion of antifouling material residues, and local anthropogenic activities, including fertilizers and manures. Furthermore, metals were mainly in silts and fine sediments, associated with residual speciation, followed by organic fractions, oxides, and high fractions of exchangeable Cd. These results provide important insights into the accumulation of metals in sediments for better managing marine aquaculture in Japan.

Heavy Metal Accumulation in Sediments of a Non-Perennial River in South India: Implications for Ecology and Human Health – A Multi-Index and Statistical Assessment

ABSTRACT The present study assessed the heavy metal pollution in sediment samples collected from the Noyyal River basin (river and lake sediments) during the monsoon and summer seasons. The geo-accumulation index (Igeo) categorizes metals as extremely polluted during monsoon and heavily contaminated to extremely contaminated during summer. The enrichment factor (EF) of metals Mn during monsoon and Cd during summer indicates extremely severe enrichment (EF > 50) and Mo exhibited very high contamination (CF > 6) throughout the basin during monsoon. The average risk index of heavy metal in the basin followed the order Cd (164.15) > Ni (14.82) > Co (4.84) > Cr (2.55) > Cu (1.89) > Zn (1.38) > Mn (0.40) during monsoon and Cd (153.07) > Ni (7.96) > Cu (5.13) > Co (4.63) > Cr (1.89) > Zn (1.21) > Mn (0.3) during summer showing that the PERI of each element was minimal except for Cd. Adverse health-related effects are confirmed by the cumulative total hazard index (THI) for children with HQ ingestion and HI values >1 in all sample locations over both seasons. Principal component and cluster analysis show metals accumulate in sediments mainly through industrial wastewater discharge and also experience significant natural source weathering through rainfall runoff. This research emphasizes the need for enhanced wastewater treatment facilities in metropolitan areas situated along the Noyyal River to potentially reduce the release of heavy metals from both domestic and industrial sources.

Sustainable carbon sequestration via olivine based ocean alkalinity enhancement in the east and South China Sea: Adhering to environmental norms for nickel and chromium

Enhancing silicate weathering to increase oceanic alkalinity, thereby facilitating the absorption of atmospheric carbon dioxide (CO2), is considered a highly promising technique for carbon sequestration. This study aims to evaluate the feasibility and potential of olivine-based ocean alkalinity enhancement (OAE) for the removal of atmospheric CO2 and its storage in seawater as bicarbonates in the East and South China Seas (ESCS). A particular focus is placed on the potential ecological impacts arising from the release of nickel (Ni) and chromium (Cr) during the olivine weathering process. We considered two extreme scenarios: one where Ni and Cr are entirely retained in seawater, and another where they are completely deposited in sediments. These scenarios respectively represent the maximum permissible concentrations of Ni and Cr in seawater and sediments during the OAE process. Current marine environmental quality standards (EQS) were utilized as the threshold limits for Ni and Cr in both seawater and sediment, with concentrations exceeding these EQS potentially leading to significant adverse effects on marine life. When all released Ni is retained in seawater, the allowable dosage of olivine varies from 0.05 to 13.7 kg/m2 (depending on olivine particle size, temperature, and water depth); when all released Ni is captured by sediment, the permissible addition of olivine ranges from 0.21 to 2.1 kg/m2 (depending on mixing depth). Given the low solubility of Cr, it is not necessary to consider the scenario where Cr exceeds the limit in seawater. The allowable amount of Cr entirely retained in sediments ranges from 0.69 to 47.2 kg/m2.In most scenarios, the accumulation of metals in sediments preferentially exceeds the corresponding threshold value rather than remaining in seawater. Therefore, we recommend using alkalization equipment to fully dissolve olivine before discharging into the sea, enabling a larger-scale application of olivine without significant negative ecological impacts.

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.

