Creek Sediments Research Articles

A multi-tiered approach to assess fecal pollution in an urban watershed: Bacterial and viral indicators and sediment microbial communities

Development of effective pollution mitigation strategies require an understanding of the pollution sources and factors influencing fecal pollution loading. Fecal contamination of Turkey Creek in Gulfport, Mississippi, one of the nation's most endangered creeks, was studied through a multi-tiered approach. Over a period of approximately two years, four stations across the watershed were analyzed for nutrients, enumeration of E. coli, male-specific coliphages and bioinformatic analysis of sediment microbial communities. The results demonstrated that two stations, one adjacent to a lift station and one just upstream from the wastewater-treatment plant, were the most impacted. The station adjacent to land containing a few livestock was the least impaired. While genotyping of male-specific coliphage viruses generally revealed a mixed viral signature (human and other animals), fecal contamination at the station near the wastewater treatment plant exhibited predominant impact by municipal sewage. Fecal indicator loadings were positively associated with antecedent rainfall for three of four stations. No associations were noted between fecal indicator loadings and any of the nutrients. Taxonomic signatures of creek sediment were unique to each sample station, but the sediment microbial community did overlap somewhat following major rain events. No presence of Escherichia coli (E. coli) or enterococci were found in the sediment. At some of the stations it was evident that rainfall was not always the primary driver of fecal transport. Repeated monitoring and analysis of a variety of parameters presented in this study determined that point and non-point sources of fecal pollution varied spatially in association with treated and/or untreated sewage.

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.

Ecotoxicological status, source apportionment and human health risk assessment of potential toxic element in surface water and sediments of creeks along Bonny River, Nigeria

Potentially toxic elements (PTEs) are naturally available in the environment; however, anthropogenic activities encourage their high concentration, posing environmental and human health risks. The ecotoxicological status, source apportionment and health risk assessment of PTEs (Iron (Fe), Nickel (Ni), Cadmium (Cd), Selenium (Se), Zinc (Zn), Lead (Pb), Chromium (Cr) and Copper (Cu)) in creeks (Fibiri and Iwoama) along Bonny River were examined through laboratory analysis (American Public Health Association standard), indicators and statistical techniques. The PTEs concentration of surface water and sediment for both creeks exceeded the WHO allowable limit, and the surface water trended as Cr > Pb > Fe > Ni > Cd > Zn > Cu > Se for Fibiri creeks, Fe > Cr > Pb > Ni > Cd > Zn > Cu > Se for Iwoama creek while the sediment trended as Fe > Pb > Ni > Cr > Zn > Cd > Cu > Se for both creeks. The contamination factor (CF) of the creek’s sediment showed low CF (Zn and Cu), moderate CF (Ni, Pb and Cr) and very high CF (Fe and Cd), while risk index status ranged from low risk (Ni, Zn, Pb, Cr and Cu), moderate risk (Fe) and significantly high risk (Cd). The human health risk revealed that children could be exposed to potential non-carcinogenic effect (HI > 1) with Zn (1.64 and 2.03), and the Total Carcinogenic Risk (TCR) for children indicated high carcinogenic risk (TCR > 1 × 10−4) for Ni, Pb, Cr and Cd of the creeks’ environmental mediums. The similarity in the trend and status of the creeks suggested that both environments are exposed to similar anthropogenic activities impact.

Factors determining contamination and time trends in cyclic and linear siloxanes in sediments from an industrialized lake in Korea

