We investigated the effects of four commercial formulations of herbicides (glyphosate [GLY], metsulfuron-methyl [MET], bispyribac-sodium [BIS], and picloram [PIC]) individually, and in three 50:50 mixtures (GLY–MET, GLY–BIS, GLY–PIC) on the common toad Rhinella arenarum (Anura: Bufonidae) tadpoles. Enzymatic parameters such as, glutathione S-transferase (GST), butyrylcholinesterase (BChE) and acetylcholinesterase (AChE) activities, as well as erythrocyte nuclear abnormalities (ENA) were studied. Interactions between herbicides in mixtures were evaluated and classified as additive, synergistic, or antagonistic. Toxicity results (48-h LC₅₀) showed that PIC was the most toxic herbicide, followed by BIS, GLY, and MET, while GLY–PIC was the most toxic mixture, followed by GLY–BIS, and GLY–MET. All commercial herbicide formulations and their mixtures significantly inhibited BChE activity in exposed tadpoles. The AChE activity was also inhibited by all herbicides and their mixtures, except by GLY–BIS. The inhibition of GST activity was only significant for GLY, MET, PIC, and GLY–MET. A significant increase in the frequency of ENA was found for tadpoles exposed either to commercial herbicide formulations or to mixtures, except for GLY. All the mixtures showed synergism for BChE activity while for AChE only the GLY–MET and GLY–PIC mixtures acted synergistically. GLY–MET showed synergism for GST, whereas for ENA, the mixture GLY–BIS was antagonistic. This study with R. arenarum tadpoles demonstrates that the interactions between three of the most intensively used herbicides in soybean crops results in synergistic effects on mortality and neurotoxicity and synergistic or additive effects in genotoxicity.

A study was carried out under in vitro conditions to characterize the growth of blue green alga, Spirulina platensis, in standard CFTRI medium containing different nanoparticles of copper oxide (CuO) (50 nm, 10 ppm), zinc oxide (ZnO) (50 nm, 10 ppm), tricalcium phosphate (TCP) (<100 nm, 90 ppm), and hydroxy apatite (HA) (<200 nm, 90 ppm). S. platensis exhibited significant higher growth in standard CFTRI medium containing 90 ppm phosphorus as nanoparticles of TCP and HA. On the other hand, calcium phosphate nanoparticles caused significant reduction in nitrate reductase activity as well as in protein content of the alga. Marked change in chlorophyll-a/b ratio was also noted when phosphorus was supplied through nano tricalcium phosphate and nano hydroxy apatite particles as compared to ionic form (K2HPO 4). The study revealed that the growth of Spirulina in the presence of ZnO nanoparticles was retarded, while no growth was observed with CuO nanoparticles. It was concluded that alga Spirulina showed much sensitivity to nanoparticles of zinc and copper (<50 nm) and was able to tolerate the toxicity of nanophosphate (tricalcium phosphate <100 nm; hydroxy apatite <200 nm). © 2013 Springer Science+Business Media Dordrecht.

Biowastes and inorganic additives are acknowledged efficient but site-dependent alternatives for in situ metal immobilization. The present study evaluates food waste-based compost, a particularly abundant type of biowaste in South Korea, and zeolite as amendments for increasing pH and reducing metal leaching potential in weathered tailings from an abandoned mine site. Two types of biowaste were used: food waste compost (60 % food waste and 40 % sawdust) and market compost (50 % food waste, 10 % agricultural waste, 10 % manure, and 30 % lime). Materials were thoroughly characterized. Leaching tests were then performed in reactors filled with various mixtures of organic–inorganic amended tailings, over a 4-week period. The in situ metal immobilization efficiency of compost was evaluated based on collected leachate quality. Results indicated that both organic and inorganic materials were successful for increasing pH (from 3.0 to up to 8.1) and metal immobilization, except for Pb and As, with which leaching potential increased in most amended reactors relative to un-amended tailings (up to 43 and 158 %, respectively). Over the duration of the experiment, the cumulative reduction of metal leaching potential ranked as follows: Zn (44–91 %) > Mn (4–76 %) > Cr (20–53 %) > Fe (34–44 %) > Cd (17–43 %) > Al (0.5–24 %). Among mixtures, combined biowaste and zeolite-amended tailings showed the best performance for increasing pH (7.5–8.1) and for metal immobilization. Chemical and biological processes, such as sorption and precipitation processes, were predominant. Overall, the study provides useful data on the efficient use of food waste compost for acid mine drainage prevention in South Korea.

