The Relationship Between the Chemical Structure of Poly(alkylene glycol)s and Their Aerobic Biodegradability in an Aqueous Environment

The relationship between the chemical structure of poly(alkylene glycol)s (PAGs) and their biodegradability was studied using a set of polymeric fluids that included poly(ethylene glycol), poly(propylene glycol) (PPG), random copolymers of ethylene oxide (EO) and propylene oxide (PO) differing in the EO/PO ratio as well as PAGs capped with ether or acyl moieties. The PAGs that were tested had an average molecular weight (MW) in the range of 350–3,600 Da and differed in their polymer backbones by either linear (diol type) or branched (triol type) molecules. The ultimate biodegradability of the PAGs was determined according to ISO 14593 (CO₂ headspace test) with a non-pre-exposed (as in OECD 310 test) and pre-exposed (adapted) inoculum. PAGs with the structure of PPG and copolymers of EO/PO of diol or triol structures with average molecular weights lower than 1,000 Da can be considered as readily biodegradable. Their ultimate biodegradation exceeds the limit of 60 % (according to the criteria of the OECD 310 test). PAGs with a copolymer structure and MW values ranging between 1,000 and 3,600 Da are not readily biodegradable, but they can be considered as those of inherent ultimate biodegradability. The increased EO content in PAG structures and the acylation of the terminal hydroxyl groups with carboxylic acids favourably influenced their biodegradability. Capped PAGs containing terminal ether groups appeared to be resistant to biodegradation.     

Sulfadimethoxine and sulfaguanidine: their sorption potential on natural soils

Sulfonamides (SAs) are one of the oldest groups of veterinary chemotherapeutic agents. As these compounds are not completely metabolized in animals, a high proportion of the native form is excreted in feces and urine. They are therefore released either directly to the environment in aquacultures and by grazing animals, or indirectly during the application of manure or slurry. Once released into the environment, SAs become distributed among various environmental compartments and may be transported to surface or ground waters. The physicochemical properties of SAs, dosage and nature of the matrix are the factors mainly responsible for their distribution in the natural environment. Although these rather polar compounds have been in use for over half a century, knowledge of their fate and behavior in soil ecosystems is still limited. Therefore, in this work we have determined the sorption potential of sulfadimethoxine and sulfaguanidine on various natural soils. The influence on sorption of external factors, such as ionic strength and pH, were also determined. The sorption coefficients (K_d) obtained for the sulfonamides investigated were quite low (from 0.20 to 381.17 mL g⁻¹ for sulfadimethoxine and from 0.39 to 35.09 mL g⁻¹ for sulfaguanidine), which indicated that these substances are highly mobile and have the potential to run off into surface waters and/or infiltrate ground water. Moreover, the sorption of these pharmaceuticals was found to be influenced by OC, soil solution pH and ionic strength, with higher K_d values for soils of higher OC and lower K_d values with increasing pH and ionic strength.     

Freshwater Ulva (Chlorophyta) as a bioaccumulator of selected heavy metals (Cd, Ni and Pb) and alkaline earth metals (Ca and Mg)

We analyzed the ability of freshwater taxa of the genus Ulva (Ulvaceae, Chlorophyta) to serve as bioindicators of metal in lakes and rivers. Changes in heavy metal (Ni, Cd and Pb) and alkaline earth metal (Ca and Mg) concentrations in freshwater Ulva thalli were investigated during the period from June to August 2010. The study was conducted in two ecosystems in Western Poland, the Malta lake (10 sites) and the Nielba river (six sites). Three components were collected for each sample, including water, sediment and Ulva thalli. The average concentrations of metals in the water sample and in the macroalgae decreased in the following order: Ca > Mg > Ni > Pb > Cd. The sediment revealed a slightly altered order: Ca > Mg > Pb > Ni > Cd. Ca and Mg were found at the highest concentrations in thalli due to the presence of carbonate on its surface. Among the examined heavy metals in thalli, Ni was in the highest concentration, and Cd found in the lowest concentration. There were statistically significant correlations between the levels of metals in macroalgae, water and sediment. Freshwater populations of Ulva exhibited a greater efficiency to bioaccumulate nickel as compared to species derived from marine ecosystems.     

