Bioaccumulation of heavy metals (Hg, Cd and Ni) by sentinel crab (Macrophthalmus depressus) from sediments of Mousa Bay, Persian Gulf

The role of the carapace in the accumulation of metals from seawater in the green crab (Carcinus maenas): Studies with radio-labeled calcium, zinc, and nickel

The role of the carapace in the uptake and storage of newly accumulated metals was investigated in the green crab exposed to environmentally relevant concentrations of calcium ([Ca] = 389 mg L-1 or 9.7 mmol L-1), zinc ([Zn] = 82 μg L-1 or 1.25 μmol L-1), and nickel ([Ni] = 8.2 μg L-1 or 0.14 μmol L-1) in 12 °C seawater, using radio-tracers (45Ca, 65Zn, 63Ni). After 24-h exposure, carapace exhibited the highest concentration of newly accumulated Ca, whereas carapace and gills exhibited the highest concentrations of both newly accumulated Zn and Ni relative to other tissues. For all three metals, the carapace accounted for >85 % of the total body burden. Acute temperature changes (to 2 °C and 22 °C) revealed the highest overall temperature coefficient Q10 (2.15) for Ca uptake into the carapace, intermediate Q10 for Ni (1.87) and lowest Q10 (1.45) for Zn. New Ca uptake into the carapace continued linearly with time for 24 h, new Zn uptake gradually deviated from linearity, whereas Ni uptake reached a plateau by 6 h. Attachment of a rubber membrane to the dorsal carapace, thereby shielding about 20 % of the total crab surface area from the external water, eliminated both new Zn and Ni incorporation into the shielded carapace, whereas 36 % of new Ca incorporation persisted. When recently euthanized crabs were exposed, new Zn uptake into the carapace remained unchanged, whereas Ca and Ni uptake were reduced by 89 % and 71 %, respectively. We conclude that the carapace is a very important uptake and storage site for all three metals. All of the uptake of new Zn and new Ni, and most of the uptake of new Ca into this tissue comes directly from the external water. For Zn, the mechanism involves only physicochemical processes, whereas for Ca and Ni, life-dependent processes make the major contribution.

Rare Earth Element Accumulation in Fiddler Crabs (Minuca rapax) from the Rio Doce Tropical Estuary Strongly Affected by Mine Tailings Following the Fundão Disaster

A mining tailing dam rupture in Brazil in November 2015 released millions of tons of mining waste into the Rio Doce ecosystem, leading to long-term aquatic ecosystem impacts. Although multiple lines of evidence indicate tailings associations with potentially toxic elements in estuarine sediments and biological impact and bioaccumulation pathways in fishes, the extent of contamination in base benthic species is still largely unknown. Moreover, Rare Earth Elements (REE) have not received any attention in this regard. This study assessed REE in fiddler crabs (Minuca rapax) sampled from the Rio Doce estuary in 2017, nearly 2 years after the disaster. The ΣREE in crab hepatopancreas and muscle were high (327.83 mg kg-1 w.w. and 33.84 mg kg-1 w.w., respectively, compared to other assessments in crabs, indicating a preference for REE bioaccumulation in the hepatopancreas compared to muscle. Neodimium, La, and Ce were detected at the highest concentrations. The REE from the Rio Doce Basin were, thus, transported and deposited in the estuary with the mine tailings slurry, leading to bioaccumulation in crabs. This may lead to trophic effects and other ecological impacts not readily measured by typical impact assessment studies, revealing an invisible and not typically acknowledged damage to the Rio Doce estuary.

Assessing the ecological risk of heavy metal sediment contamination from Port Everglades Florida USA

