Cultivation of the macrophyte Lemna minor and the microalgae Chlorella sorokiniana in thermal mineral waters: Biomass characteristics, radioisotopes and heavy metals content.

Microalgae and macrophytes are commonly used as human and animal food supplements. We examined the cultivation of the microalgae Chlorella sorokiniana and the duckweed Lemna minor in thermal waters under batch and sequencing batch conditions and we characterized the produced biomass for the presence of essential nutrients as well as for heavy metals and radioisotope content. The highest specific growth rate for the microalgae was observed when 5 or 15 mg/L N were supplemented while the optimal conditions for Lemna minor were observed in the co-presence of 5 mg/L N and 1.7 mg/L P. Lemna minor presented higher concentrations of proteins and lipids comparing to the studied microalgae. Both organisms contained high amounts of lutein (up to 1378 mg/kg for Lemna minor) and chlorophyll (up to 1518 mg/kg for Lemna minor) while ß-carotene and tocopherols were found at lower concentrations, not exceeding a few tens of mg/kg. The heavy metal content varied between the two species. Lemna minor accumulated more Cd, Cu, K, Mn, Na, Ni, and Zn whereas Al, Ca and Mg were higher in Chlorella sorokiniana. Both organisms could be a significant source of essential metals but the occasional exceedance of the statutory levels of toxic metals in food products raises concern for potential risk to either humans or animals. Application of gamma-spectroscopy to quantify the effective dose to humans from 228Ra, 226Ra and 40K showed that Chlorella sorokiniana was well under the radiological limits while the collected mass of Lemna minor was too small for radiological measurements with confidence.

Broomrape Species Parasitizing Odontarrhena lesbiaca (Brassicaceae) Individuals Act as Nickel Hyperaccumulators.

The elemental defense hypothesis supports that metal hyperaccumulation in plant tissues serves as a mechanism underpinning plant resistance to herbivores and pathogens. In this study, we investigate the interaction between Odontarrhena lesbiaca and broomrape parasitic species, in the light of the defense hypothesis of metal hyperaccumulation. Plant and soil samples collected from three serpentine sites in Lesbos, Greece were analyzed for Ni concentrations. Phelipanche nowackiana and Phelipanche nana were found to infect O. lesbiaca. In both species, Ni concentration decreased gradually from tubercles to shoots and flowers. Specimens of both species with shoot nickel concentrations above 1000 mg.kg-1 were found, showing that they act as nickel hyperaccumulators. Low values of parasite to O. lesbiaca leaf or soil nickel quotients were observed. Orobanche pubescens growing on a serpentine habitat but not in association with O. lesbiaca had very low Ni concentrations in its tissues analogous to excluder plants growing on serpentine soils. Infected O. lesbiaca individuals showed lower leaf nickel concentrations relative to the non-infected ones. Elevated leaf nickel concentration of O. lesbiaca individuals did not prevent parasitic plants to attack them and to hyperaccumulate metals to their tissues, contrary to predictions of the elemental defense hypothesis.

Comparing the use of a two-stage MBBR system with a methanogenic MBBR coupled with a microalgae reactor for medium-strength dairy wastewater treatment.

Two systems were compared for medium-strength dairy wastewater treatment. The first comprised a methanogenic Moving Bed Biofilm Reactor (AnMBBR) and an aerobic MBBR (AeMBBR), while the second an AnMBBR and a sequencing batch reactor (SBR) with Chlorella sorokiniana. The AnMBBR, under ambient conditions, achieves biogas production sufficient enough to attain energy autonomy. The produced energy was 0.538 kWh m-3, whereas the energy consumption 0.025 kWh m-3. Its coupling with the AeMBBR removed COD, NH4-N TKN, and PO4-P by 93 ± 4%, 97 ± 3%, 99 ± 1% and 49 ± 15%, respectively, while the use of the SBR as a second step eliminated totally COD but partially the other pollutants. The higher nitrogen removal in the first system was due to nitrification occurring in the AeMBBR. The acclimatization of microalgae to dairy wastewater enhanced their growth. Their protein content was 54.56%, while starch and lipids were 3.39% and 23.1%, respectively.

