Compost-assisted revegetation of highly phytotoxic sulfidic tailings with Medicago sativa L. plants grown from the seed to seedpod stage under greenhouse experimental mesocosms conditions.

The revegetation of highly phytotoxic sulfidic tailings is a challenging task which may often be successfully accomplished only following the addition of soil amendments. This study evaluated the use of green compost at increasing rates (10, 25 and 50% v/v) for the revegetation of extremely acidic sulfidic tailings of the North Mathiatis mine, Cyprus, with the use of alfalfa (Medicago sativa L.) plants, under greenhouse conditions. Alfalfa seeds were successfully germinated in tailings amended either with 25% or 50% (v/v) compost (52 and 85%, respectively). Plants managed to complete their life cycle and produce seeds only in the tailings amended with 50% (v/v) compost, since plants grown in tailings amended with lower rates of compost (i.e., 10 or 25% v/v) showed severe symptoms of phytotoxicity and eventually died. The amendment of tailings with 50% (v/v) green compost resulted in increased pH values, water holding capacity and organic content levels, soil respiration rates, as well as changes in soil elemental composition compared with tailings alone treatment, which in turn facilitated the growth and development of alfalfa plants during the whole experimental period (140 days). Plants managed to reach the late seedpod growth stage, indicating their potential regeneration and continual existence to the amended tailings, simultaneously uncovering the development of favorable conditions in the rhizosphere for the successful revegetation of studied tailings.

Occurrence and Distribution of Hexavalent Chromium in Ground and Surface Waters in Cyprus.

The origin and distribution of hexavalent chromium, Cr (VI) over four seasonal cycles was investigated through a conceptual model that included three aquifer systems in Cyprus. An extensive water sampling grid covered two sea water intruded coastal aquifers, namely the Kokkinochoria (A1) and Kiti-Pervolia (A2) aquifers and the Troodos massif (A3). Analytical results give a first insight to the presence of Cr (VI) in Cyprus ground and surface waters. The highest Cr (VI) value of 26 µg L-1 is observed in the Troodos area (A3) where Cr(VI) is detected in all sampled water systems (surface and ground/spring). Nonetheless, the highest median values of 4.6 and 4.5 µg L-1 are observed in the Kokkinochoria (A1) and Kiti-Pervolia (A2) study areas respectively, where the local aquifers are under increased pressure from agriculture, urbanization and seawater intrusion. Stable isotopes were used to discern the effect of return irrigation and seawater intrusion. Stable isotope analyses from Troodos samples show two distinct groups of meteoric and near meteoric waters whereas isotopically enriched water is shown to correspond to the Kiti and Kokkinochoria area.

Legacy soil contamination at abandoned mine sites: making a case for guidance on soil protection.

Within the European Union, guidance in the form of a uniform Soil Directive does not exist and member states are left to enact their own legislation governing historic soil contamination. Several historic or "legacy" sites exist in Cyprus - an EU member state with a long history of mining and a significant number of abandoned mining sites. The gold-silver enrichment plant of Mitsero village was abandoned 70 years ago, yet soil samples inside and outside the plant were extremely low in pH, exhibited high leachability of heavy metals and high cyanide levels. Water samples collected from an ephemeral stream located down-gradient of the site contained high levels of heavy metals. Two abandoned open-pit mines (Kokkinopezoula and Mathiatis) were investigated, where elevated metal content in soil samples from the surrounding streams and spoil heaps, and extremely low pH and high metal content in water samples from the mine crater were measured.

Biogeochemical response of Pinus brutia and Olea europaea to lithological variations and Cu mineralisation in Cyprus.

Regional geochemical mapping programs are predominantly based on regolith materials as the sampling media. The use of plant organs has been more limited, despite potential advantages demonstrated in more localised studies that have examined biogeochemical responses to various types of mineralisation or contamination, or sought to identify species with phytoremediation potential. This study investigated the effects of variations in lithology and mining wastes on the multielement chemistry of Pinus brutia (pine) needles and O. europaea (olive) leaves, obtained from low-density traverses across Cyprus and detailed sampling around two Cyprus-style VHMS Cu-deposits. A total of 476 samples were analysed by a combination of inductively-coupled plasma mass spectrometry (ICP-MS) and portable X-ray fluorescence spectrometry (pXRF). At the regional scale there are substantial differences in the composition of the pine needles, especially for Ni, Ba, Sr, Mn and Zn, between the major lithological groups that range from the ultramafic and mafic units of the Troodos Ophiolite to the mineralised pillow basalts and various marine carbonate units. Both pine needles and olive leaves display intense Re anomalies in areas with mine wastes and consistently low concentrations in background areas. The response for Cu and other macro- or micronutrient elements to contamination is less pronounced and may reflect barriers to uptake by the plants. The relative magnitude of variations between the different lithologies in median plant metal concentrations is equivalent to that displayed in soils of the Geochemical Atlas of Cyprus (e.g. REE, Zn and Sr), but for some elements the patterns differ substantially. There is close correlation between the ICP-MS and pXRF data for elements where most values are above pXRF detection limits. The study further demonstrates the potential of plants in regional geochemical mapping for a range of applications, in combination with or as an alternative to conventional regolith media.

