Metal Concentrations In Seawater Research Articles

Low cobalt inventories in the Amundsen and Ross seas driven by high demand for labile cobalt uptake among native phytoplankton communities

Abstract. Cobalt (Co) is a scarce but essential micronutrient for marine plankton in the Southern Ocean and coastal Antarctic seas, where dissolved cobalt (dCo) concentrations can be extremely low. This study presents total dCo and labile dCo distributions measured via shipboard voltammetry in the Amundsen Sea, the Ross Sea and Terra Nova Bay during the CICLOPS (Cobalamin and Iron Co-Limitation of Phytoplankton Species) expedition. A significantly smaller dCo inventory was observed during the 2017/2018 CICLOPS expedition compared to two 2005/2006 expeditions to the Ross Sea conducted over a decade earlier. The dCo inventory loss (∼ 10–20 pM) was present in both the surface and deep ocean and was attributed to the loss of labile dCo, resulting in the near-complete complexation of dCo by strong ligands in the photic zone. A changing dCo inventory in Antarctic coastal seas could be driven by the alleviation of iron (Fe) limitation in coastal areas, where the flux of Fe-rich sediments from melting ice shelves and deep sediment resuspension may have shifted the region towards vitamin B12 and/or zinc (Zn) limitation, both of which are likely to increase the demand for Co among marine plankton. High demand for Zn by phytoplankton can result in increased Co and cadmium (Cd) uptake because these metals often share the same metal uptake transporters. This study compared the magnitudes and ratios of Zn, Cd and Co uptake (ρ) across upper-ocean profiles and the observed order-of-magnitude uptake trends (ρZn > ρCd > ρCo) that paralleled the trace metal concentrations in seawater. High rates of Co and Zn uptake were observed throughout the region, and the speciation of available Co and Zn appeared to influence trends in dissolved metal : phosphate stoichiometry and uptake rates over depth. Multi-year loss of the dCo inventory throughout the water column may be explained by an increase in Co uptake into particulate organic matter and subsequently an increased flux of Co into sediments via sinking and burial. This perturbation of the Southern Ocean Co biogeochemical cycle could signal changes in the nutrient limitation regimes, phytoplankton bloom composition and carbon sequestration sink of the Southern Ocean.

Assessment of metal trace elements in the echinoderm Paracentrotus lividus from the North-Eastern coast of Algeria

The echinoderm sea urchin Paracentrotus lividus Lamarck, 1816 (Echinodermata, Echinoidea) is a good species to be used in environmental and toxicology research, in particular as a heavy metal bio-indicator. Our study’s objective is to evaluate the amounts of Zn, Pb, Fe, and Cu in sea urchin specimens collected from the coast of Skikda (Northeast Algeria) in order to validate the fact that sea urchins are good indicators of metal pollution and can be used effectively for environmental biomonitoring. To realize our objectives, three sampling sites were chosen based on suspected forms and sources of contamination. The main physicochemical parameters of the seawater were measured to determine their quality. 15 specimens of urchins in each station were obtained from exposed rocky surfaces and transported to the laboratory. Before dissection, the biometric parameters and the total wet weight were determined. The soft organs (gut and gonads) of individuals were separated and utilized to evaluate the levels of heavy metals. The condition index and metal indices were also determined. Our study confirmed that P. lividus may be considered a valuable bioindicator of heavy metal contamination in marine ecosystems. The results show that the amounts of heavy metals differed significantly between stations. Samples taken from the Larbi Ben M’hidi station showed greater amounts of Pb, Zn, and Cu. These amounts are above the recommended limits for fish and aquatic animals. Also, the heavy metals found in sea urchins vary depending on the physicochemical parameters, trace metals in the seawater, and the individual biometric parameters. These higher concentrations of metals in seawater and in P. lividus individuals at the Larbi Ben M’hidi station are largely caused by the construction of a massive oil industry complex and terminal with several refineries and petrochemical units near this station, as well as by a considerable amount of domestic wastewater. Finally, to avoid this metallic pollution risk, it is necessary that permanent controls be imposed as soon as possible. Urban and industrial wastes must be treated before being released, in the hope of reducing future metal concentrations.

