Changes In Metal Concentrations Research Articles

Determining toxic metal concentration changes in landscaping plants based on some factors

Toxic metals are one of the most culpable air pollutants. They do not dissolve naturally. Rather, they tend to be bioaccumulative, and some of them have toxic or carcinogenic effects even at low measures. Therefore, the ability to measure and monitor toxic metal concentrations in the air is vital in fighting pollution. To achieve this, bioindicators are widely used due to their efficiency and global availability. Bioindicators are plants that accumulate some of the toxic metals found in the soil or air. This study aims to determine the differences in toxic metal concentrations depending on plant species, plant organelles, and traffic density in certain landscaping plants grown in Kastamonu town center. The results showed that the elements subjected to the study varied significantly between the different species. The highest accumulation values of such metals were obtained in cherry plum (Prunus cerasifera), and the lowest values of all metals were found in the European ash (Fraxinus excelsior). Based on our observations in this study, we determined that the most suitable species used as biomonitor is the cherry plum (Prunus cerasifera). We noticed that the concentrations of the metals differed significantly according to the species. The biggest difference recorded was five times more in Ni metal concentration. The concentrations of the studied elements were also varied depending on organelles and on traffic density, which will be discussed in detail in this paper.

Metal-responsive RNA polymerase extracytoplasmic function (ECF) sigma factors.

SummaryIn order to survive, bacteria must adapt to multiple fluctuations in their environment, including coping with changes in metal concentrations. Many metals are essential for viability, since they act as cofactors of indispensable enzymes. But on the other hand, they are potentially toxic because they generate reactive oxygen species or displace other metals from proteins, turning them inactive. This dual effect of metals forces cells to maintain homeostasis using a variety of systems to import and export them. These systems are usually inducible, and their expression is regulated by metal sensors and signal‐transduction mechanisms, one of which is mediated by extracytoplasmic function (ECF) sigma factors. In this review, we have focused on the metal‐responsive ECF sigma factors, several of which are activated by iron depletion (FecI, FpvI and PvdS), while others are activated by excess of metals such as nickel and cobalt (CnrH), copper (CarQ and CorE) or cadmium and zinc (CorE2). We focus particularly on their physiological roles, mechanisms of action and signal transduction pathways.

Dredging impact on trace metal behavior in a polluted estuary: a discussion about sampling design

Studies involving coastal sediment resuspension have shown that trace metals could be released to the water column due to changes in physical-chemical conditions. Therefore, if environmental agencies adopt screening protocols with insufficient evaluations of contaminant mobilization risks for a given area, the prediction of environmental impacts caused by dredging may be limited. This work evaluates the influence of spatial variation on the geochemical mobility of trace metals (Cd, Cu, Ni, Pb, Zn) after artificial sediment resuspension, using as study case the Iguaçu River estuary (Guanabara Bay, Brazil). The Iguaçu River drains the industrial complex of the metropolitan area of Rio de Janeiro State, besides the presence of agriculture and the input of untreated domestic wastes. Surface estuarine sediments were submitted to resuspension experiments in an open system, during 1h and 24h of agitation on local water. A clear tendency of metals’ solubilization was observed after resuspension, especially considering the dissolved concentrations of Cu (average: 8.0 µg L-1) and Zn (average: 0.9 mg L-1), especially for the samples from the transects 2 and 3. However, evaluations of water quality changes due to sediment resuspension are not requested by the legislation regulating the dredging activities. In the sediments, the results suggested a higher geochemical mobility of Cu, indicated by the massive increase on the bioavailable fraction after resuspension, mainly on the transect number 3, on the river’s mouth. The effects of resuspension were distinct between samples, suggesting that even in a small scale, important differences on metals’ mobility are found. Thus, the combined assessment of changes in metal concentrations in water and in the metal partitioning linked to the solid-phase was demonstrated to be a promising tool for predicting the environmental risks of dredging due to changes in the bioavailability of metals.

