Salt marsh macrophyte Phragmites australis strategies assessment for its dominance in mercury-contaminated coastal lagoon (Ria de Aveiro, Portugal)

Introduction and aims

The dominance of a plant species in highly metal-contaminated areas reflects its tolerance or adaptability potential to these scenarios. Hence, plants with high adaptability and/or tolerance to exceptionally high metal-contaminated scenarios may help protect environmental degradation. The present study aimed to assess the strategies adopted by common reed, Phragmites australis for its dominance in highly mercury-contaminated Ria de Aveiro coastal lagoon (Portugal).

Materials and methods

Both plant samples and the sediments vegetated by monospecific stand of Phragmites australis were collected in five replicates from mercury-free (reference) and contaminated sites during low tide between March 2006 and January 2007. The sediments?? physico-chemical traits, plant dry mass, uptake, partitioning, and transfer of mercury were evaluated during growing season (spring, summer, autumn, and winter) of P. australis. Redox potential and pH of the sediment around roots were measured in situ using a WTW-pH 330i meter. Dried sediments were incinerated for 4?h at 500??C for the estimation of organic matter whereas plant samples were oven-dried at 60??C till constant weight for plant dry mass determination. Mercury concentrations in sediments and plant parts were determined by atomic absorption spectrometry with thermal decomposition, using an advanced mercury analyzer (LECO 254) and maintaining the accuracy and precision of the analytical methodologies. In addition, mercury bioaccumulation and translocation factors were also determined to differentiate the accumulation of mercury and its subsequent translocation to plant parts in P. australis.

Results and conclusions

P. australis root exhibited the highest mercury accumulation followed by rhizome and leaves during the reproductive phase (autumn). During the same phase, P. australis exhibited ??5 times less mercury-translocation factor (0.03 in leaf) when compared with the highest mercury bioaccumulation factor for root (0.14). Moreover, seasonal variations differentially impacted the studied parameters. P. australis?? extraordinary ability to (a) pool the maximum mercury in its roots and rhizomes, (b) protect its leaf against mercury toxicity by adopting the mercury exclusion, and (c) adjust the rhizosphere-sediment environment during the seasonal changes significantly helps to withstand the highly mercury-contaminated Ria de Aveiro lagoon. The current study implies that P. australis has enough potential to be used for mercury stabilization and restoration of sediments/soils rich in mercury as well.     

Chemical, biological, and ecotoxicological assessment of pesticides and persistent organic pollutants in the Bahlui River, Romania

Background, aim, and scope  

Current knowledge on environmental impacts of industrial activities in Romania, particularly persistent organic pollutants (POPs), indicates that environmental standards of the European Union are not systematically met. In our study area, additional sources of POPs are agriculture and domestic wastes. Very scarce information is available upon environmental contaminations and effects. In the present study, we investigated the chemical pollution and their eventual impact on the ecosystem by measuring POPs and by using biological indicators of pollution.     

Immunosuppression in the infaunal bivalve Scrobicularia plana environmentally exposed to mercury and association with its accumulation

This study aimed to test the hypothesis whether mercury (Hg) activates or suppresses inappropriately the immunity of the bivalve Scrobicularia plana inhabiting a Hg contaminated area (Laranjo basin, Ria de Aveiro, Portugal). Immunity endpoints, as well as lipid peroxidation (LPO) as a sign of damage, were evaluated in parallel with total Hg burden. Bivalves from both moderately (MO) and highly (HI) contaminated sites displayed higher haemolymph Hg load and reduced plasma agglutination. Increased haemocytes density and decreased phagocytosis were observed at HI, whereas increased oxidative burst activity (OBA) was observed at MO, pointing out that the immunotoxicity is a result of Hg direct contact involving no ROS intervention. OBA observed at MO was concomitantly associated to peroxidative damage as depicted by LPO increase in haemocytes and haemolymph plasma. Thus, S. plana can be suggested as a suitable bioindicator of metal pollution in coastal areas on the basis of Hg bioaccumulation and immunotoxicity responses.     

