Sequestration of metals through association with pyrite in subtidal sediments of the Nanpaishui Estuary on the Western Bank of the Bohai Sea, China

Measurements were made of the degree of trace metal pyritization (DTMP) and ancillary characteristics of four undisturbed sediment cores collected from the subtidal zone of the Nanpaishui Estuary on the Western Bank of the Bohai Sea, a seriously polluted inland sea in northeastern China. The remarkably low concentrations of organic carbon (<0.72%) in these sediments likely constrained sulfate reduction rates, and the low concentrations of acid volatile sulfide (AVS) (<12.5 μmol g⁻¹) limited the sequestration of metals through association with pyrite. The most consistent cause of inter-station differences and depth variations in the degree of pyritization was differences in pyrite metal concentrations rather than reactive metal concentrations. Reactive metal concentrations were in several cases negatively correlated with pore water concentrations, consistent with a dissolution/precipitation mechanism. The relationship between pore water metal concentrations and DTMPs was evidenced by a qualitative similarity of the inter-station variability of these same parameters.     

Influence of Mixtures of Phenols and Metals on Luminous Bacteria

The toxic action of bicomponent mixtures of phenols and heavy metals on luminous bacteria has been studied. It was established that phenolic compounds displaying properties of structural-specific agents whose influence is based on chemical reactions with receptors in mixtures with heavy metals of mercury, cadmium in low concentrations caused additive, and with the increase of metal concentration-more than additive, effects. Phenolic compounds acting as structurally-nonspecific agents (resorcinol), whose toxicity is stipulated by their physico-chemical properties, produce a less than additive effect in a mixture with heavy metals.     

Metals in Pocillopora damicornis exposed to tin smelter effluent

Metal concentrations in tissues and skeleton of the coral Pocillopora damicornis were compared from intertidal reefs adjacent to a tin smelter at Phuket, Thailand. Tissue concentrations of ten metals were significantly higher for corals collected at the tin smelter than at control reefs, 1 km distant. Elevated tissue metal concentrations were considered not to be derived from particulate material but probably from solution. Analyses of skeletal material revealed no differences in metal concentrations between study sites. The implications of elevated tissue metal concentrations are discussed in relation to reduced growth rates and low abundance of branching coral species at the reef adjacent to the tin smelter when compared to the control reefs.     

Spatial and temporal dynamics of bacterial contamination in South France coastal rivers: focus on in‐stream processes during low flows and floods

Faecal indicator bacteria (thermotolerant coliform and faecal streptococci) were enumerated in a Mediterranean coastal river to evaluate bacterial contamination levels in relation to hydrological conditions, to estimate delivery of bacterial loads to transitional and coastal waters (Thau lagoon) and to identify bacterial sources of pollution and their contribution to the bacterial flow. Results showed that (1) in low flow conditions, mean bacterial concentrations were higher than EU guidelines for bathing waters; (2) floods had higher concentrations of indicator bacteria than low flows; (3) low flow conditions represented a negligible proportion of bacterial loads compared with high flow and flood periods; (4) during medium and low flow conditions, bacteria were stored in riverbed fine sediments forming in‐stream stores that may be flushed during floods; (5) the first flush effect was highlighted during an early autumn flood as was the role of in‐stream stores during the course of the flood; and (6) point sources that continuously feed the river are contributing to the pool of bacteria accumulated in the riverbed sediment. Copyright © 2013 John Wiley & Sons, Ltd.     

Biomonitoring with benthic macroalgae and direct assay of heavy metals in seawater of the Oporto coast (northwest Portugal)

The concentrations of dissolved Cd, Cu, Hg and Pb in seawater and algae (Enteromorpha spp. and Porphyra spp.) were determined in parallel on three beaches located in the Oporto coast (Portugal), during 8 successive months, comprising periods of low and high biological productivity. The concentrations of dissolved metals in seawater varied markedly during the sampling period and exhibited seasonality. The concentrations of Cd were high in autumn and winter, but low in spring. The concentrations of Cu and Hg were high in autumn, low in winter and peaked in May. The concentrations of Pb were low in autumn and winter, and also peaked in May. It is likely that biological activity was, at least partially, responsible for the observed seasonal changes. The mean concentrations of dissolved metals in seawater were similar to those reported for polluted and industrialized european coastal areas. Metal concentration factors, calculated month-to-month for each alga, metal and site, varied markedly during the sampling period, indicating that concentration factors based on single or few determinations could be misleading. On the contrary, mean concentration factors (calculated by dividing the mean metal concentration in the algae by the mean metal concentration in seawater) were relatively constant at all three sites, indicating that in the Oporto coast, Enteromorpha spp. can be used to estimate the mean concentration of dissolved Cd, Cu and Hg in seawater, and Porphyra spp., the mean concentration of Cd, Cu and Pb. However, considering that future estimates of the concentrations of these metals in seawater should be based on determinations of the metal contents in Enteromorpha spp. and Porphyra spp. carried out on several occasions spanning a considerable period of time, the use of these algae as monitors of heavy metal pollution can have limited practical advantages over the direct assay of the metals in seawater.     