GEOCHEMICAL REACTIVE MODELING OF FLOW AND TRANSPORT PROCESS AT A MINE SITE IN NORTHERN TERRITORY, AUSTRALIA

Subsurface contamination of metals and radionuclides are common problems in abandoned mine sites. Metals and radionuclides are likely to occur in the mobile phase or may bind to soil particles and geologic framework. The transport process for reactive contaminants also include chemical reactions in groundwater aquifers, which are complex physical and biogeochemical processes. Accurate tools to reliably predict the movement and changes in concentration of metals and their daughter products (radionuclides) formations in the subsurface environment is important for decision makers to analyze impact, and to evaluate the effectiveness of remediation strategies. An advanced numerical model can provide such useful direction of predictions. A 3-D contaminant transport model for fluid flow, hydrogeologic transport, and biogeochemical kinetic and equilibrium reactions in saturated and unsaturated media was calibrated, validated and implemented to model the hydrogeochemical processes that occur in the subsurface at such a complex contaminated site, consisting of waste rock dumps and flooded mine pits of this abandoned uranium mine site. The developed flow and transport simulation model for no longer in use mine site in Northern Territory of Australia is discussed.

Using hysteresis analysis to infer controls on sediment-associated and dissolved metals transport in a small humid temperate catchment

Understanding the metal dynamics in natural waters is critical to assessing the process and flow pathways that deliver these constituents to the stream network. Metal dynamics can be addressed by an analysis of concentration-discharge relationship across a large spectrum of hydrological conditions. However, metal-discharge responses have only been studied in detail for short periods or a few selected events. In this study, a detailed analysis of the hysteresis loops exhibited by metal concentration-discharge relationship was undertaken to assess the Al, Fe, Mn and Cu dynamics and factors controlling changes in metal concentrations in a small scale rural catchment. Metal (sediment-associated and dissolved) concentrations were measured at high temporal resolution during storm events in a small rural headwater catchment in Galicia (NW Spain). Hysteresis analysis indicated a contrasting concentration-discharge dynamic for sediment-associated and dissolved metals, highlighting a strong decoupling between the two due to their different sources or delivery pathways. For sediment-associated metals, clockwise hysteresis (56%) was the predominant pattern, highlighting the rapid sediment-associated metal mobilisation via surface runoff from sources located near the stream channel. In contrast, dissolved metal showed predominantly anticlockwise hysteresis (58% of storm events), emphasising the role of subsurface flow and soil leaching processes. The different flushing mechanisms between sediment-associated and dissolved metals imply that different catchment management strategies should be implemented for the control of metal export.

The response of metal leaching from soils to climate change and land management in a temperate lowland catchment

Changes in soil hydrology as a result of climate change or changes in land management may affect metal release and leaching from soils. The aim of this study is to assess the cascading response of SOM and DOC levels and metal leaching to climate change in the medium-sized lowland Dommel catchment in the southern part of the Netherlands. We implemented the CENTURY model in a spatial setting to simulate SOM, DOC, and water dynamics in topsoils of the Dutch portion of the Dommel catchment under various climate and land management scenarios. These CENTURY model outputs were subsequently used to calculate changes in the topsoil concentrations, solubility, and leaching of cadmium (Cd) and zinc (Zn) for current (1991–2010) and future (2081–2100) conditions using empirical partition-relations. Since the metal leaching model could not be evaluated quantitatively against measured values, we focus mainly on the trends in the projected metal concentrations and leaching rates for the different scenarios. Our results show that under all climate and land management scenarios, the SOM contents in the topsoil of the Dommel catchment are projected to increase by about 10% and the DOC concentrations to decrease by about 20% in the period from present to 2100. These changes in SOM and DOC only have a minor influence on metal concentrations and leaching rates under the climate change scenarios. Our scenario calculations show a considerable decrease in topsoil Cd concentrations in the next century as a result of increased percolation rates. Zinc, however, shows an increase due to agricultural inputs to soil via manure application. These trends are primarily controlled by the balance between atmospheric and agricultural inputs and output via leaching. While SOM and DOC are important controls on the spatial variation in metal mobility and leaching rates, climate-induced changes in SOM and DOC only have a minor influence on metal concentrations and leaching rates. The climate-induced changes in metal concentrations in both the topsoil and the soil leachate are primarily driven by changes in precipitation and associated water percolation rates.

