This study investigated lead (Pb) sorption by inorganic and acid-non-soluble organic fractions, which were physicochemically fractionated from cattle, swine, and poultry composts, to understand how Pb is immobilized by animal manure compost and to evaluate the contribution of each fraction in Pb immobilization. Pb was predominantly sorbed on humic acid in the acid-non-soluble organic fraction; on the other hand, Pb sorption by the inorganic fraction could be attributed to the precipitation of Pb compound minerals such as lead phosphate and lead sulfate. The amounts of Pb sorbed on the inorganic fraction were 4.1–8.1 times higher than that sorbed on the acid-non-soluble organic fraction. The amount of Pb sorbed on the inorganic fraction and acid-non-soluble organic fractions was 37–60 and 19–43 %, respectively, of the total Pb sorbed. The results of this study clearly show that the inorganic fraction in the composts effectively immobilizes Pb. Furthermore, the high content of the inorganic components, particularly phosphorus, is important in Pb immobilization.

Seed priming effects on Trifolium repens were analysed both in Petri dishes and in two soils (one unpolluted soil and a soil polluted with Cd and Zn). Priming treatments were performed with gibberellic acid 0.1 mM at 22 °C during 12 h or with polyethylene glycol (−6.7 MPa) at 10 °C during 72 h. Both priming treatments increased the germination speed and the final germination percentages in the presence of 100 μM CdCl₂or 1 mM ZnSO₄. Flow cytometry analysis demonstrated that the positive effect of priming was not related with any advancement of the cell cycle in embryos. Seed imbibition occurred faster for primed seeds than for control seeds. X-ray and electronic microscopy analysis suggested that circular depressions on the seed coat, in addition to tissue detachments inside the seed, could be linked to the higher rate of imbibition. Priming treatments had no significant impact on the behaviour of seedlings cultivated on non-polluted soil while they improved seedling emergence and growth on polluted soil. The two priming treatments reduced Zn accumulation. Priming with gibberellic acid increased Cd accumulation by young seedlings while priming with polyethylene glycol reduced it. Priming improved the light phase of photosynthesis and strengthened the antioxidant system of stressed seedlings. Optimal priming treatment may thus be recommended as efficient tools to facilitate revegetation of former mining area.

The influence of structure on degradation of five halogenated phenols (XPs) by UV/H₂O₂process was investigated. The combined influence of type or number of substituents and UV/H₂O₂process parameters (pH and [H₂O₂]) on the degradation kinetics of 2-fluorophenol (2-FP), 2-chlorophenol (2-CP), 2-bromophenol (2-BP), 2,4-dichlorophenol (2,4-DCP), and 2,4,6-trichlorophenol (2,4,6-TCP) was studied using modified miscellaneous 3³full factorial design and response surface modeling (RSM). Studied XPs obey first-order degradation kinetics within the investigated range of process parameters. Determined degradation rate constants (kₒbₛ) were correlated with process and structural parameters by the quadratic polynomial models. Analysis of variance (ANOVA) demonstrated RSM models’ accuracy and showed that, in addition to pH and [H₂O₂], model terms related with the pollutant structure are highly influential. kₒbₛof mono-XPs follow the decreasing order 2-FP, 2-CP, and 2-BP, while CPs follow the decreasing order 2-CP, 2,4-DCP, and 2,4,6-TCP. Biodegradability (biochemical oxygen demand (BOD)₅/chemical oxygen demand (COD)) and toxicity (TU) were evaluated prior to the treatment and at the reference time intervals. The observed differences are correlated with the structural characteristics of studied XPs.