Port sediments are often contaminated with metals and organic compounds from anthropogenic sources. Remobilization of sediment during a planned expansion of Port Everglades near Fort Lauderdale, Florida (USA) has the potential to harm adjacent benthic communities, including coral reefs. Twelve sediment cores were collected from four Port Everglades sites and a control site; surface sediment was collected at two nearby coral reef sites. Sediment cores, sampled every 5 cm, were analyzed for 14 heavy metals using inductively coupled plasma-mass spectrometry. Results for all three locations yielded concentration ranges (µg/g): As (0.607-223), Cd (n/d-0.916), Cr (0.155-56.8), Co (0.0238-7.40), Cu (0.004-215), Pb (0.0169-73.8), Mn (1.61-204), Hg (n/d-0.736), Mn (1.61-204), Ni (0.232-29.3), Se (n/d-4.79), Sn (n/d-140), V (0.160-176), and Zn (0.112-603), where n/d = non-detected. The geo-accumulation index shows moderate-to-strong contamination of As and Mo in port sediments, and potential ecological risk indicates moderate-to-significantly high overall metal contamination. All four port sites have sediment core subsamples with As concentrations above both threshold effect level (TEL, 7.24 µg/g) and probable effect level (PEL, 41.6 µg/g), while Mo geometric mean concentrations exceed the background continental crust level (1.5 µg/g) threshold. Control site sediments exceed TEL for As, while the reef sites has low to no overall heavy metal contamination. Results of this study indicate there is a moderate to high overall ecological risk from remobilized sediment due to metal contamination. Due to an imminent dredging at Port Everglades, this could have the potential to harm the threatened adjacent coral communities and surrounding protected habitats.

Mercury contamination in seafood from an aquatic environment impacted by anthropic activity: seasonality and human health risk

Petroleum activity and the dumping of domestic and industrial sewage are important sources of mercury (Hg) contamination in the aquatic environment. Thus, this article aimed to biomonitor the Hg concentration in fish, mussels, and swimming crabs of commercial importance in southeastern Brazil. The quantifications were carried out over a year to verify the influence of seasonality. Finally, a risk assessment was applied to identify whether the concentrations found could lead to long-term damage to the population. Our results indicate that the contaminations were higher in spring, summer, and winter than in autumn, mainly among fish and swimming crabs. The results of quantification in the animal and estimated monthly intake, despite being below the limit established nationally and internationally, were indicative of risk for these two animals after calculating the Hazard quotient. The highest risk values were attributed to the infant population. Based on the data generated by this work, the consumption of mussels is encouraged throughout the year, to the detriment of the other types of seafood studied, especially during summer, spring, and winter. Our work reinforces the importance of risk assessment for a more reliable understanding of the impact of contaminants in seafood on the population's health.

Assessment of potential ecological risk based on the vertical characteristics of potential toxic elements in sediments from a high-density cage culture reservoir in China

The pollution of sediments around Lu Ban Island is a serious environmental issue that is threatening human health. The concentration of As, Cd, Cu, Cr, Hg, Ni, Pb, and Zn at 73 layer points were investigated, vertical distribution characteristics, correlation among potential toxic elements and potential ecological risks of sediments at different depth were analyzed. The following results were obtained, (1) the hypothesis that there was a linear relationship between concentration of potential toxic elements and the reciprocal of deep was reasonable. Based on hypothesis, the ultimate value of concentration by making depth go to infinity was regarded as the background concentration. The background concentration of As, Cd, Cu, Cr, Hg, Ni, Pb, and Zn are respectively 4.94 mg/kg, 0.20 mg/kg, 15.48 mg/kg, 58.41 mg/kg, 0.062 mg/kg, 26.96 mg/kg, 20.29 mg/kg, and 53.31 mg/kg. (2) But correlation between Ni and As was relatively weak, high degree of correlation among other potential toxic elements were found. Based on their correlation, eight potential toxic elements were classified into three groups. First group included Ni and Cr, mainly releasing by coal burning; Cu, Pb, Zn, Hg, and Cd were grouped together, possibly due to their shared source of fish cage culture; Arsenic with relatively weak correlation with other potential toxic elements was classified as a separate class, which was usually one important mineral resource associated with phosphate. (3) Potential ecological risk index (PERI) of sediment above - 0.40 m belonged to moderate risk, the PERI of sediment in - 0.10 m, - 0.20 m, and - 0.40 m were 289.06, 254.33, and 201.44, respectively. Sediment below - 0.40 m belonged to low risk with average PERI value 112.82, with no significant changes in PERI values. The order of contribution to PERI was Hg > Cd > As > Cu > Pb > Ni > Cr > Zn. (4) According to result of cluster analysis and potential ecological risk, the potential ecological risk of sediment above - 0.40 m mainly contributed by potential toxic elements of Cu, Cd, Hg, Pb, and Zn sharing source of fish cage culture.

