Depth profiles of lithogenic and anthropogenic mercury in the sediments from Thane Creek,Mumbai, India

Mercury（Hg） is well known as one of the most toxic elements to man.The coastal environments adjacent to industrial areas are reported to often be contaminated with mercury.Mercury becomes more toxic in the form of methylmercury（Me-Hg） which is converted from inorganic mercury in aqueous systems by microbial activity and can bio-magnify through the food chain.A simple method for the determination of total mercury and methylmercury in sediments was optimized by slightly modifying an old method using the direct mercury analyzer technique.Core sediment samples from Thane Creek,Mumbai,India were collected and analysed for total mercury and methylmercury.The Hg concentration in the creek varied between 0.54 to 16.03 μg g~（-1） while Me-Hg concentrations ranged between0.04 to 1.07 μg g~（-1）.In surface sediment,mercury concentrations ranged from 4.33 μg g~（-1） to 12.16μg g~（-1）.Total organic carbon content was found to be around 2 percent in different layers of the sediments.The enrichment factors,which indicate the extent of pollution in sediments,were estimated to range from 26 to 50 at different locations in the creek.Lithogenic and anthropogenic concentrations of mercury in the creek were also determined to compare the impact of anthropogenic and natural sources.Anthropogenic inventories were about 5-70 times more in concentration than the lithogenic in the different core sediments.     

Environmental Emission of Mercury During Gold Mining by Amalgamation Process and its Impact on Soils of Gympie, Australia

— The aims of this study were to estimate the total amount of mercury released to the environment during 60 years of gold mining (1867–1926) at Gympie, Queensland, Australia and to measure the mercury levels in soil samples surrounding the mining activity. We estimated that 1902 tonnes of mercury was released to the environment and about 1236 tonnes of which was released to the air. The mean mercury in the soil samples in the vicinity of the Scottish battery varied from 1.07 to 99.26 μg g^?1 as compared to 0.075 μg g^?1 as background mercury concentrations. The maximum mercury concentration measured in sediments of the Langton Gully was 6.12 μg g^?1. These results show that large amount of mercury was used in this area during gold mining. Since mining is active in the area and Langton Gully flows into Mary River, we therefore, recommend that mercury concentration in air and fish should be monitored.     

Monitoring polycyclic aromatic hydrocarbons in the Northeast Aegean Sea using Posidonia oceanica seagrass and synthetic passive samplers

The concentrations of 22 polyaromatic hydrocarbons (PAH) in Posidonia oceanica seagrass, sediments, and seawater from the Alexandroupolis Gulf in the Aegean Sea, were investigated from 2007 to 2011. Temporal trends of total PAH contents in P. oceanica and sediments were similar. PAH levels in seawater, sediments, and seagrasses generally decreased with increasing distance from Alexandroupolis Port. Leaves and sheaths of P. oceanica had higher PAH levels than roots and rhizomes. P. oceanica accumulates PAHs and has good potential as a bioindicator of spatiotemporal pollution trends. PAH concentrations were also examined using in situ passive seawater sampling and were compared to results of passive sampling in the laboratory using local sediments and seawater. Levels of high molecular weight PAHs assessed using passive samplers confirmed the decreasing gradient of pollution away from Alexandroupolis Port. Passive sampling also proved useful for investigating sources of PAHs in P. oceanica meadows.     

Mercury contamination in tropical algal species of the Island of Penang,Malaysia

An investigation on the levels of mercury contamination in one species of the Cyanophyta, 14 species of the Rhodophyta, five species of the Phaeophyta and six species of the Chlorophyta from Penang waters indicated fairly low levels of bioaccumulated total mercury content. The bioaccumulated values ranged from below the detectable level to 0.35 μg g^?1 except for Padina sp. 1 which demonstrated an amount equivalent to 1.025 μg g^?1.These results indicate that the level of mercury contamination in the marine environment of Penang island falls within an acceptable range from the viewpoint of algal biodeposition.     

