Multiple linear regression models are often used to predict levels of fecal indicator bacteria (FIB) in recreational swimming waters based on independent variables (IVs) such as meteorologic, hydrodynamic, and water-quality measures. The IVs used for these analyses are traditionally measured at the same time as the water-quality sample. We investigated the improvement in empirical modeling performance by using IVs that had been temporally synchronized with the FIB response variable. We first examined the univariate relationship between multiple “aspects” of each IV and the response variable to find the single aspect of each IV most strongly related to the response. Aspects are defined by the temporal window and lag (relative to when the response is measured) over which the IV is averaged. Models were then formed using the “best” aspects of each IV. Employing iterative cross-validation, we examined the average improvement in the mean squared error of prediction, MSEP, for a testing dataset after using our temporal synchronization technique on the training data. We compared the MSEP values of three methodologies: predictions made using unsynchronized IVs (UNS), predictions made using synchronized IVs where aspects were chosen using a Pearson correlation coefficient (PCC), and predictions using IV aspects chosen using the PRESS statistic (PRS). Averaging over 500 randomly generated testing datasets, the MSEP values using the PRS technique were 50 % lower (p < 0.001) than the MSEP values of the UNS technique. The average MSEP values of the PCC technique were 26 % lower (p < 0.001) than the MSEP values of the UNS technique. We conclude that temporal synchronization is capable of significantly improving predictive models of FIB levels in recreational swimming waters.

Phosphate from agricultural runoff is a major contributor to eutrophication in aquatic systems. Vegetated drainage ditches lining agricultural fields have been investigated for their potential to mitigate runoff, acting similarly to a wetland as they filter contaminants. It is hypothesized that some aquatic macrophytes will be more effective at removing phosphate than others. In a mesocosm study, three aquatic macrophyte species, cutgrass (Leersia oryzoides), cattail (Typha latifolia), and bur-reed (Sparganium americanum), were investigated for their ability to mitigate phosphate from water. Mesocosms were exposed to flowing phosphate-enriched water (10 mg L⁻¹) for 6 h, left stagnant for 42 h, and then flushed with non-nutrient enriched water for an additional 6 h to simulate flushing effects of a second storm event. Both L. oryzoides and T. latifolia decreased the load of dissolved phosphate (DP) in outflows by greater than 50 %, significantly more than S. americanum, which only decreased DP by 15 ± 6 % (p ≤ 0.002). All treatments decreased concentrations inside mesocosms by 90 % or more after 1 week, though the decrease occurred more rapidly in T. latifolia and L. oryzoides mesocosms. By discovering which species are better at mitigating phosphate in agricultural runoff, planning the community composition of vegetation in drainage ditches and constructed wetlands can be improved for optimal remediation results.

Fluorescence in situ hybridization (FISH) technique and qPCR analyses, targeting atz genes, were applied to detect the presence of simazine-degrading bacteria in an agricultural soil with a history of herbicide application. atzB-targeted bacteria detected by FISH represented 5% of total soil bacteria with potential capability to metabolize the herbicide. The soil natural attenuation capacity was confirmed in soil microcosms by measuring simazine degradation. Moreover, four bacterial strains were isolated from the soil and identified as Acinetobacter lwoffii, Pseudomonas putida, Rhizobium sp. and Pseudomonas sp. The isolates were able to grow using different s-triazine compounds and related metabolites as the sole carbon source. Growth parameters in presence of simazine were calculated using the Gompertz model. Rhizobium sp. showed the highest simazine degradation (71.2%) and mineralization (38.7%) rates, whereas the lowest values were found to A. lwoffii—50.4% of degradation and 22.4% of mineralization. Results from qPCR analyses of atzA, atzB and atzC genes revealed their presence in Rhizobium sp. and A. lwoffii, being atzB and atzC the most abundant functional genes. Rhizobium sp. showed a higher amount of the three biomarkers compared to A. lwoffii: the atzA, atzB and atzC gene copy number per microlitre were, respectively, 101, 102 and 103-fold higher in the former. Therefore the proposed molecular approaches based on the use of atz genes as biomarkers can be considered as useful tools to evaluate the presence and potential capability of degrading-s-triazines soil microorganisms.

Many of the environmental problems related to agriculture will still be serious over the next 30 years. However, the seriousness of some of those problems may increase more slowly than in the past or even diminish in other cases (FAO 2002). Agriculture plays two different roles in climate change; on one hand, it suffers from the impact of climate change, on the other hand, it is responsible for 14 % of total greenhouse gases (MMA 2008). Nevertheless, agriculture is also part of the solution, as it is capable of mitigating a significant amount of global emissions, according to the FAO (2001). This paper aims to study the influence of edapho-climate conditions on soil CO2 emissions into the atmosphere. In order to do so, we conducted three field trials in different areas in southern Spain, which have different soil textures and different climate conditions. The results show how interaction between the temperature and rainfall recorded has a greater influence on emissions than each of the factors separately. However, at the same time, the texture of the soil at each of the locations was also found to be the most dominant variable in the gas emission process.

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.