Siloxanes, widely used in various consumer and industrial products, are emerging concerns of contaminants. Despite this, limited studies have been conducted on contamination and time trends on siloxanes in coastal environments. In the present study, four cyclic and 15 linear siloxanes were measured in sediments collected from an artificial saltwater lake in Korea during 2001–2016 to investigate contamination, time trends, and ecotoxicological concerns. Cyclic siloxanes were detected in all sediment samples, whereas linear siloxanes were not frequently detected. The highest siloxane concentrations were observed in creeks passing through various industrial complexes, indicating that industrial activities predominantly contributed to siloxane contamination in coastal environments. Decamethylcyclopentasiloxane (D5) and dodecylcyclohexasiloxane (D6) were predominant siloxanes in sediments over the last two decades. Siloxane concentrations significantly increased in creek sediments from 2008 to 2016, whereas those in inshore and offshore regions significantly decreased due to a strong dilution effect by the operation of tidal power plant. This suggests that consumption patterns and coastal development activities are crucial factors determining the contamination and time trends in the sedimentary siloxanes. The sedimentary concentrations of octamethylcyclotetrasiloxane (D4) and D5 exceeded several thresholds, raising the potentials for ecological risks to aquatic organisms.

Environmental forensics approach to source investigation in a mercury contaminated river: Insights from mercury stable isotopes

Environmental forensics approach was applied to assess the efficacy of mercury (Hg) stable isotopes for source screening and decision-making in the Hyeongsan River, South Korea. Four Hg contamination scenarios were identified− atmospheric Hg emissions from a steel manufacturing industry, upstream riverine Hg transport, and industrial Hg releases and historical landfill collapse from Gumu Creek. The absence of significant Hg isotope difference between the Hyeongsan River sediments (δ202Hg; −0.46 ± 0.17‰, Δ199Hg; −0.04 ± 0.06‰) and the Gumu Creek sediment (δ202Hg; −0.39 ± 0.26‰, Δ199Hg; −0.04 ± 0.03‰) confirm that Hg source is originated from Gumu Creek. The heterogeneous Hg distribution throughout Gumu Creek and statistically similar Hg isotope ratios between Gumu Creek and solid waste cores from the landfill suggests that the landfill collapse is the dominant source to the Hyeongsan-Gumu system. Present Hg releases is also possible given the elevated and matching Δ199Hg between some riverine sediments and wastewater sampled from the landfill. The ternary mixing model estimates that the landfill collapse and wastewater releases contribute 61 ± 25 % and 22 ± 11 %, and the regional background, reflecting terrestrial runoff using deep sediment cores, explain 17 ± 24 % of Hg to the riverine sediment. We suggest that Hg isotopes can be used for routine source screening in areas where Hg sources are unknown.

Integrons, transposons and IS elements promote diversification of multidrug resistance plasmids and adaptation of their hosts to antibiotic pollutants from pharmaceutical companies.

Plasmids are important vehicles for the dissemination of antibiotic resistance genes (ARGs) among bacteria by conjugation. Here, we determined the complete nucleotide sequences of nine different plasmids previously obtained by exogenous plasmid isolation from river and creek sediments and wastewater from a pharmaceutical company. We identified six IncP/P-1ε plasmids and single members of IncL, IncN and IncFII-like plasmids. Genetic structures of the accessory regions of the IncP/P-1ε plasmids obtained implied that multiple insertions and deletions had occurred, mediated by different transposons and Class 1 integrons with various ARGs. Our study provides compelling evidence that Class 1 integrons, Tn402-like transposons, Tn3-like transposons and/or IS26 played important roles in the acquisition of ARGs across all investigated plasmids. Our plasmid sequencing data provide new insights into how these mobile genetic elements could mediate the acquisition and spread of ARGs in environmental bacteria.

An Assessment of Southeast United States Headwater Tidal Creek Sediment Contamination Over a Twenty-Year Period in Relation to Coastal Development.

