Cu In Sediments Research Articles

Effects of ecological restoration on speciation and release of copper in lake sediments

The conclusion about the effect of macrophytes rhizosphere and mollusks bioturbation on morphology and mobility of heavy metals in the sediments is not entirely consistent. It is necessary to study further on influence mechanism of macrophytes growth and macrobenthos bioturbation on speciation and release of heavy metals in natural water body. This study intends to explore the influence mechanism of Bellamya aeruginosa (Bel) bioturbation and Pontederia cordata (Pon) growth on the speciation and release kinetics of Cu in sediment through construction of an aquatic organism-water-sediment system by indoor potted experiment. The results show that the particulate Cu in water of the control group and Pon treatment always maintain in lower level and the particulate Cu concentration in water of Bel treatment and Pon+Bel treatment appeared to a certain level of fluctuations at latter period. There was a significant positive correlation between the content of particulate Cu in water and the water turbidity. Bellamya aeruginosa bioturbation has not significantly affected the different speciation of heavy metals in surface sediments and the concentration of reducible Cu and Zn in the rhizosphere sediment was significantly lower than that in the control group.

The single or combined effects of Suaeda heteroptera and Nereis succinea on the distribution of different Cu forms in sediments

Bioavailability of copper(II) to Suaeda heteroptera and Nereis succinea was analyzed in this paper by comparing the concentrations of the copper (Cu) chemical forms in sediments to the Cu concentrations in the tissues of S. heteroptera and N. succinea. The morphological distribution of heavy metals in the sediment was related to the concentration of Cu added to the sediment. In the S. heteroptera treatment groups, available Cu in sediments decreased, and N. succinea activities improved the sediment physical and chemical properties, and thus increased the bioavailable Cu for S. heteroptera uptake. The Cu contents reached 160.75mg/kg in S. heteroptera and 2801.4mg/kg in N. succinea. When S. heteroptera and N. succinea were combined, significantly more Cu was removed from the sediments than for the two working separately. Therefore, the existence of N. succinea could enhance the absorption of Cu in the coastal sediment planted with S. heteroptera and had a positive impact on environmental pollution.

A new bioindicator, shell of Trachycardium lacunosum, and sediment samples to monitors metals (Al, Zn, Fe, Mn, Ni, V, Co, Cr and Cu) in marine environment: The Persian Gulf as a case.

BackgroundThe present work was designed to detect heavy metal contents of Al, Zn, Fe, Mn, Ni, V, Co, Cr and Cu in sediments and shells of the Trachycardium lacunosum collected in polluted and unpolluted areas along the Persian Gulf.MethodsThe samples were taken from surface sediments (0-10 cm) and shells of Trachycardium lacunosum in two separated areas (polluted and unpolluted) in northern part of the Persian Gulf, Asaluyeh Bay, during summer 2013. The prepared samples were analyzed by inductively coupled plasma-optical emission spectrometry (ICP-OES).ResultsBased on the results, all measured metals including Al, Zn, Fe, Mn, Ni, V, Co, Cr and Cu were meaningfully higher in the sediment samples of polluted area compared to unpolluted area and the order of metal concentrations in the sediment samples were Cr > Co > V > Ni > Zn > Cu > Fe > Al > Mn in polluted area. In the case of shell samples of Trachycardium lacunosum, polluted area contained significantly higher contents of Al, Zn, Fe, Mn, Ni, Co, Cr and Cu compared to unpolluted area and the order of metal concentrations in the shell samples were Fe > Zn > Al > Mn > Cu > Cr > Ni > Co in the polluted area.ConclusionIt was concluded that shells of the Trachycardium lacunosum can be used as a suitable bioindicator for heavy metals in the aquatic environment. Results confirmed that due to the possible contaminations by oil and gas activities near the polluted area perennial monitoring and mitigation measures is extremely necessary.