Land use in urban areas impacts the composition of soil bacterial communities involved in nitrogen cycling. A case study from Lefkosia (Nicosia) Cyprus.

The different types of land-use and soil lithology in urban and peri-urban areas of modern cities compose a complex mosaic of soil ecosystems. It is largely unknown how these differences result in changes in bacterial community composition and structure as well as in functional guilds involved in N cycling. To investigate the bacterial composition and the proportion of denitrifiers in agricultural, forested, schoolyard and industrial areas, 24 samples were collected from urban and peri-urban sites of Lefkosia. Bacterial diversity and the proportion of denitrifiers were assessed by NGS and qPCR, respectively. Proteobacteria, Actinobacteria, Bacteriodetes, Chloroflexi, Acidobacteria and Planctomycetes were identified as the most dominant phyla across all sites, while agricultural sites exhibited the highest bacterial diversity. Heavy metals such as Co, Pb, V and Al were identified as key factors shaping bacterial composition in industrial and schoolyard sites, while the bacterial assemblages in agricultural and forested sites were associated with Ca. Variance partitioning analysis showed that 10.2% of the bacterial community variation was explained by land use management, 5.1% by chemical elements due to soil lithology, and 1.4% by sampling location. The proportion of denitrifiers varied with land use management. In industrial and schoolyard sites, the abundance of the nosZII bacterial community increased while nirK abundance declined. Our data showed that land use and lithology have a moderate impact on the bacterial assemblages in urban and peri-urban areas of Lefkosia. As the nosZII bacterial community is important to the N2O sink capacity of soils, it would be interesting to elucidate the factors contributing to the proliferation of the nosZII clade in these soils.

Uptake of hexavalent chromium by Lactuca sativa and Triticum aestivum plants and mediated effects on their performance, linked with associated public health risks.

Plants exposed to toxic Cr(VI) concentrations show reduced biomass production and yield. The present study examined (1) the impacts of increasing Cr(VI) exposure (0.05, 0.5, 1, 5 and 10 mg L-1 K2Cr2O7 in irrigation water) on the growth and development, yield, and stress physiology of two important crop species, such as wheat (Triticum aestivum L.) and lettuce (Lactuca sativa L.), and (2) the associated human health risks due to the consumption of these commodities. Plants in all Cr(VI) treatments preserved similar growth rates and phenotypes with control, untreated plants, with no remarkable modulations in biomass yield (fresh/dry weight, plant height, straw/grain weight). Grains harvested from plants exposed to all Cr(VI) treatments had increased size and 1000 grain weight, partially suggesting hormetic effect. Elevated K2Cr2O7 concentrations (5 and 10 mg L-1) resulted in increased photosynthetic pigments' levels in lettuce leaves. Lipid peroxidation and H2O2 content also revealed the absence of oxidative stress in lettuce plants. Non-carcinogenic (target hazard quotient) and carcinogenic risks from the consumption of these commodities grown under the conditions described in this study were found de minimis. However, more studies are needed in order to obtain more solid information on the safety of Cr(VI)-contaminated water irrigation.

Contamination of stream waters, sediments, and agricultural soil in the surroundings of an abandoned copper mine by potentially toxic elements and associated environmental and potential human health-derived risks: a case study from Agrokipia, Cyprus.