From bioaccumulation to biodecumulation: Nickel movement from Odontarrhena lesbiaca (Brassicaceae) individuals into consumers.

Hyperaccumulation describes plants' ability to take up high amounts of soil metals such as Ni and allocate them to aboveground tissues. Little is known, however, about the rate at which Ni is allocated to different plant parts, or about the consumers related to these parts, including their pollinator mutualists. In this study, we examine the interface between the serpentine endemic Ni-hyperaccumulator Odontarrhena lesbiaca and its consumers of different plant parts: leaves (consumers), floral parts (consumers and primitive pollinators), and floral rewards (true pollinators). The study was conducted at two serpentine areas on Lesvos, Greece. Over 13 rounds of sampling during the flowering period of O. lesbiaca in both areas we collected plant stems with flowers, consumers of different plant parts, and flower visitors. Collected animals were mainly insects and some spiders. Chemical analyses showed negligible Ni-concentration differences between the two areas. Among all plant parts, the lowest Ni concentration was found in pollen and the highest in leaves. Regarding animal dietary habits, folivores accumulated the highest Ni concentrations, therefore characterized as "high-Ni insects", while floral-reward consumers, both primary (bees) and secondary (Eristalis tenax, Pygopleurus spp., and wasps), bore low Ni loads. Ni-body load of predators that fed on animals that were passing by was also low. Among floral-reward consumers, short-range fliers (bees of the genera Andrena and Lasioglossum) accumulated higher Ni loads than long-range fliers (Apis mellifera, Bombus terrestris, Eristalis tenax). Solitary Andrena bees accumulated higher Ni concentration than eusocial honeybees (Apis mellifera) and bumblebees (Bombus terrestris); a group of Lasioglossum specimens encompassing both solitary and eusocial bees lay in between. Our results show that diet, foraging distance, and sociality are important factors for Ni transferred into consumers and mutualists, mostly insects that are directly associated with different plant parts of O. lesbiaca.

Does dilute nitric acid improve the removal of exogenous heavy metals from feathers? A comparative study towards the optimization of the cleaning procedure of feather samples prior to metal analysis.

Feather analysis has been widely used as a biomonitoring tool to assess metal contamination in birds, as their sampling is a non-destructive and ethically preferable technique. However, for feathers to be useful as a biomonitor of heavy metals, exogenous contamination has to be efficiently removed. Although much effort has been put into this, no washing procedure has yet proven able to ensure the total removal of the surface-associated metals. The purpose of this study was to propose an efficient washing procedure of feather samples prior to metal analysis, on the basis of comparison of various washing schemes designed according to previous analytical trials, and of the verification of the efficacy of the optimal scheme in cleaning intentionally contaminated feathers. Our investigation showed that dilute nitric acid alone or in combination with a detergent (Extran) or acetone under mild agitation of the samples performed better that any other cleaning scheme applied. Thus, a multi-step procedure including the sequential use of all three reagents was tested against feather samples contaminated by adsorbed or particulate metal species. The procedure was able to completely eliminate the external metal loads in all cases except for the partial removal of severe contamination with adsorbed Cd.

Adaptive flammability syndromes in thermo-Mediterranean vegetation, captured by alternative resource-use strategies.

