Effects of carbon nanotube and biochar on bioavailability of Pb,Cu and Sb in multi-metal contaminated soil

This study examined the effects of carbon nanotube and biochar on the bioavailability of Pb, Cu and Sb in the shooting range soils for developing low-cost remediation technology. Commercially available multi-walled carbon nanotube (MWCNT) and biochar pyrolyzed from soybean stover at 300 °C (BC) at 0.5, 1 and 2.5% (w w^?1) were used to remediate the contaminated soil in an incubation experiment. Both DTPA (bioavailable) and TCLP (leaching) extraction procedures were used to compare the metal/loid availability and leaching by the amendments in soil. The addition of BC was more effective in immobilizing mobile Pb and Cu in the soil than that in MWCNT. The BC reduced the concentrations of Pb and Cu in the soil by 17.6 and 16.2%, respectively. However, both MWCNTs and BC increased Sb bioavailability by 1.4-fold and 1.6-fold, respectively, in DTPA extraction, compared to the control. The toxicity characteristic leaching procedure (TCLP) test showed that the leachability of Pb in the soil amended with 2.5% MWCNT was 1.3-fold higher than that the unamended soil, whereas the BC at 2.5% decreased the TCLP-extractable Pb by 19.2%. Precipitation and adsorption via electrostatic and π–π electron donor–acceptor interactions were postulated to be involved in the interactions of Pb and Cu with surfaces of the BC in the amended soils, whereas ion exchange mechanisms might be involved in the immobilization of Cu in the MWCNT-amended soils. The application of BC derived from soybean stover can be a low-cost technology for simultaneously immobilizing bioavailable Pb and Cu in the shooting range soils; however, neither of amendments was effective in Sb immobilization.     

Impact of natural and calcined starfish (<Emphasis Type="Italic">Asterina pectinifera</Emphasis>) on the stabilization of Pb,Zn and As in contaminated agricultural soil

Metal stabilization using soil amendments is an extensively applied, economically viable and environmentally friendly remediation technique. The stabilization of Pb, Zn and As in contaminated soils was evaluated using natural starfish (NSF) and calcined starfish (CSF) wastes at different application rates (0, 2.5, 5.0 and 10.0 wt%). An incubation study was conducted over 14 months, and the efficiency of stabilization for Pb, Zn and As in soil was evaluated by the toxicity characteristic leaching procedure (TCLP) test. The TCLP-extractable Pb was reduced by 76.3–100 and 91.2–100 % in soil treated with NSF and CSF, respectively. The TCLP-extractable Zn was also reduced by 89.8–100 and 93.2–100 % in soil treated with NSF and CSF, respectively. These reductions could be associated with the increased metal adsorption and the formation of insoluble metal precipitates due to increased soil pH following application of the amendments. However, the TCLP-extractable As was increased in the soil treated with NSF, possibly due to the competitive adsorption of phosphorous. In contrast, the TCLP-extractable As in the 10 % CSF treatment was not detectable because insoluble Ca–As compounds might be formed at high pH values. Thermodynamic modeling by visual MINTEQ predicted the formation of ettringite (Ca₆Al₂(SO₄)₃(OH)₁₂·26H₂O) and portlandite (Ca(OH)₂) in the 10 % CSF-treated soil, while SEM–EDS analysis confirmed the needle-like structure of ettringite in which Pb was incorporated and stabilized in the 10 % CSF treatment.     

Effect of biosolid hydrochar on toxicity to earthworms and brine shrimp

The hydrothermal carbonization of sewage sludge has been studied as an alternative technique for the conversion of sewage sludge into value-added products, such as soil amendments. We tested the toxicity of biosolid hydrochar (Sewchar) to earthworms. Additionally, the toxicity of Sewchar process water filtrate with and without pH adjustment was assessed, using brine shrimps as a model organism. For a Sewchar application of 40 Mg ha^?1, the earthworms significantly preferred the side of the vessel with the reference soil (control) over side of the vessel with the Sewchar treatments. There was no acute toxicity of Sewchar to earthworms within the studied concentration range (up to 80 Mg ha^?1). Regarding the Sewchar process water filtrate, the median lethal concentration (LC50) to the shrimps was 8.1% for the treatments in which the pH was not adjusted and 54.8% for the treatments in which the pH was adjusted to 8.5. The lethality to the shrimps significantly increased as the amount of Sewchar process water filtrate increased. In the future, specific toxic substances in Sewchar and its process water filtrate, as well as their interactions with soil properties and their impacts on organisms, should be elucidated. Additionally, it should be identified whether the amount of the toxic compounds satisfies the corresponding legal requirements for the safe application of Sewchar and its process water filtrate.     