Assessment of the use of copper alloy aquaculture nets: Potential impacts on the marine environment and on the farmed fish

The environmental effects of the copper aquaculture nets were estimated by a multidisciplinary approach. A copper alloy net (brass net) cage and a conventional net cage with Cu2O antifouling paint were established at a fish farm in Bathy Limani Bay, Paleros, Aetolia Acarnania region, Greece, for a 1-year period. Copper concentrations in abiotic (water, sediment, particulate matter) and biotic (organisms) samples were measured. The biological effects of copper on organisms (mussels, farmed fish) were further assessed with a battery of biochemical biomarkers (acetylcholinesterase, catalase, glutathione-S-transferase, metallothioneins). During the first 6months of cage installations, the copper alloy (brass) net seemed to release more Cu to the surrounding environment and affect the biota more compared to the conventional net, although non-significant correlations were found between biotic and abiotic variables. However, at the end of the experimental period, equilibrium was reached in the copper alloy (brass) net cage with similar values of dissolved Cu and Cu in organisms as the conventional net cage. An exception to these results was the sampling of August 2013, where an increased effect on water chemistry and mussels in the conventional cage was observed, which may be attributed to the use of antifoulants on the examined conventional net or on the surrounding conventional nets. No accumulation of Cu in sediment was detected. No consistent temporal or spatial trend was observed for biochemical biomarkers. In addition, for both experimental cages and in all sampling periods, dissolved Cu never reached the maximum permissible limits in the Greek legislation, and Cu concentrations in the farmed fish and mussels do not exceed established limits for edible parts set by Food and Agriculture Organization of the United Nations (FAO). Statement of relevanceIn this manuscript, a set of methodological tools and indicators were studied in order to assess the potential impacts of the use of copper alloy aquaculture nets on farmed fish and, eventually, the marine environment of the Mediterranean Sea. The authors believe that the aim of this work is within the journal's scope and the presented results, analysis and interpretation will be of interest to scientists involved in various aspects of aquaculture (management, environmental pollution, ecotoxicology, food safety etc.).

Nano-TiO2 affects Cu speciation, extracellular enzyme activity, and bacterial communities in sediments

In aquatic ecosystems, titanium dioxide nanoparticles (nano-TiO2) coexist with heavy metals and influence the existing forms and toxicities of the metal in water. However, limited information is available regarding the ecological risk of this coexistence in sediments. In this study, the effect of nano-TiO2 on Cu speciation in sediments was investigated using sequential extraction. The microcosm approach was also employed to analyze the effects of the coexistence of nano-TiO2 and Cu on extracellular enzyme activity and bacterial communities in sediments. Results showed that nano-TiO2 decreased the organic matter-bound fraction of Cu and increased the corresponding residual fraction Cu. As a result, speciation of exogenous Cu in sediments changed. During the course of the 30-day experiment, the presence of nano-TiO2 did not affect Cu-induced changes in bacterial community structure. However, the coexistence of nano-TiO2 and Cu restrained the activity of bacterial extracellular enzymes, such as alkaline phosphatase and β-glucosidase. The degree of inhibition also varied because of the different properties of extracellular enzymes. This research highlighted the importance of understanding and predicting the effects of the coexistence of nanomaterials and other pollutants in sediments.

Bioavailability of Pb and Cu in Sediments of Vegetated Seagrass, Enhalus acoroides, from Spermonde Islands, Makassar, South Sulawesi, Indonesia

Seagrass might impact metal bioavailability in sediments with physiological processes that occur at the root and rhizome. Seagrass growth may increase bioavailability due to oxygen transport from leaves to the root systems. This study aims to analyze the concentrations of bioavailable Pb and Cu in sediments with and without seagrass. This study was done at two sites in Spermonde Islands, South Sulawesi, Indonesia. All metals analysis and sediment parameters were conducted on dry, <63 μm grain size sediment samples. Metal speciation in sediment was determined using the Community Bureau of Reference (BCR) three steps sequential that extract exchangeable and acid soluble fraction, reducible and oxidisable fraction. The average concentrations of bioavailable fraction of Pb and Cu (fraction 1) was higher in vegetated sediments associated with Enhalus acoroides than in unvegetated sediments. Higher concentration of Cu in fraction 1 was also associated with higher concentration in Enhalus roots. This indicates that the presence of seagrass may increase the bioavailability of metals in sediments. Increased metal bioavailability in vegetated sediment will imply increase toxicity.