Headwater tidal creeks are a primary link between estuarine and upland habitats, serving as conduits for runoff. They are sentinel habitats, providing early warning of potential harm, thus ideal systems to evaluate the effects of coastal suburban and urban development on environmental quality. Estuarine sediments have concentrations of metals, polycyclic aromatic hydrocarbons (PAHs), pesticides, polychlorinated biphenyls (PCBs), and polybrominated diphenyl ethers (PBDEs) that are associated with human activity. High concentrations of contaminants can impair faunal communities, habitat quality, and ecosystem function. Forty-three headwater creeks were sampled between 1994 and 2006 to assess contaminants, and 18 of these were sampled again in 2014/2015. Watersheds were classified as forested, forested to suburban, suburban, or urban land. These values are based on their percent impervious cover (IC) levels and change in IC from 1994-2014. Analyses of temporal data resulted in significant relationships between IC and select metals, PAHs, pesticides, PCBs, and PBDEs. In addition, 11 of the creeks sampled in 2014/2015 have paired data from 1994/1995, allowing for change analysis over the 20 years. Results indicated increasing chemical contamination occurring with increasing levels of development, although only PAHs and total dichloro-diphenyl-trichloroethane (DDT) exhibited a statistically significant increase over time; PAHs also exhibited significantly higher concentrations in developed creeks. Additionally, several metals were deemed enriched in developed creeks based on reference conditions. These results expand our knowledge of how these systems respond to urban development and can inform managers about how human population growth along coastlines may predict altered tidal creek health.

Storm sediment contribution to salt marsh accretion and expansion

Salt marshes are ecosystems with significant economic and environmental value. However, the accelerating rate of sea-level rise is a significant threat to these ecosystems. Storms significantly contribute to the sediment budget of salt marshes, playing a critical role in salt marsh survival to sea-level rise. There are, however, uncertainties on the extent to which storms contribute sediments to different areas of marsh platforms (e.g., outer marsh vs marsh interior) and on the sediment sources that storms draw on (e.g., offshore vs nearshore). This study uses field analyses from an eight-month field campaign in the Ribble Estuary, North-West England, to understand storms' influence on the sediment supply to different marsh areas and whether storms can deliver new material onto the salt marsh platform which would otherwise not be sourced in fair-weather conditions. Field data from sediment traps indicate that storm activity caused an increase in inorganic sediment supply to the whole salt marsh platform, especially benefitting the marsh interior. Geochemistry and particle size distribution analysis indicate that the majority of the sediment supplied to the salt marsh platform during the stormy periods was generated by an increase in erosion and resuspension of mudflat and tidal creek sediments, while only a minimal contribution was given by the sediments transported from outside the intertidal system. This suggests that, in the long term, storms will promote salt marsh vertical accretion but might simultaneously reduce the overall larger-scale sediment availability with implications for the marsh lateral retreat.

EXPLORING THE BACTERIAL COMMUNITY IN THE SEDIMENTS OF AN ANTHROPICALLY POLLUTED URBAN CREEK LOCATED ON THE WEST COAST OF MUMBAI, INDIA

Microbial communities with their key roles in nutrient cycling and degradation of pollutants aresuitable bio-indicators in gauging the health of a marine ecosystem. However, insights into thestructure and diversity of bacterial communities in sediments of Versova creek of Mumbai arelacking. Here we assessed the bacterial diversity and composition in sediments collected from twosampling stations for two months in Versova creek. The total sediment DNA was extracted andsubjected to high throughput 16S rRNA sequencing technology which resulted in a total of 5467unique OTUs (Operational Taxonomic Units) from four samples. 16S rRNA sequences revealed thedominance of phyla Proteobacteria, Bacteriodetes, Tenericutes, Chloroflexi and Firmicutes. Furthertaxonomic analysis revealed the surface sediments to be abundant in sulfate reducing taxaDeltaproteobacteria (Desulfobacteraceae, Desulfobulbaceae and Desulfarculaceae). Organic matterloading and oxygen availability could be one of the prime factors affecting the bacterialcommunity structure in the sediments of Versova creek. Additionally, except for Nickel andCopper, which surpassed the toxic thresholds set by international sediment quality standards, theconcentration of most select heavy metals in the creek sediments revealed a moderate level ofcontamination. This study provides preliminary evidence of pollution in Versova creek due torelease of contaminants beyond the assimilative capacity of the ecosystem. It provides a baselineassessment that can be used as a benchmark for future studies and policies that needs to bedeployed in restoring the health of this system.