Mercury in tropical marine organisms from north Queensland

Total mercury concentrations were determined in a variety of fish and invertebrates and two dugongs from the coastal waters of Townsville on the N.E. coast of Australia. Fish generally contained the highest levels of mercury with 50% of the sharks examined having muscle concentrations above 0.5 μg g^?1 wet weight. A significantly positive correlation was found between muscle levels and body length in sharks. Seventy per cent of the teleosts examined contained less than 0.2 μg g^?1 in their muscle tissue and only 7% were above 0.5 μg g^?1. Mercury concentrations in teleost liver were significantly positively correlated with muscle levels. Of the invertebrates examined, the cephalopod molluscs contained the highest levels although none exceeded 0.5 μg g^?1. Mercury levels in the dugong were extremely low compared with most reported values for other marine mammals. It was concluded that the area contained mercury levels slightly above those considered normal for a non-contaminated marine environment.     

Spatial distribution of cyanotoxins and ratios of microcystin to biomass indicators in the reservoirs of the Volga,Kama and Don Rivers,the European part of Russia

We studied the distribution of cyanotoxins and potential producers, as well as the variability of microcystin to biomass parameters (chlorophyll-a; MC/Chl-a; and biovolume; MC/BV) in 12 drinking water reservoirs of the world’s largest reservoir system, the Volga-Kama-Don cascade (European part of Russia) during the summers of 2016 and 2018. MC concentrations varied from below 0.1 μg L⁻¹ in June up to 16.4 μg L⁻¹ in August and exceeded 1 μg L^-1 in 25 % of the samples. This MC variability was associated to changes in the abundance of widespread bloom formers such as Microcystis spp., Dolichospermum spp. and Planktothrix agardhii. Ratios of MC/Chl-a and MC/BV_cyano ranged up to 0.88 μg μg⁻¹ and 4.5 μg mm⁻³, respectively. Together with microcystin profiles MC/BV_cyano ratios characterized cyanobacterial populations along the reservoir cascade and they indicated a potential toxin hazard better than MC/Chl-a. The neurotoxin anatoxin-a was observed only in the most southern and hypereutrophic Tsimlyansk Reservoir (maximum 0.01 μg L⁻¹). Toxin gene analysis revealed that MC mostly originated from Microcystis and Dolichospermum. During their co-existence up to 14 MC congeners co-occurred. Cuspidothrix issatschenkoi cf. Raphidiopsis mediterranea was identified as possible neurotoxin producers.     

Bioaccumulation of mercury in starfish from contaminated mussels

In the course of our works on mercury metabolism in marine organisms, we investigated in laboratory the technical feasibility and the scientific relevance of the simple benthic food chain ‘particles-mussel-starfish’. Mature starfish, Leptasterias polaris, fed over 45 days with contaminated mussels (Mytilus edulis), bioaccumulated organic mercury in all their tissues. The absorption rate of mercury in the first weeks of the experiment was respectively 0.238, 0.094, and 0.015 μg.g⁻¹ d⁻¹ (wet wt) in pyloric caeca, stomachs and body walls. Starfish retained about 50% of the organic mercury ingested mostly in pyloric caeca and calcerous skeleton (96–98%). After four weeks of regular accumulation, an auto-depuration process took place and mercury concentration in digestive organs was reduced even if the contaminated food was still provided. Coelomic fluid seems to be a barrier to the rapid dispersion of methylmercury into the whole animal and may play a role in the depuration process. These results provide evidence for the strong interest in the mussel-starfish food chain for fundamental studies of metal biotransfer in invertebrate marine organisms.     

The effect of tributyltin oxide on growth of Mytilus edulis

Juvenile Mytilus edulis were exposed to 0.1–10.0 μg TBTO l⁻¹ in flowing raw seawater, and the shell length growth was measured in 24–48 h intervals for 7 days. Significant reductions in length growth rate occurred at ≥0.4 μg TBTO l⁻¹. The relationship between TBTO concentration and growth response is approximately hyperbolic.     

