This comprehensive field survey on indigenous European chub (Squalius cephalus L.) presents, for the first time, site-specific variability of trace metal concentrations in the gut content, gastrointestinal tissue and two gastrointestinal sub-cellular fractions, operationally defined as metal-sensitive fraction (S50, which was isolated at 50,000 × g and contains total water soluble proteins), and metal detoxified fraction (heat-treated S50 (HT S50), which contains heat-stable proteins like metallothioneins). At five sampling sites along the Sava River in Croatia 1 to 5-year-old chub were collected in the post-spawning period (September) in order to estimate if metal concentrations in fish intestine are related to their levels in the gut content or fish age. Concentrations of essential metals (Zn, Fe, Cu, Mn) and non-essential Cd decrease in the gut content as follows: Fe > Mn > Zn > Cu > Cd, while in the gastrointestinal tissue: Zn > Fe > Cu ≥ Mn > Cd. Observed difference in metal abundance between the gut content and gastrointestinal tissue points to the selective metal absorption in fish intestine. Relationship among metal concentrations in the gastrointestinal tissue and two sub-cellular fractions (S50/HT S50) is significant for all analysed metals, with Spearman correlation coefficients (r) at p < 0.01 for Zn 0.84/0.73, Cu 0.73/0.73, Fe 0.62/0.58, Mn 0.81/0.78, Cd 0.81/0.82. Site-specific differences point to the age-related increase of gastrointestinal Cu, Mn and Cd towards the downstream sites, while significant correlation between metal concentrations in the gut content and fish age exists only for Mn. In the sub-cellular gastrointestinal fractions, site-specific differences were not recorded on total water-soluble protein and metallothionein concentrations, which might be ascribed to the constitutional level.

Comparison of event-based precipitation collected during 1 year showed that samples from a Yankee Environmental Systems collector had significantly higher volume, higher concentrations, and higher deposition of all ions analyzed except PO 4 3− and NH 4 + compared to samples collected simultaneously with an Aerochem Metrics collector.

Elevated emissions of nitrogen oxides (NOx) in the Athabasca Oil Sands Region, Alberta and higher foliar nitrogen (N) concentrations in jack pine (Pinus banksiana) needles close to major emission sources has led to concerns that the surrounding boreal forest may become N-saturated. Despite these concerns, N deposition and impacts on upland forests in the region is poorly quantified. The objective of this study was to characterize N cycling in five plots representing the two dominant upland forest types (jack pine and trembling aspen, Populus tremuloides) close (<30 km) to the largest mining operations in the region, during a 2-year period. Despite the high level of NOx emissions, bulk throughfall and deposition measured at both study sites were surprisingly very low (<2 kg N ha−1 year−1). Internal N cycling was much greater in aspen stands; annual N input in litterfall was ten times greater, and net N mineralization rates were two to five times greater than in jack pine stands. Nitrogen use efficiency (NUE) was much greater in jack pine when calculated based on N litterfall indices, but not when N pools in biomass were considered. Despite differences in internal cycling among forest types, nitrate leaching from mineral soil in both forest types was negligible (<0.1 kg N ha−1 year−1) and patterns of 15N in roots, foliage, and mineral soil were typical of N-limited ecosystems, and both sites show no evidence of N saturation.

A directly amine-functionalized mesoporous silica (AMS) was prepared via an anionic surfactant-mediated synthesis method and used as adsorbents for deep removal of Cu ions from aqueous solution at room temperature. The synthesized AMS had been characterized by X-ray diffraction, nitrogen physisorption measurement, and thermogravimetric analysis. The amine groups prefer to position to the surface of AMS material due to the SN ∼ I mechanism. Copper adsorption process had been studied from both kinetic and equilibrium points of view for AMS material. Experiments proved that the aqueous Cu adsorption rates were fast and adsorption capacity was about 53.3 mg/g.

Two types of hydrogels with different functional groups, trimethylamine on quaternary ammonium and dimethylethoxyamine on quaternary ammonium, were synthesized. Type 1 and type 2 hydrogels were characterized with Fourier transform infrared, X-ray photoelectron spectroscopy and zeta potential analysis. The anion selectivity of these two hydrogels was investigated. The surface charges of the type 2 hydrogel were lower than those of type 1, probably because of the presence of the hydroxyl group in the ethoxy group. The Cr(VI) removal capacity of type 2 hydrogel was, therefore, less than that of type 1 hydrogel, although their adsorption rates were similar. The anion selectivity of the hydrogels was found to have a similar order: Cr(VI) > sulphate > bromide > As(V). Under the co-presence of Cr(VI) and sulphate conditions, type 2 hydrogel shows a higher selectivity towards Cr(VI). The higher hydrophobicity was caused by the presence of the ethoxy group on the quaternary ammonium in type 2 hydrogel and thus increased in selectivity towards monovalent ions (i.e. HCrO 4 − ). In addition, the hydrogels have a high reusability. Compared with type 1 hydrogel, type 2 hydrogel has an advantage for applications in Cr(VI) removal and recovery processes.