The Effects of Cobalt Mining on Water Quality and the Dispersion of Contaminants in the Environment

Cobalt mining, essential for various technological advancements including battery production and electronics, has raised significant environmental concerns due to its potential impact on water quality and the release of contaminants into the surrounding ecosystems. This study aims to assess the repercussions of cobalt mining activities on water bodies and the fate of associated contaminants within the environment.Through a comprehensive literature review and field investigations, this research examines the mechanisms by which cobalt extraction processes, including open-pit mining and leaching techniques, contribute to water contamination. The study evaluates the release of heavy metals such as cobalt, nickel, copper, and arsenic, along with the formation of acid mine drainage (AMD), resulting from sulfide mineral exposure during mining operations. Furthermore, this investigation delves into the persistence and behavior of contaminants released during cobalt mining. It explores the long-term implications of heavy metal accumulation in sediments, soils, and biota, emphasizing the potential for biomagnification and ecological disruption within aquatic ecosystems.Human health concerns related to waterborne contaminants originating from cobalt mining activities are also addressed in this study, highlighting the risks associated with the consumption of contaminated water by local communities.The research findings underscore the necessity for robust environmental regulations, sustainable mining practices, effective waste management strategies, and remediation efforts to mitigate the adverse impacts of cobalt mining on water quality and environmental health. Furthermore, the study emphasizes the importance of continued monitoring and research to better understand the full extent of the problem and develop targeted solutions to safeguard water resources and ecosystems affected by cobalt mining. Keywords: Cobalt mining, Water contamination, Heavy metals, Acid mine drainage (AMD), Environmental impacts, Water quality degradation, Contaminants in mining, Aquatic ecosystems

Attribution of sources to heavy metal accumulation in the anthropogenically impacted Bach Dang River Estuary, Vietnam

In the present study, concentrations of 10 heavy metals (Ti, Cr, Mn, Fe, Ni, Cu, Zn, As, Cd and Pb) were determined in superficial sediments from 20 sites within the Bach Dang Estuary, Vietnam. An integrated approach including correlation analysis, principal components analysis and positive matrix factorization was successfully applied to identify possible sources of these heavy metals. The results of this study identified four sources of the heavy metals, namely: natural geogenic, mixed anthropogenic, marine transportation and antifouling paint related sources, contributing 34.33 %, 14.80 %, 23.02 % and 27.86 % to the total metal concentrations, respectively. From an environmental impact perspective, these findings could provide a scientific basis for prevention and control of sediment metal pollution. Accordingly, the use of more environmental friendly antifouling paints should be encouraged to minimize metal accumulation in sediments.

Low carbon accumulation in a macro‐tidal mangrove forest on the Amazon coast

AbstractThe important role mangrove forests play in sequestering organic carbon is well known, yet rates of organic carbon accumulation in macro‐tidal mangrove ecosystems are poorly resolved. Here we use 210Pb dating to present a 125‐yr record of carbon, nutrient and trace metal accumulation in sediments from an Amazon macro‐tidal mangrove forest. We find that the rate of organic carbon accumulation ranged from 23.7 to 74.7 g m−2 yr−1 (average 38 ± 13.5 g m−2 yr−1), significantly lower than global averages for mangrove forests. These low rates may be associated with sediment grain‐size and sediment–water interface processes that drive organic matter oxidation and reduce carbon stocks in these highly dynamic macro‐tidal forests. Total nitrogen accumulation ranged from 1.4 to 5.1 g m−2 yr−1 (average 2.7 ± 0.9 g m−2 yr−1) and phosphorus from 1.5 to 8.4 g m−2 yr−1(average 4.3 ± 1.9 g m−2 yr−1). Trace metal accumulation rates (As, Pb, Cr, Cu, Mn, Ni, Zn, Hg, Bo, V, Co, Mo, S, and Ba) were also lower than other tropical mangrove forests globally, but trace metal in more recent sediments for Mn, As, Cu, and Hg were elevated, likely reflecting human footprint in the region since early the 20th century. The ability to accurately quantify carbon accumulation rates in mangrove ecosystems is critical for climate change mitigation strategies and the implementation of carbon offset schemes globally.

Human-induced metals accumulation in sediments of an industrialized bay of northern Chile. An enrichment and ecological risk assessment based on preindustrial values

Environmental assessment in marine systems is difficult because most of the time their preindustrial characteristics are not available.Four sediment cores taken in Mejillones bay (northern Chile) were used to establish preindustrial metals concentrations, and to assess the environmental status of this industrialized zone.According to historical documents, the beginning of the industrial era start in 1850 CE. Considering this, the preindustrial concentration of some metals was established, by mean of a statistical approach.Most of the metals increase their concentration from the preindustrial to the industrial period. Environmental assessment showed an enrichment of Zr and Cr, a moderately polluted condition, and a low probability of toxic effect on the biological communities.The preindustrial values derived from sediment cores are a good tool to evaluate the environmental condition of Mejillones bay. However new information (backgrounds with a higher spatial representativity, toxicological threshold, and others) it is necessary to improve the environmental assessment of this environment.