Sublethal effects of bis(tri-n-butyltin)oxide on Crassostrea gigas spat

Hatchery produced spat of the Pacific Oyster Crassostrea gigas were exposed to low levels of bis(tri-n-butyltin)oxide (TBTO) 0.2, 0.1, 0.05, 0.02, and 0.01 μg I⁻¹. Their oxygen consumption, feeding rate, compensation for hypoxia, and growth rate was examined after exposure to TBTO and compared to their performance prior to this. In all cases highly significant relationships between TBTO concentration and the physiological variable in question were observed. Significant effects were found down to levels of 0.05 μg I⁻¹ for oxygen consumption and feeding rate, to 0.02 μg I⁻¹ for growth and to 0.01 μg I⁻¹ for compensation for hypoxia. These levels are far lower than those reported for many UK sites and the results are discussed in relation to the possible environmental impact of the observed effects.     

Inorganic and methylmercury: do they transfer along a tropical coastal food web?

Methylmercury (MeHg) and inorganic mercury (Hg_inorg) were evaluated in the water of a Brazilian estuary, with two size classes of plankton and seven fish species of different feeding habits. Water partition coefficients (PCs) in microplankton were fourfold higher for MeHg than for Hg_inorg; and water PCs in mesoplankton were 26 times higher for MeHg than Hg_inorg. Difference between microplankton and mesoplankton MeHg bioaccumulation factor (BAF) was higher (0.60 log units) than Hg_inorg BAF (0.24 log units), indicating that trophic transfer of MeHg between planktonic organisms is more efficient than Hg_inorg transference. MeHg concentrations, proportion of mercury as MeHg and its biotransference factors (BTFs) in the microplankton, mesoplankton and fish increased with increasing trophic level while biotic concentrations of Hg_inorg and proportion of mercury as Hg_inorg decreased thus indicating that MeHg was indeed the biomagnified species of mercury. MeHg reflected the vertical trophic guilds distribution, due to the fact that the top predator fish presented the highest concentration (0.77 μg g⁻¹ d.w.), followed by the less voracious species (0.43 μg g⁻¹ d.w.); while planktivorous fish presented the lowest concentrations (0.044 μg g⁻¹ d.w.). Hg_inorg did not present the same behavior. Results suggest that feeding habits and trophic guild are important parameters, influencing biotransference and biomagnification processes.     

Trace Metal Concentrations in Shallow Ground Water

Trace metal clean sampling and analysis techniques were used to examine the temporal patterns of Hg, Cu, and Zn concentrations in shallow ground water, and the relationships between metal concentrations in ground water and in a hydrologically connected river. Hg, Cu, and Zn concentrations in ground water ranged from 0.07 to 4.6 ng L⁻¹, 0.07 to 3.10 μg L⁻¹, and 0.17 to 2.18 μg L⁻¹, respectively. There was no apparent seasonal pattern in any of the metal concentrations. Filtrable Hg, Cu, and Zn concentrations in the North Branch of the Milwaukee River ranged from below the detection limit to 2.65 ng Hg L⁻¹,0.51 to 4.30 μg Cu L⁻¹, and 0.34 to 2.33 μg Zn L⁻¹. Thus, metal concentrations in ground water were sufficiently high to account for a substantial fraction of the filtrable trace metal concentration in the river. Metal concentrations in the soil ranged from 8 to 86 ng Hg g⁻¹, 10 to 39 μg Cu g⁻¹, and 15 to 84 μg Zn g⁻¹. Distribution coefficients, K_D, in the aquifer were 7900,22,000, and 23,000 L kg⁻¹ for Hg, Cu, and Zn, respectively. These values were three to 40 times smaller than K_D values observed in the Milwaukee River for suspended particulate matter.     

Legal protection is not enough: Posidoniaoceanica meadows in marine protected areas are not healthier than those in unprotected areas of the northwest Mediterranean Sea

Using the Conservation Index, which measures the proportional amount of dead matte relative to live Posidonia oceanica, we assessed the health of 15 P. oceanica meadows at a regional scale along the coast of Liguria (NW Mediterranean). These areas were characterized by different degrees of anthropization, from highly urbanized sites to marine protected areas. Two different scenarios were identified according to depth: in shallow zones, the health of P. oceanica meadows was related to the degree of anthropization along the coastline. In contrast, in deep zones, most meadows exhibited poor health, independent of both the degree of disturbance and the legal measures protecting the area. Working synergistically with the regional impact of increased water turbidity, local impacts from the coast were recognized as the main causes of the severe regression of most Ligurian P. oceanica meadows. We conclude that marine protected areas alone are not sufficient to guarantee the protection of P. oceanica meadows. We emphasize the need for a management network involving the Sites of Community Interest (SCIs) containing P. oceanica meadows.     