Geochemical speciation and risk assessment of metals in the river sediments from Dan River Drainage, China

ABSTRACTThis study investigates the partitioning of metals in surface sediments from the Dan River drainage basin, the source of drinking water for the South to North Water Transfer Project, China, to determine their bioavailability and associated levels of risk. Sediment samples were collected from 99 sites along the Dan River, and the concentration of each element fraction was determined using sequential extraction and inductively coupled plasma-mass spectrometry. The residual fraction was the major phase for most metals sampled. Among the non-residual fractions, greater proportions of Zn, Mn and Cd were transported in in the available phase, whereas Ba, Sb, Pb and As were mainly found in the reducible phase. The oxidisable phase was important for the transport of Ni, Co, Cr and Cu in sediments. This analysis of sediments from the Dan River basin indicates a very high risk of pollution from Cd, Co, Mn, Sb and Zn. Combined with the sediments with extremely high concentrations, the Dan, Laoguan and Yinhua rivers, which have been affected by ore-mining activities, pose a very high risk to the surrounding areas and should be the subject of future studies.

Correlations between Geo-Chemical Speciation of Heavy Metals (Cu, Zn, Pb, Cd and Ni) in Surface Sediments and Their Concentrations in Giant Mudskipper (&amp;lt;i&amp;gt;Periophthalmodon schlosseri&amp;lt;/i&amp;gt;) Collected from the West Coast of Peninsular Malaysia

Surface sediments and giant mudskipper (Periophthalmodon schlosseri) were collected in August and September 2008 and in March and June 2010 from six sampling sites in the west coast of Peninsular Malaysia to assess heavy metals accumulation in the giant mudskipper. Sequential extraction technique was used to fractionate the sediments into four different geo-chemical fractions; easily, freely or leachable and exchangeable (EFLE), acid reducible, oxidizable organic and resistant fractions. Heavy metals concentrations (Cu, Zn, Pb, Cd and Ni) in the surface sediments and giant mudskipper were determined by using air acetylene flame atomic absorption spectrophotometer (AAS) Perkin Elmer Analyst 800. The results of Pearson’s correlation analyses showed that metal concentrations in the tissues of P. schlosseri were significantly correlated (p p P. schlosseri and Cu in the sediment (oxidisable-organic, resistant and total Cu), Zn in P. schlosseri and Zn in the sediment (EFLE and total Zn), Pb in P. schlosseri and Pb in the sediment (with all the four fractions of Pb), Cd and Ni in P. schlosseri and Cd and Ni in the sediment (with all fractions of Cd and Ni except acid-reducible Cd and Ni) which might suggest the use of P. schlosseri as a biomonitoring agent for heavy metals pollution in the west coast of Peninsular Malaysia.

Spatial Evaluation of Heavy Metals Concentrations in the Surface Sediment of Taihu Lake.

With regard to the size of China’s freshwater lakes, Taihu Lake ranks third and it plays an important role in the supply of drinking water, flood prevention, farming and navigation, as well as in the travelling industry. The problem of environmental pollution has attracted widespread attention in recent years. In order to understand the levels, distribution and sources of heavy metals in sediments of Taihu Lake, random selection was carried out to obtain 59 samples of surface sediment from the entire lake and study the concentrations of Pb, Cd, Cu, Zn, Cr and Ni. Toxic units were also calculated to normalize the toxicities caused by various heavy metals. As a result, Cd and Cu in sediment were considered lower than the effect range low (ERL) at all regions where samples were gathered, while Pb and Ni were categorized into ERL-effect range median (ERM) at over 22% of the regions where samples were obtained. Nevertheless, all average concentrations of the samples were below the level of potential effect. According to the findings of this research, significant spatial heterogeneity existed in the above heavy metals. In conclusion, the distribution areas of heavy metals with higher concentrations were mainly the north bays, namely Zhushan Bay, Meiliang Bay as well as Gonghu Bay. The distribution areas of Cu, Zn, Cr and Ni with higher concentration also included the lake’s central region, whereas the uniform distribution areas of those with lower concentrations were the lake’s southeast region. In addition, it was most probable that the spatial distribution of heavy metals was determined by river inputs, whereas atmospheric precipitation caused by urban and traffic contamination also exerted considerable effects on the higher concentrations of Pb and Cd. Through evaluating the total amount of toxic units (ΣTU), it was found that higher toxicity existed primarily in the north bays and central region of the lake. If the heavy metals were sorted by the reduction of mean heavy metal toxic units in Taihu Lake in descending order, it would be Pb, Cr, Ni, Cd, Zn and Cu. Generally speaking, these result of analyses are conducive to alleviating the contamination of heavy metals in Taihu Lake.