ВЛИЯНИЕ ГИДРОМЕТЕОРОЛОГИЧЕСКИХ УСЛОВИЙ НА ПРОСТРАНСТВЕННОЕ РАСПРЕДЕЛЕНИЕ ТЯЖЕЛЫХ МЕТАЛЛОВ В ВОДЕ УСТЬЕВОГО ВЗМОРЬЯ ВОЛГИ

The paper presents the spatiotemporal dynamics of heavy metal distribution (for zinc, copper, lead, cadmium, mercury) in the water of the Volga mouth offing in the Caspian Sea in 2011-2020, depending on meteorological and hydrological conditions. Based on the analysis of the state environmental pollution monitoring data, statistically significant coefficients of correlation between the metal concentrations in seawater and the parameters of the Volga runoff and wind were obtained. It was found that the concentration of metals in the water of the Volga delta watercourses was several times lower than in seawater in this period, which calls into question the widespread belief about the Volga runoff as the main contributor to the pollution of the Caspian Sea.

Interspecies calibration for biomonitoring metal contamination in coastal waters using oysters and mussels

Differences in metal bioaccumulation among species make it difficult to compare biomonitoring results obtained using different marine bivalve species. To address this challenge and improve the interpretation of biomonitoring data, we studied the toxicokinetic mechanisms underlying these differences and developed a method to estimate seawater metal concentrations based on metal concentrations in the organisms. We transplanted six common species of oysters and mussels found in Chinese coastal waters into the Jiulong River estuary and monitored metal concentrations in the organisms, water, and suspended particles every three days over a six-week period. A one-compartment first-order toxicokinetic model was used to describe the relationship between metal bioaccumulation and metal concentrations in the environment. The model parameters, including aqueous uptake (ku) and dietary assimilation (kp) rate constants, and elimination rate constant (ke), were estimated using a Markov Chain Monte Carlo fitting method with a priori information from a systematic review we conducted. The toxicokinetic model successfully fitted the temporal changes in metal bioaccumulation in all six bivalve species and explained the interspecies differences. Using the calibrated models, we were able to calculate metal concentrations in the seawater at the bivalve collection sites and enable comparisons of biomonitoring data across multiple species. In conclusion, we have established a toxicokinetic framework to explain interspecies differences in metal bioaccumulation in six commonly found bivalves and provided a useful tool for interpreting biomonitoring data in coastal environments.

Use of Me/Ca ratios as proxies for coastal marine conditions in ostracod shells of Sinocytheridea impressa and Neomonoceratina delicata

Paleo-reconstructions using element to calcium ratios (Me/Ca) of marine ostracods were usually focused on Mg/Ca and Sr/Ca, whereas paleo-environmental applications using other ostracod Me/Ca including Na/Ca, Ba/Ca, Mn/Ca, Zn/Ca, Ni/Ca, Cd/Ca, Cu/Ca and Cr/Ca have been rather limited due to the lack of a general understanding of the control of physicochemical marine variables on trace-elements uptake. Ba/Ca and Na/Ca were linked to temperature, while Mn/Ca was suggested to be an indicator of redox conditions and used to track oxide contamination in marine shells. The potential of other ostracod ratios as environmental proxies has rarely been investigated. Here, we study the empirical relations between seawater physicochemical variables and several Me/Ca of ostracod shells in shallow marine waters. Our results suggest that shallow sea parameters related to the control of metal concentrations in seawater and sediments such as suspended solids, salinity, electrochemical potential and total carbon are correlated to Me/Ca such as Mn/Ca and Zn/Ca in ostracod shells of Sinocytheridea impressa and Neomonoceratina delicata from Hong Kong coastal waters. Correlations are not always significant for both species, indicating that other factors such as species-specific habitats or biomineralization processes may also play a role in the incorporation of metals. We demonstrate that the combination of multiple linear regressions using several significant sea parameters provides useful information to reconstruct shallow marine conditions including water temperature, salinity, suspended solid and total carbon in sediments. Thus, a detailed description of the marine environment in Hong Kong coastal waters can be achieved.

