How can plants manage polycyclic aromatic hydrocarbons? May these effects represent a useful tool for an effective soil remediation? A review

Plants are autotrophic organisms which are able to use sunlight and carbon dioxide as the sources of energy and carbon. Plants' roots absorb a range of natural and anthropogenic toxic compounds for which they have developed some extraordinary detoxification mechanisms. From this point of view, plants can be seen as natural, solar-powered pump-and-treat systems for cleaning up contaminated soils, leading further to the concept of phytoremediation. The phytoremediation of polycyclic aromatic hydrocarbons (PAHs) refers to the use of plants and associated soil microorganisms in terms of reducing the concentrations or toxic effects of these contaminants in the environment. Although there is little evidence to prove that PAHs from soils are accumulated considerably in plants' parts, there is a lot of evidence that in soils vegetated with grasses and legumes, a significant dissipation of PAHs occurs. Namely, the primary mechanism controlling this process is the rhizospheric microbial degradation, where soil microbial populations use organic compounds as carbon substrates for its growth. This is usually stimulated by roots exudates. The final result of this process is the breakdown and eventual total mineralization of the contaminants. The main challenge in PAH phytoremediation is to improve the performances of plants and rhizospheric microorganisms requiring thus more basic research and knowledge on natural detoxification mechanisms