Miedź, nikiel, ołów i cynk w strefach wpływu eksploatacji złóż miedzi Dolnego Śląska

Copper, nickel, lead and zinc in the zones affected by exploitation of copper deposits in the Lower Silesia. A b s t r a c t. Base metals (Cu, Zn and Pb) as the main resources of the Lower Silesian copper deposits have significantly been influencedby different enviromental factors. In this paper, changes in metal concentrations on the surface in relation to deeper layers of the sediments were examined. The concentration of metals in the whole sediment, and in selected grain fractions was studied. The contents of these metals in the soils of areas adjacent to the deposit are diverse and are in the range of: 3.0–1082.9 mg/kg Cu; 3.5–106.1 mg/kg Pb; 27.6–49.3 mg/kg Zn, and 1.33–23.0 mg/kg Ni in the old deposit district and Cu 0.91–1655.0 mg/kg Pb; 10.0–1792.0 mg/kg Zn; 3.38–1129.0 and 0.47–32.7 mg/kg Ni in the new deposit district. The increase of metal concentration in the fine fractions has been observed. Moreover, the decrease in the metal content with depth was observed in all investigated profiles.

Using moss and lichens in biomonitoring of heavy-metal contamination of forest areas in southern and north-eastern Poland

In the years 2014–2016 biomonitoring studies were conducted in the forest areas of south and north-eastern Poland: the Karkonosze Mountains, the Beskidy Mountains, the Borecka Forest, the Knyszyńska Forest and the Białowieska Forest. This study used epigeic moss Pleurozium schreberi and epiphytic lichens Hypogymnia physodes. Samples were collected in spring, summer and autumn. Approximately 500 samples of moss and lichens were collected for the study. In the samples, Mn, Ni, Cu, Zn, Cd, Hg and Pb concentrations were determined. Based on the obtained results, the studied areas were ranked by extent of heavy-metal deposition: Beskidy > Karkonosze Mountains > forests of north-eastern Poland. Some seasonal changes in concentrations of metals accumulated in moss and lichens were also indicated. There was observed, i.a., an increase in Cd concentration at the beginning of the growing season, which may be related to low emissions during the heating season. Analysis of the surface distribution of deposition of metals in the studied areas showed a significant contribution of nearby territorial emissions and unidentified local emission sources. The contribution of distant emission to Zn, Hg and Pb deposition levels in the Karkonosze and Beskidy region was also indicated.

Native and engineered sensors for Ca2+ and Zn2+: lessons from calmodulin and MTF1.

Ca2+ and Zn2+ dynamics have been identified as important drivers of physiological processes. In order for these dynamics to encode function, the cell must have sensors that transduce changes in metal concentration to specific downstream actions. Here we compare and contrast the native metal sensors: calmodulin (CaM), the quintessential Ca2+ sensor and metal-responsive transcription factor 1 (MTF1), a candidate Zn2+ sensor. While CaM recognizes and modulates the activity of hundreds of proteins through allosteric interactions, MTF1 recognizes a single DNA motif that is distributed throughout the genome regulating the transcription of many target genes. We examine how the different inorganic chemistries of these two metal ions may shape these different mechanisms transducing metal ion concentration into changing physiologic activity. In addition to native metal sensors, scientists have engineered sensors to spy on the dynamic changes of metals in cells. The inorganic chemistry of the metals shapes the possibilities in the design strategies of engineered sensors. We examine how different strategies to tune the affinities of engineered sensors mirror the strategies nature developed to sense both Ca2+ and Zn2+ in cells.