Preparative isolation and characterization of heavy metal complexes from acid mine drainage and surface wastewater

A preparative method was developed to sample dissolved organic carbon (DOC) and heavy metals (Ni, Mn) from polluted surface waters. Main focus was set on the preparative production of freeze‐dried samples mainly composed of organic ligands from heavy metal complexes. First characterizations were done in the aqueous phase. Finally, freeze‐dried samples provide stable organic matter for multiple characterizations. Acid mine drainage of the former mining area of Ronneburg (Germany) hold elevated concentrations of heavy metals and low concentrations of DOC. Municipal wastewater, passing the spoil pile, held elevated concentrations of DOC and low concentrations of heavy metals. Dissolved components smaller than 0.45 μm and larger than 1 nm were concentrated by nanofiltration. Organic heavy metal complexes were isolated from this solution by size‐exclusion chromatography (SEC). Different size classes of molecules were collected from the column effluent, depending on their elution time, and were characterized by UV spectroscopy, ICP‐OES, and DOC measurements. All samples held organic heavy metal compounds with different retention times. The organic heavy metal complexes in acid mine drainage had higher retention times than complexes from municipal wastewater. Most interestingly, we found different affinities of heavy metals to different size classes of DOC. This affinity of the heavy metals differs with size and origin of the DOC.     

Effects of the Ixtoc I blowout on heterotrophic bacteria

Heterotrophic and hydrocarbonoclastic bacteria were enumerated at the water surface and in sediment at 14 stations located in the Ixtoc I area. The distribution of heterotrophic bacteria in water and in sediment seems to be influenced by the river waters and the characteristics of sediments. The concentrations of hydrocarbonoclastic bacteria in sediments are low, and their relative percentage in regard to the heterotrophic bacteria, which are in general less than 1%, lead us to believe that the area studied was not affected by the Ixtoc I blowout.     

Sponges and sediments as monitoring tools of metal contamination in the eastern coast of the Red Sea, Saudi Arabia

Sediments and sponges were collected from various locations along the eastern coast of the Red Sea, the Kingdom of Saudi Arabia. Total concentrations of Cd, Zn, Ag, Cu, Pb, As and Hg in the sediments were measured. Metal contamination was not significant in most of the studied sites and only one site was moderately polluted by Zn, Cu, and Pb. Sponges accumulated specific metals readily even though the metal exposure was low in the ambient environment. Contrasting interspecies differences in metal accumulation patterns were observed among the nine collected species of sponges. Significant positive correlations were found between the metal concentrations in the two species of sponges collected from the same sites. The strong ability to accumulate specific metals and the diversity of sponges that live in the Red Sea coastal areas make them a promising biomonitor of metal contamination in the areas.     

Tissue distribution of heavy metals in Weddell seals (Leptonychotes weddellii)

Tissue distributions of heavy metals were investigated in the Weddell seal collected around Syowa Station, Antarctica. Generally, the metal concentrations were high in liver and kidney and low in brain, blubber and skin. Fe in blood and spleen, Zn in bone, and Mn and Cd in pancreas and gastrointestinal organs were also relatively high. Wide variations of the metal concentrations in different bones were also observed. The concentrations of Fe and Cd were positively correlated with moisture content of the bones, while those of Mn and Zn increased with increase of Ca content in the bone. Majority of the metal burden in the body existed in muscle and liver. A relatively high burden of Cd was in the kidney. Based upon these results, the suitability of the tissues of a seal for ecological and toxicological comparisons is discussed.     