Petroleum hydrocarbons in the bilge water of small fishing vessels are continuously released into the environment. The bilge water samples usually contained low amounts of oil-degrading bacteria; therefore, this study examines application of polyurethane foam (PUF)-immobilized Gordonia sp. JC11, a known lubricant-degrading bacterial inoculum, for the treatment of bilge water. Batch microcosm experiments showed that the PUF-immobilized bacteria were more efficient at removing oil than indigenous microorganisms and were able to remove approximately 40-50 % of the boat lubricant (1,000 mg L-1). The immobilized PUF samples rapidly adsorbed oil from the bilge water inside a small fishing vessel; however, the uninoculated PUF contained more oil than the inoculated PUF at most time points. The hydrocarbon components were also different when comparing inoculated and uninoculated PUF. These results indicate that the oil accumulated inside the PUF containing immobilized bacteria was being degraded by the Gordonia sp. JC11. However, these bacteria gradually die off after repeated oil exposure, and it is suggested that PUF-immobilized cells be replaced at timed intervals. This technique is considered simple and cheap; thus, it could be used to reduce chronic oil pollution from the release of bilge water. © 2013 Springer Science+Business Media Dordrecht.

The release of heavy oil from laboratory-contaminated sediments was studied in a series of kinetic and equilibrium experiments. The kinetic curves could be interpreted by a two-compartment first-order equation including rapid and slow release steps. The slow step was dominant and the rate constant was 3 orders of magnitude smaller than for the rapid step. Equilibrium experiments for the slow step revealed that the isotherms could be described by the Freundlich equation. The release of heavy oil was found to correlate with higher contamination level, larger particle size, lower salinity, and higher temperature. The effect of coexisting surfactant on the release was also investigated and the results showed that the presence of Tween-20 promoted the process. The oil release process was endothermic and the randomness at the solid–liquid interface increased during the desorption process. The values of activation energy and standard enthalpy change indicated that this process was a physical one.

Oxidative degradation of ethylenediaminetetraacetic acid (EDTA) in aqueous solution at normal temperature and pressure by the bimetallic Fe–Cu was investigated in this work. The results showed that the removal efficiency of EDTA, total organic carbon (TOC), and total nitrogen (TN) could be about 95, 62.5, and 39 %, respectively, after 3-h reaction. The degradation of EDTA followed the pseudo-first-order reaction kinetics and would not be affected by the continuous use of bimetallic Fe–Cu. The degradation products were iminodiacetate, formate, and acetate determined by ion chromatogram. The effects of initial pH, initial concentration of EDTA, Cu content, Fe–Cu loading, and atmosphere were also investigated. Significantly, the bimetallic Fe–Cu process exhibited higher reactivity than ZEA process for the degradation of EDTA and it would not cause new heavy metal pollution in effluent. Reactive oxygen species (ROS) of OH was generated in situ. The evidence of oxidative degradation of EDTA was verified by electron spin resonance (ESR) spectroscopy and the product of para-hydroxybenzoic acid (p-HBA) by OH and benzoic acid (BA).

Two methods to measure mercury concentration in soil are compared, and their compliance with international standards is determined: cold vapour atomic absorption spectrometry and thermal decomposition, amalgamation and atomic absorption spectrophotometry. The detection limit, quantification limit and uncertainty of these two analytical methods were evaluated and compared. The results indicated that thermal decomposition, amalgamation and atomic absorption spectrophotometry had a lower quantification limit and uncertainty than cold vapour atomic absorption spectrometry (quantification limit, 0.27 vs. 0.63 mg kg⁻¹; expanded uncertainty, 9.30 % vs. 10.8 %, respectively). Thermal decomposition, amalgamation and atomic absorption spectrophotometry allowed the determination of the base values for the concentration of mercury in soil recommended by international standards, achieving a lower detection limit than cold vapour atomic absorption spectrometry under the study conditions. In addition, thermal decomposition, amalgamation and atomic absorption spectrophotometry represent a more environmentally friendly alternative for mercury determination because this method uses fewer reagents and therefore generates less waste.