Temporal and spatial changes of PAH concentrations in Mytilus galloprovincialis from Ria de Vigo (NW Spain)

The aim of this study was to establish the temporal trends and spatial distribution of Polycyclic Aromatic Hydrocarbons (PAHs) in Ria de Vigo by means of studying the PAH burden in wild mussels. The samples were collected in eight sites along the margins of the Ria de Vigo during November from 1998 to 2008 and Polycyclic Aromatic Hydrocarbon contents were determined using high performance liquid chromatography–fluorescence derivatization (HPLC–FLD). Quality of chemical analysis was guaranteed by participation in QUASIMEME intercalibration exercises carried out during the period of analysis. The concentrations for the sum of 13 PAHs were in the range 24–480 μg/kg dw, typical of an urban and industrialized area (50–500 μg/kg dw) except for a punctual input in La Guía in 1998 that led to a concentration above 1,000 μg/kg dw. In general, the sites in the outermost section of the estuary (ría) showed the lowest values, with an increasing gradient in the medium and inner parts of the ría. Temporal patterns show, in general, a downward trend. The relative proportion of 3 and 4 ring PAHs also varies with the site, the former being predominant in the outermost area and the latter in the medium and inner parts of the ría. This is consistently related with the sources and processes taking place in different areas of the estuary.     

Fluorescence and DOC contents of estuarine pore waters from colonized and non-colonized sediments: effects of sampling preservation

The influence of the colonization of salt marsh sediments with Halimione portulacoides was evaluated by analysing the fluorescent dissolved organic matter (FDOM) in sediment pore waters from a salt marsh at different depths. Cores of sediments at colonized and non-colonized sites were collected from a coastal lagoon (Ria de Aveiro, Portugal). The DOC content of extracted pore waters was determined and characterized by synchronous molecular fluorescence (Deltalambda=60nm) and UV-visible spectroscopies. The common practice of freezing sediment cores for further and later chemical investigation was shown not to be an appropriate methodology of sample preservation. On the contrary, freezing of extracted and filtered pore water seemed not to affect either the DOC content or the fluorescence properties of pore waters. Two types of fluorescent substances were found in the pore waters spectra; one corresponding to humic-like substances and another one resembling proteins. However, major differences were found in the spectra of pore waters depending on both depth and the presence/absence of vegetation colonization.     

Partitioning of endocrine disrupting compounds in inland waters and wastewaters discharged into the coastal area of Thessaloniki,Northern Greece

Background, aim, and scope  

In the Water Framework Directive 2000/60/EC, environmental objectives for the proper quality of inland, surface, transitional, coastal, and ground waters have been set. Member states are required to identify chemical pollutants of significance in the water bodies, to establish emission control measures, and to achieve quality standards. A specific category of pollutants are the compounds that may possess endocrine-related functions known as endocrine disrupting compounds (EDCs). This means that member states have the obligation to take action in order to prevent human exposure to these compounds via aquatic environment. The objective of this research was to study the occurrence and distribution of phenolic and steroid EDCs in inland waters and wastewaters discharged in the area of Thermaikos Gulf, Thessaloniki, Northern Greece.     

Impact of fluorotelomer alcohols (FTOH) on the molecular and macroscopic phenotype of <Emphasis Type="Italic">Tetrahymena thermophila</Emphasis>

Background, aim, and scope  

As possible precursors of PFOA, fluorotelomer alcohols are a class of highly fluorinated and volatile compounds. Although they are widespread in the environment, little toxicity data is available. The present study focused on testing the population growth impairment potential of FTOH. Moreover, certain efforts were made to find the possible effect mechanism of these compounds.     

Thorough analysis of polyhalogenated compounds in ray liver samples off the coast of Rio de Janeiro, Brazil

Introduction  

Five liver samples of two different ray species (Gymnura altavela and Zapteryx brevirostris) off the coast of Rio de Janeiro, Brazil, were analyzed for their pollution with anthropogenic and naturally occurring organohalogen compounds.     