The impact of freshwater metal concentrations on the severity of histopathological changes in fish gills: A statistical perspective

The purpose of this study was to relate the severity of histopathological changes in fish gills with changes in metal concentrations of freshwater samples, and to use the relationships as premature warnings of impairment in aquatic fauna populations. The investigated species were the native barbel (Luciobarbus bocagei) and boga (Pseudochondrostoma sp.), and the introduced trout (Oncorhynchus mykiss), collected from 6 northern Portuguese rivers in a total of 249 individuals. The sampling sites have been linked to different ecological status by the official authorities. The sampling has been repeated 4 times to cover different hydrologic and environmental conditions. The analyzed metals were aluminum, arsenic, cadmium, cobalt, chromium, copper, manganese, nickel, lead and zinc. For each fish, 30 filaments of a gill arch were observed in a light microscope, and the histopathological changes evaluated according to a 6-degree gradation scale that combines the extent and severity of each lesion. The relationships between the histopathological and the chemical results were investigated by the non-parametric Goodman Kruskal gamma correlation and Partial Least Squares regression (PLS). The statistical results highlighted the importance of filament epithelium proliferation (FEP) as key biomarker to the toxicity of sub lethal concentrations of metals, because FEP was significantly correlated with all analyzed metals and explained through PLS regression by concentration changes of Cu, Zn, Mn, Cr and As. A refined regression analysis, where histopathological data on the 3 species were processed in separate, revealed that FEP severity is especially sensitive to changes in metal concentrations in boga. Thus, monitoring studies on the ecological status of northern Portuguese rivers would benefit in time and cost if FEP is used as biomarker and boga as species. Naturally, the option for this species depends on the availability of boga individuals along the stream reaches selected for the monitoring programs.

Effect of episodic rainfall on aqueous metal mobility from historical mine sites

Environmental contextEpisodic extreme rainfall events may affect metal dynamics in rivers flowing within historical metal mining areas. This study provides an analysis of the water chemistry and geochemical processes associated with mobilisation of metals during episodic rainfall events. Findings could be used to assess the environmental quality of streams draining spoil waste areas with similar geochemical conditions, and thereby be used to guide future management strategies. AbstractThe increasing frequency and magnitude of episodic rainfall events may affect historical metal mining areas by remobilisation and deposition of metal-rich sediments and enhancing metal-rich run off, impacting river water quality. This study assesses the effects of episodic rainfall in a Carboniferous headwater catchment contaminated by historical Pb and Zn mining. Comprehensive hourly water chemistry measurements combined with modelling using PHREEQC, WHAM/Model VII and WHAM-FTOX were used in this assessment. For the episodic event, we measured flow increases from a baseline of 0.05 to 2.12 m3 s−1 at peak flow. Changes in metal concentration were most marked for ephemeral tributary, with Pb increasing from a baseline concentration of 55 μg L−1 to a peak of 576 μg L−1. Behaviour for Pb showed great affinity to form organic complexes or bind to colloidal Al and Fe oxides, whereas for Zn and the tributary flowing subsurface a more complex behaviour was observed. For example, the dissolution of secondary metal carbonate minerals (e.g. smithsonite (ZnCO3)) is likely constrained by higher concentrations of carbonate and bicarbonate derived from increased bedrock weathering under flow conditions induced by episodic rainfall. The abundance of secondary mineral sources and circumneutral pH present during episodic rainfall are important factors controlling the mobilisation of Pb and Zn. Furthermore, episodic rainfall events could enhance metal toxicity but there are aggravating and mitigating factors that depend on site-specific chemical changes. Overall, this study highlighted the complexity of metal mobility and toxicity during these events.

Impacts of elevated dissolved CO2 on a shallow groundwater system: Reactive transport modeling of a controlled-release field test