The application of sediment quality guidelines and toxicity assessment to identify contaminant hotspots in an urbanised West Australian estuary.

This paper presents a tiered assessment approach that enabled identification, triage, interrogation and confirmation of significantly contaminated areas of an urbanised West Australian estuary. The spatial distribution of organochlorine pesticides (OCPs), polycyclic aromatic hydrocarbons (PAHs) and bioavailable metals was determined in surficial sediments of the Swan-Canning Estuary through broad-scale screening (500 cores, 100 composite samples, 20 locations). The application of sediment quality guideline values (SQGVs) enabled ranking of locations through risk-based scoring and identification of contaminant hotspots. Subsequent targeted ecotoxicological and chemical assessment was undertaken at the highest scoring location in each tributary (80 cores, 16 composite samples, 3 locations, 16 sites). In the Canning tributary, Bull Creek sediments demonstrated the highest metal concentrations and greatest number of SQGVs exceeded. High-level toxicity was experienced in copepods and moderate toxicity in mussels (test sensitivity: copepod>mussel>amphipod). Toxicity-inducing contamination was attributable to two stormwater outfalls and limited to 300 m from points of discharge. In the Swan tributary, Claisebrook sediments demonstrated the highest concentrations of all PAHs, most OCPs and metals and the greatest number of SQGVs exceeded. High-level toxicity was reported in fish and mussels and moderate toxicity in copepods and amphipods (test sensitivity: fish>mussel>amphipod>copepod). Toxicity-inducing contamination included a stretch of estuary >1 km long, and two stormwater outfalls in the area were likely sources. The distribution and nature of PAH contamination suggested an additional source at Claisebrook. This combined chemistry and biological effects dataset provides critical information for the management of planned major development and concomitant estuary-bed disturbance in the coming decade.

Field and laboratory investigations on factors affecting the diel variation of arsenic in Huangshui Creek from Shimen Realgar Mine, China: implications for arsenic transport in an alkali stream.

The release of arsenic and related species from mining activities has been investigated widely at both seasonal and diel scales, contributing to the understanding of arsenic cycles, its ultimate fate, and enabling accurate estimates of arsenic flux in specific areas. To enrich the research in this area, a case study was undertaken in Huangshui Creek, Hunan province, China. Here, arsenic is present in the sediment at the Creek entrance to a reservoir and in the widely developed alkali realgar(α-As4S4)-calcite(CaCO3)-dolomite[CaMg(CO3)2] strata (pH 7-11). Water from different levels in the Huangshui Creek, the Creek/reservoir entrance, and the downstream reservoir together with corresponding sediments were collected and analyzed. The local algae were separated and cultured. A diel variation of arsenic (688 ug/L in AM 3:50-1152 ug/L in PM 19:50) was observed in the Creek. The largest difference in arsenic concentration between the upper and lower water body was at the mixed creek/reservoir site (364 ug/L). Laboratory experiments showed that arsenic release from Creek sediment and pristine realgar was 1.3-2.7 times and 2.0-2.3 times at 25 and 37°C, respectively, than low-temperature samples (8°C) over 24h. However, temperature variation is not the only factor controlling arsenic release from Huangshui Creek. Batch experiments show that both sediment and pristine realgar can release arsenic(III). In addition, the presence of bicarbonate promotes arsenic(V) release by 15.2-24.3 times for the sediment and by 1.7-3.4 times for pristine realgar compared to the control, though it restrains arsenic(III) release. High levels of algae have a complex effect on arsenic release; it increases arsenic(V) release by accelerating dissolution of realgar but decreases arsenic(III) release through adsorption. The field observations-variation of bicarbonate (67mg/L in day and 201mg/L in night) and chlorophyll-a (0.06-0.87)-support that both dissolved bicarbonate and algae affect arsenic concentration. These factors establish a circadian rhythm in the Creek, which coupled with arsenic release, ultimately affect the fate of arsenic.