Natural heavy metal concentrations in seawater as a possible cause of low survival of larval mussels

BackgroundA period of seismic activity starting in 2010 coincided with a decline in commercial catches of wild seed mussels in a major aquaculture production region of New Zealand. Analyses of over 40 years of mussel seed catch data from in the Pelorus and Kenepuru Sounds, confirmed a marked decline since 2010 in catches of the preferred, green-lipped mussel (Perna canaliculus), the larvae of which is known to have low tolerance of heavy metals in seawater. MethodsHeavy metal mean concentrations were measured throughout the Pelorus and Kenepuru Sounds. The concentrations ranged from < 0.60–3.24, < 16.94–74.35, < 1.47–4.00, 2.23–19.02, 1.86–3.29 and 0.12–0.52 µg L−1 for Cr, Fe, Cu, Zn, As, and Cd, respectively. Seawater from six locations in the Sounds, historically associated with high commercial catches of settling mussel larvae, was used for experimental rearing of green-lipped mussel larvae. ResultsNo mussel embryos survived when incubated in these seawater samples. The mean concentrations of Cr, Fe, As, and Cd were significantly higher in the seawater from the Sounds than in the hatchery seawater. A higher concentration of one or a combination of these heavy metals could be the cause of the poor larval survival. These findings could be crucial for the sustainability of mussel farming in the area.

Heavy metal accumulation in marine water: An assessment of ONGC’s blocks in Krishna-Godavari Basin, Bay of Bengal

Heavy metal pollution, in the aquatic ecosystem, has become an area of concern garnering increasing attention since the past few decades. These metals are introduced into the marine ecosystem mainly due to anthropogenic activities including offshore Oil and Gas exploration and production activities Though rich in aliphatic and aromatic hydrocarbons, crude oil also contains some trace element like vanadium, nickel, iron, aluminium, copper and some heavy metals like lead and cadmium. Poisonous or hazardous components of crude oil are mainly benzene and heavy metals which vary depending on the source of the crude oil. Elements like copper, mercury, lead, cadmium, zinc and chromium are very toxic. Except copper and zinc, others are nonessential and toxic. In fact, all metals are toxic at high concentrations. The heavy metal overload has inhibitory effects on the development of aquatic organisms such as phytoplankton, zooplankton, and fish. The metallic compounds could disturb the oxygen level and mollusc’s development, byssus formation, as well as reproductive processes. Hence, monitoring the heavy metal concentrations in sea water over a period of time is of great help in checking the pollution level and identifying the trend, which in turn will be instrumental in formulating sustainable practices. The paper mainly focuses on the study of the concentration of non-essential heavy metals in sea water around the operational areas of ONGC in western offshore area. The distribution of heavy metals in the seawater of ONGC’s exploratory blocks in Krishna-Godavari Basin, Bay of Bengal was investigated. Fifty four sea water samples collected as per OSPAR guidelines from each blocks (Vasihta G1 PML-65, Yaman PML, Godavari PML-46, DWN M-3, KG OS DW III 62, and KG DWN 98/2-1) of Krishna-Godavari Basin, Bay of Bengal and processed samples were analyzed by ICP-MS for Pb, Cr, As, and Cd. Comparison of average results in studied 6 blocks with various seawater quality guidelines is discussed to assess the present contamination. It reveals that seawater in study area are not contaminated with respect to perceived heavy metals. Generated data will assist in future for proactive measures and minimize the impact of anthropogenic sources.