Abandoned mining areas have left a legacy of environmental damage with potential public health implications. The present study aimed at (1) assessing the level of contamination of the sites surrounding the Agrokipia abandoned copper mine in Cyprus through the mobilization of potentially toxic elements (PTEs), (2) correlating results with the mineralogy of the area, (3) discussing potential ecological and human health risks, and (4) proposing regeneration strategies. To this effect, the levels of 22 PTEs and other major elements were assessed in the acidic water of pit lakes, the tailings, the waters, and sediments of several streams originating from the mining site and flowing through the village of Agrokipia, and from agricultural soil from an impacted adjacent olive orchard. The pH values of water (pH < 2.7) in the pit lakes uncovered the acidic and oxidizing conditions that prevailed in the area. The acidity and the examined PTE concentrations in stream waters followed a decreasing trend with increasing distance from the tailing, reaching background values in a distance of 1500 m. The tailing spoil-heap was significantly enriched with Cu, Zn, Pb, Cd, Cr, and Ag (e.g., enrichment factor values up to 29 for Cu and 120 for Ag). Stream sediments and agricultural soil were contaminated with PTEs (mainly Cu, Zn, Pb, Cd, Cr, Ag, and Li), as evident by several contamination indices (i.e., enrichment and contamination factor). The level of contamination was correlated with the reported mineralogy of the site. The values of the degree of contamination (Cdeg = 62) and pollution load index (PLI = 2.4) indicated contamination of the sediments of the Voulgarides stream flowing through the village, suggesting potential public health implications to the local community. In addition, the values of the ecological risk factor suggested that the studied streams pose moderate ecological risks, mainly mediated by Cd and Cu. Overall, the results highlighted the need for undertaking regeneration measures for safeguarding environmental sustainability and public health.

Hexavalent chromium leads to differential hormetic or damaging effects in alfalfa (Medicago sativa L.) plants in a concentration-dependent manner by regulating nitro-oxidative and proline metabolism.

Chromium has been proven to be extremely phytotoxic. This study explored the impacts of increasing Cr(VI) exposure (up to 10 mg L-1 K2Cr2O7) on the growth and development of alfalfa plants and adaptation responses employed, in an environmentally relevant context. The threshold concentration of K2Cr2O7 in irrigation water beyond which stress responses are initiated is 1 mg L-1. Lower Cr(VI) exposure (0.5 mg L-1 K2Cr2O7) induced hormesis, evident through increased biomass and larger leaves, likely mediated by increased NO content (supported by elevated NR enzymatic activity and overexpression of NR and ndh genes). Elevated Cr(VI) exposure (5 and 10 mg L-1 K2Cr2O7) resulted in reduced biomass and smaller leaves, and lower levels of photosynthetic pigment (10 mg L-1 K2Cr2O7). Higher levels of lipid peroxidation, H2O2 and NO contents in these plants suggested nitro-oxidative stress. Stress responses included increased SOD and CAT enzymatic activities, further supported to some extent by MnSOD, FeSOD, Cu/ZnSOD and CAT transcripts levels. GST7 and GST17 gene expression patterns, as well as proline content, P5CS enzymatic activity and corresponding P5CS and P5CR gene expression levels emphasized the role of proline and GSTs in the adaptation responses. Results highlight the importance of managing Cr(VI) levels in irrigation water.

Application of hydrogen bonding calculations in property based drug design.

A drug can be characterized by "descriptors" that include size (volume) and H-bond acidity and H-bond basicity. These descriptors can be rapidly estimated from structure by a fragment scheme and used to predict physicochemical and transport properties of drug candidates (e.g. logP, solubility, gastrointestinal absorption, permeability and blood-brain distribution). The solvation equations can be interpreted to provide a qualitative chemical insight into biological partition and transport mechanisms. Applications to blood-brain partition and human intestinal absorption (HIA) are discussed.

Determination of sets of solute descriptors from chromatographic measurements.

The use of gas-liquid chromatographic (GLC) retention data to obtain sets of solute descriptors is outlined, with reference to the schemes of Laffort and of Weckwerth. The method of Snyder and Dolan to obtain a set of solute descriptors from reverse phase high performance chromatographic (RP-HPLC) measurements is described. The work of Abraham on the construction of solvation parameters, or descriptors, from water-solvent partitions, GLC retention data and RP-HPLC data is considered in some detail. A comparison is made between the schemes of Laffort, Weckwerth and Abraham, and it is shown that the latter two yield exactly the same fits for a test data set of gas-methanol partition coefficients, although the distribution of chemical information amongst the terms in the multiple linear regressions is not quite the same. A comparison between the above 'experimental' descriptors and theoretical descriptors is made, and it is shown that the experimental Abraham and the theoretical Klamt descriptors encode almost the same chemical information. It is concluded that for processes that entail transfer of a solute from one phase to another, only a small number of solute descriptors, no more than five or six, is needed to provide a reasonably accurate analysis of the process.

Geochemical patterns in the soils of Cyprus.

