We examined long-term changes in soil solution chemistry associated with experimental, whole watershed-acidification at the Bear Brook Watershed in Maine (BBWM). At BBWM, the West Bear (WB) watershed has been treated with bimonthly additions of ((NH₄)₂ SO₄) since 1989. The adjacent East Bear (EB) watershed serves as a biogeochemical reference. Soil solution chemistry in the EB watershed was relatively stable from 1989–2007, with the exception of declining SO₄–S concentrations associated with a progressive decline in SO₄–S deposition during this period. Soil solution chemistry in WB reflected a progressive change in acid-neutralization mechanisms from base cation buffering to Al buffering associated with treatment during this period. Total dissolved Al concentrations progressively increased over time and were ~4× higher in 2007 than in 1989. Treatment of WB was also associated with long-term increases in soil solution H⁺, SO₄–S, and NO₃–N, whereas soil solution dissolved organic carbon (DOC) was unresponsive to treatment. For solutes such as Ca, H⁺, and SO₄–S, changes in stream chemistry were generally parallel to changes in soil solution chemistry, indicating a close coupling of terrestrial and aquatic processes that regulate the chemistry of solutions in this first-order stream watershed. For other solutes such as Al and DOC, solute concentrations were higher in soil solutions compared with streams, suggesting that sorption and transformation processes along hydrologic flow-paths were important in regulating the chemistry of solutions and the transport of these solutes.

The mechanisms for translocation of heavy metals from soil to epigeal mosses were investigated. The first mechanism was demonstrated for 137Cs and involved the uplifting of the pollutant-containing dust from the soil, followed by the local secondary deposition on surfaces of epigeal mosses and epiphytic lichens. The second mechanism involved the diffusion of metal cations from the soil through water wetting the moss into the gametophyte. The mechanism was demonstrated by measuring the electric conductance of wetted gametophytes with single ends immersed in solutions of Cu and Na salts. In addition, the concentrations of Cu and Cd were compared in moss samples exposed to the natural soil and to the soil contaminated with the metals. The exposition to the contaminated soil resulted in the statistically significant increase of metal concentrations in the gametophytes.

An experiment was conducted under simulated condition to study the influence of vermicompost on growth, yield and heavy metal accumulation by chamomile (Matricaria chamomilla), an important essential oil bearing crop grown under simulated condition. Nickel and Cadmium applied at 20 mg kg−1 soil significantly enhanced the dry matter yield of the crop as compared to the control (no heavy metal). The results also revealed that addition of vermicompost (at 2.5 g kg−1 soil) enhanced the heavy metal accumulation by chamomile in metal-treated soil. Although a sizeable amount of metals were being translocated to flowers, the essential oil extracted by hydrodistillation of flowers did not contain any heavy metal. Similarly, chemical constituents of the oil of chamomile were within the range of those obtained from chamomile grown under normal soil condition.

The photochemical degradation of two widely used organophosphorothioate insecticides, fenitrothion and diazinon, was investigated in aqueous solutions containing three separate dissolved constituents commonly found in natural waters (NO 3 − , CO 3 2− and dissolved organic matter (DOC)). The effect of these constituents on pesticide photodegradation was compared to degradation in “constituent-free” pure water. Solutions were irradiated in an Atlas solar simulator fitted with a UV-filtered Xenon arc lamp with light irradiances (500 W m−2) measured using a spectral radiometer to allow derivation of quantum yields of degradation. Fenitrothion absorbs light within the solar UV range (λ, 295–400 nm) and underwent direct photolysis in pure water whereas diazinon (λ max ∼250 nm) showed no observable loss over the experimental period. However, photodegradation conforming to pseudo-first-order kinetics was observed for both chemicals in the presence of the dissolved constituents (at concentrations typically observed in natural waters), with the rates of photodecay observed in the order of NO 3 − > CO 3 2− ≅ DOC, with the highest rates observed in the 3 mM NO 3 − solutions (k Fen = 0.155 ± 0.041 h−1; k Dia = 0.084 ± 0.0007 h−1). For diazinon this rate was comparable to fenitrothion photolysis in pure water (k fen 0.072 ± 0.0078 h−1), highlighting the importance of NO 3 − on a non-photolabile pesticide, with indirect photodegradation probably attributable to the light-induced release of aqueous hydroxyl radicals (·OH) from NO 3 − . Suwannee river fulvic acid (serving as DOC) did not statistically affect the rate of photodecay for fenitrothion relative to its photolysis in MilliQ water, although measured rates in DOC solutions were slightly lower. However, measurable rates of photodecay were apparent for diazinon in the DOC solutions, indicating that fulvic acid, possibly in the form of “excited” triplet-state-DOC plays a role in diazinon transformation. Hydrolysis was not apparent for fenitrothion (in buffered solutions of pH 5–9) but was notable for diazinon at the lower pHs of 5 and 3 (k Dia-hyd 0.3414 h−1 at pH 3 and 0.228 h−1 at pH 5), resulting in the formation of the degradate, 2-isopropyl–6-methyl–4-pyrimidinol. This work highlights the importance of dissolved constituents on abiotic photodegradation of pesticides and it is recommended that these constituents be incorporated into laboratory-based fate-testing regimes.