Assessment of Heavy Metal Concentrations in Seawater in the Coastal Areas around Daerah Istimewa Yogyakarta Province, Indonesia

Due to anthropogenic influences that can cause heavy metal pollution in the aquatic environment, it is essential to know the amounts of heavy metals in coastal seawater to assess the potential damage of the ecosystem. The purpose of this study is to assess heavy metal concentrations (Cd, Pb, Cu, and Zn) in seawater in the coastal areas around Daerah Istimewa Yogyakarta Province, Indonesia. This study will be useful for the assessment and monitoring of marine pollution around the study area. A total of 9 water samples were collected in the close of nine types of coastal land use, namely mangrove ecosystem, tourist attraction, airport, harbor, mining area, bare land, shrimp pond, agricultural land, and settlement around Daerah Istimewa Yogyakarta Province in June 2021. The concentrations of Cd, Cu, and Zn were not detected, concentrations were below the limit of detection. The Pb concentrations at all sampling locations did not comply with seawater quality standards for ports, marine tourism, or marine biota based on the Ministry of Environment Decree No. 51, the year 2004 regulation. The source of Pb in the study area was estimated from anthropogenic and natural sources. The anthropogenic sources were corrosion of junk metal items, automobile traffic, resuspension of lead-contaminated soil dust, boat navigation, painting of boats, a coking coal transport service, fishing port, the supply of fuel, fertilizer, fuel for mining equipment, and transportation of mining activities. While the natural sources were the concentration of Pb contained in iron sand (a part of Quarterly Alluvium) eroded due to waves and wind then mixed in seawater.

Heavy metal uptake of nearshore benthic foraminifera during multi-metal culturing experiments

Abstract. Heavy metal pollution originating from anthropogenic sources, e.g. mining, industry and extensive land use, is increasing in many parts of the world and influences coastal marine environments even after the source has ceased to pollute. The elevated input of heavy metals into the marine system potentially affects the biota because of their toxicity, persistence and bioaccumulation. An emerging tool for environmental applications is the heavy metal incorporation into foraminiferal calcite tests, which facilitates monitoring of anthropogenic footprints on recent and past environmental systems. The aim of this study was to investigate whether the incorporation of heavy metals into foraminifera is a direct function of their concentration in seawater. Culturing experiments with a mixture of dissolved chromium (Cr), manganese (Mn), nickel (Ni), copper (Cu), zinc (Zn), silver (Ag), cadmium (Cd), tin (Sn), mercury (Hg) and lead (Pb) in artificial seawater were carried out over a wide concentration range to assess the uptake of heavy metals by the nearshore foraminiferal species Ammonia aomoriensis, Ammonia batava and Elphidium excavatum. Seawater analyses revealed increasing concentrations for most metals between culturing phases and high metal concentrations in the beginning of the culturing phases due to sudden metal addition. Furthermore, a loss of metals during the culturing process was discovered by an offset between the added and the actual concentrations of the metals in seawater. Laser ablation ICP-MS (inductively coupled plasma mass spectrometry) analysis of the newly formed calcite revealed species-specific differences in the incorporation of heavy metals. The foraminiferal calcite of all three species exhibited Pb and Ag concentrations strongly correlated with concentrations in the seawater culturing medium (partition coefficients and standard deviation for Ag – Ammonia aomoriensis, 0.50 ± 0.02; Ammonia batava, 0.17 ± 0.01; Elphidium excavatum, 0.47 ± 0.04; for Pb – Ammonia aomoriensis, 0.39 ± 0.01; Ammonia batava, 0.52 ± 0.01; Elphidium excavatum, 0.91 ± 0.01). Ammonia aomoriensis further showed a correlation with Mn and Cu, A. batava with Mn and Hg, and E. excavatum with Cr and Ni and partially also with Hg. However, Zn, Sn and Cd showed no clear trend for the species studied, which in the case of Sn was maybe caused by the lack of variation in the seawater Sn concentration. The calibrations and the calculated partition coefficients render A. aomoriensis, A. batava and E. excavatum as natural archives that enable the determination of variations in some heavy metal concentrations in seawater in polluted and pristine environments.