Heavy Metal Accumulation in Sediments of Small Retention Reservoirs—Ecological Risk and the Impact of Humic Substances Distribution

Anthropogenic pollutants that accumulate in bottom sediments may pose a serious threat to the aquatic environment and humans. The aim of the study was to determine the ecological risk related to the contamination of sediment with heavy metals and the relationship between the accumulation of heavy metals and various granulometric fractions and humic substances in the bottom sediments of small retention reservoirs located in catchments of varying anthropopressure. The research objects were five small dam reservoirs located in south-eastern Poland. The sediments of the reservoir exposed to the greatest anthropopressure from the catchment area posed a serious threat to aquatic organisms feeding at the bottom. The bottom sediments of the remaining reservoirs showed a low level of potential toxicity (or non-toxicity). The observed relationship between the enrichment of sediments with organic matter (OM) and the increased risk of their ecotoxic impact on aquatic organisms was determined by excessive exposure to heavy metal contamination. The sand content did not appear to have a clear effect on the metal accumulation, although it was associated with enrichment in OM. Due to diverse environmental conditions, it was not possible to unequivocally confirm that the accumulation of heavy metals in the sediments of small retention reservoirs directly depends on the content of organic matter and humic substances, but such relationships were observed in most of the objects.

Macrozoobenthic diversity and heavy metals (Pb and Hg) accumulation in Bone River Gorontalo Indonesia

The heavy metal pollution on benthic macroinvertebrate communities in Bone River has not been studied. This present study determined to investigate the diversity of the macrozoobenthic trough the length of Bone River concerning the heavy metals leads and mercury at eight sampling stations. The samples were taken in July 2021. A sample of four representative macro zoobenthic families (Hydropsychidae, Baetidae and Elmidae) was also used to analyze metal bioaccumulation. The macrozoobenthic recorded in this study comprise of ten orders and 35 families with a total of 3146 individuals. Diptera, Ephemeroptera, Coleoptera, and Trichoptera dominate the population size of benthic. The diversity indices show the low and medium categories but favour a better macrozoobenthic development. Monitoring studies show that the concentration of Pb in sediments is much higher than that of mercury. Metal accumulation in sediments showed fluctuations but did not reflect macrozoobenthic metal concentrations. The bioconcentration factor (BCF) value generally indicates that the three taxa are categorized in the low accumulative category.

An insight into source apportionment of metals in superficial sediments from the Tien Hai nature reserve of the Red River delta, Vietnam.

In the present study, concentrations of 23 metallic elements (Al, Fe, K, Mg, Ti, Mn, V, Cr, Co, Ni, Cu, Zn, Ga, As, Sr, Zr, Mo, Cd, Ba, W, Hg, Pb and U) were determined in superficial sediments from 20 sites within the Tien Hai nature reserve of the Red River delta. An integrated approach including correlation analysis (CA), principal components analysis (PCA) and positive matrix factorization (PMF) was combined to identify and quantify the sources of these metals. The results indicated that the correlation analysis was able to identify both allochthonous and authigenous origin of metals while the remaining methods were unable to identify these origins. With the help of CA, the PMF model performed better at the source identification of metals than the PCA. The results of PMF demonstrated that weathering products formed on different parent rocks were the biggest contributor to natural sources of metals in the superficial sediments, while agricultural activities were regarded as the major contributor to anthropogenic sources of metals. These findings could provide a scientific basis for environmental protection authority to prevent and control the sediment metal pollution. Accordingly, application of organic amendments and reduction of inorganic fertilizer should be encouraged to minimize metal accumulation in sediments.

