1,720,993 research outputs found
Emerging contaminants in sediments: a review
No full textEmerging Contaminants (ECs) are chemicals for which new concerns have recently raised in terms of occurrence, fate, adverse effects on human health and the environment. ECs include pharmaceuticals, nanomaterials, compounds used in personal care products, plastics, pesticides and flame retardants, and compounds with a large variety of uses (e.g., phenolic and perfluorinated compounds, chlorinated paraffins, etc.).
The EU Water Framework Directive 2013/39/EU deals with the status of water bodies and reports an updated list of priority substances. Some of these (e.g., nonylphenols, di(2-ethylhexyl)phthalate DEHP, perfluorooctane sulfonate PFOS, hexabromocyclododecanes, polybrominated diphenyl ethers, etc.) are emerging contaminants with high affinity towards suspended solids and sediments, due to their physicochemical properties (e.g., Koc value, etc.). The review focuses on this group of pollutants, reporting about the occurrence and distribution in sediments and biota, bioaccumulation and ecotoxicity, and the target or limit values that have been set in order to protect the aquatic environment and the human health
Design of permeable reactive barriers and examples of full scale treatments
No full textPermeable reactive barriers (PRBs) are innovative technologies for the in situ remediation of contaminated groundwater. The technology involves the emplacement, into an excavated zone of the aquifer across the flow path of the contaminated groundwater, of a "reactive" filling material permeable to groundwater to intercept and treat the contaminants as the plume flows through under the influence of the natural hydraulic gradient.
A wide range of materials are currently available. Some of them remove contaminants through non-destructive mechanisms, such as precipitation, sorption or cation exchange (also promoted by geochemistry modifications in the treatment zone), other through destructive mechanisms, such as abiotic degradation or biological degradation (in biobarriers). The choice among these is primarily based on the contaminant to remove and the abatement required, but the hydrogeological and the biogeochemical conditions of the aquifer may have great influence as well. Sometimes, concurrently mechanisms acts in removing the pollutants. Multilayer barrier systems can be developed in order to treat groundwater affected by different kinds of pollutants
Pollutants in Groundwater
No full textGroundwater contamination generically refers to modifications in biological, physical or chemical characteristics (e.g., salinity, temperature, etc.), the presence of undesirable solutes at significant concentrations, or radioactivity. It may be: (i) of natural origin, (ii) the result of human activity; or (iii) a combination of the previous two. Naturally occurring processes, such as decomposition of organic material in soils or leaching of mineral deposits, can result in increased concentrations of several substances such as manganese, sulphate, chloride, organic matter, fluoride, arsenic, nitrate, selenium, uranium, and radon. Sources of groundwater contamination due to human activities are widespread and include diffuse sources as well as point-sources of pollution, such as land application of animal manure containing contaminants (e.g., veterinary pharmaceuticals) and agrochemicals in agriculture, leakages from sewers or sanitation systems, from waste disposal sites, landfills, underground storage tanks and pipelines, and accidental spills in mining, industry, traffic, health care facilities and military sites. The exploitation of petroleum products and the development of the industrial chemistry have given rise to a large number of organic chemicals, many of which are found in the environment. Various studies have shown that anthropogenic chemicals such as pesticides, pharmaceuticals and personal care products, industrial chemicals, and fuel additives occur in groundwater. U.S. Geological Survey (USGS) investigations have assessed the occurrence, distribution, and benchmark exceedance of various contaminants in water from public-supply wells and domestic wells, including pesticides, volatile organic compounds, pesticides and nitrate. Chemical mixtures were frequently detected, often with concentrations of individual contaminants approaching human-health benchmarks. Chemical mixtures that most frequently occurred and had the greatest potential toxicity were composed of arsenic, strontium, uranium, radon, and nitrate. Many organic chemicals are known to have potential human health impacts, and some of these may occur in groundwater at relevant concentrations. The list of those for which guideline values and national quality standards have been developed has been continually extended and revised. Among these: mono-aromatic hydrocarbons (benzene, toluene, ethylbenzene and xylenes - BTEX), volatile chlorinated hydrocarbons (tetrachloroethene - PCE, trichloroethene - TCE), and pesticides. This chapter focuses on chemical substances that have reasonable potential to contaminate groundwater and have human health impacts. It provides information about: i) the major sources of pollution; ii) inorganic contaminants, iii) organic contaminants; and iv) emerging issues
Do Emerging Contaminants Translocate from Soil to Lettuce?