Phenological development stages variation versus mercury tolerance,accumulation, and allocation in salt marsh macrophytes <Emphasis Type="Italic">Triglochin maritima</Emphasis> and <Emphasis Type="Italic">Scirpus maritimus</Emphasis> prevalent in Ria de Aveiro coastal lagoon (Portugal)

Efficient and sustainable management of rapidly mounting environmental issues has been the focus of current intensive research. The present study aimed to investigate the impact of plant phenological development stage variation on mercury (Hg) tolerance, accumulation, and allocation in two salt marsh macrophytes Triglochin maritima and Scirpus maritimus prevalent in historically Hg-contaminated Ria de Aveiro coastal lagoon (Portugal). Both plant samples and the sediments vegetated by monospecific stands of T. maritima and S. maritimus were collected from reference (R) and sites with moderate (M) and high (H) Hg contamination in Laranjo bay within Ria de Aveiro lagoon. Hg tolerance, uptake, and allocation in T. maritima and S. maritimus, physico-chemical traits (pH, redox potential, and organic matter content) and Hg concentrations in sediments vegetated by these species were impacted differentially by phenological development stages variation irrespective of the Hg contamination level. In T. maritima, Hg concentration increased with increase in Hg contamination gradient where root displayed significantly higher Hg followed by rhizome and leaf maximally at H. However, in S. maritimus, the highest Hg concentration was perceptible in rhizome followed by root maximally at M. Between the two studied plant species, S. maritimus displayed higher Hg tolerance index (depicted by higher plant dry mass allocated to reproductive stage) and higher available Hg at M (during all growth stages) and H (during senescent stage) when compared to T. maritimus. Both plant species proved to be Hg excluder (low root/rhizome–leaf Hg translocation). Additionally, T. maritima also acted as Hg stabilizer while, S. maritimus as Hg accumulator. It can be inferred from the study that (a) the plant phenological development stage variations significantly influenced plant Hg sensitivity by impacting sediment chemistry, plant growth (in terms of plant dry mass), Hg accumulation, and its subsequent allocation capacity, contingent to Hg contamination gradient; (b) S. maritimus accumulated higher Hg but restricted its translocation to above-ground part using exclusion process at both M and H due to its accelerated growth during Hg-tolerant reproductive/metabolically active phenological development stage greater than its counterpart T. maritima; and (c) the studied salt marsh plants although hailed from the same C3 and monocot group did not necessarily display similar phenotypic plasticity and behavior towards Hg-contaminated scenario during their life cycle.     

Production and release of dimethylsulphide from an estuary in Portugal

The distribution of dimethylsuphide (DMS) and its precursor dimethylsulphoniopropionate, in both particulate (DMSP_p) and dissolved fractions (DMSP_d) was surveyed along estuarine water profiles of Canal de Mira (Ria de Aveiro, Portugal), on 45 occasions during one year. The field campaigns revealed pronounced gradients, which were to some extent interpreted with reference to supporting hydrographic parameters like salinity, temperature and chlorophyll a. Surface water concentrations showed a clear seasonal variation with peak values during the warmer months. Mean summer concentrations for DMS, DMSP_p and DMSP_d, were, respectively, a factor of 1.8, 1.9 and 2.9 times higher than winter concentrations. Surface water concentration was the main factor controlling DMS emissions into the atmosphere, which were estimated to be, as a mean, 5.4 and 27.3 nmol m^-2 h^-1 for winter and summer, respectively. In addition, DMS fluxes from two intertidal mud flat sites in Canal de Mira were examined monthly over a year. Average emission rates were a factor of 2–5 times higher than those estimated for estuarine waters and revealed strong seasonal variations, with summer peaks apparently related to ambient temperature. The relative contribution of estuarine waters and mud flats for local DMS budget is discussed in terms of tidal cycles and exposed surface area.     

Morphological,compositional and ultrastructural changes in the Scrobicularia plana shell in response to environmental mercury – An indelible fingerprint of metal exposure?