Geochemical speciation, ecological risk, and source identification of heavy metal(loid)s in sediments and waters from Musa Estuary, Persian Gulf

Surface sediment and water samples from 12 stations were collected from Musa Estuary. Metals concentrations (Al, As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Sb, and Zn) were analyzed by ICP-MS. The highest contribution to ecological risk belonged to Cd (49 %) based on the PERI index. The Tessier procedure showed that with increasing contamination, exchangeable and carbonate fractions of Cd, Pb, Ni, Zn, and Cu increased by 25 %, 18 %, 17 %, 10 %, and 9 %, respectively. Cadmium and Pb have a high risk of release according to mobility factor (30 < MF < 50) and individual contamination factor (3 < ICF < 6) indices. Cluster analysis revealed that Al-Fe-Co-V-Mn-Cu-Pb derived from lithogenic resources, while As-Cd-Ni-Zn-Cr originated from anthropogenic sources. The adsorption of Co, Ni, V, and Zn to sediments was strongly influenced by Eh/pH, DOC/temperature, and salinity (r > 0.79, r < -0.78, and r < -0.69; p < 0.01).

Metals bioaccumulation, possible sources and consumption risk assessment in five Sillaginid species, a case study: Bandar Abbas (Persian Gulf) and Chabahar Bay (Oman Sea), Iran

In this study, the concentrations of 10 metals (As, Al, Cd, Cr, Cu, Fe, Hg, Ni, Pb and Zn) in different tissues (gill, muscle and otolith) of five sillaginid species (Sillago arabica, S. attenuata and S. sihama from the Persian Gulf and S. indica, S. sihama and Sillaginopodys chondropus from the Oman Sea) were analyzed using ICP-MS, and the potential human health risk assessment for local consumers was also conducted using standard indices. The concentration of trace metals (μg g^-1 dw) in fish ranged from 0.24 to 16.09 (As), 7.88 to 167.51 (Al), 0.005 > -0.866 (Cd), 0.006 > -7.95 (Cr), 1.02-5.58 (Cu), 24.86 to 390.85 (Fe), 0.005 > -1.93 (Hg), 0.021 > -7.80 (Ni), 0.33-4.41 (Pb) and 4.78-170.43 (Zn). The levels of trace metals varied significantly among sampling sites, fish species and their tissues. Gill tissues accumulate higher concentrations of the analyzed elements, except for As and Hg, whose higher concentrations were found in muscle tissues. Among the species, S. sihama in the Persian Gulf showed the highest levels of toxic metals compared to the other species. The dendrogram of metal association in fish muscle tissues revealed that Ni, Cr, Cd, Pb and Hg in muscles mainly originated from anthropogenic sources, especially petroleum activities. A second dendrogram based on the association of these five metals in the muscle tissue separated the sillaginid species of the Persian Gulf from the Oman Sea. The mean concentrations of the analyzed metals in the edible tissues were lower than international standards of maximum permissible limits (MPL), except for inorganic As (_iAs) and Pb. The index of estimated daily intake (EDI) for Cr and Hg in all sillaginid species, and _iAs, Pb and Ni only in the Persian Gulf's sillaginid species was higher than the recommended values. The value of the target hazard quotient (THQ) indicated that the intake of individual heavy metals due to the consumption of sillaginid species was safe for human health (except Hg in S. arabica) whereas combined heavy metals' intake revealed potential health problems in the case of increased consumption for all three sillaginids in the Persian Gulf. Target cancer risk (TR) for _iAs in all species and Cd, Cr and Ni in Persian Gulf species was higher than the acceptable range. The results indicated the health issues associated with high consumption, especially for sillaginids in the Persian Gulf, which should be considered in food safety monitoring for local people in the area.

Heavy metal pollution in leachates and its impacts on the quality of groundwater resources around Iringa municipal solid waste dumpsite

Heavy metal pollution in groundwater due to leachates leaking from the Iringa municipal dumpsite was investigated. The pollution was studied by analyzing pH, electrical conductivity (EC), total dissolved solids (TDS), and heavy metals (Fe, Pb, Cr, Cd, Cu, Ni, Mn, and Zn) in leachates collected within the dumpsite and groundwater samples from residential wells close to the dumpsite. The pH of the leachate samples varied from 7.40 to 9.10, implying alkaline behavior and the methanogenic phase of solid waste deposits. The levels of EC, TDS, and heavy metals (Fe, Pb, Cr, Cu, Ni, Mn, and Zn) in leachates were above the national and/or international standards. On other hand, groundwater samples presented pH values ranging from 7.15 to 7.60 which were within the World Health Organization acceptable limit. The concentrations of EC, TDS, Fe, Pb, Ni, Mn, and Zn in most groundwater samples exceeded the national and/or international permissible limits for drinking water. In addition, the water quality indices (WQI) of groundwater samples ranged between 8.30 and 17.90, which implied the excellent quality of groundwater sources. However, the presence of high levels of heavy metals above the permissible limits in both leachate and groundwater samples signified potential risks to the environment and public health. Therefore, the present study calls for proper management of municipal solid waste to reduce the potential risks of further contamination on the groundwater resources and environment around the Iringa municipal dumpsite.