Seasonal variations of some heavy metal concentrations in seawater, sediment, and the surf clam, Mactra olorina (Philippi, 1846) in the Great Bitter Lake, Suez Canal, Egypt

Seasonal variations of some heavy metal concentrations in seawater, sediment, and the surf clam, Mactra olorina (Philippi, 1846) in the Great Bitter Lake, Suez Canal, Egypt

Manganese Benefits Heat-Stressed Corals at the Cellular Level

The intensity and frequency of coral bleaching events have increased worldwide especially due to thermal stress and seawater pollution. Although it has been observed that metal concentration in seawater can affect the coral’s ability to adopt cellular defensive mechanisms to counteract bleaching, more investigations are needed to better understand the role of metals in coral physiology. In this study, we analyzed the individual and combined effects of prolonged heat stress and manganese (Mn) and iron (Fe) enrichments at the cellular level on the coralStylophora pistillata. Thermal stress caused an up-regulation in the expression of the host Heat shock proteins (Hsps) 60 and 70, which showed a parallel pattern of modulation in all treatments, as well as an increase of lipid peroxidation (LPO) in the holobiont. Fe enrichment did not induce any change in Hsp expression or in the oxidative status of the corals both at the ambient temperature of 26°C or at increased temperature, suggesting that Fe didn’t seem to play a role in mitigating the cellular damages and the coral bleaching. Mn or MnFe enrichment at 26°C seemed to increase the oxidative stress in zooxanthellae, since high LPO and glutathione reductase (GR) levels were recorded, but it did not cause any effect on polyp Hsp expression, probably due to the antioxidant action of GR. With the temperature increase, Mn enrichments prevented any increase in Hsp levels and caused a significant decrease of LPO and GR activity, strengthening a previous hypothesis suggesting that Mn could mitigate the negative cellular effects produced by the thermal stress.

Determination of heavy metals in selected fish species and seawater from the South Durban Industrial Basin, KwaZulu-Natal, South Africa

The South Durban Industrial Basin (SDIB), South Africa, an economic hub that spans a long coastline, is a disaster management hotspot, which threatens the sustainability of the fishing industry in this region. This study investigated the elemental concentrations in fish and seawater from a mini-ecosystem in the SDIB, to determine if a direct relationship exists between these two matrices, and to assess for metal toxicities. The results showed As and Cr to be above the maximum permissible limits (MPLs) of the World Health Organization (WHO) for all fish species (blacktail, karanteen, five finger, mullet, and pompano), while fish from Isipingo Beach exceeded the WHO MPLs for Pb, As, and Cr. Fish did not display signs of metal toxicity indicating either a harmless form of metals or high tolerance levels. Typical concentrations of metals in seawater (mg L-1) at (Isipingo Beach, Cuttings Beach, and Amanzimtoti Beach) were found to be for Al (3, 2.7, and 16.4), As (0.17, 0.11, and 0.19), Cr (0.16, 0.17, and 0.23), Cu (0.15, 0.13, and 0.24), Fe (2.7, 3.45, and 33.9), and Zn (2, 2.1, and 2.12). Except for As, estimated daily intakes, target hazard quotients, and carcinogenic risks indicated no associated health risks due to consumption of the fish from the SDIB. However, due to target hazard quotients and carcinogenic risks for As being above 4 and 0.0001, respectively, fish from the SDIB should be consumed in moderation or not consumed to prevent long-term toxic effects of As.

Evaluation of the Effect of Local Water Chemistry on Trace Metal Accumulation in Puget Sound Shellfish Shows That Concentration Varies With Species, Size, and Location