The soil geochemical atlas of Cyprus is a recent addition to the series of national to continental-scale geochemical mapping programmes implemented over the last two decades for environmental and resource applications. The study has been conducted at the high sampling density of 1 site per 1km(2), with multi-element and multi-method analysis performed on samples of top soil (0-25cm) and sub soil (50-75cm) from a grid of over 5350 sites across a major portion of Cyprus. Major and most trace elements display sharp concentration changes across the main geological boundaries but a high degree of spatial continuity and consistency of values within those boundaries. Some elements display one to two orders of magnitude difference in median concentrations between the soils developed over ultramafic or mafic units and those developed over sedimentary rocks or alluvial units. The ratio of aqua regia-extractable to total metal contents provides an indication of the general mineralogical host for a number of trace elements. The majority of soils are near-neutral to alkaline with the small proportion of areas with soil pH<5 largely restricted to the major Cu deposits. There is strong correlation between top soil and sub soil geochemical values. Where the concentrations of some elements (including Pb, Hg and Sn) are indicative of contamination, the values are typically higher in the top soil samples in these areas. Variations in the concentration of elements with strong redox controls on mobility are linked to changes in sedimentary environment between deep and shallow marine conditions. Some element patterns can be related to the effects of urbanisation and sulphide mining operations; however the dominant control on soil geochemistry is the parent geology and regolith forming processes. The atlas demonstrates the effectiveness of high-density sampling in mapping local to regional-scale features of the geochemical landscape.

Determination of McGowan volumes for ions and correlation with van der Waals volumes.

The McGowan volume has been widely used for the analysis of physicochemical and biochemical properties in chemistry and drug industry. Because McGowan volumes are not available for ions, its application is limited to only neutral compounds. Pauling radii of metallic ions have been collected and studied to obtain McGowan volumes for ions. Regression analysis was carried out between Pauling radii (R(p)) and McGowan radii (R(x)) for a wide range of compounds. It was found that Pauling radii and McGowan radii derived from McGowan volumes by using a volume-radius formula are linearly related (R(x) = 1.115R(p) + 0.0623, r(2) = 0.995). This equation is then used to calculate McGowan volumes for various ions and charged groups. McGowan volumes have been calculated for inorganic, organic, and organometallic compounds and correlated with van der Waals volumes. Results show that McGowan volumes (V(x)) are entirely equivalent to computer-calculated van der Waals volumes.

Fast calculation of van der Waals volume as a sum of atomic and bond contributions and its application to drug compounds.

The van der Waals volume is a widely used descriptor in modeling physicochemical properties. However, the calculation of the van der Waals volume (V(vdW)) is rather time-consuming, from Bondi group contributions, for a large data set. A new method for calculating van der Waals volume has been developed, based on Bondi radii. The method, termed Atomic and Bond Contributions of van der Waals volume (VABC), is very simple and fast. The only information needed for calculating VABC is atomic contributions and the number of atoms, bonds, and rings. Then, the van der Waals volume (A(3)/molecule) can be calculated from the following formula: V(vdW) = summation operator all atom contributions - 5.92N(B) - 14.7R(A) - 3.8R(NR) (N(B) is the number of bonds, R(A) is the number of aromatic rings, and R(NA) is the number of nonaromatic rings). The number of bonds present (N(B)) can be simply calculated by N(B) = N - 1 + R(A) + R(NA) (where N is the total number of atoms). A simple Excel spread sheet has been made to calculate van der Waals volumes for a wide range of 677 organic compounds, including 237 drug compounds. The results show that the van der Waals volumes calculated from VABC are equivalent to the computer-calculated van der Waals volumes for organic compounds.

A comparison between the two general sets of linear free energy descriptors of Abraham and Klamt.

Two sets of molecular descriptors, the five experimental Abraham, and the five COSMOments of Klamt's COSMO-RS, have been compared for a data set of 470 compounds. Both sets are considered as almost complete sets of LFER. The two sets of descriptors are shown to exhibit a large overlap as far as their chemical content. The chemical information however is distributed differently in each set with the Abraham set incorporating extra information in the excess molar refraction descriptor E. Regression equations have been constructed to predict the experimental Abraham descriptors from theoretically calculated COSMOments. The chemical interpretation of these equations is however difficult because of the lack of clustering which characterizes the distribution of chemical information through the two sets of descriptors. The predictability of the regression equations is tested successfully using a reasonably large set of data, and the method is compared to recent attempts to calculate the Abraham descriptors from various theoretical bases.