Nutrient (C, N and P) and metal (Cr, Cu, Ni, Pb and Zn) content and dynamics of suspended and channel bed sediments were analysed within the rural Attert River basin (Luxembourg). This basin is representative of the main physiographic characteristics of the country, where there is currently little information available on the composition and dynamics of fluvial sediment. Stream bed fine-grained sediment samples (n = 139) collected during low flow conditions and time-integrated suspended sediment samples (n = 183) collected during storm runoff events (October 2005 to April 2008) in seven nested basins ranging from 0.45 to 247 km² were analysed. Nutrient and metal spatial patterns, temporal trends and the relationship between their content and storm runoff characteristics (e.g. maximum discharge and sediment concentration) were assessed. Results showed a high spatial and temporal variability, mainly associated with basin characteristics and local inputs. Higher values of total C were measured in the highly forested basins located in the northern part of the Attert River basin, whereas the highest values of total P were mainly associated with material coming from grassland and with the inflow of wastewater treatment plants (i.e. higher values of total P were measured in the southern part of the basin). The abundance of metals, not only in suspended but also in channel bed sediments, was generally as follows: Zn > Cr > Ni > Pb > Cu. Both nutrient and metal concentrations were at a maximum at the beginning of the wet season, after having been accumulated during the summer. These values tended to decrease during autumn and winter due to sediment mobilisation, and a higher flow capacity to transport coarser particle fractions from the sources. In general, concentrations of nutrients and metals on suspended sediment were negatively correlated with antecedent precipitation, total precipitation, total specific discharge and maximum discharge, which has been previously associated to a ’dilution’ effect during storm runoff events. Results show that both sediment sources and hydrologic events play an important role on the spatial and temporal variability of sediment-associated nutrient and metal contents.

Simulated magnetic contamination of plants during early ontogenetic stages was studied in arranged laboratory conditions using magnetic nanoparticles based on compound metal oxides. Aqueous suspensions of magnetic colloidal nanoparticles of Fe3O4, CoFe2O4, and ZnFe2O4, were administrated to freshly germinated sunflower seeds in the same array of dilutions (v/v): 20–40–60–80–100 μl/l, the results of their genetic impact in the root tip cells being qualitatively and quantitatively analyzed. Cytogenetic tests carried out by optical microscopy means provided data on the types of abnormal cell divisions as well as on the mitosis rate and total percentage of chromosomal aberrations. Considerable diminished mitosis rate was evidenced in all situations, while remarkably enhanced number of chromosomal aberrations was also evidenced for all three cases with higher nanotoxicity revealed in the case of ZnFe2O4 and CoFe2O4. Chromosome fragments, interchromatidian bridges and micronuclei appeared in most analyzed samples with no noticeable difference for one type of magnetic nanoparticles or other.