Evaluation of heavy metal accumulation in sediment, surface water and some plants in the Karasu Riparian Zone

ABSTRACT. This study aims to determine and compare the heavy metal concentrations in the water, sediment, and plants of the Karasu river in Erzurum, Türkiye. In this context, aluminum (Al), manganese (Mn), iron (Fe), nickel (Ni), zinc (Zn), and barium (Ba) concentrations were measured for this study. Salix excelsa (willow), Rosa canina L., Pyrus elaeagnifolia (wild pear), Malus sylvestris (wild apple), and Hippophae rhamnoides L. (sea buckthorn) plants were used as samples. Heavy metal concentrations follow the order of Al3+ > Fe2+ > Mn2+ > Ba2+ > Ni2+ > Zn2+ in the sediment. Heavy metal concentrations follow the order of Al3+ > Fe2+ > Ba2+ > Mn2+ > Zn2+ > Ni2+ in water. The leaf part of Salix excelsa has the highest bioconcentration factor (BCF) for Mn among plant parts. Mean BCF values were as follows: Zn2+ > Mn2+ > Ba2+ > Ni2+ > Al3+ ≈ Fe2+. In addition, the highest plant translocation factor (PTF) values were determined in Salix excelsa for Al and Fe; in Rosa canina L. for Ni and Zn; in Hippophae rhamnoides L. for Mn and in Malus sylvestris for Ba.
 
 KEY WORDS: Heavy metals accumulation, Sediment, Water, Plant, Riparian Zone
 Bull. Chem. Soc. Ethiop. 2023, 37(1), 35-45. 
 DOI: https://dx.doi.org/10.4314/bcse.v37i1.4

Heavy Metals in Sediments and Greater Flamingo Tissues from a Protected Saline Wetland in Central Spain

Aquatic ecosystems often act as sinks for agricultural, industrial, and urban wastes. Among potential pollutants, heavy metals can modify major biogeochemical cycles by affecting microorganisms and other biota. This study assessed the distribution and concentration of heavy metals (Cd, Hg, Cu, Pb, and Zn) in Pétrola Lake, a heavily impacted area in central Spain where the greater flamingo Phoenicopterus roseus breeds. This study was designed to determine the concentration and identify the potential sources of heavy metals in Pétrola Lake protected area, including sediments, agricultural soils, and tissues of the greater flamingo. A six-step sequential extraction was performed to fractionate Cu, Pb, and Zn from lake sediments and agricultural soil samples to gain insight into different levels of their bioavailability. Our results showed that Pb and Cd accumulated in lake sediments and agricultural soils, respectively, most likely derived from anthropogenic sources. Multivariate analysis revealed differences between these (Pb and Cd) and the remaining studied elements (Cu, Hg, and Zn), whose concentrations were all below the pollution threshold. Lead pollution in sediments was apparently dominated by organic matter binding, with fractions up to 34.6% in lake sediments. Cadmium slightly accumulated in agricultural soils, possibly associated with the use of fertilizers, but still below the pollution thresholds. In the flamingo samples, low bioaccumulation was observed for all the studied elements. Our study suggests that human activities have an impact on heavy metal accumulation in sediments and soils, despite being below the pollution levels.

Sedimentation of metals in Sundarban mangrove ecosystem: Dominant drivers and environmental risks.

Metal contamination from upstream river water is a threat to coastal and estuarine ecosystem. The present study was undertaken to unveil sedimentation processes and patterns of heavy metal deposition along the salinity gradient of a tropical estuary and its mangrove ecosystem. Sediment columns from three representative sites of differential salinity, anthropogenic interference, and sediment deposition pattern were sampled and analyzed for grain size distribution and metal concentrations as a function of depth. Sediments were dominantly of silty-medium sand texture. A suite of fluvial and alluvial processes, and marine depositional forcing control the sediment deposition and associated heavy metal loading in this estuary. The depth profile revealed a gradual increase in heavy metal accumulation in recent top layer sediments and smaller fractions (silt + clay), irrespective of tidal regimes. Alluvial processes and long tidal retention favor accumulation of heavy metals. Enrichment factor (0.52-15), geo-accumulation index (1.4-5.8), and average pollution load index (PLI = 2.0) indicated moderate to higher heavy metal contamination status of this estuary. This study showed that alluvial processes acted as dominant drivers for the accumulation of metals in sediments, which prevailed over the influence of marine processes. Longer tidal retention of the water column favored more accumulation of heavy metals. Metal accumulation in the sediments entails a potential risk of bioaccumulation and biomagnification through the food web, and may increasingly impact estuarine ecology, economy, and ultimately human health.