Kancerogeni policiklični aromatični ugljovodonici u ekonomiji i zakonodavstvu

There are certain opposites in the relation of economy and ecology, but at the present days the ultimate task is to realize reciprocity between them. The interaction between economy and nature has come to the phase which demands permanent tracking, and action as well. This is a necessity not only due to the restricted natural resources, but primarily due to the releasement of waste materials which exceeds the absorption capacity of global environment. Every responsible economy has to develop strategies of environmental protection and sustainable development. These strategies have to be based on objective, and professionally determined state, economic and law principles. Recently, an increasing public concern and a scientific investigations have been focused on the occurrence of PAHs and their control in air, water, soil, and herbal and animal products. Polyciclyc Aromatic Hydrocarbons (PAHs) are a class of several hundred diverse compounds usually containing two to seven fused benzene rings. They belong to a special group of ubiquitous contaminants known as Persistent Organic Pollutants (POPs), which are subject to long-range atmospheric transport (LRAT), and most can be photo-oxidized and degraded to simpler substances, which is very important for their distribution and fate in the environment and biota. PAH exposure through air, water, soil, tobacco smoke and food sources, occurs on a regular basis for most people. Routes of exposure include ingestion, inhalation, and dermal contact in both occupational and non-occupational settings. It was essential, in order to protect public health, and environment in general, to keep these contaminants, which are considered to be genotoxic carcinogens, at levels which are toxicologically acceptable. Maximum levels in foodstuffs, water, and air have been set at a strict levels by specific agencies in many countries. The 16 PAHs are included in the list of priority pollutants in EU: benzo(a)pyrene (BaP), cyclopenta(c,d)pyrene (CPP), indeno(1,2,3-cd)pyrene (IcP), benzo(c)fluorene (BcL), benzo(a)anthracene (BaA), chrysene (CHR), 5-methylchrysene (5MC), benzo(b)fluoranthene (BbF), benzo(j)fluoranthene (BjF), benzo(k)fluoranthene (BkF), benzo(g,h,i)perylene (BgP), dibenzo(a,h)anthracene (DhA), dibenzo(a,e)pyrene (DeP), dibenzo(a,h)pyrene (DhP), dibenzo(a,i)pyrene (DiP) and dibenzo(a,l)pyrene (DlP). The most known potent carcinogen, benzo(a)pyrene, is commonly used as an environmental indicator for PAHs. A recent directive of the European Commission (The Commission of the European Communities) uses BaP as a marker for the carcinogenic risk of PAHs and sets a limit value for this toxicant, to be attained as far as possible 1 ng/m3. The carcinogenicity of BaP and of other PAHs is well established in laboratory animals. Researchers have reported incidences of skin, lung, bladder, liver, and stomach cancers, in animals. Animal studies showed that certain PAHs also can affect the immune systems and produce reproductive, neurologic, and developmental effects.Na relaciji ekonomija - ekologija postoje određene suprotnosti, ali je u današnjem trenutku nužno iznalaženje njihove uzajamnosti. Interakcija privrede sa prirodom ušla je u fazu koja iziskuje permanentno praćenje i aktivne mere. Ovo je neophodno ne samo zbog limitiranosti prirodnih resursa, već pre svega zbog ispuštanja otpada koji prevazilazi apsorpcioni kapacitet globalnog prirodnog okruženja. Svaka odgovorna nacija mora da razvije strategije ekološke zaštite i prihvatljivog i održivog razvoja. Te strategije se moraju zasnivati na objektivno, stručno utvrđenom stanju, ekonomskim principima i zakonskim mogućnostima. U najnovije vreme, povećana zabrinutost javnosti, kao i naučna istraživanja, bili su fokusirani na postojanje policikličnih aromatičnih ugljovodonika (Polycyclic Aromatic Hydrocarbons, PAHs) i njihovu kontrolu u vazduhu, vodi, zemljištu, kao i biljnim i životinjskim produktima. PAH-ovi pripadaju klasi od nekoliko stotina različitih jedinjenja, koja uobičajeno sadrže dva do sedam kondenzovanih benzenovih prstenova. Oni takođe pripadaju posebnoj grupi sveprisutnih kontaminanata poznatih kao perzistentni organski zagađivači (Persistent Organic Pollutants, POPs) i podležu transportu na velike udaljenosti (long-range atmospheric transport, LRAT), kao i foto-oksidaciji i degradaciji u jednostavnije supstance, što je od velikog značaja za njihovu disrtibuciju i sudbinu u životnoj sredini i živom svetu. Za većinu ljudi, izloženost PAH-ovima ide preko vazduha, vode, zemljišta, duvanskog dima i hrane. Putevi izloženosti uključuju ingestiju, inhalaciju i preko kože i to kako u okruženju radnog mesta, tako i van njega. Da bi se zaštitilo javno zdravlje i uopšte, životna sredina, od esencijalne važnosti je bilo da se ovi kontaminanti koji se smatraju genotoksičnim kancerogenima, drže na nivoima koji su toksikološki prihvatljivi. Maksimalne dozvoljene koncentracije u namirnicama, vodi i vazduhu ustanovljene su od strane odgovarajućih agencija u mnogim državama. Na listi prioritetnih zagađivača u EU nalazi se 16 PAHs jedinjenja: benzo(a)piren (BaP), ciklopenta(c,d)piren (CPP), indeno(1,2,3-cd)piren (IcP), benzo(c)fluoren (BcL), benzo(a)antracen (BaA), hrizen (CHR), 5-metilhrizen (5MC), benzo(b)fluoranten (BbF), benzo(j)fluoranten (BjF), benzo(k)fluoranten (BkF), benzo(g,h,i)perilen (BgP), dibenzo(a,h)antracen (DhA), dibenzo(a,e)piren (DeP), dibenzo(a,h)piren (DhP), dibenzo(a,i)piren (DiP) i dibenzo(a,l)piren (DlP). Najpoznatiji potencijalni kancerogen, benzo(a)piren, uobičajeno se koristi kao karakterističan indikator za PAH jedinjenja u životnoj sredini. Poslednja preporuka Evropske komisije (The Commission of the European Communities), koristi BaP kao marker kancerogenog rizika i definiše njegov maksimum od 1 ng/m3. Kancerogenost BaP i drugih PAH-ova temeljno je ispitana na eksperimentalnim životinjama. Istraživači su kod životinja zabeležili slučajeve kancera kože, pluća, bešike, jetre i želuca. Studije na životinjama pokazale su da neki PAHovi mogu da utiču na imuni sistem i da izazovu reproduktivne, neurološke i razvojne efekte

Formulation and characterization of electrolyte for decorative gold plating based on mercaptotriazole

AbstractA procedure for the formulation and characterization of a gilding electrolyte based on mercaptotriazole is described. It was found that the electrolyte can be synthesized in a wide pH range, so solutions with different pH values (2, 4, 7, 9 and 12) have been prepared and analyzed. Inductively coupled plasma atomic emission spectroscopy and ultraviolet–visible spectroscopy were used for the chemical characterization of the prepared solutions. Electrochemical characterization is performed by open circuit potential measurement, cyclic voltammetry and polarization measurements