Assessment of crabs from Trindade, a Brazilian remote island: Support to marine studies

Trindade is a remote island far from 1170 km of the Brazilian coast in the Atlantic Ocean, between South America and South Africa. The island has great biodiversity and scientific studies on the fauna and flora of Trindade are still scarce. Accordingly, since crustacean species of the island are also little known, this research features an unprecedented data set, which provides information on the level of potential toxic elements in two crab species: the Grapsus grapsus (herbivore) and the endemic species Gecarcinus lagostoma (omnivorous) which is in threatened status. Although Trindade has experienced contamination from human activities, mainly plastic debris, the element levels found in the samples suggest that there are no relevant inorganic sources into the island. Since minor and trace elements accumulated by marine invertebrates does not present a pattern behavior, our results can support other studies focused on the impact of global warming to the marine ecosystem.

Geochemical Speciation, Risk Assessment, and Sources Identification of Heavy Metals in Mangrove Surface Sediments from the Nanliu River Estuary of the Beibu Gulf, China

To better understand heavy metal pollution and the potential ecological risk of mangrove sediments in the Nanliu River estuary, the speciation and distribution characteristics of heavy metals Fe, Mn, Zn, Co, Ni, Cd, Cr, Cu, and Pb in 13 surface sediments in the study area were determined and analyzed using a modified four-step BCR extraction method, and the ecological risk of heavy metals was assessed using the Geo-accumulation Index (Igeo), Potential Ecological Risk Index (RI), Risk Assessment Code (RAC), Pollution Load Index (PLI), Individual contamination factors (ICF) and Global contamination factor (GCF) methods, and source analyses were performed using correlation analysis and cluster analysis. The results showed that the heavy metal was in the order of Fe > Mn > Cu > Zn > Cr > Pb > Co > Ni > Cd. Except for Fe, Zn, Ni, Cr, Pb, and Co, the average heavy metal content of Mn, Cd, and Cu all exceeded the environmental background value; the Fe, Zn, Co, Ni, Cr, Cu, and Pd are mainly in the residual speciation, while Mn and Cd are mainly weak acid extraction and oxidation, respectively, both of which are predominantly in unstable speciation and are easily released into the environment. Mn and Cd pose a substantial ecological risk, while Cu and Pb present a moderate risk and require precaution. The source analysis results indicate that Fe, Mn, Zn, Ni, Cr, and Pb are most likely to originate from natural sources and the transportation industry, Co and Cu are likely to be mainly from ship manufacturing industrial activities, and Cd is likely to be mainly from agriculture and aquaculture. The GCF and PLI results show that places with high heavy metal enrichment and ecological risk are primarily located in areas with high industrial, agricultural, or human activity impacts.

A Systematic Review on Metal Dynamics and Marine Toxicity Risk Assessment Using Crustaceans as Bioindicators

Metals, many of which are potentially toxic, are present in the aquatic environment originated from both natural and anthropogenic sources. In these ecosystems, these elements are mostly deposited in the sediment, followed by water dissolution, potentially contaminating resident biota. Among several aquatic animals, crustaceans are considered excellent bioindicators, as they live in close contact with contaminated sediment. The accumulation of metal, whether they are classified as essential, when in excessive quantities or nonessential, not only cause damage to the health of these animals, but also to the man who consumes seafood. Among the main toxic elements to animal and human health are aluminum, arsenic, cadmium, chromium, copper, lead, mercury, nickel and silver. In this context, this systematic review aimed to investigate the dynamics of these metals in water, the main bioaccumulative tissues in crustaceans, the effects of these contaminants on animal and human health, and the regulatory limits for these metals worldwide. A total of 91 articles were selected for this review, and an additional 68 articles not found in the three assessed databases were considered essential and included, totaling 159 articles published between 2010 and 2020. Our results indicate that both chemical speciation and abiotic factors such as pH, oxygen and salinity in aquatic environments affect element bioavailability, dynamics, and toxicity. Among crustaceans, crabs are considered the main bioindicator biological system, with the hepatopancreas appearing as the main bioaccumulator organ. Studies indicate that exposure to these elements may result in nervous, respiratory, and reproductive system effects in both animals and humans. Finally, many studies indicate that the concentrations of these elements in crustaceans intended for human consumption exceed limits established by international organizations, both with regard to seafood metal contents and well as daily, weekly, or monthly intake limits set for humans, indicating consumer health risks.