High As groundwater normally contained high concentrations of Cl⁻ and HCO ₃ ⁻ . This study examined the effects of Cl⁻, HCO ₃ ⁻ , and As species on As uptake by hyperaccumulator Pteris vittata. Plants were exposed hydroponically to 5.0 mg/L As(III) or As(V) in the presence of 0, 0.5, 1, 2, 5, 10, and 20 mM of Cl⁻ or HCO ₃ ⁻ for 10 days. Addition of high Cl⁻ concentrations (>10 mM) slightly inhibited P. vittata growth (biomass), while generally had no significant effect on plant As uptake. High solution pH resulted in reduced plant growth and As uptake, which attributed to the inhibitory effects in HCO ₃ ⁻ treatments with the high pH of the high HCO ₃ ⁻ concentration. It was speculated that addition of HCO ₃ ⁻ (<20 mM) would have no significant effect on plant growth and As uptake. The inhibitory effect of HCO ₃ ⁻ on As translocation was less apparent in the As(III) solutions than the As(V) solutions. For the high As groundwater with As(III) as the predominant species, high pH, instead of high concentrations HCO ₃ ⁻ and Cl⁻, was expected to inhibit As uptake. The results suggested that optimum plant growth and maximum As hyperaccumulation could be achieved by adjusting solution pH in the growth media (around 7.2).

Redox stratification, especially hypolimnetic anoxia resulting from eutrophication, and salinization resulting from application of salts for road deicing is investigated in three kettle lakes in southwest Michigan. Two of the lakes (Asylum and Woods Lakes) are located in urban Kalamazoo, Michigan, and the third (Brewster Lake) is located in rural Hastings, Michigan. In summer, the water columns of all three lakes are distinctly redox stratified, with anoxic hypolimnia and significant accumulation of reduced solutes (e.g., Mn(II), Fe(II), ammonia) in the lake bottom waters. Extremely elevated conductivity, chloride, sodium, and potassium levels are observed in the urban Asylum and Woods Lakes compared to the rural Brewster Lake, presumably due to runoff of road salt deicers applied in the surrounding watershed. These significant changes in water quality are of concern because they may detrimentally impact lake mixing, biodiversity, and ecosystem function in the urban lakes.

We evaluated the imbalance of the oxidative status in zebra mussel (Dreissena polymorpha) specimens exposed for 96 h to environmentally relevant concentrations (0.1, 0.5, and 1 μg/L) of the 2,2′,4,4′,5,6′-hexa BDE (BDE-154). The activities of three antioxidant enzymes, catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx), and the phase II detoxifying enzyme glutathione S-transferase (GST), were measured in the cytosolic fraction from a pool of zebra mussels. Significant variations in the activity of each single enzyme were noticed at each treatment, indicating that exposure to BDE-154 was able to impair the oxidative status of treated bivalves through the increase of reactive oxygen species. In detail, SOD and GPx were significantly induced, while CAT and GST were depressed with respect to the baseline levels. These data have confirmed that the raise of oxidative stress is the main cause of the BDE-154-induced genetic damage observed in a previous study on the zebra mussel.

This study concentrated on the direct immobilization of anatase nano titanium dioxide particles (TiO₂, 44 nm particle size) into or onto a biodegradable polymer, polycaprolactone, by solvent-cast processes. The photocatalytic properties of the produced materials were tested by photocatalytic removal of organic contaminant 4-chlorophenol. Produced TiO₂ immobilized polymer successfully removed 4-chlorophenol (4-CP, 20 ppm which is equal to 1.56 × 10⁻⁴ M) from aqueous solution without additional pH arrangement employing a UV-A light (365 nm) source. Immobilization of n-TiO₂ onto polycaprolactone (PCL) produced improved 4-CP removal percentages, reaching to nearly 85 %. Increased PCL mass significantly increases the removal percentage of 4-CP. When a UVC lamp emitting 254 nm light is used, the removal percentage reaches to 89 %. UV irradiation did not cause any change in the microstructure of the polymeric material (confirmed with ATR-FTIR analysis). This is an important evidence that the material could be reused for further photocatalytic treatments. Produced material seems to be highly promising for successful removal of organic pollutants beside its biodegradable nature.

Reaeration coefficient (k), the rate of oxygen exchange between the atmosphere and water surface, is an important parameter for understanding water quality impairment and stream metabolism. We modified the propane injection method to measure gas exchange coefficients and evaluated its application for small streams. The tracer solution was prepared by solubilizing propane directly in a conservative solute solution, and it was injected as a constant-rate injection, a single slug, or an extended slug. Water samples were taken at four to five sampling stations along the study reach at the tracer concentration peak, and propane and conductivity were measured. The propane exchange rate (k ₚᵣₒₚₐₙₑ) was calculated using the regression method with the propane/conductivity ratio against solute travel time (in hours). The mixed tracer injection method was conducted in four streams, and all k ₚᵣₒₚₐₙₑ measurements (n = 8) were statistically significant (p < 0.05). The short-duration constant rate injection and extended slug injection provided k ₚᵣₒₚₐₙₑ estimates with higher r ² than the single slug injection. The k ₂₀ measured with propane injection ranged from 5.4 to 40.0 day⁻¹, and they were significantly correlated with empirically estimated k. The mixed tracer injection method with propane could potentially reduce field time, crew demands, and field equipment; thus, it would potentially lower the overall cost of gas exchange coefficient measurements and be an effective method in small, remote streams.