Fire affects and is affected by leaf functional traits indicative of resource allocation trade-offs. Global change drivers constrain both the resource-use strategies and flammability of coexisting species. However, small attention has been given in identifying links among flammability and plant economics. Ambiguity comes from the fact that flammability is a multidimensional trait. Different flammability attributes (i.e. ignitibility, sustainability, combustibility and consumability) have been used to classify species, but no widely-accepted relationships exist between attributes. We hypothesised that flammability is a spectrum (defined by its four attributes) and the alternative flammability syndromes of coexisting species can be captured by their resource-use strategies. Furthermore, we argue that flammability syndromes are adaptive strategies that ensure persistence in the post-fire community. We conducted a large-scale study to estimate all flammability attributes on leaves from nine, dominant, thermo-Mediterranean species with alternative resource-use and fire-response strategies across a wide environmental and geographic gradient. We assessed the interdependence among attributes, and their variation across ecological scales (genus, species, individual, site and region). Furthermore, we collected 10 leaf functional traits, conducted a soil study and extracted long-term climatological data to quantify their effect on flammability attributes. We found that leaf flammability in thermo-Mediterranean vegetation is a continuous two-dimensional spectrum. The first dimension, driven by leaf shape and size, represents heat release rate (combustibility vs. sustainability), while the second, controlled by leaf economics, presents ignition delay and total heat release (i.e. consumability). Alternative flammability syndromes can increase fitness in fire-prone communities by offering qualitative differences in survival or reproduction. Trade-offs and constraints that control the distribution of resource-use strategies across environmental gradients appeared to drive leaf flammability syndromes as well. Tying the flammability spectrum with resource allocation trade-offs on a global scale can help us predict future ecosystem properties and fire regimes and illustrate evolutionary constraints on flammability.

An integrated phenotypic trait-network in thermo-Mediterranean vegetation describing alternative, coexisting resource-use strategies.

Vascular plants have been found to align along globally-recognised resource-allocation trade-offs among specific functional traits. Genetic constrains and environmental pressures limit the spectrum of viable resource-use strategies employed by plant species. While conspecific plants have often been described as identical, intraspecific variation facilitates species coexistence and evolutionary potential. This study attempts to link an individual's phenotype to its environmental tolerance and ecosystem function. We hypothesised that: (1) seasonal variation in water availability has selected for tight phenotypic integration patterns that shape Mediterranean vegetation; however, (2) coexisting species employ alternative resource-use strategies to avoid competitive exclusion; specifically (3) species with smaller climatic niches (i.e. potential distributions) display higher functional diversity. We examined the interdependence among and the sources of variation within 11 functional traits, reflecting whole-plant economics (e.g. construction costs, hydraulics, defences, water storage capacity), from nine dominant, thermo-Mediterranean species measured across a wide environmental and geographic gradient. Furthermore, we delineated the phenotypic and climatic hypervolumes of each studied species to test for climatic niche overlap and functional distinctiveness. By adopting this multidimensional trait-based approach we detected fundamental phenotypic integration patterns that define thermo-Mediterranean species regardless of life history strategy. The studied traits emerged intercorrelated shaping a resource-allocation spectrum. Significant intraspecific variability in most measured traits allowed for functional distinctiveness among the measured species. Higher functional diversity was observed in species restricted within narrower climatic niches. Our results support our initial hypotheses. The studied functional traits collectively formed an integrated space of viable phenotypic expressions; however, phenotypic plasticity enables functionally distinctive species to succeed complementary in a given set of environmental conditions. Functional variability among coexisting individuals defined species' climatic niches within the trait-spectrum permitted by Mediterranean conditions. Ultimately, a species establishment in a locality depends on the extent that it can shift its trait values.

Growth inhibition and fate of benzotriazoles in Chlorella sorokiniana cultures.

Benzotriazoles are among the most commonly found organic micropollutants in the aquatic environment. In this study, toxicity experiments were conducted in order to investigate the effects of different benzotriazoles on Chlorella sorokiniana growth. Four compounds were tested; 1H-benzotriazole (BTR), xylytriazole (XTR), 5-methyl-1H-benzotriazole (5TTR) and 5-chlorobenzotriazole (CBTR). The fate of these micropollutants was also studied under batch conditions and the effect of different mechanisms on their elimination was investigated. According to the results, the EC50 values in single-substance toxicity experiments were calculated to 8.3 mg L-1 for BTR, 22 mg L-1 for 5TTR and 38.7 mg L-1 for CBTR. A slight inhibition on microalgae growth was noted at the maximum tested concentration of XTR (77 mg L-1), while no inhibition was observed when a mixture of target BTRs was tested at 200 µg L-1. Calculation of the Risk Quotient (RQ) showed no possible ecological threat in the presence of 5TTR, XTR and CBTR, while RQ values close or higher than 1 were estimated for BTR. All target contaminants were significantly eliminated in microalgae experiments that lasted 16 days. Their removal efficiency ranged between 42.2 ±â€¯3.1% (XTR) to 97.2 ±â€¯0.9% (XTR), while their half-life values were estimated to 2.4 ±â€¯0.5 days for 5TTR, 6.5 ±â€¯0.6 days for BTR, 15.2 ±â€¯1.4 days for CBTR and 20.7 ±â€¯2.0 days for XTR. Photodegradation was the main mechanism affecting BTR, XTR and CBTR removal, while bioremoval processes enhanced 5TTR elimination. The addition of sodium acetate decreased the removal efficiency of BTRs possibly due to catabolite repression. This is the first study investigating the toxicity and fate of BTRs in microalgae cultures.