Distribution and environmental geochemical indices of mercury in tar contaminated beaches along the coast of Qatar

The current study aimed to gauge total mercury (THg) concentration and the environmental geochemical indices in tarmat contaminated sediments and test their presence in targeted coastal species. Layers of hard asphalt-like tarmats and sediment samples were collected from 34 sites along the coast of Qatar. The mean concentration of THg in tarmat-sediment mixture is 89 ± 20 ng·g^-1. THg concentration varies significantly between the northern and eastern coasts. Geographically, sampling area were divided into four zones according to the relative closeness with low to serious potential ecological risk index (E_r), moderate pollution load index (PLI), moderate Geoaccumulation index (I_geo), and no toxic risk (TRI) trending as Northern (Zones 4, 3) > North-Eastern (Zone 1) > Western (Zone 2) coasts. Three biota classes (Gastropoda, Bivalvia, and Crustacea) were sampled on the tarmat which the hermit crab (Clibanarius signatus) from Ras Rakan island obtained the highest THg (977 ng·g^-1) and BSAF (29.70).

Exposure of Metal Oxide Nanoparticles on the Bioluminescence Process of Pu- and Pm-lux Recombinant P. putida mt-2 Strains

Comparison of the effects of metal oxide nanoparticles (NPs; CuO, NiO, ZnO, TiO₂, and Al₂O₃) on different bioluminescence processes was evaluated using two recombinant (P_m-lux and P_u-lux) strains of Pseudomonas putida mt-2 with same inducer exposure. Different sensitivities and responses were observed according to the type of NPs and recombinant strains. EC₅₀ values were determined. The negative effects on the bioluminescence activity of the P_m-lux strain was greater than for the P_u-lux strains for all NPs tested. EC₅₀ values for the P_m-lux strain were 1.7- to 6.2-fold lower (corresponding to high inhibition) than for P_u-lux. ZnO NP caused the greatest inhibition among the tested NPs in both strains, showing approximately 11 times less EC_50s of CuO, which appeared as the least inhibited. Although NPs showed different sensitivities depending on the bioluminescence process, similar orders of EC_50s for both strains were observed as follows: ZnO > NiO, Al₂O₃ > TiO₂ > CuO. More detailed in-depth systematic approaches, including in the field of molecular mechanisms, is needed to evaluate the accurate effect mechanisms involved in both bioluminescence metabolic processes.

The concentration of potentially hazardous elements (PHEs) in the muscle of blue crabs (Callinectes sapidus) and associated health risk

In this study, the concentration of potentially hazardous elements (PHEs) in the muscle of Blue crabs (Callinectes sapidus) from the Strait of Hormuz was analyzed and following the health risk in the consumers by uncertainty and sensitivity analysis in the Monte Carlo simulation (MCS) technique was estimated. Fifty-eight blue card samples (male blue crabs = 33 samples; female blue crabs = 25 samples) were collected in the Strait of Hormuz from May to September 2020 for analysis of Nickel (Ni), Lead (Pb), Cadmium (Cd), and Iron (Fe) using Flame Absorption Spectrometer (FAAS). The order of PHEs in the in muscle male blue crabs was Fe (414.37 ± 288.07 μg/kg.ww) > Pb (238.78 ± 87.83 μg/kg.ww) > Ni (92.57 ± 39.72 μg/kg.ww) > Cd (52.73 ± 18.39 μg/kg.ww) and in female blue crabs Fe (461.16 ± 320.56 μg/kg.ww) > Pb (230.79 ± 125.59 μg/kg.ww) > Ni (84.13 ± 46.07 μg/kg.ww) > Cd (67.412 ± 43.93 μg/kg.ww). The concentration of PHEs muscle of male blue crabs and female blue crabs was not significantly different (P-value > 0.05). Uncertainty of non-carcinogenic risk revealed that P95% of total target hazard quotient (TTHQ) in the adult and children consumers due to ingestion male blue crabs was 5.30E-3 and 1.08E-3, respectively, and P95% of TTHQ in the adult and children due to ingestion female blue crabs was 7.05E-3 and 1.20E-3, respectively. P95% of TTHQ in both adult and children consumers was lower than one value. Therefore, consumers are at the acceptable range of the non-carcinogenic risk due to ingestion muscle of male and female blue crabs in Bandar Abbas. Although the non-carcinogenic risk of blue crab was in the safe range, due to the increase in its consumption and the increase of pollution sources in the Persian Gulf, it is recommended to monitor PHEs in Blue's muscle crabs.