Intrabasinal conditions promoting the development of a biogenic carbonate sedimentary facies associated with the seagrass Posidonia oceanica

This paper aims to elucidate the spatial relationships between the distribution and growth dynamics of Posidonia oceanica, the sedimentary depositional facies (carbonate vs. siliciclastic), and the hydrodynamic features of the Gulf of Oristano (Western Sardinia, Mediterranean sea), a complex depositional system characterized by multiple sources of sediments and a marked hydrodynamic gradient.     

Fast and easy method for seagrass monitoring: application of acoustic telemetry to precision mapping of Posidonia oceanica beds

Posidonia oceanica is an endemic seagrass from the Mediterranean Sea. It is an indicator of water quality and of the ecological state of coastal ecosystems. The aim of this paper is to test acoustic telemetry for monitoring the position of P. oceanica meadow limits with varied types. After evaluating the accuracy of the system, we present results from a spatiotemporal survey of P. oceanica meadows on nine sites located on the French coast. The method has been demonstrated to be highly efficient for high precision underwater mapping regardless of meadow type, with 1 cm accuracy for a distance of 40 m between the base and the pointer. A temporal survey led at Cerbere-Banyuls shows a weak global progression of 4 m² (progression of 26 m² - regression of 22 m²) between 2006 and 2010. Finally, we discuss the cost and efficiency of this method, and wether it should be generalized for further studies.     

Diphenyl ether—Another marine environmental contaminant

Residues of diphenyl ether, a compound which has been used industrially for several decades, have been found in samples of seawater, lake water and snow (all in the ng I.^?1 range) and in fat from fish, a seal and a gull (all in the μg g^?1 range) collected from various points around Nova Scotia.     

Hg bioaccumulation in marine copepods around hydrothermal vents and the adjacent marine environment in northeastern Taiwan

The Hg concentration in seawater and copepod samples collected from the area around hydrothermal vents at Kueishan Island and the adjacent marine environment in northeastern Taiwan were analyzed to study Hg bioaccumulation in copepods living in polluted and clean marine environments. The seawater collected from the hydrothermal vent area had an extremely high concentration of dissolved Hg, 50.6–256 ng l⁻¹. There was slightly higher Hg content in the copepods, 0.08–0.88 μg g⁻¹. The dissolved Hg concentration in the hydrothermal vent seawater was two to three orders of magnitude higher than that in the adjacent environment. The bioconcentration factor of the studied copepods ranged within 10³–10⁶, and showed higher dissolved concentration as the bioconcentration factor was lower. A substantial abundance, but with less copepod diversity was recorded in the seawater around the hydrothermal vent area. Temora turbinata was the species of opportunity under the hydrothermal vent influence.     

Assessment of the ecological status of Mediterranean French coastal waters as required by the Water Framework Directive using the Posidonia oceanica Rapid Easy Index: PREI

This paper describes the PREI (Posidonia oceanica Rapid Easy Index), a method used to assess the ecological status of seawater along Mediterranean French coasts. The PREI was drawn up according to the requirements of the Water Framework Directive (WFD 2000/60/EC) and was tested on 24 and 18 stations in PACA (Provence-Alpes-Côtes d’Azur) and Corsica, respectively. The PREI is based on five metrics: shoot density, shoot leaf surface area, E/L ratio (epiphytic biomass/leaf biomass), depth of lower limit, and type of this lower limit. The 42 studied stations were classified in the first four levels of status: high, good, moderate and poor. The PREI values ranged between 0.280 and 0.847; this classification is in accordance with our field knowledge and with our knowledge of the literature. The PREI was validated regarding human pressure levels (r² = 0.74). (http://eurex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2000:327:0001:0072:EN:PDF).     