Potential of Common Well Casing Materials to Influence Aqueous Metal Concentrations

Static leaching and sorption laboratory studies were performed to assess the potential of polyvinyl chloride (PVC), polytetrafluoroethylene (PTFE), and two types of stainless steel (SS 304 and SS 316) well casing materials to influence metal concentrations in ground water solutions with low dissolved oxygen. Overall, PTFE was inert, whereas one or both stainless steels significantly altered the solution concentrations of Cd, Cr, Cu, Pb, Fe, and Ni. PVC was generally more reactive than PTFE, but did not significantly alter the solution metal concentrations as often, or as greatly, as either of the stainless casings.     

The toxicity of marine sediments in Victoria Harbour, Hong Kong

When the toxicity of marine sediment in Hong Kong was evaluated, it was found that the seven sediments collected within Victoria Harbour were severely contaminated with heavy metals, at concentrations many times higher than those in sediments collected from outside the harbour. The highest metal content was recorded in site VS14 (located near the airport runway and the industrialized area), with copper, zinc, lead and chromium values of 3789, 610, 138 and 601 mg kg⁻¹ dry wt, respectively. This site also had the greatest alkaline phosphatase activities (15 fluorescent intensity unit g⁻¹ wet wt), the largest number of total coliforms (910 CFU g⁻¹ wet wt) and sulphate-reducing bacteria (8.5 × 10⁴ cells g⁻¹ wet wt), implying that site VS14 was also contaminated with organic matter and nutrients. Sediment bioassays, Microtox and algal tests, demonstrated that sediment elutriates obtained from site VS14 were of greatest toxicity. The EC₁₀ value in Microtox tests was 17% elutriate, and the 96-h IC₅₀ values using Skeletonema costatum and Dunaliella tertiolecta were 40 and 79% elutriate, respectively. No toxic effects were found in sediment samples collected from the control site outside Victoria Harbour. Significant correlations were found between the results of the algal toxicity test (using S. costatum) and the coliform count and metal content of the sediments. The Microtox test was less sensitive than the algal bioassay, and no sediment elutriate, even from the site mostly contaminated by heavy metals, caused more than 50% inhibition of the light-emitting activity of the bacteria. In this study, S. costatum (the diatom) provided a more sensitive and reliable test species than D. tertiolecta (the flagellate) in differentiating the toxicity of marine sediments.     

Photosynthetic pigments and peroxidase activity as indicators of heavy metal stress in the Grey mangrove, Avicennia marina (Forsk.) Vierh

Mangroves have been observed to possess a tolerance to high levels of heavy metals, yet accumulated metals may induce subcellular biochemical changes, which can impact on processes at the organism level. Six month-old seedlings of the grey mangrove, Avicennia marina (Forsk.) Vierh, were exposed to a range of Cu (0-800 micrograms/g), Pb (0-800 micrograms/g) and Zn (0-1000 micrograms/g) concentrations in sediments under laboratory conditions, to determine leaf tissue metal accumulation patterns, effects on photosynthetic pigments (chlorophyll a, chlorophyll b and carotenoids), and the activity of the antioxidant enzyme peroxidase. Limited Cu uptake to leaves was observed at low sediment Cu levels, with saturation and visible toxicity to Cu at sediment levels greater than 400 micrograms/g. Leaf Pb concentrations remained low over a range of Pb sediment concentrations, up to 400 micrograms/g Pb, above which it appeared that unrestricted transport of Pb occurred, although no visible signs of Pb toxicity were observed. Zn was accumulated linearly with sediment zinc concentration, and visible toxicity occurring at the highest concentration, 1000 micrograms/g Zn. Significant increases in peroxidase activity and decreases in photopigments were found with Cu and Zn at concentrations lower than those inducing visible toxicity. Significant increases in peroxidase activity only, were found when plants were exposed to Pb. Positive linear relationships between peroxidase activity and leaf tissue metal concentrations were found for all metals. Significant linear decreases in photosynthetic pigments with increasing leaf tissue metal concentrations were observed with Cu and Zn only. Photosynthetic pigments and peroxidase activity may be applicable as sensitive biological indicators of Cu and Zn stress, and peroxidase activity for Pb stress in A. marina.     

