1,721,035 research outputs found
Processes Causing Attenuation in Aquifers
No full textTwo zones are considered the most relevant physical media controlling the movement of water and pollutants: the unsaturated (vadose) zone and saturated depths. Contaminants arising from both point and non-point sources, such as municipal and hazardous waste landfills, suburban septic systems, mining and petroleum production, and agriculture, all filter through the vadose zone, where resident microbes, plant roots (rhizosphere), macrofauna (earthworms, ants, and termites), and organized colloids (humic matter, minerals) reduce their concentrations to levels acceptable by sanitary authorities. The principles of the vadose zone’s functioning are not completely understood because of the presence of the many subsystems and their chemico-physical and biological interactions. The vadose zone (through the many microbiological and chemico-physical processes taking place) is potentially capable of blocking or/and
degrading any natural or artificially introduced contaminants flowing in deep waters. Soil overlying the water table provides the primary protection against groundwater pollution. Bacteria, sediment, and other insoluble forms of contamination become trapped within the soil pores. Some chemicals are absorbed or react chemically with various soil constituents, thereby preventing or slowing the migration of these pollutants into the groundwater. In addition, plants and soil microorganisms use some potential pollutants, such as nitrogen, as nutrients for growth, thereby depleting the amount that reaches the groundwater. In soils and sediments, the microbial mediated attenuation processes (natural or engineered) usually work through coupling electron acceptors such as nitrate, sulfate, and carbon dioxide with electron donors such as organic compound
Ricerca degli elementi-guida della nutrizione mediante spettroscopia ad assorbimento atomico sui resti scheletrici di Alba-S. Cassiano (Cuneo)
No full textIndagini paleonutrizionali e determinazione del Piombo osseo mediante spettroscopia ad assorbimento atomico sui resti scheletrici di epoca tardo-romana (IV secolo d.C.) della Villa dei Gordiani (Roma)
No full textRicerca degli elementi guida della nutrizione e di alcuni metalli pesanti mediante spettroscopia ad assorbimento atomico. Gortina I
No full textRiuso agricolo di sedimenti di dragaggio contaminati
No full textI risultati del progetto europeo AGRIPORT per la decontaminazione di sedimenti di quattro siti portuali del bacino Mediterraneo mediante fitodepurazion
Phytoremediation applied to contaminated sediments: site-specific risk assessment and possible solutions
No full textEnhanced heavy metal phytoextraction from marine dredged sediments comparing conventional chelating agents (citric acid and EDTA) with humic substances
No full textLaboratory experiments were carried out to examine the effects of chelating agents on heavy metal extraction from slightly contaminated dredged sediments from the port of Livorno (Italy). Ethylene diamine tetraacetate (EDTA), citric acid (CA) and humic substances (HS) were tested in two different concentrations each: 120 and 480, 500 and 2,000, 500 and 1,000 mg/l, respectively. Solubilisation of heavy metals (Cu and Zn) was observed for both EDTA and HS in the extraction kinetic experiments: 58% of the total Cu and 50% of the total Zn in the sediment were mobilised from the solid matrix using EDTA (480 mg/l) and 32% of the total Cu and 5% of the total Zn, using HS (1,000 mg/l). It was observed that solubilized metal levels were positively related to the chelating agent concentration. HS performance in the heavy metals mobilisation and phyto-toxicity tests was considered promising. HS represent an innovation in enhanced phytoextraction techniques: they can be considered an environmentally non-impacting bio-agronomic amendment. CA induced no significant effects on heavy metal mobilisation and it also negatively affects seed germination (Germination Index < 40%). Laboratory experiments with plants showed that none of the treatments significantly affected the biomass production and a trend could only be detected for the heavy metal uptake into shoots of Paspalum vaginatum sp. Transplantation of seashore paspalum is useful as a pre-treatment of contaminated dredged sediments, since it is a salt-tolerant species and it can be easily adaptable on a nutrient poor and fine textured medium
Efficiency assessment of a reed bed pilot plant (Phragmites australis) for sludge consolidation in Tuscany
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