Heavy metal spatial variation, bioaccumulation, and risk assessment of Zostera japonica habitat in the Yellow River Estuary, China

Globally, seagrass habitats are decreasing due to both natural and environmental contaminations by human activities, including heavy metal pollution. To expand the global seagrass detection network, this study reports the spatial distributions of Zostera japonica seagrass habitats in the Yellow River Estuary, China. In addition, heavy metal concentrations of Z. japonica tissue, sediment, and surface seawater were analyzed to determine the bioaccumulation and consequent ecological risk to Z. japonica habitats due to the effects of heavy metals. It was found that concentrations of heavy metals were 1.00–2.03 times higher in seagrass-rooted sediment than in adjacent non-seagrass sediment, except for Mn (with a factor of 0.99). Pb and Hg concentrations in sediments exceeded background values more than the other heavy metals, by factors of 1.74 and 1.24, respectively. Metal concentrations in the surrounding seawater were 2.60–4.63 times higher at seagrass sites than at non-seagrass sites, except for Hg (factor of 0.97). Metal concentrations were much higher in seagrass tissues than in the sediment (e.g., bioconcentration factor of Cd is 30.95). Pb concentrations in water may cause the greatest adverse reactions among aquatic organisms, while As, Cr, Hg, Mn and Cu in sediments may occasionally cause negative ecological effects. Z. japonica showed higher bioaccumulation of Cd and Pb in the above-ground tissues. Among other recent studies of seagrasses from other parts of the world, Cd concentrations are similar to the results of the present study, but Pb concentration in present study is higher than in other studies. In conclusion, Pb and As in the surrounding environment present potential risks to the seagrass habitats of the Yellow River Estuary, China.

Copper Sediment Toxicity and Partitioning during Oxidation in a Flow-Through Flume.

The bioavailability of transition metals in sediments often depends on redox conditions in the sediment. We explored how the physicochemistry and toxicity of anoxic Cu-amended sediments changed as they aged (i.e., naturally oxidized) in a flow-through flume. We amended two sediments (Dow and Ocoee) with Cu, incubated the sediments in a flow-through flume, and measured sediment physicochemistry and toxicity over 213 days. As sediments aged, oxygen penetrated sediment to a greater depth, the relative abundance of Fe oxides increased in surface and deep sediments, and the concentration of acid volatile sulfide declined in Ocoee surface sediments. The total pool of Cu in sediments did not change during aging, but porewater Cu, and Cu bound to amorphous Fe oxides decreased while Cu associated with crystalline Fe oxides increased. The dose-response of the epibenthic amphipod Hyalella azteca to sediment total Cu changed over time, with older sediments being less toxic than freshly spiked sediments. We observed a strong dose-response relationship between porewater Cu and H. azteca growth across all sampling periods, and measurable declines in relative growth rates were observed at concentrations below interstitial water criteria established by the U.S. EPA. Further, solid-phase bioavailability models based on AVS and organic carbon were overprotective and poorly predicted toxicity in aged sediments. We suggest that sediment quality criteria for Cu is best established from measurement of Cu in pore water rather than estimating bioavailable Cu from the various solid-phase ligands, which vary temporally and spatially.