Accumulation of Heavy Metals in Dam Sediments Effects on Plankton Productivities of the Arabian Gulf

Purpose: Metal accumulation in sediments threatens adjacent ecosystems due to the potential of metal mobilization and the subsequent uptake into food webs. Dams produce important changes in flow regime and sediment deposition. When inundation starts with the building of dams, water surface area increases, flow rate decreases, and sediment carried by the valleys is deposited in the dams. However, there is a lack of research on the chemical properties of deposited sediment in dams. Method: We aimed to fill this gap in the literature by providing valuable data on the particle size and heavy metal of sediment in different dams. Therefore, the aim of this study conducted within the Northern emirates of United Arab Emirates dams, to estimate heavy metal concentration of sediment, including particle size distribution. A total of eight sediment samples from each dams were collected and analyzed for heavy metals. The concentrations of Iron (Fe), Nickle (Ni), Copper (Cu), Zinc (Zn), Lead (Pb), Cadmium (Cd), Chromium (Cr), and Cobalt (Co) in sediment samples were determined using Atomic Absorption Spectrophotometer (AAS). Results: The concentrations of the heavy metals studied in the sediment samples were accumulated as Fe> Ni> Cr> Zn> Co> Pb> Cu. The concentrations of Ni and Cr have exceeded the threshold in the sediments of in line with W.H.O standards. Cadmium was not detected in soil, while other elements detected were in trace amount below the allowable limits in soil. The consideration of environmental factors is required to develop pollution managements and assess environmental risks for dam sediments. Conclusion: The studies conducted provide background to a discussion on the extent of anthropogenic pressure on the natural environment in the Arabian Gulf, further underlining the relationship between retention of sediments in the dam and the increase in heavy metal contamination of bottom sediments and to the marine environment which effects possible to plankton productivity.

The impact assessment of desalination plant discharges on heavy metal pollution in the coastal sediments of the Persian Gulf

In recent decades the development of desalination plants (DPs) for desalination of seawater has increased dramatically, while little attention has been paid to the effects of this activity on the accumulation of heavy metals (HMs) in the sediments of affected ecosystems. The present study was implemented to evaluate (1) heavy metal accumulation in sediments impacted by DPs discharges, (2) spatial and temporal changes of HMs and the contamination degree by different types of pollution indexes (single and integrated indices), and (3) ecological risk assessment of cadmium (Cd), lead (Pb), zinc (Zn) and copper (Cu) in sediments affected by DPs discharges. A total of 288 sediment samples were collected seasonally at 24 stations from November 2019 to October 2020. Analysis of HMs concentrations in sediments near the desalination plant discharge provided evidence of local contamination. Maximum concentration of Cu and Pb elements were found in sediments near the desalination plant discharge point. Hierarchical cluster analysis revealed clear segregation of stations impacted by desalination plant discharges and away from discharges. The values of PLI index in sediments of all sampling stations were < 1, indicating that there was no metal pollution by this index. The potential ecological risk index (PERI) ranged from 5.33 ± 0.51 to 11.81 ± 4.98 in sampling sediments and were classified as “low potential ecological risk”. These results demonstrate that the DPs discharge increased HMs concentrations in the sediments in close proximity to outlets. The necessary and practical regulations and policies regarding the rejection of the DPs discharge and disposal of chemical compounds must be implemented and enforced.

Contributions of Wetland Plants on Metal Accumulation in Sediment

Wetlands, and especially salt marshes, are well-known sinks of metals, which limit toxic amounts of metals from entering the food chain. This study investigated metal concentrations (Cr, Cu, Fe, Mn, Ni, Pb, Zn) in a highly urbanised estuary, and compared vegetated rhizosediment (Salicornia tegetaria, Spartina maritima, and Zostera capensis) with bare sediment, in a depositional and non-depositional site, in the intertidal zone of the Swartkops Estuary. The samples were collected at two sites along the middle and lower reaches of the estuary and analysed using a Total X-ray Fluorescence (TXRF) spectrometer. It was found that the rhizosediment contained more metals and that metal concentrations in the sediment decreased as follows: S. tegetaria &gt; S. maritima &gt; Z. capensis &gt; bare sediment. Although metal accumulation was similar in bare sediment for the depositional (Site B) and the non-depositional site (Site A), the rhizosediment displayed higher metal accumulation in the depositional site (Site B). However, regardless of site-specific depositional tendencies, rhizosediment displayed higher metal accumulation than bare sediment. These results indicate that vegetated sites and vegetated depositional sites should be the focus of monitoring metals in estuaries around the world.