Comprehensive Assessment and Potential Ecological Risk of Trace Element Pollution (As, Ni, Co and Cr) in Aquatic Environmental Samples from an Industrialized Area

A global assessment of arsenic (As), nickel (Ni), cobalt (Co) and chromium (Cr) was performed in environmental samples from an important industrial bay. Different fractions of water, sediments and tissues from four species of fish were analysed. Samples were collected from selected sampling sites during four consecutive samplings in spring and autumn seasons, in order to evaluate concentrations and their possible correlations among the aquatic compartments. While a higher availability of Cr and Ni was found in water, Co and As were the most available elements in sediments. In fish, the liver was the tissue with the highest proportion of As and Co, and gills showed the highest concentrations of Ni and Cr. Significance differences were observed among sites showing the pollution sources. In sediments, high correlations were found between total Co content and the most available fractions. Total Ni content highly correlated with the oxidisable fraction, while Cr total content tightly correlated with the least available fractions. Quality guideline values for sediments were frequently exceeded. In sediments and biota, concentrations were slightly higher than in other ecosystems, indicating that maritime, industrial and urban activities are affecting this type of ecosystem with great anthropogenic influence.

Release of heavy metals under pre-set redox potentials in Musa estuary sediments, northwestern of Persian Gulf

Sediments are capable of adsorbing and desorbing heavy metals (HMs) under various environmental conditions. This study investigated the impact of pre-set redox potential (Eh) on the release dynamics of HMs (Co, Cr, Cu, Ni, Pb, V, and Zn) from sediment in an automated biogeochemical microcosm. The release of Co, Pb, and V under reducing conditions increased that may increase the potential risks in the aquatic environment. This phenomenon could be attributed to the decrease in pH, the reductive dissolution of FeMn oxides, and the complex of HMs with dissolved organic carbon (DOC). However, the soluble Cr, Cu, Ni, and Zn decreased at redox potentials as low as -150 mV. Co, Ni, Pb, and Zn were observed in mobile fractions while Cu primarily existed in the residual fraction (indicating lithogenic source). HPI and HEI indexes showed that water quality concerning HMs would become more unsuitable for aquatic life by reducing Eh.

The mysterious mass death of marine organisms on the Kamchatka Peninsula: A consequence of a technogenic impact on the environment or a natural phenomenon?

The increased incidence of environmental disasters in recent years is a matter of serious concern. The reasons for the disaster on the Kamchatka Peninsula (Russia), which occurred in September 2020 and caused the mass death of marine organisms, have not yet been established. This is the first study of the environmental disaster on Kamchatka and should shed light on the possible impact of two main man-made factors associated with an oil spill and a rocket fuel spill. The traces of oil products found in marine organisms could not have led to their death, as they indicate old oil pollution, heavy metals concentrations did not exceed the average values for the studied objects. The propellant and its transformation products were not found in the samples. Thus, having excluding the two main technogenic factors of the death of marine organisms, we can conclude that it was probably caused by a natural phenomenon.