Microbial modulation in the biomass and toxin production of a red-tide causing alga

The effect of S₁₀, a strain of marine bacteria isolated from sediment in the Western Xiamen Sea, on the growth and paralytic shellfish poison (PSP) production in the alga Alexandrium tamarense (A. tamarense) was studied under controlled experimental conditions. The results of these experiments have shown that the growth of A. tamarense is obviously inhibited by S₁₀ at high concentrations, however no evident effect on its growth was observed at low concentrations. Its PSP production was also inhibited by S₁₀ at different concentrations, especially at low concentrations. The toxicity of this strain of A. tamarense is about (0.95–12.14) × 10⁻⁶ MU/cell, a peak toxicity value of 12.14 × 10⁻⁶ MU/cell appeared on the 14th day, after which levels decreased gradually. The alga grew well in conditions of pH 6–8 and salinities of 20–34‰. The toxicity of the alga varied markedly at different pH and salinity levels. Toxicity decreased as pH increased, while it increased with salinity and reached a peak value at a salinity of 30‰, after which it declined gradually. S₁₀ at a concentration of 1.02 × 10⁹ cells/ml inhibited growth and the PSP production of A. tamarense at different pH and salinity levels. S₁₀ had the strongest inhibitory function on the growth of A. tamarense under conditions of pH 7 and a salinity of 34‰. The best inhibitory effect on PSP production by A. tamarense was at pH 7, this inhibitory effect on PSP production did not relate to salinity. Interactions between marine bacteria and A. tamarense were also investigated using the flow cytometer technique (FCM) as well as direct microscope counting. S₁₀ was identified as being a member of the genus Bacillus, the difference in 16S rDNA between S₁₀ and Bacillus halmapalus was only 2%. The mechanism involved in the inhibition of growth and PSP production of A. tamarense by this strain of marine bacteria, and the prospect of using it and other marine bacteria in the bio-control of red-tides was discussed.     

Denitrifying bacteria and hydrogeochemistry in a natural wetland adjacent to farmlands in Chiba,Japan

This study combined bacterial incubation and hydrogeochemical methods to investigate denitrification in the surface water, top soil (0–20 cm), and shallow groundwater of the Ochi wetland in Japan. Surface water was rich in nitrate (40 mg/l) and denitrifying bacteria (700 per ml). Three functional zones in the wetland were identified in the top soil and shallow groundwater. In the upstream portion of the wetland (Zone I), the counts of denitrifying bacteria in top soil increased from 5200 to 14 970 per ml and nitrate decreased from 25·4 to 1·8 mg/l. Organic carbon concentrations decreased as sulfate increased from 4·0 to 9·6 mg/l in this zone. In the middle‐stream of the wetland (Zone II), all concentrations of major anions, iron, organic carbon, and total nitrogen content in top soil were relatively constant, but the counts of denitrifying bacteria increased up to 70 200 per ml. In the downstream portion of the wetland (Zone III), complete removal of nitrate resulted in sharp reduction of counts of denitrifying bacteria. Correspondingly, dissolved oxygen (DO), organic carbon, and total nitrogen increased in this zone. Counts of denitrifying bacteria were lower in shallow groundwater than in top soil; nitrate concentrations in shallow groundwater were also very low in this zone. DO and the oxidation/reduction potential data suggest that groundwater flows to the surface along an extended flow path, thus providing nitrate for the denitrifying community. Copyright © 2011 John Wiley & Sons, Ltd.     

Fate of copper and cadmium in a sediment-water system,and effect on chitin degrading bacteria

Fate and effect of copper and cadmium on the degradation of chitin were studied in sediment microcosms. Artificial sediment was spiked with metals, and metal partitioning between sediment components, overlying water and bacteria was described. Most of the added metals were bound to sediment particles. Remarkable metal enrichments were found on Fe-oxide, Mn-oxide, and chitin. In sediments containing the nominal concentration of 100 mg/kg Cu, the chitin-degrading bacteria Cytophaga johnsonae showed a significant decrease in N-acetylglucoseaminidase activity. Toxicity of copper was attributed to free ions in the overlying water. The bacteria were more sensitive to copper than to cadmium. Inhibitory effects of cadmium were primarily caused by sediment-associated cadmium.     