The study aimed to assess morphological, structural and compositional alterations in Scrobicularia plana nacre environmentally exposed to mercury in order to seek out the possibility of the assessed alterations as a monitoring tool to handle complexity and interactions of metals in the environment involving a non-invasive methodology. Bivalves were collected from a mercury contaminated site (Laranjo basin – Ria de Aveiro, Portugal) and a reference site in the same aquatic system. The combination of scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDS) technique depicted a sheet like morphology of bivalve nacre collected from the reference site. Moreover, EDS plot exhibited the presence of potassium, oxygen, calcium, and carbon elements. Shells collected from the contaminated area depicted lamellar patches like structures with particle like morphology composition. SEM images corresponding to the elemental analysis by EDS plot clearly denoted the presence of mercury. SEM images from the other locations of the contaminated shells depicted large surface area, a broken or ruptured symmetry of organic matrix as well as crack-like gaps. The influence of environmental mercury affecting the surface morphology of S. plana nacre showed dimple like morphology (as proved by transmission electron microscopy, TEM). The possible explanation may be the replacement of calcium elements with other elements or alloys from the nacre composite collected from contaminated region. Therefore, the nacre fingerprint may be useful as innovative knowledge and applicable tool aiming at risk reduction from noxious mercury present in the environment. Overall results suggested the use of shell as an indelible fingerprint of metal exposure.     

Evaluation of surface water quality using an ecotoxicological approach: a case study of the Alqueva Reservoir (Portugal)

Background, aim, and scope  

Freshwater reservoirs can be impacted by several hazardous substances through inputs from agricultural activity, sewage discharges, and groundwater leaching and runoff. The water quality assessment is very important for implementation of the monitoring and remediation programs to minimize the risk promoted by hazardous substances in aquatic ecosystems. Evaluation of the degree of contamination of aquatic environments must not take in account only its chemical characterization but it must be complemented with biological assays, which determine potential toxic effects and allows an integrated evaluation of its effects in populations and aquatic ecosystem communities. The application of this type of strategy has clear advantages allowing a general evaluation of the effects from all the water components, including those due to unknown substances and synergic, antagonistic, or additive effects. There are only a few studies that reported ecotoxicological acute end points, for the assessment of surface water quality, and the relationship among toxicity results and the anthropogenic pollution sources and the seasonal period. The aim of this study was to assess the ecotoxicological characterization of the surface water from Alqueva reservoir (South of Portugal) and to evaluate the influence of anthropogenic sources of pollution and their seasonal variation in its toxicity. The construction of Alqueva reservoir was recently finished (2002) and, to our knowledge, an ecotoxicological assessment of its surface water has not been performed. Because of that, no information is available on the possible impact of pollutants on the biota. The surface water toxicity was assessed using acute and chronic bioassays. The results are to be used for developing a monitoring program, including biological methods.     

The Cl-initiated oxidation of CH3C(O)OCH=CH2, CH3C(O)OCH2CH=CH2, and CH2=CHC(O)O(CH2)3CH3 in the troposphere

Background, aim, and scope  

Unsaturated esters are emitted to the atmosphere from biogenic and anthropogenic sources, including those from the polymer industry. Little information exists concerning the atmospheric degradation of unsaturated esters, which are mainly initiated by OH radicals. Limited information is available on the degradation of alkenes by Cl atoms and almost no data exists for the reactions of unsaturated esters with Cl atoms. This data is necessary to assess the impact of such reactions in maritime environments where, under circumstances, OH radical- and Cl atom-initiated oxidation of the compounds can be important. Rate coefficients for the reactions of chlorine atoms with vinyl acetate, allyl acetate, and n-butyl acrylate have been determined at 298 ± 3 K and atmospheric pressure. The kinetic data have been used in combination with that for structurally similar compounds to infer the kinetic contributions from the possible reaction channels to the overall reaction rate.     

Aliphatic hydrocarbons, polycyclic aromatic hydrocarbons, polychlorinated biphenyls, organochlorine, and organophosphorous pesticides in surface sediments from the Arc river and the Berre lagoon, France

Introduction  

The Arc River and Berre lagoon are one of important river basin hydrosystem in the South of France that receives industrial and municipal wastewaters from the adjacent area.     

Seasonality of PCDD/Fs in the ambient air of Malopolska Region,southern Poland

Background, aim, and scope  

The aim of the study was to identify the impact of polychlorinated dibenzo-p-dioxin and furan (PCDD/F) emission sources on ambient air concentrations in the Malopolska Region, southern Poland. Three sites were selected: the city center of Krakow (Aleje), an industrial area (Nova Huta), and a rural site (Zakopane). In order to investigate the annual variations of PCDD/F sources, summer and winter time samples were taken.     