Laboratory experiments were carried out to study the uptake kinetics of selected metals and metalloids in the aquatic moss Fontinalis antipyretica. For this purpose, moss specimens from a clean site were exposed to concentrations of As, Hg, Sb, and Se ranging from 0.1 to 10,000 μg l−1, for incubation times of between 1 and 22 days, and the tissue concentrations of the metals in the moss specimens were then measured. Uptake kinetics followed different patterns in relation to exposure time, although the most common was Michaelis–Menten kinetics. On the contrary, the contamination factors followed very similar patterns in relation to the exposure concentrations in all cases, with a good fit to logarithmic equations. The bioconcentration factors tended to decrease as exposure concentration increased. The bioconcentration factors for Hg were extremely high, even at the lowest concentration in water and for the shortest incubation time, which implies that F. antipyretica has a high capacity to magnify Hg levels in water, which is an important characteristic in a good biomonitor. According to the time to reach equilibrium, the minimum exposure time recommended for use in active biomonitoring by means of transplants is very variable, although high levels of the elements, except Sb, were found in the moss tissues within a few days. We do not recommend the use of this moss species to biomonitor low concentrations of Sb in water. The differences in maximum contamination factors and lowest bioconcentration factors suggest that As and Se were the most toxic of the elements under study.

A simple spectrophotometric method was developed to quantify chlorophenol (CP) concentrations after reaction with potassium permanganate and quenching with sodium sulfite. Other quenching agents (peroxide, sodium thiosulfate and hydroxylamine hydrochloride) were found to create absorbance in the spectral range required for CP quantification. Analysis at pH 12 gave greater absorption and sensitivity for the method compared with pH 5.6. The calibration curves of the proposed methods were linear in the concentration ranges 0.0061–0.61 and 0.0078–0.78 mM with detection limit of 0.0006 and 0.0008 mM for dichlorophenols and monochlorophenols, respectively. The oxidation kinetics of five chlorophenols in aqueous solution with excess potassium permanganate were evaluated using the analytical method. The pseudo-first-order reaction rates were found to be relatively rapid 1.42 × 10−3 to 0.024 s−1 and followed the sequence 2-chlorophenol (2-CP) > 2,6-dichlorophenol (2,6-DCP) > 4-chlorophenol (4-CP) > 2,4-dichlorophenol (2, 4-DCP) > 3-chlorophenol (3-CP). The apparent second-order rate constant was calculated from the measured pseudo-first-order rate constant with respect to CP with initial KMnO4 concentration (1.5 mM) and follows the same sequence of pseudo-first-order rate constant. This shows that chlorine atoms in the structure of chlorophenol had a significant influence on the oxidation of chlorophenols by potassium permanganate. Permanganate can be used for the treatment of chlorophenol-contaminated soil and groundwater.

This paper analyses the influence of activated sludge technologies on the Particle Size Distribution (PSD) of urban wastewater treatment plants operating under real conditions. The activated sludge treatment systems selected for the analysis are the most widely used in wastewater treatment installations: (a) double step activated sludge, (b) medium load activated sludge, (c) prolonged aeration, and (d) membrane bioreactors The main quality parameters (suspended solids, turbidity, and COD) and PSD in the influent and effluent of each different activated sludge treatment were analyzed during 1 year. The PSD was fitted using the power law ([Formula: see text]) obtaining coefficients A and b to define the particle distribution. Mathematical correlations between this coefficients and the rest of parameters studied were found [Formula: see text]. The relation with the average particle size by mass was also found, ([Formula: see text]). Moreover, a relation between PSD and the particle elimination efficiency of the secondary treatment was study, ([Formula: see text]). Finally, the particulate matter nature was assessed by SEM-EDX. It can be concluded that membrane bioreactor is the technology that produces the best water quality effluent due to physic process of particle separation by ultrafiltration membrane technology.

A series of aluminum oxyhydroxide-incorporated titania composites were prepared by a one-pot synthetic procedure using aluminum tri-sec-butoxide as a precursor. The as-synthesized samples were characterized by Fourier transform infrared spectrophotometer, X-ray diffraction, thermogravimetry and differential scanning calorimetry, nitrogen physisorption, and scanning electron microscopy. It was identified that aluminum oxyhydroxide (γ-AlOOH, or boehmite) was produced as aluminum matrix into which titania, commercially available P25, was incorporated. Photocatalytic activity of all nanocomposites was evaluated with respect to the photodecolorization of methyl orange under UV irradiation and almost complete decolorization was eventually achieved under optimum experimental conditions.

Over a century of metal processing activity has resulted in widespread metal contamination of soils in Sudbury, ON, Canada. To assess the potential for recovery from the large reductions in metal deposition, critical loads were estimated for metals at 415 sites in Sudbury using an ‘effects based’ approach that is based on exceedance of provincial soil guidelines using multiple independent estimates of metal partitioning (Kd) for each metal. Sudbury soils are heavily contaminated with copper (Cu) and nickel (Ni), with 74 % of samples currently exceeding the provincial soil guideline for Cu and 87 % of samples exceeding the guideline for Ni. Both metals are strongly correlated with other metals (zinc (Zn), cadmium (Cd), lead (Pb)), although they rarely exceed provincial guidelines Copper and Ni are also strongly correlated with organic matter but not soil pH. Based on the most recent Cu and Ni deposition estimates (mid-1990s), it is estimated that between 20 % and 51 % of the sites receive deposition in excess of the ‘effects based’ critical load for Cu and between 5 % and 97 % of sites receive atmospheric deposition in excess of the ‘effects based’ critical load for Ni. These results suggest that Cu and Ni concentrations in soil will generally decrease resulting in slightly fewer sites that exceed the provincial soil guideline, but that the timeframe of this response will be very slow, with relatively little change occurring over the next 100 years. Even assuming a best case deposition scenario whereby Cu and Ni deposition were to immediately fall to background levels, the percentage of sites with Cu and Ni levels in excess of the OMOE guideline would still be between 69 % and 72 %, and 56 % and 86 %, respectively, demonstrating that while recovery of the Sudbury soils is possible, greater reductions in metal deposition are needed and even so, it will be a process that takes several centuries.