Global climate change is causing ocean acidification (OA), warming, and decreased dissolved oxygen (DO) in coastal areas, which can cause physiological stress and compromise the health of marine organisms. While there is increased focus on how these stressors will affect marine species, there is little known regarding how changes in water chemistry will impact the bioaccumulation of trace metals. This study compared trace metal concentrations in tissue of Mediterranean mussels (Mytilus galloprovincialis) and Olympia oysters (Ostrea lurida) in Puget Sound, Washington, a region that experiences naturally low pH, seasonal hypoxia, and is surrounded by urbanized and industrialized areas. Shellfish were held at three sites (Carr Inlet, Point Wells, and Dabob Bay) where oceanographic data was continuously collected using mooring buoys. Using inductively coupled plasma mass-spectrometry (ICP-MS) to measure trace metals in the tissue, we found differences in accumulation of trace metals based on species, location, and shellfish size. Our study found differences between sites in both the mean metal concentrations and variability around the mean of those concentrations in bivalves. However, high metal concentrations in bivalves were not associated with high concentrations of metals in seawater. Metal concentrations in shellfish were associated with size: smaller shellfish had higher concentrations of metals. Carr Inlet at 20 m depth had the smallest shellfish and the highest metal concentrations. While we could not eliminate possible confounding factors, we also found higher metal concentrations in shellfish associated with lower pH, lower temperature, and lower dissolved oxygen (conditions seen at Carr Inlet at 20 m and to a lesser extent at Point Wells at 5 m depth). There were also significant differences in accumulation of metals between oysters and mussels, most notably copper and zinc, which were found in higher concentrations in oysters. These findings increase our understanding of spatial differences in trace metal bioaccumulation in shellfish from Puget Sound. Our results can help inform the Puget Sound aquaculture industry how shellfish may be impacted at different sites as climate change progresses and coastal pollution increases.

Kandungan Logam Kadmium (Cd) pada Air Laut, Sedimen, dan Kerang Hijau di Perairan Tambak Lorok dan Perairan Morosari

Cadmium metal is dangerous for green mussel organisms because it can interfere with fertility. Green mussels are organisms widely distributed, can survive in poor environments, and sedentary organisms. Green shellfish is a filter feeder and is used as a bioindicator to monitor the concentration of Cd metal in the waters. The research objective was to measure the concentration of Cd metal in sea water, sediment, and green mussel meat in the waters of Tambak Lorok and Morosari. The Cd metal contents of seawater, sediments, and green mussels were measured using Atomic Absorption Spectrophotometer. The results showed that Cd metal concentrations in seawater in May, July, and August 2018 in Tambak Lorok and Morosari waters were below the detection limit (0.001mg/L); 0.002 mg/L; and 0.002 mg/L, respectively. The concentrations of cadmium in sediment in May, July, and August in Tambak Lorok waters were below the detection limit (0.004 mg/kg); 0.0023 mg/kg; and 0.0021 mg/kg, respectively, and in Morosari waters were below the detection limit (0.004 mg/kg); 0.002 mg/kg; and 0.0114 mg/kg, respectively. Cd metal concentrations in green mussel meats in May, July, and August in Tambak Lorok waters were below the detection limit (0.01mg/kg); 0.0060; and 0.1277 mg/kg, respectively, and in Morosari water were below the detection limit (0.01mg/kg); 0.0067 mg/kg; and 0.0493 mg/kg, respectively. Cd metal concentrations in sea water and green mussels in the waters of Tambak Lorok and Morosari were below the quality standard and the concentrations of Cd metal in seawater, sediments, and green mussel meat in the waters of Tambak Lorok and Morosari were not significantly different.   Keywords: cadmium, green mussels, morosari, seawater, sediments, Tambak Lorok

Effects of sea reclamation project on heavy metal concentrations in seawater- a case study in Qixingtu

Sea reclamation will pollute the environment and reduce the quality of marine water. In order to discuss the impact of reclamation on seawater, 4 heavy metals (Cu, Pb, Zm, Cd) in seawater near Qixingtu were analysized for three time periods: 2007(before the reclamation), 2016(not long after the reclamation) and 2018 (after the reclamation). As a result, concentrations of all the 4 heavy metal met the standard requirements in surrounding seawater of Qixingtu, which indicated a good sea water quality in this area. Except for Cd, all the other heavy metals showed a trend of increasing first and then decreasing. Sea reclamation could indeed aggravate the heavy metal pollution in the surrounding seawater but the impact would recover through reasonable treatment and protection.

Risk Assessment of Heavy Metals in Selected Marine Fish Species of Gadani Shipbreaking Area and Pakistan.