One of the risks that CO2 geological sequestration imposes on the environment is the impact of potential CO2/brine leakage on shallow groundwater. The reliability of reactive transport models predicting the response of groundwater to CO2 leakage depends on a thorough understanding of the relevant chemical processes and key parameters affecting dissolved CO2 transport and reaction. Such understanding can be provided by targeted field tests integrated with reactive transport modeling. A controlled-release field experiment was conducted in Mississippi to study the CO2-induced geochemical changes in a shallow sandy aquifer at about 50m depth. The field test involved a dipole system in which the groundwater was pumped from one well, saturated with CO2 at the pressure corresponding to the hydraulic pressure of the aquifer, and then re-injected into the same aquifer using a second well. Groundwater samples were collected for chemical analyses from four monitoring wells before, during and after the dissolved CO2 was injected. In this paper, we present reactive transport models used to interpret the observed changes in metal concentrations in these groundwater samples. A reasonable agreement between simulated and measured concentrations indicates that the chemical response in the aquifer can be interpreted using a conceptual model that encompasses two main features: (a) a fast-reacting but limited pool of reactive minerals that responds quickly to changes in pH and causes a pulse-like concentration change, and (b) a slow-reacting but essentially unlimited mineral pool that yields rising metal concentrations upon decreased groundwater velocities after pumping and injection stopped. During the injection, calcite dissolution and Ca-driven cation exchange reactions contribute to a sharp pulse in concentrations of Ca, Ba, Mg, Mn, K, Li, Na and Sr, whereas desorption reactions control a similar increase in Fe concentrations. After the injection and pumping stops and the groundwater flow rate decreases, the dissolution of relatively slow reacting minerals such as plagioclase drives the rising concentrations of alkali and alkaline earth metals observed at later stages of the test, whereas the dissolution of amorphous iron sulfide causes slowly increasing Fe concentrations.

Particle-bound metal transport after removal of a small dam in the Pawtuxet River, Rhode Island, USA.

The Pawtuxet River in Rhode Island, USA, has a long history of industrial activity and pollutant discharges. Metal contamination of the river sediments is well documented and historically exceeded toxicity thresholds for a variety of organisms. The Pawtuxet River dam, a low-head dam at the mouth of the river, was removed in August 2011. The removal of the dam was part of an effort to restore the riverine ecosystem after centuries of anthropogenic impact. Sediment traps were deployed below the dam to assess changes in metal concentrations and fluxes (Ag, Cd, Cr, Cu, Ni, Pb, and Zn) from the river system into Pawtuxet Cove. Sediment traps were deployed for an average duration of 24 days each, and deployments continued for 15 months after the dam was removed. Metal concentrations in the trapped suspended particulate matter dropped after dam removal (e.g., 460 to 276 mg/kg for Zn) and remained below preremoval levels for most of the study. However, particle-bound metal fluxes increased immediately after dam removal (e.g., 1206 to 4248 g/day for Zn). Changes in flux rates during the study period indicated that river volumetric flow rates acted as the primary mechanism controlling the flux of metals into Pawtuxet Cove and ultimately upper Narragansett Bay. Even though suspended particulate matter metal concentrations initially dropped after removal of the dam, no discernable effect on the concentration or flux of the study metals exiting the river could be associated with removal of the Pawtuxet River dam. Integr Environ Assess Manag 2017;13:675-685. Published 2016. This article is a US Government work and is in the public domain in the USA.

First report of a novel multiplexer pumping system coupled to a water quality probe to collect high temporal frequency in situ water chemistry measurements at multiple sites

The increasing availability and use of high-frequency water quality sensors has enabled unprecedented observations of temporal variability in water chemistry in aquatic ecosystems. However, we remain limited by the prohibitive costs of these probes to explore spatial variability in natural systems. To overcome this challenge, we have developed a novel auto-sampler system that sequentially pumps water from up to 12 different sites located within a 12 m radius to a single water quality probe. This system is able to generate high temporal frequency in situ water chemistry data from multiple replicated units during experiments as well as multiple sites and depths within natural aquatic ecosystems. Thus, with one water quality probe, we are able to observe rapid changes in water chemistry concentrations over time and space. Here, we describe the coupled multiplexer-probe system and its performance in two case studies: a mesocosm experiment examining the effects of water current velocity on nitrogen dynamics in constructed wetland sediment cores and a whole-ecosystem manipulation of redox conditions in a reservoir. In both lotic and lentic case studies, we observed minute-scale changes in nutrient concentrations, which provide new insight on the variability of biogeochemical processes. Moreover, in the reservoir, we were able to measure rapid changes in metal concentrations, in addition to those of nutrients, in response to changes in redox. Consequently, we believe that this coupled system holds great promise for measuring biogeochemical fluxes in a diverse suite of aquatic ecosystems and experiments.

