Animal wastes are commonly used in a sustainable manner to fertilize crops. However, manures contain numerous pathogenic bacteria that can impact animal and human health. Treatment of animal waste by anaerobic digestion has the potential to reduce pathogen loading to land. This study was conducted to determine the fate of bacteria applied in raw and anaerobically digested dairy slurries that were broadcast and subsurface applied in a field of forage grasses. Digested slurry had significantly fewer indicator bacteria, Escherichia coli and fecal coliform at time of application. Anaerobic digestion did not increase the survivability of indicator bacteria. Waste treatment and application method did not affect the rate of bacteria die-off. There were fewer E. coli and fecal coliform at the end of each trial in the soils that received digested slurry. Anaerobic digestion of dairy waste has the potential to reduce pathogenic bacteria loading to cropland.

The goal of our study was to identify pharmaceuticals, their potential sources and consumption level in two different socioeconomic and geographical regions—Bordeaux, France and Kharkiv, Ukraine. These substances were monitored in rivers water during contrasted seasonal conditions with application of passive samplers. The 21 pharmaceuticals (psychiatric drugs: alprazolam, amitriptyline, diazepam, fluoxetine, nordiazepam, carbamazepine, bromazepam; analgesics: aspirin, paracetamol; broncholidator: clenbuterol, salbutamol, terbutaline; non-steroidal anti-inflammatory drug: diclofenac, ibuprofen, ketoprofen, naproxen; lipid regulator: gemfibrozil; stimulants: caffeine, theophylline) were identified in sites upstream and downstream of urban areas and discharge of wastewaters. Caffeine, carbamazepine, and diclofenac were relatively abundant into the surface water and could be considered as potential anthropogenic markers of wastewater discharges into rivers. A mass balance modeling has been applied to calculate approximate consumption rates for carbamazepine, diclofenac, and caffeine in both regions to assess socio-economic factors linked with pharmaceuticals behavior.

This study presents the application of multivariate statistical tools for the evaluation of spatial variations and the interpretation of water quality data obtained in a monitoring program of Lis river basin surface water, Portugal. Twenty-seven physicochemical and microbiological parameters were determined in six water sampling campaigns at 16 monitoring sites during the period from September 2003 to November 2006. Correlation analysis, principal component analysis, and cluster analysis were performed to evaluate the main water pollution sources and to characterize the spatial distribution of water pollution profiles in river basin. The results achieved with the statistical methodologies led to distinguish natural and anthropogenic pollution sources. Additionally, monitoring sites with similar water pollution profile were identified, indicating that some monitoring locations can be changed to improve the spatial characterization of water quality in the river basin. CBO, CQO, P, and N were identified as significant variables affecting spatial variations, namely in the Lis river middle reach. Besides the identification of main pollution sources, the applied statistical tools were able to identify spatial patterns of water pollution in Lis river basin, which further helps in the reassessment of the number and location of monitoring sites.

Most previous studies investigating controls on nitrous oxide (N2O) emissions have relied on plot-scale experiments and focused on relative homogeneous biotic and abiotic factors such as soil, vegetation, and moisture. We studied soil N2O flux at 11 chamber sites along a 620 m topographic gradient in upstate New York, USA, aiming at identifying patterns of N2O flux and correlating them to hydrological factors and soil substrate properties along the gradient. The topographic gradient is a complex slope with an overall gradient of 8%, covering plant communities of pasture, forest, alfalfa field, and riparian area from the top to the bottom. Mean fluxes of N2O measured from late March to May ranged from 4.45 to 343 μg N m−2 h−1, and these fluxes were not significantly different among chamber sites located in different communities. With the descending of the slope, N2O fluxes increased with the increase of soil water content, except for the riparian site. Statistically, N2O fluxes were not strongly correlated with soil temperature, soil bulk density, and water filled pore space (p > 0.05). Instead, strong correlations (p < 0.05) were found between N2O fluxes and soil C and N content including NO 3 − , NH 4 + , total organic carbon, and C/N ratio. Multiple linear regression analyses including both soil physical and substrate properties highlighted the significance of soil NO 3 − content and C/N ratio in regulating N2O fluxes along the gradient.