A comparative study of the hopanoid hydrocarbons in sediments of two lakes (Fuxian and Changdang) with contrasting environments

Biologically configured ββ-hopanes, geologically configured αβ-hopanes and the biogenic hopenes were determined in dated sediment cores from Lake Fuxian in SW China and Lake Changdang in Eastern China in order to investigate anthropogenic influences on the abundance, composition and provenance of hopanoid hydrocarbons in lake sediments. Based on the results, hopenes were prevalent, with maximum values reaching 148.9 μg g⁻¹ TOC in sediments of Lake Fuxian, an oligotrophic deep lake (average depth 89.6 m), where the long water column provided ample potential for the growth of hopene-producing bacteria especially the cyanobacteria. Sediment hopenes have diminished in abundance to values of 13.4–78.5 μg g⁻¹ TOC in Lake Changdang, a eutrophic shallow (average 0.8–1.2 m) body, reflecting comparatively reduced importance of nutrient level on hopene production. Historical trends in hopenes input to the sediments of each lake are strongly dependent on nutrient status. During the last few decades, human-induced eutrophication has greatly boosted bacterial production, enhancing the accumulation of hopenes in sediments. Inputs of petroleum-derived αβ-hopanes were exceptionally high (average 71.2 μg g⁻¹ TOC) in post-1968 sediments from Lake Changdang, their increase coinciding with the advent and acceleration of petroleum product use around the lake, in particular by fishing boats. Lake Fuxian on the other hand, has undergone slower economic development and the appearance of petroleum-derived αβ-hopanes in sediments was delayed to 1990 since when the average value has been 27.1 μg g⁻¹ TOC. The abundance of αβ-hopanes in Lake Changdang has created a marked decrease in the relative contribution of hopenes to total hopanoids since 1968. Conversely, the amounts of αβ-hopanes introduced to Lake Fuxian since 1990 has yet to yield a clear change in the overall proportion of hopenes, but the abundance of ββ-hopanes has declined relative to total hopanoid levels for the period.     

High mortality of the larvae of the common mussel at low concentrations of tributyltin

Laboratory reared veliger larvae of the common mussel Mytilus edulis were grown for 15 days in filtered seawater containing 10 μg l^?1, 1 μg l^?1 and 0.1 μg l^?1 tributyltin oxide (TBTO), the biocide in recent antifouling paint formulations. No larvae survived longer than 5 days in 10 μg l^?1 TBTO or 10 days in 1 μg l^?1 TBTO. Approximately half the larvae subjected to 0.1 μg l^?1 TBTO were dead by day 15 (approximate 15 day LC₅₀ = 0.1 μg l^?1 TBTO) and most of the surviving larvae were moribund and had grown significantly more slowly than controls. It is noted that current recorded levels of TBT at several UK estuarine sites are higher than 0.1 μg l^?1 and there has therefore probably been a high mortality of mussel larvae at such sites. The results are discussed in relation to the reported short-term toxicity of organotins to other marine organisms and the value of carrying out longer-term tests at low levels of TBT is pointed out.     

Mercury levels in selected bycatch fish species from industrial shrimp-trawl fishery in the SE Gulf of California

Baseline Hg concentration in bycatch fish from the SE Gulf of California were determined in muscle and liver of 19 species. Levels of Hg in muscle were compared with legal limits of this element in national and international legislation. Considering all fish species, mean concentrations in liver (2.458 ± 1.997 μg g⁻¹) were significantly higher (p < 0.05) than in muscle (0.993 ± 0.670 μg g⁻¹). The sequence of averaged Hg concentrations in most ichthyofauna was liver > muscle. Highest level of Hg in muscle (2.556 μg g⁻¹) and liver (7.515 μg g⁻¹) corresponded to Diapterus peruvianus and Ophioscion strabo, respectively. Considering muscle samples, none of the species had levels of Hg above the limit (1.0 μg g⁻¹ wet weight) in the Mexican legislation; with respect to the Japanese (0.4 μg g⁻¹ wet weight) and British (0.3 μg g⁻¹ wet weight) legislations, 26.3% and 31.6% of the species respectively, were above the corresponding limits.