Biodegradation of different tall oil soaps was studied in order to examine the behaviour of these bioproducts in natural environments and to study their biodegradation rates. The rates of biodegradation were studied by modelling the biodegradation phenomenon as a pseudo-first-order reaction. Biodegradation was studied in seven different environments. Four of these were water phases: groundwater in aerobic and anaerobic conditions, river water and Office of Environmental Compliance and Documentation (OECD) 301 F standard conditions. In addition, three solid phases, sand, acidic forest soil and topsoil, were used as a solid matrix. The results showed that the matrix and the concentration had a strong effect on both the rate and degree of the biodegradation reaction. As a result, all of the tall oil soaps were about 57–85 % biodegradable in OECD 301 F conditions, but only moderately biodegradable in Finnish river water taken in the summer. When compared to the sample taken in the autumn, the biodegradation degree was considerably higher. In groundwater, biodegradation degree was low, even negligible in anaerobic conditions. With ten times less sample content, the biodegradation degrees in groundwater and surface water increased to 60 % for all the tall oil soaps, with one soap, in particular, up to 80 % during 100 days of measurement. In the topsoil, biodegradation was vague, and in slightly acidic forest soil, the decomposition reactions were complex. This is probably due to gas formation in the side reactions. In sand, tall oil soaps did not biodegrade at all.

The Lea Navigation in the north-east of London, a canalized reach of the River Lea, is affected by episodes of very low levels of dissolved oxygen. The problem was detected by the Environment Agency from the confluence with Pymmes Brook (which receives the final effluent of Deephams sewage treatment works) to the Olympic site (Marshgate Lane, Stratford). In this study, possible causes and sources of the poor water quality in the Lea Navigation were investigated using algal bioassays and detailed spatial seasonal mapping of the physico-chemical parameters collected in situ. Results showed chronic pollution and identified polar compounds in the river water and high bacterial concentrations as possible causes of low dissolved oxygen levels. This study confirmed the negative impact of Deephams sewage treatment works (via Pymmes Brook) on the water quality of the Lea. However, whilst the Environment Agency had previously focused on the pollution created by the sewage treatment works, results showed evidence of other sources of pollution; in particular, Stonebridge Brook was identified as an uncontrolled source of pollution and untreated wastewater. This study demonstrates the value of conducting combined methodologies and detailed monitoring. Other possible sources include Old Moselle Brook, diffuse pollution from surface run-off, boat discharges and other undetected drainage misconnections.

Acidification of lakes and rivers is still an environmental concern despite reduced emissions of acidifying compounds. We analysed trends in surface water chemistry of 173 acid-sensitive sites from 12 regions in Europe and North America. In 11 of 12 regions, non-marine sulphate (SO₄*) declined significantly between 1990 and 2008 (−15 to −59 %). In contrast, regional and temporal trends in nitrate were smaller and less uniform. In 11 of 12 regions, chemical recovery was demonstrated in the form of positive trends in pH and/or alkalinity and/or acid neutralising capacity (ANC). The positive trends in these indicators of chemical recovery were regionally and temporally less distinct than the decline in SO₄* and tended to flatten after 1999. From an ecological perspective, the chemical quality of surface waters in acid-sensitive areas in these regions has clearly improved as a consequence of emission abatement strategies, paving the way for some biological recovery.

The aim of this work was to study the short-term effect of clear-cut harvest on concentrations of dissolved organic carbon (DOC), B, Al, Zn, Cu, Ni, Cr, Cd and Pb in drainage water from northern peatland catchments in Finland underlain by granitic or black shale bedrock, the latter having higher concentrations of several trace elements, such as Ni and Zn. Stem-only harvest (SOH) or whole-tree harvest (WTH) with stump removal were carried out at coniferous sites. Controls were left unharvested. DOC and trace element concentrations were monitored during one pre-treatment and two post-treatment years. There was no constant increase in the element concentrations. However, there were signs that both SOH and WTH clear-cut harvest on northern peatland catchments increases the concentrations of DOC, B, Al, Zn and Ni in ditchwater in some sites irrespective of the bedrock type. The greatest increases were observed in WTH sites but the study does not allow us to assess the statistical significance of the magnitude of the difference between SOH and WTH. We conclude that the element concentrations in ditchwater depend largely on site characteristics masking the possible effect of harvest.