Limnological studies on a shallow reservoir in western Venezuela (Tulé Reservoir)

Limnological features of Tulé Reservoir, a large and shallow reservoir in western Venezuela were studied from May 1992 to December 1993. This reservoir is polymictic, with a low water transparency. Levels of nitrogen were high and phytoplankton productivity was low. The phytoplankton productivity values may be explained by the low concentrations of orthophosphate during the larger part of the sampling period and the frequent mixing and resuspension of sediments. Heterotrophic bacteria were between 1651.67 and 4365.00 Colony-forming Units/ml. Species composition of the crustacean zooplankton community was similar to other neotropical eutrophic reservoirs.     

A Screening Procedure for Heavy Metals in Soil Extracts by Alcohol Dehydrogenase and Urease Inhibition Eine Screening-Methode für Schwermetalle in Extrakten aus Bodenproben,basierend auf der Inhibierung der Enzyme Alkoholdehydrogenase und Urease

A screening method for heavy metals in aqueous extracts of soil is presented which is based on inhibition of the enzymes urease and alcohol dehydrogenase. The method is suitable to detect cupric and mercury ions in concentrations below 0.01 mg/L and several other heavy metal ions in 1000 fold higher concentration. It is shown that the test may be used for screening of mercury ion concentrations exceeding 0.03 mg/L in aqueous solution when copper chelators are added to the test system. The usefulness of the presented tests to detect heavy metals eluted from soil was verified with samples from ore mining waste. The concentration of copper, lead, and zinc eluted from these samples to different amount was determined by atomic absorption spectrometry and was in good agreement with the enzyme inhibition data obtained with these samples.     

Reconstructing floodplain sedimentation rates from heavy metal profiles by inverse modelling

The embanked floodplains of the lower River Rhine in the Netherlands contain large amounts of heavy metals, which is a result of many years deposition of contaminated overbank sediments. Depending on local sedimentation rates and changing pollution trends in the past, the metal pollution varies greatly between different floodplain sections as well as vertically within the floodplain soil profiles. Maximum metal concentrations in floodplain soils vary from 30 to 130 mg/kg for Cu, from 70 to 490 mg/kg for Pb and from 170 to 1450 mg/kg for Zn. In the present study these metals were used as a tracer to reconstruct sedimentation rates at 28 sites on the lower River Rhine floodplains. The temporal trend in pollution of the lower River Rhine over the past 150 years was reconstructed on the basis of metal concentrations in sediments from small ponds within the floodplain area. Using a one‐dimensional sedimentation model, average sedimentation rates over the past century were determined using an inverse modelling calibration procedure. The advantage of this method is that it uses information over an entire profile, it requires only a limited number of samples, it accounts for post‐depositional redistribution of the metals, and it provides quantitative estimates of the precision of the sedimentation rates obtained. Estimated sedimentation rates vary between about 0·2 mm/year and 15 mm/year. The lowest metal concentrations are found in the distal parts of floodplain sections with low flooding frequencies and where average sedimentation rates have been less than about 5 mm/year. The largest metal accumulations occur in low‐lying floodplain sections where average sedimentation rates have been more than 10 mm/year. Copyright © 2002 John Wiley & Sons, Ltd.     

MELIMEX,an experimental heavy metal pollution study: Behaviour of heavy metals in an aquatic food chain

Phytoplankton, periphyton and zooplankton samples, chironomid andSialis sp. larvae, and fry of trout and bream collected from unpolluted and artificially metal-polluted limno-corrals were analyzed for mercury, copper, cadmium, zinc and lead. The results indicate that these metals are not accumulated through the food chain and suggest that increased metal concentrations in the environment favor the growth of phytoplankton organisms with a low metal sorption capacity.     

Evaluations of heavy metal pollution in sediment and Mullus barbatus from the Izmir Bay (Eastern Aegean) during 1997-2009

Izmir Bay is one of the great natural bays of the Mediterranean. The surface sediment and fish samples were collected during 1997-2009. The sediment concentrations of inner bay showed significant enrichments during sampling periods. Outer and middle bays exhibited low levels of metal enrichments except the estuary of Gediz River. The concentrations were generally higher than the background levels from the Mediterranean and Aegean except Cd and Pb levels gradually decreased. Metal EF is used as an index to evaluate anthropogenic influences of metals in sediments. Maximum metal enrichment was found for Hg in the outer bay, while Pb indicated maximum enrichment in the middle-inner bays. Metal levels were evaluated in sediments in accordance with the numerical SQG of the USEPA. The levels of fish tissues were lower than the results reported from polluted areas of the Mediterranean. The highest BAFs were detected for Hg and Cd in fish.