Pesticide burial grounds in Poland: a review

Obsolete pesticides were stored in Poland from the middle sixties until the late eighties of the 20th century mostly in underground disposal sites, called "pesticide burial grounds" or "pesticide tombs". The total amount of pesticide waste and packaging materials disposed of in these landfills exceeded 20000 Mg. Typically, the content of a pesticide tomb was dominated by organochlorine pesticides (comprising 10-100% of the total waste volume) with DDT as the prevailing compound. Other pesticide types, such as phosphoroorganic, carbamate insecticides, dinitrophenols, phenoxyacids, and inorganic compounds were stored in smaller quantities, usually not exceeding 10-20% of the total waste volume. With the growing awareness of the threats that these landfills posed to the environment, the first inventory for the whole country was made in 1993 and remediation was initiated in 1999. The total amount of waste, which had to be removed from the known pesticide tombs (hazardous substances, contaminated soils, construction materials etc.) was about 100000 Mg. According to the National Waste Management Plan, the reclamation of pesticide tombs was assumed to have been finished by the end of 2010, however, this goal has not been achieved. The aim of this review is to present a historical perspective of pesticide burial grounds in Poland with an emphasis on their creation, function, inventory, and remediation. Based on unpublished reports, and other published materials of limited availability written in Polish, this review may serve as a source of information for representatives of other countries, where remediation of pesticide burial grounds is still in progress. The experience gained over a ten-year period, when restoration of pesticide tombs was implemented in Poland, reveals that there are many obstacles to this action arising not only from technical, but also from economic and social issues.     

Influence of academic education on the perception of wood in watercourses

Human perception of in-channel wood can influence decision-making about wood reintroduction in watercourses for restoration purposes. A questionnaire survey was conducted among first-year and advanced Polish students and professionals involved in the management and protection of watercourses in Poland. The purpose was to assess their perception of river scenes with and without wood in terms of naturalness, aesthetics, danger and need for improvement. Generally, students perceived riverscapes with wood to be less aesthetic, more dangerous and needing more improvement than riverscapes without wood. However, many aspects of the riverscape perception are subject to changes as the student progresses in studying. The culturally conditioned, negative perception of in-channel wood is reduced during the education of geography and biology students but enhanced in the course of water engineering studies. The improved perception of watercourses containing wood was most pronounced for the advanced geography students from a university in which some tutors conducted research on in-channel wood and could have transferred knowledge about and positive attitudes toward wood to their students. A comparison of the riverscape evaluation by biology students and national park managers indicates that education in the discipline facilitates understanding of the environmental significance of in-channel wood although its effects are highly insufficient to form the positive attitude toward wood-containing watercourses typical of the managers. In turn, the education of water engineering students about in-channel wood apparently dominantly emphasizes threats caused by its presence in watercourses, so that the students' highly negative attitude toward wood needs to be significantly moderated when the graduates begin working as water authority managers.     

Biodegradation and sorption of nodularin (NOD) in fine-grained sediments

Nodularin (NOD) is a cyclic pentapeptide hepatotoxin produced by the bloom forming cyanobacterium Nodularia spumigena. The fate of the toxin in the aquatic environment has not been fully evaluated. In the current study the changes in NOD concentration caused by biodegradation and sorption in samples from the Baltic were studied. Seawater of various salinities (0, 4, 8 and 12 PSU) and three forms of fine-grained sediment (sterile wet sediment, non-sterile wet sediment, and combusted sterile sediment) were incubated with 34.7 μg of NOD. The toxin was seen to be highly stable both in sterile and non-sterile seawater. During the 21-day experiment NOD concentrations in solutions overlying the combusted sediment and the sterile wet sediment were reduced to 12.5 ± 2.6% and 59.8 ± 2.4% of the initial value. The greatest loss of the toxin (up to 100%) was observed in the non-sterile seawater incubated with non-sterile wet sediment. These results indicate an important role of benthic microbial community in nodularin removal. Two biodegradation products with similar spectral characteristics to NOD were detected; one of which was identified as Adda amino acid.     

The differences in phenolic content in rivers exposed and non-exposed to anthropogenic contamination

The purpose of the work was to determine the differences in a kind, number and concentrations of phenol, chlorophenols, chlorocatechols chlorinated methoxyphenols (chloroguaiacols, chlorosyringols) and 3,4,5-trichloroveratrole in the drainage of the Dzierzazna river, the flow non-exposed to anthropogenic contamination and in the Ner river, the flow exposed to anthropogenic pollution. The samples of water were collected in the Dzierzazna river in the Swoboda locality, the inflow of the Dzierzazna river - the Ciosenka river and, also, in the spring situated in Ciosny Sady locality. Water of the Ner river was collected in points near ?ód?, Konstantynów, Poddebice and Dabie towns. The compounds were condensed (adsorbed) and eluted with methylene chloride on octadecyl C18 layer in a Baker Separex system. The obtained eluent was separated using the method of gas chromatography and analysed using mass spectrometry technique. In samples collected from the drainage of the Dzierzazna river phenol, chlorophenols, guaiacol, trichloroguaiacol, tetrachloroguaiacol, trichlorosyringol and 3,4,5-trichloroveratole were determined. As no anthropogenic sources are situated within the drainage of the Dzierzazna river, we may suppose that most of the determined compounds are mainly of natural origin. No or trace concentrations of chlorinated methoxyphenols were noted in the water of the Ner river, but a higher number, and concentrations of chlorophenols and additionally chlorocatechols were determined in this flow. It is also apparent that changes in a number and concentrations of phenols in the water of the Ner river did not prove a seasonal character, which was typical of the Dzierzazna drainage waters.     