Mangrove Creeks Are a Sink for Isoprene—A Functional Link Between Ecosystems

AbstractIsoprene is an important biogenic volatile organic compound with atmospheric emissions contributing to climate regulation. Because isoprene is predominantly sourced terrestrially, there is limited knowledge on the role it might play in marine systems. Here, we report for the first time isoprene concentrations and tidal fluxes from two subtropical mangrove creeks in Moreton Bay, Queensland, Australia: Jacob's Creek and Turkey Boat Creek in 2017 and 2019. Isoprene concentrations tracked the tide height with higher concentrations at high tide and lower concentrations at low tide in both creek systems, showing that isoprene was imported into the creeks on the flood tide. Mangrove creeks in Moreton Bay were a sink (−9.53 ± 9.10 nmol m−2 h−1) for isoprene. Isoprene was most likely produced in the open water by either phytoplankton or nearby seagrass beds and then consumed by bacterial communities as a carbon source within the mangrove creek sediments. Mangrove creeks in Moreton Bay are estimated to uptake isoprene at a rate of −6 mg m−2 y−1, leading to a total global isoprene sink of −0.69 Gg C y−1. While only a small component of the global marine atmospheric flux of 11,600 Gg C y−1, isoprene constitutes an important functional link between marine ecosystems.

Severe contamination and time trend of legacy and alternative plasticizers in a highly industrialized lake associated with regulations and coastal development

Few studies have been conducted on aquatic contamination by alternative plasticizers. Phthalates and novel plasticizers were measured in sediments from a highly industrialized lake to assess occurrence, sources, time trends, and ecological risks. Legacy and alternative plasticizers were detected in all sediments. Di(2-ethylhexyl) phthalate (DEHP) was a predominant plasticizer, indicating its popular industrial consumption for the last two decades. Predominant novel plasticizers were changed over time. The highest sedimentary DEHP level was recorded on the global scale. Legacy and alternative plasticizers in creek sediments significantly increased from 2008 to 2016, while those from inshore and offshore regions of the lake significantly decreased in association with a dilution effect caused by the operation of a tidal power plant. Concentration ratios of alternative plasticizers to DEHP increased for the last decade, implying a shift in consumption of plasticizers. Sedimentary DEHP concentrations in creeks exceeded almost all threshold values associated with ecological risks.

Microplastics pollution in the sediments of creeks and estuaries of Kenya, western Indian Ocean

Microplastic pollution has been recognised as a global threat in marine environments and a danger to prey, predators and humans. Yet, there have been few studies in the western Indian Ocean, specifically along the Kenyan coast, which makes it difficult to estimate the extent of such pollution in the region. This is the first study on microplastics (MPs) in the sediments within creeks and estuaries (Tudor, Port Reitz and Mida creeks) on the Kenyan coast. In January/February and September 2018 sediment samples were collected for MPs analysis. The concentration of MPs differed between the sampling seasons and was distinctively higher in the second sampling season across particle sizes, suggesting that there were more MPs from larger terrestrial discharges due to increased runoff. The concentrations of total MPs, and the occurrence of different sizes, shapes and colours, were established under a microscope. The overall mean concentration was highest for the large size category of MPs (500–4 999 µm) at 9.1 (SE 0.8) particles cm−2, with Tudor Creek being more polluted with MPs than Port Reitz and Mida creeks. We recommend formulation of policies on proper plastic waste management and disposal to protect nearshore ecosystems which are rich in marine biodiversity.

Characterization of Burkholderia cepacia complex from environment influenced by human waste

ABSTRACT The natural environment is a primary source of infections caused by members of Burkholderia cepacia complex (BCC), but the release of human waste may in return enrich the natural environment with clinically relevant BCC. Seven BCC isolates from environment influenced by human liquid or solid waste across Croatia, and one clinical isolate was characterised. B. multivorans recovered from the soil at illegal dumpsite belonged to sequence type (ST)19; B. ambifaria from the agricultural soil fertilized with swine or poultry manure to ST927 or new ST; B. cenocepacia from creek sediment, river water and wound swab to new STs. Antimicrobial susceptibility of isolates ranged from sensitive to multidrug-resistant. A variety of bla TEM genes was confirmed in isolates. Isolates expressed the virulence factors and survived in river water during 50 days. The BCC present natural environments influenced by the human waste are of clinical relevance and a potential source of sporadic infections.