Seasonal and spatial variation of arsenic in groundwater in a rhyolithic volcanic area of Lesvos Island, Greece.

A survey conducted in water wells located in the rhyolithic volcanic area of Mandamados, Lesvos Island, Greece, indicated that significant seasonal variation of arsenic concentration in groundwater exists mainly in wells near the coastal zone. However, there were differences among those coastal wells with regard to the processes and factors responsible for the observed seasonal variability of the element, although they are all located in a small homogeneous area. These processes and factors include (a) a higher rate of silicate weathering and ion exchange during the dry period followed by the dilution by the recharge water during the wet period, (b) enhanced desorption promoted by higher pH in summer and subsequent dilution of As by rainwater infiltration during the wet period, and (c) reductive dissolution of Mn during the wet period and by desorption under high pH values during the dry period. On the other hand, in wells located in higher-relief regions, the concentration of As in groundwater followed a fairly constant pattern throughout the year, which is probably related to the faster flow of groundwater in this part of the area due to a higher hydraulic gradient. In general, seasonal variation of As in groundwater in the study area was found to be related to geology, recharge rate, topography-distance from coast, and well depth.

Heavy Metals in Liver and Brain of Waterfowl from the Evros Delta, Greece.

The concentrations of six heavy metals (cadmium [Cd], chromium [Cr], copper [Cu], manganese [Mn], lead [Pb], and zinc [Zn]) were determined in liver and brain of nine species of waterfowl from the Evros Delta, one of the most important wetlands in Greece, to assess metal contamination and potential risk to waterfowl. Significant differences among species were found for hepatic Cr, Cu, Pb, and Zn; the highest levels of all metals were found in liver of mute swans. Cd increased significantly with age in both organs of wigeon; some differences were also observed between males and females of the same species. Feeding habits were found to significantly affect hepatic Cr, Zn, and Cu concentrations with greater concentrations found in herbivorous than omnivorous species. Several significant positive correlations between metals were detected mainly in liver samples, which were attributable either to their association to metallothioneins or to common routes of exposure of waterfowl. Hepatic and cerebral concentrations of Cd and Pb correlated positively. Given the discrepancies in the thresholds or critical levels of metals in tissues of waterfowl, our survey showed that environmental exposure to increased levels of heavy metals may threaten, at least to some degree, the populations of waterfowl wintering in the Evros Delta. In a small percentage of birds, values indicative of severe adverse effects were determined. Swans that had been found dead showed some of the highest values, whereas accumulation levels did not follow a consistent pattern among the ducks examined.

Is it worth hyperaccumulating Ni on non-serpentine soils? Decomposition dynamics of mixed-species litters containing hyperaccumulated Ni across serpentine and non-serpentine environments.