The Accumulation and Transformation of Heavy Metals in Sediments of Liujiang River Basin in Southern China and Their Threatening on Water Security.

Heavy metal (HM) pollution in sediments is tightly related to the security of water quality in rivers, but the accumulation and conversion of HMs are poorly researched, so that a field study was conducted as an example in the Liujiang River Basin. Seven HMs were analyzed to determine between the overlying water and sediments. Moreover, the regulation of HMs speciation and environmental factors in their accumulation and conversion were identified. The obtained results suggested the HM concentrations in water are far below the primary standard of water quality, but in sediments, the contents of Cd and Zn are significantly higher than their corresponding baseline of soil. Only Cd and Pb are dominantly in non-residual form (carbonate-bound fraction and reducible fraction, respectively). The non-significant correlations suggested pH and Eh may be hard to influence HMs in water, while the significant correlations highlighted the regulations of Eh, organic matter and mean grain size on the accumulation of metals in sediments. The opposite correlations between EC, TDS, pH and Cd confirmed the emission of acid wastewater contributed to the accumulation of Cd in sediment. The conversion of metals between water and sediments were found to be significant only in specific forms of Cd, As, Cu, Zn and Pb, suggesting the conversion of HMs in sediments should be largely regulated by their specific forms. The very high risk disclosed by the higher values of and RI are only found upstream, while the higher risk of Cd should be treated as a critical environmental threat.

Ecological assessment of heavy metals accumulation in sediments and leaves of Avicennia marina along the Diu coast of the northeast Arabian Sea

The Coastal region of Diu is the natural habitat dominated by Avicennia marina mangrove species at the southeast coast of Saurashtra in Gujarat state of India. However, Diu being a famous industrial and tourism place survival of these mangrove species is threatened due to anthropogenic activities. In present studies, sediment and leaf samples of A. marina were collected from the Diu coast to evaluate the ecological threat of heavy metals accumulation in the marine habitat. There was remarkable presence of heavy metals such as copper, nickel, cadmium, chromium and lead in sediments and leaf samples of A. marina. The values of Biological concentration factors (BCFs) of heavy metals in leaf samples were high for cadmium, chromium and lead which suggest chelation of these heavy metals with biomolecules. The geo-accumulation index suggested that Site-4 and Site-5 were heavily contaminated with copper and nickel. The ecological risk index suggested that there is no significant effect of heavy metals on growth of plants in the mangrove ecosystem. Principal component analysis revealed that the samples collected from the natural habitats (Site-4 and Site-5) near the fishing and industrial areas were the main sources of heavy metal contamination. Hence, it was concluded that the concentration of heavy metals in the studied ecosystem had limited impact on growth of plants at Site-1, Site-2 and Site-3. However, growth of plants at Site-4 and Site-5 were threatened due to the toxic effect of copper and nickel present in its sediments.

Assessment of heavy metal contamination within the sediments in some fresh water lakes of Udaipur

Heavy metal concentrations were assessed in sediment samples collected from three lakes of Udaipur, Rajasthan. The aim of the present investigation was to compare the lakes for season wise addition of pollution load. The assessment of heavy metals was done using Contamination factor (CF), Geo accumulation index (Igeo) and Pollution load index (PLI). In summer CF varied from 0.01 to 7.43 i.e low to very high but in winter season all three lakes represented high CF factor. Likewise Igeo index in the sediments for summer ranged between 0.41 to 14.48 mg/kg i.e uncontaminated to moderate to heavy to extreme levels in sediments of lakes and trends were of the order Mn>Zn>Pb>Ni>Cu>Cd. In winter Igeo index ranged between 1.34 to 19.3 mg/kg which is uncontaminated to extreme contamination in bottom sediments and trends were of the order Mn>Zn>Pb>Ni>Cu>Cd. Pollution load index in winter season represented high value i.e more than 1 in both Dudh Talai and Udai Sagar Lake. The proposed study suggested that heavy metal accumulation in sediments during winter was higher than summer season. This has a very significant relevance where the contaminated sediments have one of the most challenging pollution issues owning to the toxicity persistence and bioaccumulation issues of food web.