The effects of a five-pesticide mixture on pesticide accumulation, phytohormone levels (indole-3-acetic acid, gibberellic acid, jasmonic acid, and salicylic acid), pigment contents (total chlorophyll and carotenoid), antioxidant enzyme (catalase and guaiacol peroxidase) activities, lipid peroxidation product (malondialdehyde), and DNA profiles were investigated in the leaves of Veronica beccabunga. Laboratory-acclimatized plants were treated with a mix of five pesticides (atrazine, disulfoton, chlorpyrifos, metalaxyl, and ethion) in doses of 50 ppt, 1 ppb, 100 ppb, and 1 ppm for 1, 3, and 6 days. The accumulation of each pesticide, from highest to lowest, was as follows: chlorpyrifos, atrazine, metalaxyl, disulfoton, and ethion. The amounts of total chlorophyll and protein decreased with increased pesticide concentration. Antioxidant enzyme activities and malondialdehyde amount increased linearly with increasing pesticide exposure. However, the highest pesticide concentration caused decreases in guaiacol peroxidase (POD) activity and malondialdehyde (MDA) content at all treatment times. Both jasmonic and salicylic acid levels increased with pesticide exposure and decreased gradually after. It was also determined that application of the pesticide mixture affected the DNA profiles of V. beccabunga. The most band changes were detected on the sixth day of treatment.

Spherical particles have been sampled from soils and silica-rich rock coatings close to major smelter centers at Coppercliff, Coniston, and Falconbridge in the Sudbury area, Canada. Detailed analyses employing optical microscopy, scanning electron microscopy, transmission electron microscopy, micro-Raman spectroscopy, and Mössbauer spectroscopy have been conducted to elucidate their nature, origin and potential alteration. The spherical particles are on the nano- to millimeter-size range and are composed principally of magnetite, hematite, Fe-silicates (olivine, pyroxenes), heazlewoodite, bornite, pyrrhotite, spinels (including trevorite and cuprospinel), delafossite, and cuprite or tenorite. The spinels present have variable Cu and Ni contents, whereas delafossite and cuprite are Ni free. Texturally, the spherical particles are composed of a Fe-oxide–Fe-silicate matrix with sulfide inclusions. The matrix displays growth features of a Fe-rich phase that commonly form during rapid cooling and transformation processes within smelter and converter facilities. Examination of weathered spherical particles indicates that some sulfide inclusions have dissolved prior to the alteration of the Fe-silicates and oxides and that the weathering of Fe-silicates occurs simultaneously with the transformation of magnetite into hematite. A higher proportion of Cu vs. Ni in the clay and organic fraction noted in the Sudbury soils is explained by (1) the formation of stronger adsorption complexes between Cu and the corresponding surface species and (2) the preferential release of Cu vs. Ni by smelter-derived particles. The latter mechanism is based on the observations that (a) cuprospinels have higher dissolution rates than Ni spinels, (b) a larger proportion of Cu occurs in the nanometer-size (and thus more soluble) fraction of the emitted particles, and (c) Ni spinels of relatively low solubility form in the alteration zone of heazlewoodite inclusions.

Understanding the dynamics of naturally occurring dissolved organic carbon (DOC) in a river is central to estimating surface water quality, aquatic carbon cycling, and global climate change. Currently, determination of DOC in surface water is primarily accomplished by manually collecting samples for laboratory analysis, which requires at least 24 h. In other words, no effort has been devoted to monitoring real-time variations of DOC in a river due to the lack of suitable and/or cost-effective wireless sensors. However, when considering human health, carbon footprints, effects of urbanization, industry, and agriculture on water supply, timely DOC information may be critical. We have developed here a new paradigm of a dynamic data-driven application system (DDDAS) for estimating the real-time load of DOC into a river. This DDDAS was validated with field measurements prior to its applications. Results show that the real-time load of DOC in the river varied over a range from −13,143 to 29,248 kg/h at the selected site. The negative loads occurred because of the back flow in the estuarine reach of the river. The cumulative load of DOC in the river for the selected site at the end of the simulation (178 h) was about 1.2 tons. Our results support the utility of the DDDAS developed in this study for estimating the real-time variation of DOC in a river ecosystem.

In the present paper, the Eulerian–Lagrangian localized adjoint method (ELLAM) formulation developed by Younes et al. (Advances in Water Resources 29:1056–1074, 2006) is combined with the sequential noniterative approach to accurately simulate 2D multicomponent reactive transport in saturated/unsaturated porous media. The performance and accuracy of the developed model, named ELLAM_REACT, are compared against those of an existing numerical model based on a combination of discontinuous Galerkin and multipoint flux approximation methods (DGMPFA_REACT). Three studied test cases, dealing with reactive transport in saturated and unsaturated porous media and involving chemical reactions with only aqueous species or both fixed and aqueous species, show the superiority of the ELLAM_REACT model compared to the DGMPFA_REACT model.