Full text linkBisphenol A (BPA), nonylphenol (4-NP), benzophenone (BP), and
benzophenone-3 (BP-3) are emerging contaminants (ECs) having the potential to enter
the soil and food, and cause adverse effects in humans, wildlife, and the environment. In
order to understand the potential translocation to edible vegetables and risk for humans
due to their consumption, lettuce was cultivated for 54 d on artificially polluted soils and
uncontaminated (blank) soil. BPA contamination in soil resulted in a very rapid
degradation and no BPA was found in the vegetable. Lettuce from the 4-NP
contaminated pot had higher concentrations compared to the vegetables from the blank
pot; p-cresol was the most frequently detected 4-NP degradation product. BP and BP-3
concentrations in lettuce from the contaminated pot and the uncontaminated pot were
similar
Bioremediation of Hexavalent Chromium—A Few Significant Site Histories in Italy
Full text linkIn Lombardy (Italy), about 25% of the sites ranked in the Regional Plan of Contaminated Sites are affected by Cr(VI) in groundwater and/or soil. Therefore innovative sustainable remediation techniques are under investigation, with pilot- or full-scale applications. In situ bioremediation has a significant role in the remediation techniques for its general sustainability in terms of environmental impact and costs. However, while organics can be mineralized, inorganics can only change their oxidation state, hopefully reducing their toxicity and mobility in the environment. Various patented products were used at five polluted sites in order to reduce Cr(VI) to Cr(III) via bio-induced reduction, bio-reduction and bioimmobilization. The experience pointed out that Cr(VI) concentration in groundwater can be significantly reduced (up to three order of magnitudes), but the unsaturated zone should be treated as well in order to solve the problem definitely. Soil heterogeneity is a critical issue and mixtures usually have to be injected at different depths. Iron, manganese and sulphate side-contamination can result in groundwater after injections
State of the Art on Contaminated Sediments in Italy
No full textItaly has about 7900 km of coastline, which is densely populated and has
a strategic role for the national economy. The marine areas facing the coasts have often
heavily polluted sediments. No official data are available about the amount dredged
annually. Unfortunately, the laws pertaining to the topic are quite numerous and tangle
the management of the dredged materials. At some sites, in situ sediments are classified
according to the pollutant concentrations, resulting in different requirements,
remediation priorities or different management options. At other sites, sediments are
also checked from the ecotoxicological point of view. Treatments and/or reuse options
(landfarming, phytoremediation, supercritical water extraction, electrokinetics, sandy
fraction recovery, extraction of metallurgical silicon, and reuse of sediments for
cementitious mixtures) are being investigated in few research projects involving
Italian/foreign universities or research centers, national/international private companies
and, in most cases, public authorities
Trattamenti di ossidazione e di riduzione chimica per la bonifica di sedimenti contaminati
No full textLa gestione dei sedimenti dragati rappresenta
una complessa problematica in tutti i paesi industrializzati
per gli ingenti quantitativi di materiale asportati e per le loro caratteristiche di qualità ambientale. Le opzioni più diffuse prevedono il refluimento nel corpo idrico di origine (per i sedimenti non contaminati), lo smaltimento
in discarica o il trattamento per raggiungere specifici obiettivi di bonifica. Le principali alternative di trattamento
ad oggi identificate sono essenzialmente mutuate dalle tecniche di decontaminazione dei terreni; i sedimenti
possiedono tuttavia caratteristiche peculiari che possono complicarne l???esecuzione, ridurne l???efficienza o incrementarne drasticamente i costi. Tra le opzioni disponibili,
i trattamenti di ossidazione e di riduzione chimica sono stati usati con successo in vari casi reali, ma la loro applicabilità ed efficacia dipendono fortemente dalle caratteristiche
del sedimento e della contaminazione.
In questo lavoro vengono presentati i principali risultati ottenuti a scala di laboratorio su due differenti sedimenti contaminati sottoposti a trattamenti chimici. Sedimenti provenienti da Porto Marghera (VE, Italia) sono stati trattati con sistemi di ossidazione ???tipo Fenton??? o con sistemi di riduzione basati su ferro zero valente per rimuovere
idrocarburi del petrolio, Idrocarburi Policiclici Aromatici (IPA) e policlorobifenili. Materiali dragati da un canale industriale di New York City (USA) sono invece
stati trattati con differenti ossidanti (???tipo Fenton???, persolfato e perossido-acido) per rimuovere IPA e valutare
le possibili alterazioni sulla mobilità dei metalli e sulla resistenza alla filtrazione
Sustainable Remediation: Which Approach Shall I Use?
No full textSustainability in remediation of contaminated sites is a recent concept that aims at having a holistic approach capable to assess the global impacts of remediation at the environmental, economic and social levels. A common definition and guidelines shared at international level are still lacking and various approaches and tools are used. A "green remediation" approach is usually based on: i) the environmental footprint analysis (EFA), which can be performed with tools such as SEFA, SRT or SiteWise, or ii) a life cycle assessment (LCA), for which SimaPro is the most used tool, though not specific for cleanup purposes. A sustainable remediation process should also consider economic and social issues. As far as costs are concerned, the available tools include RACER and REC. No tools are available to quantify social benefit, which might include commercial, health or education services, increase in local occupation or real estate values
Camera di Flusso Dinamica Aperta
No full textCamera di flusso dinamica aperta comprendente: un
corpo scatolare avente una apertura inferiore atta ad
essere appoggiata su una superficie emettente; un
ingresso per un gas vettore, posto su detto corpo
scatolare; una uscita per la miscela di gas presente in
detto corpo scatolare, posta su detto corpo scatolare;
almeno un foro di sfiato per mettere in contatto la miscela
di gas presente in detto corpo scatolare con l’ambiente
esterno, posto su detto corpo scatolare; caratterizzata dal
fatto di comprendere un frangivento di forma tubolare
posto a protezione di detto almeno un foro di sfiato avente
una lunghezza maggiore di 25 cm ed una larghezza
maggiore di 5 cm. (Fig. 5
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