Effects of nanoparticles in species of aquaculture interest

Recently, it was observed that there is an increasing application of nanoparticles (NPs) in aquaculture. Manufacturers are trying to use nano-based tools to remove the barriers about waterborne food, growth, reproduction, and culturing of species, their health, and water treatment in order to increase aquaculture production rates, being the safe-by-design approach still unapplied. We reviewed the applications of NPs in aquaculture evidencing that the way NPs are applied can be very different: some are direclty added to feed, other to water media or in aquaculture facilities. Traditional toxicity data cannot be easily used to infer on aquaculture mainly considering short-term exposure scenarios, underestimating the potential exposure of aquacultured species. The main outputs are (i) biological models are not recurrent, and in the case, testing protocols are frequently different; (ii) most data derived from toxicity studies are not specifically designed on aquaculture needs, thus contact time, exposure concentrations, and other ancillary conditions do not meet the required standard for aquaculture; (iii) short-term exposure periods are investigated mainly on species of indirect aquaculture interest, while shrimp and fish as final consumers in aquaculture plants are underinvestigated (scarce or unknown data on trophic chain transfer of NPs): little information is available about the amount of NPs accumulated within marketed organisms; (iv) how NPs present in the packaging of aquacultured products can affect their quality remained substantially unexplored. NPs in aquaculture are a challenging topic that must be developed in the near future to assure human health and environmental safety.

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Adsorption mechanism of chromium(III) using biosorbents of Jatropha curcas L.

Environmental Science and Pollution Research - The removal of Cr3+ from water solutions by biosorbents from the rind, endosperm, and endosperm + episperm of the Jatropha curcas was evaluated....     

Evaluation of chemical and ecotoxicological characteristics of biodegradable organic residues for application to agricultural land

The use of organic waste and compost as a source of organic matter and nutrients is a common practice to improve soil physico-chemical properties, meanwhile reducing the need for inorganic fertilisers. Official guidelines to assess sewage sludge and compost quality are mostly based on total metal content of these residues. Measurement of the total concentration of metals may be useful as a general index of contamination, but provides inadequate or little information about their bioavailability, mobility or toxicity when the organic residue is applied to the soil. However, ecotoxicity tests provide an integrated measure of bioavailability and detrimental effects of contaminants in the ecosystem. In the present study, three different types of biodegradable organic residues (BORs) have been considered: sewage sludge from municipal wastewater treatment (SS), compost from the organic fraction of unsorted municipal solid waste (MSWC), and garden waste compost (GWC). The BORs were subjected to chemical characterisation and total metal quantification (Cd, Cr, Cu, Ni, Pb and Zn), in order to verify their suitability for land application. Water leachability was determined through the DIN 38414-S4 method, while the modified BCR sequential extraction procedure was used for metal speciation. Ecotoxicity of the BORs was studied by direct and indirect bioassays. Direct toxicity bioassays were: plant growth tests with cress (Lepidium sativum L.) and barley (Hordeum vulgare L.), and earthworm (Eisenia fetida) mortality. On the other hand, indirect exposure bioassays, with leachate from the residues, took into account: luminescent bacteria (Vibrio fischeri), seed germination (L. sativum and H. vulgare) and Daphnia magna immobilization. As far as total metal concentration is concerned, with particular reference to Zn, SS resulted neither suitable for the use in agriculture nor compatible to be disposed of as an inert material into landfill, according to the Directive 1999/31/EC. Zinc in SS was mainly present in exchangeable form (28.5%), appearing as highly bioavailable. As a consequence, SS exhibited either high ecotoxicity effects with the indirect exposure bioassays or significant mortality with the earthworm bioassay. Total content of metals in MSWC allowed its classification as "stabilised biowaste", according to 2nd draft [DG Env.A.2. Working document of Biological treatment of biowaste - 2nd draft. Directorate-General Environment, Brussels, 12th February; 2001. accessed in:http://europa.eu.int/comm/environment/waste/facts_en.htm, at 10/09/2002] while leachate, on the basis of the concentration of these contaminants, could be classified as "inert waste". This residue showed significant ecotoxicity effects with direct exposure bioassays as well as with the luminescent bacteria bioassay. However, it resulted less toxic than SS. Finally, GWC could be classified as a Class 2 compost, with no detectable toxic effects on the organisms used in the bioassays, except for the luminescent bacteria. In this case, an EC(50) of 73.0% was observed. Considering the results, the use of a battery of toxicity test in conjunction with chemical analysis should be suggested, in order to correctly assess possible environmental risks deriving from disposal or land application of biodegradable organic residues.     