BACKGROUND AND AIMS: Nickel (Ni)-hyperaccumulating species produce high-Ni litters and may potentially influence important ecosystem processes such as decomposition. Although litters resembling the natural community conditions are essential in order to predict decomposition dynamics, decomposition of mixed-species litters containing hyperaccumulated Ni has never been studied. This study aims to test the effect of different litter mixtures containing hyperaccumulated Ni on decomposition and Ni release across serpentine and non-serpentine soils. METHODS: Three different litter mixtures were prepared based on the relative abundance of the dominant species in three serpentine soils in the island of Lesbos, Greece where the Ni-hyperaccumulator Alyssum lesbiacum is present. Each litter mixture decomposed on its original serpentine habitat and on an adjacent non-serpentine habitat, in order to investigate whether the decomposition rates differ across the contrasted soils. In order to make comparisons across litter mixtures and to investigate whether additive or non-additive patterns of mass loss occur, a control non-serpentine site was used. Mass loss and Ni release were measured after 90, 180 and 270 d of field exposure. KEY RESULTS: The decomposition rates and Ni release had higher values on serpentine soils after all periods of field exposure. The recorded rapid release of hyperaccumulated Ni is positively related to the initial litter Ni concentration. No differences were found in the decomposition of the three different litter mixtures at the control non-serpentine site, while their patterns of mass loss were additive. CONCLUSIONS: Our results: (1) demonstrate the rapid decomposition of litters containing hyperaccumulated Ni on serpentine soils, indicating the presence of metal-tolerant decomposers; and (2) imply the selective decomposition of low-Ni parts of litters by the decomposers on non-serpentine soils. This study provides support for the elemental allelopathy hypothesis of hyperaccumulation, presenting the potential selective advantages acquired by metal-hyperaccumulating plants through litter decomposition on serpentine soils.

Evaluation of polar organic micropollutants as indicators for wastewater-related coastal water quality impairment.

Results from coastal water pollution monitoring (Lesvos Island, Greece) are presented. In total, 53 samples were analyzed for 58 polar organic micropollutants such as selected herbicides, biocides, corrosion inhibitors, stimulants, artificial sweeteners, and pharmaceuticals. Main focus is the application of a proposed wastewater indicator quartet (acesulfame, caffeine, valsartan, and valsartan acid) to detect point sources and contamination hot-spots with untreated and treated wastewater. The derived conclusions are compared with the state of knowledge regarding local land use and infrastructure. The artificial sweetener acesulfame and the stimulant caffeine were used as indicators for treated and untreated wastewater, respectively. In case of a contamination with untreated wastewater the concentration ratio of the antihypertensive valsartan and its transformation product valsartan acid was used to further refine the estimation of the residence time of the contamination. The median/maximum concentrations of acesulfame and caffeine were 5.3/178 ng L(-1) and 6.1/522 ng L(-1), respectively. Their detection frequency was 100%. Highest concentrations were detected within the urban area of the capital of the island (Mytilene). The indicator quartet in the gulfs of Gera and Kalloni (two semi-enclosed embayments on the island) demonstrated different concentration patterns. A comparatively higher proportion of untreated wastewater was detected in the gulf of Gera, which is in agreement with data on the wastewater infrastructure. The indicator quality of the micropollutants to detect wastewater was compared with electrical conductivity (EC) data. Due to their anthropogenic nature and low detection limits, the micropollutants are superior to EC regarding both sensitivity and selectivity. The concentrations of atrazine, diuron, and isoproturon did not exceed the annual average of their environmental quality standards (EQS) defined by the European Commission. At two sampling locations irgarol 1051 exceeded its annual average EQS value but not the maximum allowable concentration of 16 ng L(-1).

Lesser White-fronted (Anser erythropus) and Greater White-fronted (A. albifrons) Geese wintering in Greek wetlands are not threatened by Pb through shot ingestion.