Simple SummaryProtection of the coastal ecosystem from hazardous heavy metals is vital as it provides valuable habitat for numerous fish species and is a key resource for the coastal communities. Gadani shipbreaking is the third largest shipbreaking in the world, located on the coastline of Balochistan, Pakistan. The impact of this dismantling on the quality of the local fish species is still unknown. This is the first study to determine heavy metals’ content in fish and seawater of Gadani shipbreaking area. Metal accumulations in fish species both in gills and muscles ranged from 1.33 to 5.26 μg/g. Among trace metals, the level of Pb in all fish species was highest, followed by Ni, Mn, and Cd. However, all the analyzed fish species from the Gadani coast were found safe for human consumption, but there is a need for continuous monitoring of the coastal environment.Gadani shipbreaking area, located on the coastline of Pakistan, is an important fish production area. In this study, levels of four metals (Ni, Pb, Cd, and Mn) in 148 muscle and gill samples of seven fish species (Small-scale terapon, Torpedo scade, Sicklefish, Saddle grunt, Gold silk seabream, Indian mackerel, Spotted sickle fish) and seawater samples, taken from 9 sampling sites in the shipbreaking area, were determined. In addition, multiple approaches were used to assess human health risks from fish consumption. Trace metal concentration in seawater ranged from 0.05 to 1.96 mg/L in shipbreaking vicinity and 0.03 to 0.97 mg/L in the reference site (Miani Hor). However, metal accumulations in fish species ranged from 1.33 to 5.26 μg/g. Among trace metals, the level of Pb in all fish species was highest, followed by Ni, Mn, and Cd. The bioaccumulation factors (BAFs) for both gills and muscles displayed the order: Mn > Cd > Ni > Pb. Estimated daily intake (EDI) values were below the tolerable daily intake (TDI). Based on target hazard quotient (THQ), the investigated fish species were safe regarding Pb and Mn (THQ < 1), while they may cause potential risk regarding Cd and Ni (THQ > 1). After comparison with maximum permissible limits, heavy metal concentration in the edible muscle tissues of all the analyzed fish species from the Gadani coast were found safe for human consumption.

Monitoring of heavy metals in seawater using single chamber foraminiferal sclerochronology

The establishment of sustainable coastal industries requires better temporal and spatial monitoring of heavy metal (HM) pollutants, even at low concentrations and during pulse-release events, before their accumulation becomes hazardous for local ecosystems or for the use of seawater in desalination (for drinking water). Foraminifera, unicellular marine organism, build their shells by sequential addition of chambers made of calcite, which contains impurities reflecting the composition of the growth medium. Therefore, the chemical composition of each chamber reflects HM in the ambient water at the time of calcification. To test the applicability of single-chamber analyses of foraminifera shells as a tool for HM monitoring in seawater, we conducted culturing experiments to calibrate the relationship of zinc and lead in foraminiferal shells and the ambient seawater. Two species of the cosmopolitan genus Amphistegina were cultured under a range of concentrations of both metals and two temperatures. We show that concentrations of zinc and lead in shells increase linearly with metal concentration in seawater with no difference between species and no effect of temperature. Our experiments further show that the concentrations in seawater can be directly inferred from concentrations in the shells at least up to the levels representing chronic pollution for both metals (68 ug/L for Zn and 8 ug/L for Pb). Combined with their high abundances in all marine environments and good preservation of their shells in sediments, our results demonstrate that foraminifera represent a powerful natural recording system offering high spatial and temporal resolution, allowing the establishment of historical baselines and detection of confined or short-term events of HM release, which could escape traditional monitoring methods.