A new distribution of Caucasian wingnut (Pterocarya fraxinifolia (Poiret) Spach) in the Kahramanmaras region, Turkey

Caucasian wingnut (Pterocarya fraxinifolia (Poiret) Spach) is a relict tree species having limited natural distribution in Turkey. In this study, a new distribution of this species in the Kahramanmaras region was explained. This distribution occurs in Onsenhopuru and Yavuzlar villages and Yesilyore town of Turkoglu district, at elevations between 600 and 640 m along Orcan stream, and continues about 4 km. In this area, Caucasian wingnut had about 100 trees. This distribution area of the species, quite important for biodiversity, should be protected and the existing individuals should be evaluated as a gene resource. Especially vegetative reproduction of the species should be started and the seedlings obtained should be used at the margins of lakes and streams, parks and large gardens, avenues, boulevards, and streets in the region.     

The effects of air pollution and meteorological parameters on respiratory morbidity during the summer in São Paulo City

Effects of meteorological variables and air pollutants on child respiratory morbidity are investigated during two consecutive summers (December-March 1992/1993 and 1993/1994) at the Metropolitan Area of S?o Paulo (MASP), Brazil. The MASP, with almost 17 million inhabitants, is considered the most populous region in South America. Due to warmer temperatures, increased rainfall and consequent low levels of air pollutants during the summer compared to winter, less attention has been paid to epidemiological studies during this season, especially in tropical urban areas such as S?o Paulo. In the present work, principal component analysis (PCA) is applied to medical end environmental data to identify patterns relating child morbidity, meteorological variables and air pollutants during the summer. The following pollutant concentrations are examined: SO2, inhalable particulate matter (PM10), and O3. The meteorological variables investigated are air temperature, water vapor (water vapor density) and solar radiation. Although low correlation between respiratory morbidity and environmental variables are, in general, observed for the entire dataset, the PCA method indicates that child morbidity is positively associated with O3 for the 1992/1993 summer. This pattern is identified in the third principal component (PC3), which explains about 19% of the total variance of all data in this summer. However, the 1993/1994 summer shows a more complex association between both groups, suggesting stronger ties with meteorological variables. Marked changes in synoptic conditions from the end of January to end of March of the 1993/1994 summer seem to have played an important role in modulating respiratory morbidity. A detailed examination of meteorological conditions in that period indicates that prefrontal (postfrontal), hot (cold) and dry (wet) days favored the observed decrease (increase) of respiratory morbidity.     

Biology,population dynamics and secondary production of<Emphasis Type="Italic"> Tylos europaeus</Emphasis> (Isopoda,Tylidae) on the western coast of Portugal

The biology, population dynamics, and production of Tylos europaeus were studied in two sandy beaches of the western coast of Portugal. At both sites, reproduction occurred seasonally, from April to July, with only one new cohort produced per year. Regarding population dynamics, cohort-splitting events were detected in males at the beginning of the reproduction period (April/May), resulting in two groups with distinct growth rates (fast-growing vs slow-growing males). Different biological characteristics were consequently detected in these two groups, namely regarding body size, lifespan, and contribution to the reproductive effort. Lifespan was estimated as approximately 3 years, for females and fast-growing males, and 4 years for slow-growing males. Cohort-splitting among males appeared as a possible strategy to cope with the highly male-biased sex ratios observed, which could lead to a strong male-male competition for mating. T. europaeus appeared as an annual species, with a univoltine life-cycle (one generation per year), and iteroparous females reproducing twice during their lifespan. Average growth production (P) was estimated at 0.082 g.m^–2.yr^–1 AFDW (ash-free dry weight) and the average annual biomass () (standing stock) at 0.052 g.m^–2, resulting in a P/ ratio of 1.58. These results produced baseline information for the construction of a population-dynamics model and highlighted the potential of this species as an environmental quality-assessment bioindicator on sandy shores.Communicated by S.A. Poulet, Roscoff