Detecting long-term temporal trends in sediment-bound trace metals from urbanised catchments

The shift from rural lifestyles to urban living has dramatically altered the way humans interact and live across the globe. With over 50% of the world’s populations living within cities, and significant increases expected over the next 50 years, it is critical that changes to social, economic and environmental sustainability of cities globally be implicit. Protecting and enhancing aquatic ecosystems, which provide important ecosystem services, is challenging. A number of factors influence pollutants in urban waterways including changes in land-use, impervious area and stormwater discharges, with sediment-bound pollution a major issue worldwide. This work aimed to investigate the spatial and temporal distribution of trace metals in freshwater sediments from six urbanised catchment over a 30-year period. It provides an estimate of pollution using a geoaccumulation index and examines possible toxicity using a probable effect concentration quotient (mPECq). Results showed significant temporal changes in metal concentrations over time, with lead generally decreasing in all but one of the sites, attributed to significant changes in environmental policies and the active elimination of lead products. Temporal changes in other metals were variable and likely dependent on site-specific factors. While it is likely that diffuse pollution is driving changes in zinc, for metals such as lead, chromium and copper, it is likely that watershed landuse and/or point sources are more important. The results clearly indicated that changes to watershed landuse, environmental policy and pollution abatement programs are all driving changes in sediment quality, highlighting the utility of long-term sediment monitoring for assessment of urban watershed condition. While this study has demonstrated the utility of detecting long-term changes in metal concentrations, this approach could easily be adapted to detect and assess future trends in other hydrophobic contaminants and emerging chemicals of concern, such as synthetic pyrethroids, providing essential information for the protection of catchment.

Complexing capacity of electroplating rinsing baths—a twist to the resolution of two ligand families of similar strength

The presence of ligands affects metal behavior when removing metals from wastewaters. So far, most of the attention has been paid to strong ligands; however, experimental observations indicate that also weaker complexing agents may play a key role in the availability of metals in waters and in the success of the treatment to be applied. In particular, we have analyzed wastewaters of an electroplating facility during an 8-h workday. Total metal content (copper, zinc, cadmium, and lead) was determined; ligands were characterized by concentration (Lt) and strength (conditional stability constant, K'f). This work focuses on ligands of moderate strength which, as far as we know, have been overlooked in the literature. A two-moderate-ligand system was used to mimic the wastewaters. N-(2-hydroxyethyl)iminodiacetic acid and nitrilotriacetic acid were used as model ligands. Electrochemical titration data (obtained by square wave anodic stripping voltammetry) were analyzed combining the Scatchard linearization method with a standard non-linear curve fitting function to focus on the resolution of two ligand families of similar strength. Correctness was tested both for the analytical procedure and data analysis. Most significant changes in metal concentration were related to zinc and lead that increased along the workday. Copper and cadmium contents were negligible. The model system and wastewater samples were successfully characterized by this methodology. Two ligand families of constants K'f1 (4.07 ± 0.69 )× 106 and K'f2 (5.56 ± 0.78) × 105 were discriminated in the micromolar range using zinc in the titration of the wastewater sample. A combined strategy involving electrochemical techniques, the Scatchard linearization, and a non-linear curve fitting function was successfully applied to the model system, within experimental error. Our main goal was to characterize two moderate ligand families of similar strength in the wastewater samples by means of the same strategy, a task that so far has not been described. The combined strategy used in this particular case may be of interest for different environmental matrixes.

Molecular screening of microbial communities for candidate indicators of multiple metal impacts in marine sediments from northern Australia.

Coastal sediments accumulate metals from anthropogenic sources and as a consequence industry is required to monitor sediment health. The total concentration of a metal does not necessarily reflect its potential toxicity or biological impact, so biological assessment tools are useful for monitoring. Rapid biological assessment tools sensitive enough to detect relatively small increases in metal concentrations would provide early warning of future ecosystem impact. The authors investigated in situ populations of Archaea and Bacteria as potential tools for rapid biological assessment in sediment at 4 northern Australian coastal locations over 2 yr, in both wet and dry seasons. The 1 M HCl-extractable concentrations of metals in sediment were measured, and Archaeal and Bacterial community profiles were obtained by next-generation sequencing of sediment deoxyribonucleic acid (DNA). Species response curves were used to identify several taxonomic groups with potential as biological indicators of metal impact. Spatial variation, sediment grain size, water depth, and dissolved oxygen also correlated with microbial population shifts. Seasonal variation was less important than geographic location. Metal-challenge culture trials supported the identification of metal-resistant and -sensitive taxa. In situ Archaea and Bacteria are potentially sensitive indicators for changes in bioavailable concentrations of metals; however, the complexity of the system suggests it is important to identify metal-specific functional genes that may be informed by these sequencing surveys, and thus provide a useful addition to identity-based assays.