Fecal lead (Pb) levels were investigated in the threatened European population of the Lesser White-fronted Goose (LWfG, Anser erythropus) and of the non-threatened Greater White-fronted Goose (GWfG, Anser albifrons) wintering in two wetland areas in northern Greece in order to assess the potential risk from Pb exposure. Fecal, soil and food plant samples were analyzed. Levels of Pb were normalized using Al concentrations in order to separate the effect of possible ingestion of Pb shot from that of soil or sediment accidentally ingested with food. All concentrations are expressed on a dry weight basis. Geometric means of Pb content in the feces of LWfG were 6.24 mg/kg at Evros Delta and 7.34 mg/kg at Lake Kerkini (maximum values of 28.61 mg/kg and 36.68 mg/kg, respectively); for fecal samples of GWfG geometric means were 2.39 mg/kg at Evros Delta and 6.90 mg/kg at Kerkini (corresponding maximum values of 25.09 mg/kg and 42.26 mg/kg). Soil Pb was in the range of 5.2-60.2mg/kg (geometric mean = 22.6 mg/kg) for the Evros Delta and between 13.4 and 64.9 mg/kg (geometric mean=28.1mg/kg) for Kerkini. A general linear model fitted to the data showed that Pb levels were very closely dependent on Al levels in the feces from both species and at both sites indicating soil or sediment were the only significant source of Pb; species and site, as well as their interaction, were not statistically significant factors. For both species and at both sites exposure to Pb was evidently very mild and the observed levels of Pb were well below the proposed thresholds for lethal or sublethal effects of Pb poisoning. Soil ingestion appeared to gradually increase from October to December for LWfG at Kerkini, corresponding to a gradual depletion of their food source.

Bioactive microconstituents and antioxidant properties of wild edible mushrooms from the island of Lesvos, Greece.

Crude composition, fatty acids, sterols, total phenolic content (TPC), individual polyphenols and terpenic acids were determined in five wild edible mushrooms species (Lactarius deliciosus, Lactarius sanguifluus, Lactarius semisanguifluus, Russula delica, Suillus bellinii) from Lesvos Island, Greece. In addition, the DPPH scavenging capacity, the ferric ion reducing power (FRAP) and the ferrous ion chelating activity of mushroom methanolic extracts were assessed. Among sterols, ergosterol predominated at concentrations 9.2-18.0mg/100g fw. Total phenolic content of mushroom extracts ranged from 6.0 to 20.8mg GAE/100g fw. Up to 19 simple polyphenols were determined in mushrooms extracts, the more abundant being p-OH-benzoic acid, p-OH-phenylacetic acid, o-coumaric acid, ferulic acid and chrysin. In addition, the triterpenic acids oleanolic and ursolic were detected for the first time in mushrooms. All species exerted antioxidant activity and ferrous ion chelating capacity. Principal component analysis revealed good correlations between TPC, DPPH and FRAP but not with metal chelating activity. It seems that mushrooms polyphenols exert antiradical and reducing activities, but they are not strong metal chelators, the observed chelating ability being probably due to other classes of compounds. To our knowledge, this is the first report on the bioactive microconstituents and antioxidant activity of wild Greek edible mushrooms.

Influence of geology on arsenic concentrations in ground and surface water in central Lesvos, Greece.

The occurrence of As was studied in groundwater used for human consumption and irrigation, in stream water and sediments and in water from thermal springs in the drainage basin of Kalloni Gulf, island of Lesvos, Greece, in order to investigate the potential influence of the geothermal field of Polichnitos-Lisvori on the ground and surface water systems of the area. Total dissolved As varied in the range <0.7-88.3 microg L(-1) in groundwater, 41.1-90.7 microg L(-1) in thermal spring water and 0.4-13.2 microg L(-1) in stream water, whereas As concentrations in stream sediments varied between 2.0-21.9 mg kg(-1). Four out of 31 groundwater samples exceeded the EC standard of 10 microg L(-1). The survey revealed an enrichment in both surface and groundwater hydrological systems in the northern part of the area (average concentrations of As in groundwater, stream water and stream sediment: 8.0 microg L(-1), 8.8 microg L(-1) and 15.0 mg kg(-1) respectively), in association with the volcanic bedrocks, while lower As concentrations were found in the eastern part (average concentrations in groundwater, stream water and stream sediment: 2.9 microg L(-1), 1.7 microg L(-1) and 5.9 mg kg(-1) respectively), which is dominated by ophiolitic ultramafic formations. The variation of As levels between the different parts of the study area suggests that local geology exerts a determinant influence on As geochemical behaviour. On the other hand, the geothermal activity manifested in the area of Polichnitos-Lisvori does not affect the presence of As in groundwater and streams.