DISTRIBUTION OF HEAVY METALS IN NATUNA COASTAL WATERS

ABSTRACTThe study of Pb, Cd, Cu, Hg, and As and Fe in Natuna coastal waters, Riau Islands was conducted in November 2012. Water and sediment samples were collected from 35 stations by purposive sampling method and those heavy metals were analysed using Atomic Absorption Spectrophotometer, flame type (FAAS). The results showed that concentrations of total Pb, Cd, Cu, Hg, and As in surface water were below instrument detection limit (2 µg/L for Pb, Cd, and Cu; 0.02 µg/L for Hg and As). Moreover, the concentration of metal Fe in surface water was 0.021-0.054 mg/L. Concentrations of Pb and Cu in sediment were 0.05-22.67 mg/kg and 3.77-11.00 mg/kg, respectively, at which the highest concentrations were found near Binjai Estuary. Those concentrations were significantly below the standard levels set by CCME (2002) and ANZECC/ARMCANZ (2000). Concentration of Fe in sediment varied from 751.13-2309.12 mg/kg and showed similar spatial distribution to Cu-in-sediment. No standard level for Fe in waters was available. Generally, it can be concluded that Natuna coastal water was still uncontaminated. Keywords: heavy metals, iron metal, Natuna coastal waters.

An assessment of the effects of hospital wastes released to Nilwala river, Matara

Wastewater from hospitals either treated or partially treated can alter water quality and biological diversity in adjacent water. This study focused to assess effects of hospital wastes discharged from the General Hospital Matara to the Nilwala River. Two sampling sites were located upstream of the entrance of wastewater while two sites were located downstream of the entrance of wastewater discharge and one site was selected at the entrance of the wastewater channel. Water, sediment and plankton samples were collected biweekly during February to April, 2012. Nitrate, phosphate, pH and Cu concentrations in water sampled from the hospital wastewater discharging canal were significantly (One-way ANOVA, p&lt;0.05) different from the other sampling sites. However, Cu concentration in surface water did not exceed the EU limits of 0.0005-0.112mg/l for fisheries and aquatic life and similarly water pH did not exceed the maximum allowable limit (6-8.5) for fisheries and aquatic life in Sri Lanka. Mean concentration of Cu in sediment collected at the entrance of the wastewater channel was 0.75±0.05 mg/g dw. Although total coliform concentration (MPN/100ml) did not vary significantly among the sampling sites, it was relatively low (39.66±17.7) at the waste discharging canal due to the presence of disinfectants in hospital wastewater. Pediastrum simplex was the most abundant phytoplankton species at all the five sampling sites. Cladocera was the most abundant group of zooplankton in all the sites except at the entrance of wastewater discharging canal and Protozoa was the most abundant group present at the wastewater discharging canal. According to rotated matrix of Principle Component Analysis (PCA) water pH, PO4−3, NO3−, TDS, Salinity and Zooplankton abundance can be considered as important parameters at the study site of wastewater entrance (site 3). The toxicity (72h EC50) of hospital wastes on Pediastrum simplex was 0.08 Toxic Units (TU) and it was not an acute toxic effect on the alga when compared with hazard classification systems for wastes discharge into the aquatic environment. DOI: http://dx.doi.org/10.4038/jur.v2i1-2.7852 J. Univ. Ruhuna 2014 2:33-39

Environmental Risk Assessment of Mn, Cu and Fe in the Lam Takhong Reservoir, Nakhon Ratchasima Province, Thailand

Recently, usage of the metal-based pesticide especially manganese (Mn) and copper (Cu) have been widely used in the agricultural area around the Lam Takhong Reservoir; the major water resource of Nakhon Ratchasima Province and the Southern I-Sarn. The exposures of these metals can causes neurological and Parkinson diseases. Therefore the objectives of this study were to investigate Mn, Cu, and Fe contaminations in the reservoir as well as the environmental risks by using hazard quotient (HQ). The results showed that the average concentrations of Mn, Cu, and Fe in water column were 0.05 mg/l, 0.01 mg/l, 0.39 mg/l in dry season and 0.08 mg/l, 0.01 mg/l, 0.53 mg/l in wet season, respectively. Mn and Cu concentrations were in normal range except those of Fe that were extremely high. Also, Mn and Cu in sediment were found in the normal range. Interestingly, high concentrations of Fe in sediment were found at many stations with respect of the parent materials in this area. Fortunately, there were no risks of Mn and Cu in both water column and sediment. However, Fe in sediment exceeded the recommended guideline. These results suggested that using Mn/Cu-based synthetic pesticides in this area might be limited with respect of Fe abundance that could enhanced the toxicity of Mn/Cu and might increased the incidents of neurological and Parkinson diseases.