Isotope investigation of mercury sources in a creek impacted by multiple anthropogenic activities

To investigate mercury (Hg) sources responsible for contamination at Gumu Creek in South Korea, Hg concentration (THg) and Hg isotope ratios were measured in the soil and sediment of Gumu Creek and the samples from a hazardous waste landfill (HWL). The THg ranged between 0.29–327 mg kg−1 and 9.5–414 mg kg−1 in the soil and sediment, respectively, reflecting heterogeneous distribution and elevated levels across the entire Gumu Creek. Without the soil with the lowest THg (0.30 ± 0.01 mg kg−1, n = 3), the δ202Hg (−0.83 to −0.18‰) and Δ199Hg (−0.24 to 0.01‰) of the sediment and soil of Gumu Creek were within the ranges of the HWL samples (δ202Hg; −1.29 to −0.38‰, Δ199Hg; −0.31 to 0.01‰). The comparison with the literature reporting sediment Hg isotope ratios impacted by various anthropogenic Hg sources revealed a presence of diverse Hg sources at Gumu Creek, including commercial liquid Hg, phenyl-Hg, and fly ash, consistent with the types of waste deposited within the HWL. Using commercial liquid Hg, fly ash, and the soil with the lowest THg as end-members, the ternary mixing model yielded 25–88% and 12–57% contributions from commercial liquid Hg and fly ash to the Gumu Creek sediment, respectively. The results of our study suggest that Hg isotope ratios are an effective tool for screening potential Hg sources at sites where the distribution of Hg is heterogeneous and multiple anthropogenic activities exist.

Draft Genome Sequence of Bordetella sp. Strain FB-8, Isolated from a Former Uranium Mining Area in Germany.

Here, we present the draft genome sequence of Bordetella sp. strain FB-8, a mixotrophic iron-oxidizing bacterium isolated from creek sediment in the former uranium-mining district of Ronneburg, Germany. To date, iron oxidation has not been reported in Bordetella species, indicating that FB-8 may be an environmentally important Bordetella sp.

Mobility and Bioavailability of Metal(loid)s in a Fluvial System Affected by the Mining and Industrial Processing of Pb

The abandoned mining district of Linares (South Spain) is marked with waste from the mining and the processing of metal ores that pose an environmental hazard to watercourses. A combined analysis of waste, sediments and water was carried out to analyse the impact of a smelter on Baños Creek. The composition of the facility waste was determined using X-ray diffractometry and scanning electron microscopy. The total contents of the metal(loid)s in the waters and sediments of the watercourse were analysed, and sequential metal(loid) extraction of solid samples was carried out. The facility wastes consisted mainly of secondary minerals, such as natropharmacosiderite and spertiniite, as well as rare metal salts, such as mopungite and NaPb2(CO3)2(OH). The leachates generated by these wastes were highly alkaline, with a pH of 10 and a total dissolved solids concentration of approximately 9 g L−1. This Na-bicarbonate-type water had an As concentration above 200 mg L−1 and elevated levels of Pb, Sb and Zn (5029 µg L−1, 841 µg L−1 and 525 µg L−1, respectively). This highly contaminated lixiviate had a significant effect on the chemical quality of the waters and the bioavailability of metal(loid)s in the creek sediments, especially in the headwaters. In this zone, the As, Pb, Sb and Zn concentrations in the most mobile fraction of the sediments reached 1035 mg kg−1, 261 mg kg−1, 45 mg kg−1 and 30 mg kg−1, respectively. By comparison, smelter slag and mining waste have a much lower impact on the waters and the mobile fraction of the sediments, while significantly increasing the total concentration of these potentially toxic elements in creek sediments.