Determination and comparison of selected heavy metal concentrations in seawater and sediment samples in the coastal area of Suva, Fiji

The coastal area of Suva, Fiji is exposed to high degree of metals input from different sources such as land-based industrial activities like metal fabrication and construction, paint manufacturing, petroleum storage and garment manufacturing, food processing and fish cannery as well as activities of bottling plants. It is therefore essential to have continuous monitoring and environmental management for the coastal area. Thus, to assess the degree of contamination of metals, selected metals (Cd, Zn, Pb, Cu and Ni) concentrations were analysed in seawater and sediment samples collected from ten sites in the coastal area of Suva, Fiji. The concentration of these metals in the samples was analysed using flame atomic absorption spectrometer (FAAS). The concentrations of the metal in seawater were in the range: 0.23–0.80 mg/L, 0.08–1.45 mg/L, 0.15–0.25 mg/L, 0.88–1.77 mg/L and 0.88–10.29 mg/L for Ni, Zn, Cd, Pb and Cu, respectively. The corresponding concentrations of metal in the sediment samples in dry weight (dw) basis for Ni, Zn, Cd, Pb and Cu were in the range: 17.24–28.74 mg/kg, 18.55–68.78 mg/kg, 5.49–9.16 mg/kg, 116.96–233.92 mg/kg and 78.43–490.18 mg/kg, respectively. The quality of the seawater was evaluated with respect to WHO established guidelines while the quality of the sediments evaluated using internationally accepted Sediment Quality Guidelines (SQGs). The contamination of the sediments was also assessed in terms of geo-accumulation index (Igeo), contamination factor (Cf) as well as pollution load index (PLI). Zn complied with the guidelines in all ten sites, Cu in eight sites was within the guidelines while Ni complied with the guideline in six sites. However, the levels of contamination recorded for Cd and Pb in all ten sites did not comply with the guidelines.

Cell wall thickening in two Ulva species in response to heavy metal marine pollution

The present work was aimed at evaluating the responses of two green algae, Ulva rigida and Ulva intestinalis, to heavy metal pollution in their natural environment. These species were harvested in the Atlantic shorelines of El Jadida (Morocco) at two different stations: first, a non-polluted site (S1) which served as a control, and a second one (S2), which is affected by industrial effluents, mainly from a phosphate facility. Except for iron, the heavy metal concentrations in seawater were higher in station S2 than in station S1 (notably cadmium and lead levels). Consequently, the algal samples collected from S2 presented higher levels of heavy metals compared with those collected in S1. Pollution in station S2 resulted in a reduction in size of thalli of both algal species. Optical microscopy of algal slices showed that the polluted environment induced the thickening of the cell walls along with an enlargement of cell areas. Elevated cell wall yields, higher content of polysaccharides (mainly ulvans), sulfate, and protein were also detected in algae from S2. However, the monosaccharide distribution in cell wall polysaccharides was quite identical in the two species, regardless of the station. Our results describe an adaptation mechanism mainly based on cell wall thickening which restrains the entry of toxic elements into the cells, allowing these algae to enhance their tolerance to heavy metal stress.

Trace elements, polycyclic aromatic hydrocarbons, mineral composition, and FT-IR characterization of unrefined sea and rock salts: environmental interactions.

Unrefined sea salt originates from seawater, typically by natural evaporation. Being minimally processed, it contains the natural minerals and impurities of seawater. Despite the wide applications of salt for culinary and food preservation purposes, the available composition data is particularly limited. Since seawater often contains various harmful substances at a trace or ultra-trace level, their determination in unrefined salt is significant in terms of quality control and food safety. Twenty-four (24) samples of unrefined sea and rock salts retailed in Greece were studied in terms of their trace metals and polycyclic aromatic hydrocarbon (PAH) content, which constitute the usual pollutants examined in seawater. In addition, samples' color and mineralogy were recorded and their attenuated total reflectance Fourier transform infrared (ATR FT-IR) spectra were obtained. No statistically significant differences were found between sea and rock salts regarding their trace metal (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Zn) content (excluding V) and the 15 PAHs examined. ATR FT-IR succeeded to discriminate among sea, rock, flower, and underground salty water salts. Compared with the typical trace metal concentrations in seawater, quite high Pb values were determined in both sea and rock salts, whereas outliers in the rest of the trace elements examined were scarce. Median values of the sum of PAH (ΣPAHs) concentrations were calculated equal to 2.1 and 2.6ngg-1 for sea and rock salts, respectively. Environmental interactions of salt production with trace elements and PAHs are also discussed.