The aim of this study was to evaluate the use of metal concentrations in clam organs to monitor metal contamination in coastal sediments. The concentrations of Cd, Cr, Cu, Hg, Ni, Pb, V, and Zn were measured in the kidneys, gonads, mantles, gills, digestive gland, and hearts of the infaunal clam Amiantis umbonella collected from a contaminated site near desalination and power plant discharges, and a reference site in Kuwait Bay. Metal concentrations in sediment and sediment pore water were also measured at the collection sites of individual clams at the contaminated site. The concentrations of all metals in all organs (except Zn in the digestive gland) were significantly higher in clams from the contaminated site than from the reference site. Metal concentrations in several organs in A. umbonella from the contaminated site were correlated with those in the sediments and pore waters to which they were exposed. However, fresh weights of gonads, gills, and mantles were significantly lower in clams from the contaminated site compared to the reference site, indicating that the observed elevated concentrations of metals in the organs of clams from the contaminated site largely reflect lower organ weights, rather than higher metal loads, and that these organs in A. umbonella and perhaps other clams are not appropriate for use as biomonitors of metal contamination. Metal concentrations in clam kidneys showed a wide dynamic range with respect to environmental contamination and kidney weight was not variable. Therefore, metal concentrations in clam kidneys provide a reliable biomonitor of contaminant metals in coastal marine sediments.

As global mercury emissions from coal fire power plants increase with the continuing rise of coal consumption, mercury capture methods are being developed to prevent mercury’s escape into the atmosphere. Titanium dioxide (TiO₂) in the presence of ultra violet light (UV-A; λ ₘₐₓ ∼360 nm) and oxygen will capture mercury as the solid product HgO₍ₛ₎. Testing the effects of TiO₂ in the presence of other pollutants has so far been limited. We have performed kinetic and product studies of mercury adsorption in the presence of the gaseous flue co-pollutant NO₂₍g₎. We extensively studied the gas-phase reaction of NO₂(g) with Hg ₍g₎ ⁰ . We compared the gas-phase reaction to the same reaction performed in the presence of thin TiO₂ particle surfaces from 0 to 100 % relative humidity. The second-order rate constant was measured to be k = (3.5 ± 0.5) × 10⁻³⁵ cm⁶ molecules⁻² s⁻¹, independent of the presence of titania or the total surface area available for adsorption. Exposure of NO₂₍g₎ to titania surfaces that were already saturated in captured mercury (HgO₍ₛ₎) increased total mercury uptake onto the surface. We discuss the implications of this study to the capture of mercury emissions prior to release to the atmosphere.

Clogging is the main operational problem associated with horizontal subsurface flow constructed wetlands (HSSF CWs). The measurement of saturated hydraulic conductivity has proven to be a suitable technique to assess clogging within HSSF CWs. The vertical and horizontal distribution of hydraulic conductivity was assessed in two full-scale HSSF CWs by using two different in situ permeameter methods (falling head (FH) and constant head (CH) methods). Horizontal hydraulic conductivity profiles showed that both methods are correlated by a power function (FH = CH0.7821, r 2 = 0.76) within the recorded range of hydraulic conductivities (0–70 m/day). However, the FH method provided lower values of hydraulic conductivity than the CH method (one to three times lower). Despite discrepancies between the magnitudes of reported readings, the relative distribution of clogging obtained via both methods was similar. Therefore, both methods are useful when exploring the general distribution of clogging and, specially, the assessment of clogged areas originated from preferential flow paths within full-scale HSSF CWs. Discrepancy between methods (either in magnitude and pattern) aroused from the vertical hydraulic conductivity profiles under highly clogged conditions. It is believed this can be attributed to procedural differences between the methods, such as the method of permeameter insertion (twisting versus hammering). Results from both methods suggest that clogging develops along the shortest distance between water input and output. Results also evidence that the design and maintenance of inlet distributors and outlet collectors appear to have a great influence on the pattern of clogging, and hence the asset lifetime of HSSF CWs.