Characterization of interaction between different adsorbents and copper by simulation experiments using sediment-extracted organic matter from Taihu Lake, China

The complex capacity of different types of organic matters (OMs) for Cu was quantitatively studied by simulation experiments using different adsorbents prepared from the sediment in Taihu Lake. The free Cu was measured with ion selective electrode (ISE) and complex capacity was calculated using a conditional formation constant model. The result indicated that the complex capacity was 0.048 mmol·g−1, 0.009 and 0.005 mmol·g−1for raw sediment, sediment without DOM, sediment without insoluble organic matters but with DOM and sediment without OM. Insoluble organic matter played a major role in the sorption of Cu in sediment and it can adsorb most Cu from water column. In the solution, Cu mainly existed as a complex with DOM and the DOM-Cu complexation capacity was 327.87 mg·g−1. The change of TOC and pH indicated ion-exchange in the interaction between free Cu and DOM. When the Cu concentration in the experiment reached the complex capacity of DOM, precipitation was the major mechanism to remove Cu from water phase, which was observed from UV absorbance change of DOM, that is, its aromaticity increased while molecular weight decreased. The desorption result indicated that DOM was more capable of desorbing Cu from adsorbents without OM than adsorbent with OM. The desorbed quantity with DOM was 1.65, 1.78 and 2.25 times higher than that with water for adsorbents without OM, raw adsorbents (sediment) and adsorbents without DOM.

Copper use and accumulation in catfish culture in the Mekong Delta, Vietnam

Aquaculture of Pangasius hypophthalmus (striped catfish) in Vietnam reached 1.1 million tonnes in 2011 and catfish fillets are exported worldwide. The intensive cultures of catfish mainly in earth ponds have made it necessary to apply CuSO4 and other chemicals to control external parasites and other pathogens. However, accumulation of Cu in aquaculture ponds may pose a hazard to growth of fish or to the aquatic environment. The aim of this study was to determine accumulation of Cu in sediment, water and fish in a catfish pond with a history of repeated treatment with CuSO4 in the Mekong Delta, Vietnam. Copper concentrations in pond sediment were in the interval 21.3–45.7 mg kg−1 dw and did not exceed the Vietnamese values for soil to be used for agricultural production (70 mg kg−1 dw.). During three samplings the total mean concentration of Cu in pond water (4 μg L−1) did not exceed the LC50-value (70 μg L−1) for catfish and the mean dissolved concentration of Cu (0.986 μg L−1) did not seem to constitute a risk for the stability of the aquatic ecosystem. No significant variation in Cu concentrations between sampling sites in the pond and depth of sediment profile were determined. The accumulation of Cu in catfish was highest in the liver compared to the skin, gills and muscle tissue. With the current practice of removing pond sludge three to four times during a production cycle little if any Cu seems to accumulate in catfish ponds despite repeated anti-parasite treatments with CuSO4. Further studies are needed to assess the eco-toxicity and impact on agricultural production when pond sediment is discharged into aquatic recipients and used as soil fertilizer.