Do heavy metals and metalloids influence the detoxification of organic xenobiotics in plants?

Background, aim and scope  

Mixed pollution with trace elements and organic industrial compounds is characteristic for many spill areas and dumping sites. The danger for the environment and human health from such sites is large, and sustainable remediation strategies are urgently needed. Phytoremediation seems to be a cheap and environmentally sound option for the removal of unwanted compounds, and the hyperaccumulation of trace elements and toxic metals is seemingly independent from the metabolism of organic xenobiotics. However, stress reactions, ROS formation and depletion of antioxidants will also cause alterations in xenobiotic detoxification. Here, we investigate the capability of plants to detoxify chlorophenols via glutathione conjugation in a mixed pollution situation.     

Atmospheric polycyclic aromatic hydrocarbons in remote European and Atlantic sites located above the boundary mixing layer

Background, aim and scope  

Ambient air concentrations of polycyclic aromatic hydrocarbons (PAH) were determined at five elevated mountain sites on the European continent and the Atlantic Ocean. All sites can be considered remote background areas since they are situated above the timberline and they lack local emission sources of these compounds.     

Wet air oxidation and catalytic wet air oxidation for dyes degradation

Background, aim, and scope  

Textile industry produces wastewater which contributes to water pollution since it utilizes a lot of chemicals. Preliminary studies show that the wastewater from textile industries contains grease, wax, surfactant, and dyes. The objective of this study was to determine the treatment efficiency of the nickel catalysts supported on hydrotalcites in three-dye model compounds and two types of wastewater.     

Occurrence of persistent organic pollutants in sediments and biota from Portugal versus European incidence: A critical overview

Persistent organic pollutants (POPs) are widespread compounds, such as organohalogenated compounds, polycyclic aromatic hydrocarbons (PAHs) and pesticides, which can be found in all types of environmental compartments. Their presence in the aquatic environment is a worldwide problem, with emphasis on sediments which act as depository and consequently as a source of hydrophobic, recalcitrant and harmful compounds. Besides, these pollutants might affect the reproduction and mortality of living organisms, diverging in their potential to bioaccumulate in tissues. The present paper aims to review the occurrence of POPs in sediments and biota from the coastal, estuarine and river areas of Portugal. The list of the studied compounds comprises organohalogenated compounds, PAHs, organometallic compounds, pesticides, sterols, fatty acids and pharmaceutical compounds. The contamination of sediments by various pollutants is presented, such as PAHs up to 7,350 ng g^?1 found in Sado estuary and polychlorinated biphenyls up to 62.2 ng g^?1 in the case of sediments collected in Ria de Aveiro. The occurrence of these persistent toxic substances in sediments demonstrates aquatic contamination from agricultural, industrial and urban discharges and the concern about the potential risks to aquatic organisms, wildlife and humans. In fact, several classes of POPs have also been found in biota, such as polychlorinated biphenyls up to 810.9 ng g^?1 in sentinel fish from the Douro River estuary and pesticides in bivalves from the Sado River estuary. The importance of further systematic research on sediments and biota is here highlighted to compare the contamination of these two reservoirs; to assess their spatial and temporal variation; and to determine other classes of POPs that were not investigated yet (e.g., industrial compounds, estrogens and many classes of pharmaceuticals).     

PCB and DDT contamination in cultivated and wild sea bass from Ria de Aveiro, Portugal

Polychlorinated biphenyls (PCBs) and dichlorodiphenyltrichloroethane (DDT) and metabolites were quantified in muscle and liver of sea bass (Dicentrarchus labrax) collected in Ria de Aveiro and in two fish farms. Sea bass from natural environment showed lower levels than fish from farming, which may be partly attributed to the higher lipid content of cultivated fish. PCB congener distribution in tissues of sea bass from the two farms resembled that of diet pellets suggesting that commercial diet is a major source of PCBs. However, fish in the two sites were fed with diet of similar PCB and DDT contamination but showed distinct levels in its tissues not explained by lipid content.