Toxicity assessment of total petroleum hydrocarbons in aquatic environments using the bioluminescent bacterium Aliivibrio fischeri

Toxicity monitoring of environmental pollutants especially petroleum hydrocarbons as priority pollutants is an important environmental issue. This study addresses a rapid, sensitive and cost effective method for the detection of total petroleum hydrocarbons (TPHs) using Aliivibrio fischeri bioluminescence inhibition bioassay. At the first step, the optimum conditions including time, pH and temperature for growth of A. fischeri were determined. Then, two methods were used to evaluate the toxicity of petroleum compounds. In the first method, short-term (15 min) and long-term (16 h) toxicity assays were performed. In the second method luminescence kinetics of A. fischeri was investigated during 24 h. The results demonstrated the most appropriate time for the bacterial growth occurred 16 h after inoculation and optimum temperature and pH were found 25 °C and 7, respectively. Short-term and long-term toxicity did not indicate any toxicity for various concentrations of TPHs (30, 50, 110, 160, 220 mg/L). Considering the luminescence kinetics of A. fischeri the long-term assay was introduced as 6 h. The half maximal effective concentration (EC₅₀) was achieved 1.77 mg/L of TPHs. It is concluded that the luminescence kinetics of A. fischeri can be a valuable approach for assessing toxicity of TPHs in aquatic environments.

Positive matrix factorization receptor model and dynamics in fingerprinting of potentially toxic metals in coastal ecosystem sediments at a large scale (Persian Gulf, Iran)

Effective pollution control and remediation strategies are the key to providing a major progress in conservation of coastal and marine biodiversity. For the development of such strategies, quantitative assessment of potentially toxic metals (PTMs) and the accurate identification of the pollutant sources are essential. In this study, we seek to find out spatial PTMs distribution in the coastal sediments of the Persian Gulf (Iran), to assess the potential eco-environmental risks and to identify the metal pollution sources. Total and fraction analysis indicated considerable metal (Zn, Cu, Mn, Fe, Al, Hg, Pb, Cd, As, Cr, Co, Ni and V) pollution levels, albeit in most cases PTMs were predominantly associated with the oxidizable and residual fractions. The obtained PTMs concentrations were in the range of 22.8 - 156.3, 16.6 - 161.9; 2.7 - 88; 10.4 - 107.3; 1.1 - 35.8; 0.8 - 27.9; 0.1 - 1.3; 1.1 - 21.3; 0.04 - 1.9 mg.kg^-1 for V, Ni, Cu, Zn, Cr, Co, Hg, Pb, and Cd, respectively. The combined PTM-PCA-PMF modeling approach identified four main metal sources (anthropogenic, vehicle-related, agricultural and lithogenic) in the study area. Several recognizable 'hot-spots' with extremely high metal concentrations were observed in the spatial metal pollution patterns. Some of those locations were predominantly affected by the nearby industrial activities, while others have demonstrated contributions from several sources - not only anthropogenic, but also agricultural and vehicle-related. The same spots of elevated pollution were found to demonstrate higher potential eco-environmental risk. Various indexes indicated more or less similar trends: the eco-environmental risk was gradually increasing towards the northwestern part of the study area with several peaks in the central and eastern parts directly affected by the nearby industrial activities.

Speciation and risk assessment of selected trace metals in bottom sediment of coral reef ecosystems of the Persian Gulf

To evaluate the hazard assessment of anthropogenic activities on coastal ecosystems, fractionation and bioaccumulation of trace metals were carried out for sediment and coral samples of three distinct habitats including petroleum exploration area of Kharg, the rural harbor of Chirouyeh, and unpopulated area of Hendorabi. Fractionation results suggested that Ni (~ 51%), Pb (~ 49%), and V (~ 45%) in Kharg; Ni (~ 46%), Pb (~ 84%), and Zn (~ 47%) in Chirouyeh; and Cd (~ 51%) in Hendorabi were the predominant metals in the non-resistant fractions of the sediment samples. Risk Assessment Code (RAC), individual contamination factor (ICF), and global contamination factor (GCF) were derived. The highest relative risk for Cd, Cu, and Ti was observed in Kharg, whereas the highest relative risk for Ni, Pb, V, and Zn was recorded in Chirouyeh. The lowest risk for almost all of the trace metals was observed in Hendorabi. Biota-sediment accumulation factor (BSAF) values of coral samples revealed that species examined in the present study are reliable biomonitors for Cd, Ni, Pb, and Zn contamination. Principal component analysis (PCA) and Pearson's correlation coefficient (PCC) suggested that Pb, Ni, and Zn can be considered the main pollutants of the Persian Gulf which originated mainly from petroleum industries. Furthermore, the metal uptake rates of coral samples seemed to be dependent on bioabsorption pathways and coral species. Overall, the present work constitutes a good basis for further studies on trace metal fractionation, risk assessment, and source apportionment in the Persian Gulf, which could contribute to more effective decisions for reducing the anthropogenic trace metal pollution.