Effects of post-fire soil stabilisation techniques on trace elements lost by erosion

The effect of two post-fire stabilisation techniques (Seeding and Mulching) on trace element (Al, B, Co, Cu, Fe, Mn, Mo and Zn) losses with eroded sediments was evaluated over a 13-month period following an experimental fire in a steep shrubland of a temperate-humid region (north-west Spain). With time, concentration of extractable Mn, Zn and Cu in sediments decreased, Fe tended to increase and Al, Co, B and Mo varied without a clear trend. Most sediments and trace element losses occurred during the first 3 months post-fire. Compared with the available elements in ash + burned topsoil, the fraction lost with sediments was highest for Mo (10–16%), intermediate for Mn (4%) and Zn (3%) and low for the rest (0.4–1.2%). Although minor effects of stabilisation techniques on element concentrations were found, accumulated mass losses of trace elements decreased 6–12 times in Mulching because of its 10-fold lower soil erosion rate; no significant changes were found in Seeding. Sediment nutrient losses are probably more important than those published for smoke, leaching or volatilisation. Our results suggest that the Zn and Cu enrichment in sediments from the first erosion events increase the risk of downslope water and soil contamination. In conclusion, soil stabilisation techniques are useful to prevent post-fire ecosystem damage.

Regulation of the Absorption of Cu with Various of Pollutants in Sediment through Fractional Factorial Design

The resolution IV fractional factorial design was used to study the adsorption regularity of Cu coexisted with various pollutions (Zn, Pb, Cd, Ni, atrazine, malathine, et al.) onto the sediment. The study found that the main effect and the second-order interaction effect of ten pollutions concentration had significant influence on the adsorption of Cu on the sediment. The concentration of Cu was the critical factor to the promotion of the absorption capacity of Cu in sediment, the second-order effect played the critical role in restraining the absorption of Cu. The main effect of Cd, and the second-order interaction effect include Cd, had greatly inhibited the absorption of Cu in sediment, and the contribution was over 30%, which meant there was prominent antagonism between Cu and Cd. Fractional factorial design can provide a theoretical basis for the reveal of the adsorption mechanism between the different contaminants in the water environment pollution.

The distribution of Cd and Cu in sediments covered with algal mat

In coastal marine environments, with shallow, warm and calm waters, it is sometimes possible to observe the presence of organosedimentary structures that are commonly flat and laminar in shape. These structures are called algal mats or recent stromatolites due to their remarkable similarities to fossil stromatolites. The aim of this work was the study of the distribution of the various forms of Cu and Cd in the main layers of coastal algal mats in a closed bay at Anavissos, on the coast of Saronikos Gulf. Small sediment cores were collected from one point inside the cove on a seasonal basis and the trace metals extracted according to the BCR sequential extraction method. The main results of the study were: Most of the labile Cd was associated with small inorganic grains or lime particles. The contribution of the fraction associated with Mn and Fe oxides, was similar to that adsorbed to organic compounds and sulfides. The high contribution of the labile Cd to the total element (over 85%) was a strong indication of anthropogenic origin. On the other hand, most of the Cu in the sediment was associated with the crystal lattice (74%). Cu showed increased seasonal fluctuation; most of its labile forms were associated with organic compounds and sulfides whereas the less abundant form was that associated with Mn and Fe oxides. On the whole, the sediments were slightly enriched in Cd, while the concentrations of Cu were normal for the region.

Assessment of antioxidant responses and trace metal accumulation by digestive gland of ribbed mussel Aulacomya atra atra from Northern Patagonia

Seasonal and spatial variability of trace metal concentrations and of a battery of antioxidant parameters were evaluated in digestive gland of the ribbed mussel Aulacomya atra atra. Fe, Al and Cu accumulated in tissue exhibited maximum values in winter, coinciding partially with the highest labile concentrations of Fe and Cu in sediment. Metals, as other pollutants, are known to influence the oxidative status of organisms and antioxidant enzymes have been often proposed as biomarkers of contaminant effects. Seasonal variations of trace metals did not appear to influence those of biochemical parameters, which generally showed an opposite trend with higher enzymatic activities in summer when trace metal concentrations were lower. Organisms from Punta Cuevas (control site) showed higher induction of reactive oxygen species production than those from both considered impacted sites, suggesting the possibility of some biochemical adaptation in organisms or a higher modulation of environmental and physiological factors on antioxidant responses than levels of trace metals. This study, which is the first in the area in this matter, showed that seasonal variations of potential biomarkers should be incorporated into interpretation of long-term biomonitoring studies in this marine coastal ecosystem.