Pollution by heavy metals (Co, Cu, Ni, Pb, Sb and Zn), Ra-226 and U was studied in eight profiles (1.0-1.8 m deep) in the floodplain sediments of the Ploucnice River, the Czech Republic. The element concentrations were processed by establishing local geochemical background functions from non-polluted overbank fines yet not affected by reductimorphic processes and a subsequent calculation of enrichment factors in the polluted strata. In the case of Cu and Ni, the geogenic variability of the watershed (Cretaceous marine sediments and Cenozoic volcanics and their weathering products) was successfully handled using different background functions in two parts of the studied area, which allowed us to decipher the anthropogenic and natural portions of the heavy metals and hence evaluate the history of pollution. The upper course of the river drains an extensive area of so-called chemical mining (underground acid leaching of low-grade U-bearing sediments) and hydrometallurgical processing in Straz pod Ralskem that started in the late 1960s and operated without waste-processing plants up to 1989. The river system has consequently been impacted by U and gamma-emitting Ra-226 and obviously also by divalent heavy metals (Co, Ni, Zn). In the entire study area, that pollution was preceded by increasing levels of Cu, Pb and Sb and by the Pb-206/Pb-207 ratio decreasing from 1.20 towards 1.17, which had started earlier in the twentieth century before the U mining. That pre-mining pollution can be attributed to diffuse anthropogenic activities of regional or continental importance. The most recent Pb-206/Pb-207 ratio in the Ploucnice alluvium coincides with that of peatbog profiles on the borders of the Czech Republic, showing the usefulness of floodplains as pollution archives of widespread regional to continental pollution signals.

Two Co oxide catalysts supported on natural zeolites from Indonesia (INZ) and Australia (ANZ) were prepared and used to activate peroxymonosulphate for degradation of aqueous phenol. The two catalysts were characterized by several techniques such as X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy (EDS) and N2 adsorption. It was found that Co/INZ and Co/ANZ are effective in activation of peroxymonosulphate to produce sulphate radicals for phenol degradation. Co/INZ and Co/ANZ could remove phenol up to 100 and 70 %, respectively, at the conditions of 25 ppm phenol (500 mL), 0.2 g catalyst, 1 g oxone and 25 C. Several parameters such as amount of catalyst loading, phenol concentration, oxidant concentration and temperature were found to be the key factors influencing phenol degradation. A pseudo first order would fit to phenol degradation kinetics, and the activation energies on Co/INZ and Co/ANZ were obtained as 52.4 and 61.3 kJ/mol, respectively. © 2013 Springer Science+Business Media Dordrecht.

Imperata cylindrica leaf was used as raw material to prepare two different adsorbents through chemical modification by using sulfuric acid and phosphoric acid. These two adsorbents, sulfuric acid-modified I. cylindrica leaf-based adsorbent (SIC) and phosphoric acid-modified I. cylindrica leaf-based adsorbent (PIC), were used to adsorb nickel ions (Ni²⁺) from aqueous solutions. The I. cylindrica leaf-based adsorbent and modified I. cylindrica leaf-based adsorbents were characterized by Fourier transform infrared (FT-IR) spectroscopy and scanning electron microscopy (SEM). Different operational parameters such as initial solution pH, adsorbent size, adsorbent dosage, initial Ni²⁺ ion concentration, and temperature were studied. The adsorption isotherm and the adsorption kinetics were studied systematically. Based on the FT-IR spectrum before and after adsorption of Ni²⁺ ions, the adsorption mechanism involved both ion exchange and complexation between Ni²⁺ ions and functional groups on the surface of adsorbents. There was no sulfur and phosphorus detected in the aqueous solutions after adsorption. Therefore, SIC and PIC are effective in adsorbing Ni²⁺ ions and will not cause secondary pollution to the environment.