Examination of the Level of Heavy Metals in Wastewater of Bandar Abbas Wastewater Treatment Plant

One of the main environmental pollutants is heavy metals. Due to extensive usage in industry, these metals enter biological cycle rapidly and contaminated water and soil resources rapidly. In this work, lead, copper, zinc and chromium of Bandar Abbas wastewater are examined. For this research, nine stations were set for measurement in urban level in Bandar Abbas and sampling of aforesaid metals was performed in fall and winter 2006 in these stations. After extraction and preparation operations using APDC-MIBK, samples were measured using flame atomic absorption system. According to results, concentrate of studied metals was lower than allowable standard value set by Iran environmental protection organization for agricultural purposes and sewage to ground level waters. In addition, efficiency of Bandar Abbas wastewater treatment plant to remove these metals is 40% - 70% from which highest removal is for zinc as much as 71.1% and lowest level is for copper as much as 40.5%. However, copper level was higher than allowable level for agricultural purposes in spring and summer (0.21 mg/L and 0.23 mg/L, respectively) and lower in fall and winter (0.103 mg/L and 0.098 mg/L, respectively). Furthermore, changes in concentration of metals in these stations in various seasons were measured and analyzed using one-way variance analysis and simultaneous effects of time and place on measured variables were analyzed using two-way variance analysis.

Pollutant dispersal in groundwater and sediments of gaining and losing river reaches affected by metal mining

The presented work couples groundwater and sediment chemistry in the metal mining-polluted Przemsza River valley in southern Poland to reveal regularities in pollutant distribution and to relate them to sedimentary processes and surface water/groundwater exchange. Ten piezometers were installed in transects across the low-gradient, meandering losing river reach and in the incised, channelised gaining reach. At each sampling site, cores of sediments were sampled for heavy metals and groundwater samples were collected over a year, for standard physicochemical analysis as well as Zn, Pb, Cd, Mg and Fe. In the losing river reach, the magnitude of pollution of groundwater in the levee zone was similar to that in the river, and declined in the backswamp. In the levee zone of the incised reach, minimum groundwater pollution adjacent to the highly polluted river was related to gaining relatively clean groundwater. In the losing reach, the dispersal of heavy metals in the levee zone is controlled mainly by overbank accumulation of polluted sediments. Post-depositional changes of metal concentrations in profiles of the losing reach indicate the important role of groundwater in metal dispersal. In the gaining river reach, the redistribution of metals in the profiles was not ascertained due to a much lower groundwater table.

Lead and cadmium removal from water using duckweed – Lemna gibba L.: Impact of pH and initial metal load

The aim of this study was to investigate the potential of duckweed (Lemna gibba) in heavy metal (Pb and Cd) from water under different pH and metal loads. A total of three (2, 5 and 10mg/L) strengths of Pb and Cd were used with varying pH (5, 7 and 9) and changes in metal concentration and metal uptake yield of system were recorded. The Pb and Cd removal ranged between 60.1% (2mg/L at 9 pH) and 98.1% (10mg/L at 7 pH) and 41.6% (10mg/L at pH 9) and 84.8% (2mg/L at pH 7), respectively. The duckweed set-up with pH 7 showed the optimum metal removal. The metal removal rate showed an inverse relationship with pH (r2>0.60, for all). Bioconcentration factor (BCF) and metal uptake yield per unit of dry biomass (qm) were recorded: 403–738 and 445–616, respectively for BCFPb and BCFCd. The qm suggest the dose (mg/L) 5 and 10 at pH 5 as the best combinations for the optimum removal. Results, thus suggest that L. gibba can be a suitable candidate for removal of heavy metals from pollutant water bodies.