The medium most directly affected by anthropic contamination is soil and, hence, groundwater (saturated and unsaturated zones). In the phytoremediation process, the direct absorption of soil contaminants through the roots is a surprising pollutant removal mechanism. Plants can act as a natural filter of shallow groundwater contamination, controlling and reducing the vertical percolation of contaminants into the soil, and after reaching the level of the water table, the roots can absorb contaminants dissolved in the water, thus reducing the size of the plume and protecting receptor sites (water supply wells, rivers, lakes) from possible contamination. In the first phase of the research, assays were performed to evaluate the tolerance of plant species to the direct injection of a benzene solution into the roots. Subsequent experiments involved direct absorption and spraying. The aim of this study was to evaluate the potential for tolerance and reaction to high levels of benzene. Three plant species were used, an herbaceous ornamental plant (Impatiens walleriana), a fern (Pteris vittata), and forage grass (Brachiaria brizantha). At the end of the study, the surface changes caused by VOCs (aerial structures) of benzene were evaluated, using an environmental scanning electron microscope (ESEM) to identify possible mechanisms of resistance of the plant to air pollution, i.e., hydrocarbon pollution. The plant material used here was young plant species selected for study. For the analysis by gas chromatography (GC), the plant material was separated into aerial (stem, leaves, and flowers) and underground parts (roots). A comparison of the benzene content in different parts of the plant indicated a higher concentration in the stem + leaves, followed by the roots, which is justified by its translocation inside the plant. P. vittata showed low uptake (5.88 %) mainly in the root and (<2 %) in the leaves, which was also observed in the tolerance experiment, in which visual symptoms of toxicity were not observed. I. walleriana showed benzene removal rates of approximately 18.7 % (injection into the soil) as a result of direct absorption through the roots. After the treatment was suspended, I. walleriana gradually reacted to the detoxification process by recovering its stem stiffness and normal color. B. brizantha showed intermediate behavior and did not react to the detoxification process.

Identifying the relative importance of stressors is critical for effectively managing and conserving freshwater aquatic ecosystems. However, variability in natural ecosystems and the potential for multiple stressors make understanding the effects of stressors challenging in the field. To address these challenges, we assessed four common stressors in the northeastern USA including acidification (pH), climate change (water temperature), salinization (Na and Cl), and nutrient addition using laboratory mesocosms. Each stressor was evaluated independently, with ten mesocosms assigned across a gradient of concentrations for each stressor (total N = 40). We then monitored the effects of the stressors on a model community consisting of periphyton, zooplankton, Northern watermilfoil (Myriophyllum sibericum), American ribbed fluke snail (Pseudosuccinea columella), and larval American bullfrogs (Lithobates catesbeianus). Aquatic stressors varied in the strength of their effects on community structure: Nutrient addition was the least influential stressor, with no significant effects. Acidification influenced periphyton biomass, but not higher trophic levels. Water temperature influenced primary productivity and survival of amphibian larvae, but not intermediate trophic levels. Finally, road salt led to decreases in productivity for all trophic levels included in our model systems. Our results support the findings of prior research, although the effects of acidification and nutrient addition were less pronounced in our study. Importantly, we found that road salt had the most far-reaching effects on a model aquatic community. Given that road salt is the most easily managed of the stressors we compared, our results indicate that improving the condition of freshwater aquatic ecosystems in the northeastern USA may be a feasible objective.

The study presented here focuses on the use of monolayer covers for reclaiming two acid-generating tailings sites located in Quebec, Canada. One of these covers is made of non-acid-generating tailings, and the other is made of a silty sand (till). The covers are part of the closure plans that aim at controlling acid mine (rock) drainage at these two sites. Reactive tailings and cover material samples were collected in situ and characterised in the laboratory. Large-size columns (230 cm in height) were set up to evaluate the hydrogeological and geochemical response of the tailings and cover systems. Monthly wetting and drying cycles were repeated over nearly 2 years to simulate climatic conditions. Water content, suction, and oxygen concentrations were monitored, and chemical analyses were performed on the leachate collected at the base during each cycle to follow the evolution of water quality, in terms of pH and concentrations of sulfates and metals. In addition, small columns (45 cm in height) were also set up, with a similar testing program, to assess the hydrogeochemical behaviour of exposed tailings. The specific objective of this experimental program was to evaluate the hydrogeological and geochemical behaviour of the tailings-cover systems under controlled conditions. The results indicate that, for the imposed conditions, the monolayer covers became significantly desaturated, thus insufficiently limiting the oxygen diffusion flux. Consequently, these covers do not efficiently prevent sulfide oxidation within the tailings. The implications of these results are also discussed.