Since swine wastewater is used by farmers for soil fertilization, evaluation of toxic compounds or micro-contaminants of separate streams is required. This paper uses the toxicity identification evaluation (TIE) procedure for the physicochemical and ecotoxicological characterization of swine wastewater. To distinguish the most important toxic compounds, a physicochemical characterization and phase I-TIE procedure were performed. The acute toxic effect of swine wastewater and treated fractions (phase II-TIE) were evaluated using Daphnia magna determining 48-h LC50. Results show a high level of conductivity (23.5 μS cm−1), which is explained as due to the concentration of ions, such as ammonium (NH 4 + –N 1.6 g L−1), sulfate (SO 4 2− 397.3 mg L−1), and chlorine (Cl− 1,230.0 mg L−1). The acute toxicity of the swine wastewater was evaluated on D. magna (48-h LC50 = 3.4%). Results of the different water treatments indicate that anionic exchange treatments could reduce 22.5% of swine wastewater’s acute toxicity by reducing chlorine (to around 51%) and conductivity (8.5%). On the other hand, cationic exchange treatment increased acute toxicity on D. magna (% RT = −624.4%), by reducing NH 4 + –N (around 100%) and total nitrogen (95.5%). This finding suggests that part of the toxicity comes from anionic compounds, such as chlorine.

This study examined patterns of stream sediment granulometry, organic matter (OM) and metal concentration, and surface water characteristics in a catchment in the Brazilian Iron Quadrangle that is highly impacted by surface iron mining and gully erosion. Sediment granulometry indicated fine sediment deposition at impacted stream sites, i.e., tendencies towards bimodal particle size distributions with an additional peak in the sand fraction at impacted stream sites that did not occur at pristine reference sites, as well as towards smaller mean sediment particle sizes at impacted sites than at reference sites. Impacted sites also had significantly lower sediment OM contents than reference sites. Sediment heavy metal and arsenic concentrations did not differ between impacted and reference sites and were generally below published target or threshold effect concentrations. Impacts on surface water characteristics occurred only locally at a site that received tailings pond effluent from an iron mine and had very low pH and conductivity values. Sediment characteristics exhibited substantial spatial variability in the studied tropical catchment, showing that land use impacts can hardly be detected in routine monitoring and impact assessment studies that adopt a before–after control-impact approach and do not consider pristine reference streams. These results underline the importance of high-resolution and long-term sediment monitoring as well as integrated basin-scale sediment management programs.

Histochemical and biochemical approaches were used to investigate the phytotoxicity induced by microcystin-LR (MC-LR) in the shoots of Brassica rapa seedlings. MC-LR exposure was able to induce oxidative stress by triggering the over-generation of reactive oxygen species (ROS) including superoxide anion radical (O₂ [Sʸᵐᵇᵒˡ: ˢᵉᵉ ᵗᵉˣᵗ] ⁻ ) and hydrogen peroxide (H₂O₂) in the shoots of B. rapa. MC-LR exposure led to the significant increase in the concentration of endogenous nitric oxide (NO) in B. rapa. However, such increase was completely suppressed by the treatment with nitrate reductase (NR) inhibitor NaN₃, while L-NMMA, a NO synthase (NOS) inhibitor, had only slight effect on the content of endogenous NO in MC-LR-treated plant. These data suggested that NR-dependent pathway was the main source for endogenous NO generation under MC-LR stress. Afterwards, treatment with NaN₃ reduced the ROS generation, lipid peroxidation, and loss of membrane integrity in MC-LR-treated plant. MC-LR stress induced the increase in the expression of superoxide dismutase, ascorbate peroxidase, and catalase. However, such an effect could be reversed by the treatment with NaN₃. These results indicate that NR-dependent NO production mediates MC-LR-induced oxidative stress by triggering the over-generation of ROS in B. rapa.