Speciation of scandium and gallium in soil

A method for the speciation of scandium and gallium in soil has been developed. The sequential extraction scheme of Tessier et al. for heavy metals was examined for the scandium and gallium separation. The regents proposed by Tessier were used for the extraction, and only for the residual fraction the HClO(4) was replaced with H(2)SO(4). The optimum conditions for leaching scandium and gallium from the soil were chosen for each fraction. Very sensitive, spectrophotometric methods based on the mixed complexes of Sc(III) and Ga(III) with Chrome Azurol S and benzyldodecyldimethylammonium bromide were applied for the scandium and gallium determination after their separation by solvent extraction. 100% mesityl oxide and a 0.5M solution of 2-thenoyltrifluoroacetone in xylene were chosen for the extraction of scandium and butyl acetate was selected for gallium. Soil samples from two different regions of Poland were the object of this research. The content of scandium and gallium found in the individual fractions of Upper Silesia soil (industrial region) was [in mugg(-1)] Sc: I, 1.52; II, 0.53; III, 7.78; IV, 1.79; V, 0.20; Ga: I, 24.7; III, 29.2; IV, 35.4; V, 6.9. In Podlasie soil (agricultural region), the content of both elements was clearly lower. The total content of scandium and gallium in the five soil fractions was in good correlation with the total content of these elements in the soils found after HF-H(2)SO(4) digestion. Analysis using the ICP-OES method gave comparable results.     

Transformation of phenol, catechol, guaiacol and syringol exposed to sodium hypochlorite

Germs, xenobiotics and organic matter that influence the colour, turbidity and organoloeptic properties of water are removed by chlorination. Unfortunately, chlorine oxidants including sodium hypochlorite, used in water treatment induce processes that partly convert the treated compounds to unwanted chlorinated derivatives. The purpose of this work was to analyse the efficiency of transformation of phenol, catechol, guaiacol and syringol exposed to sodium hypochlorite and determine the intermediates formed during oxidative conversion of these compounds. The analysis was performed in aerobic conditions, both in acidic (pH 4.0) and alkaline (pH 8.0) medium. The effectiveness of transformation was slightly higher in acidic in comparison to alkaline conditions. Some chlorophenols, such as 2-chlorophenol, 2,4-dichlorophenol, 2,4,5-trichlorophenol and pentachlorophenol were determined as the products of phenol conversion. Chlorophenols were also formed during catechol, guaiacol and syringol transformation by replacement of hydroxy and methoxy residues by chlorine atoms. Moreover, some chlorocatechols and chlorinated methoxyphenols were determined during catechol and methoxyphenols transformations. Higher concentrations of chlorinated compounds were observed in the alkaline environment during phenol transformation. Conversion of catechol and methoxyphenols generated higher amounts of chlorinated intermediates in the acidic medium. In samples carboxylic acids like acetic and formic acids were determined. The formation of these compounds was the result of the cleavage of aromatic structure of phenols.     

Catalytic destruction of 1,2-dichlorobenzene on V2O5-WO3/Al2O3-TiO2 catalyst

Studies on the catalytic destruction of 1,2-dichlorobenzene were carried out on a specially constructed semi-technical equipment whose most important element was a catalytic reactor with a monolithic catalyst in the form of 150 x 150 x 100 mm cubes. A catalyst made from cordierite with an active layer composed of Al2O3 - 64 wt%, TiO2 - 26 wt%, V2O5 - 6.6 wt% and WO3 - 3.4 wt% was used. The reactor made it possible to carry out the process in the temperature range 150-350 degrees C, at variable catalyst loading and different velocities of gas flow through the reactor. The content of 1,2-dichlorobenzene in the air was analysed by a chromatographic method. A significant effect of catalyst loading and temperature on 1,2-dichlorobenzene destruction efficiency was observed and no effect of the linear flow velocity through the catalyst on o-dichlorobenzene destruction efficiency was reported. The applied vanadium-tungsten catalyst on a monolithic carrier made from TiO2/gamma-Al2O3 revealed very good activity that resulted in an over 80% efficiency of 1,2-dichlorobenzene destruction at the temperature around 250 degrees C at a very high catalyst loading reaching ca. 8200 h(-1). Additionally, in this study the kinetics of 1,2-dichlorobenzene decomposition was determined, specifying the order of reaction and dependence of the decomposition rate constant on temperature, using a simple power-rate law model.