Assessment of Pollution and Ecological Risk Index of Heavy Metals in the Surface Sediment of Estuary and the Coastal Environment of Bay of Bengal

The Mahanadi River, surrounding estuaries along the coastal water are important to understand the relationship between heavy metals, ecosystem and human health, as the region being used largely by fisher communities for the potential fishing ground and agriculture. The study evaluates the ecological risk index of heavy metals in the surface sediments along the coastal environment of the Bay of Bengal between 2011 and 2012. The metals concentrations were varied from a maximum in Manganese (4,137 mg/kg) to a minimum in Cadmium (17 mg/kg). The factor analysis result shows that higher concentration of cadmium (Cd), chromium (Cr), Nickel (Ni), lead (Pb), and Zinc (Zn) were significant environmental risk in the study region. The cluster analysis indicated that the creek sediment is heavily polluted than the estuary ecosystem of the coastal environment. Enrichment factor and Geo-accumulation Index of the surface sediment resulted that, the Cd was high enrichment and was moderate to severe in the study region. Pollution load index denoted that the sampling sites in the creek sediment were more polluted than coastal due to the influence of agricultural runoff, industrial and anthropogenic. The Cr, Cu, Ni, Pb, and Cd concentrations result in the potential toxicity to the aquatic organisms based on the comparison with the SQGs. Indicates the average magnitude of the metals in the study period in the decreasing order of Mn, Cr, Cu, Ni, Pb, and Cd which were alarming except iron (Fe) in the estuary and coastal ecosystem of the Bay of Bengal. The present investigation would be a first-hand informant to understand the impact of heavy metals in the ecosystem in the region. The result inputs need to be monitored further in the long term basis for isotopic sediment dating to reconstruct the contamination history for the ecosystem modeling, sustainable ecosystem, and coastal zone management.

Interferences of trace metals between sediment and Dotillid crab (Ilyoplax frater) from three tidal creeks, Karachi, Pakistan

In the Anthropocene era, an immersion of toxic substances, i.e., trace metals, has been enhanced in the marine environment not only due to urban sprawl and industrial development but predominantly owing to incongruous management and lack of sustainable approaches. The coastal region of Pakistan shares a similar obstacle as most of the developing countries confronted. Therefore, this study was designed to investigate concentrations of eight metals (Cu, Fe, Zn, Ni, Co, Pb, Cr, and Cd) in sediment and Dotillid crab, Ilyoplax frater, at three tidal creeks in Karachi, Pakistan. All metals in sediments and crabs were analyzed by atomic absorption spectrometer. The sediment pollution was evaluated by contamination degree (CD) and potential ecological risk index (RI). After depicting the metal pollution in sediments, metal accumulation, and contamination in benthic crab were investigated through total metal concentrations in crabs, accumulation factor (AF), correlation analysis, and regression analysis. The results exhibited substantial differences in the concentrations of Zn, Ni, Pb, Cr, and Cd among the tidal creek sediments. Contamination factors indicated that the Cd and Pb had the highest sharing in sediment pollution, and the tidal creeks classified as moderately contaminated. All metal accumulations in Dotillid crabs showed notable spatial variations, and accumulation factors (AFs) for most of the metals were > 1.0, signifying the strong bioaccumulation of metals in crabs. Particularly, Cu, Co, and Cd levels were considerably greater (two to three times) in Dotillid crabs compared to creek’s sediments, even though they don’t share any relationship between two matrixes. Hydrographical and sedimentological traits also revealed significant interactions with metal levels in sediments and crabs. A substantial association was also noticed in Fe, Ni, and Pb between sediments and crabs. Interestingly, most of the metal AFs showed a notable inverse correlation with the environmental matrix. Exceptionally, a strong positive correlation found between the Pb concentration in crabs and sediments suggested that I. frater probably acts as an indicator of Pb pollution.