Surface water contamination can often be reduced by passing runoff water through perennial grass filters. Research was conducted in 2006 to 2008 to evaluate the size of cool season grass filters consisting primarily of tall fescue (Festuca arundinacea Schreb) with some orchard grass (Dactylis glomerata L.) relative to drainage area size in reducing runoff sediment and phosphorus (P). The soil was Pohocco silt loam Typic Eutrochrepts with a median slope of 5.5 %. The grass filters occupying 1.1 and 4.3 % of the plot area were compared with no filter with four replications. The filters were planted in the V-shaped plot outlets which were 3.7 × 11.0 m in size. The filter effect on sediment and P concentration was determined from four natural runoff events when nearly all plots had runoff. Filter effect on runoff volume and contaminant load was determined using total runoff and composites of samples collected from 12 runoff events. Sediment concentration was reduced by 25 % with filters compared with no filter (from 1.10 to 1.47 g L⁻¹), but P concentration was not affected. The 1.1 and 4.3 % filters, respectively, compared with having no grass filter, reduced: runoff volume by 54 and 79 %; sediment load by 67 and 84 % (357 to 58 kg ha⁻¹); total P load by 68 and 76 % (0.58 to 0.14 kg ha⁻¹); particulate P (PP) load by 66 and 82 % (0.39 to 0.07 kg ha⁻¹); and dissolved reactive P (DRP) load by 73 and 66 % (0.2 to 0.07 kg ha⁻¹), respectfully. A snowmelt runoff event had 56 % greater DRP concentration compared with rainfall-induced runoff events. Grass filters reduced sediment and P load largely by reducing runoff volume rather than reducing concentration. Well-designed and well-placed grass filters that occupy 1.0 to 1.5 % of the drainage area and intercept a uniform flow of runoff from a drainage area can reduce sediment and nutrient loss in runoff by greater than 50 %.

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.

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.

Crosslinking carboxymethyl starch (CCMS) powder of degree of substitution (DS) 0.43–0.59 was prepared by the process of two steps of alkali addition synthesis. The technique of powder coupling with ultrafiltration was used to absorb Cu2+, Zn2+, Ni2+, Pb2+, and Cd2+ from aqueous solutions. FTIR was used to demonstrate the successfully grafting of carboxymethyl groups, and the technique of microwave plasma torch atomic emission spectrometer was applied in rapid determination of the aforementioned heavy metals ions. The results revealed that the removal sequence of heavy metal ions followed the order of Pb2+>Cu2+>Cd2+>Zn2+>Ni2+. By assistant of diethylene triamine penlaacetic acid, the quaternary system of Pb2+/Ni 2+/Cd2+/Cu2+ mixture solution could have the ideal separation. Besides, the influence of pH, ζ potential, DS value, and membranes molecular weight cut-off on removal of 20 mg L−1 Pb2+ or Ni2+ was also investigated.

The sorption of four endocrine disruptors, bisphenol A (BPA), estrone (E1), 17β-estradiol (E2), and 17α-ethinylestradiol (EE2) in tropical sediment samples was studied in batch mode under different conditions of pH, time, and sediment amount. Data obtained from sorption experiments using the endocrine disruptors (EDs) and sediments containing different amounts of organic matter showed that there was a greater interaction between the EDs and organic matter (OM) present in the sediment, particularly at lower pH values. The pseudosecond order kinetics model successfully explained the interaction between the EDs and the sediment samples. The theoretical and experimentally obtained q e values were similar, and k values were smaller for higher SOM contents. The k F values, obtained from the Freundlich isotherms, varied in the ranges 4.2–7.4 × 10−2 (higher OM sediment sample, S2) and 1.7 × 10−3–3.1 × 10−2 (lower OM sediment sample, S1), the latter case indicating an interaction with the sediment that increased in the order: EE2 > > E2 > E1 > BPA. These results demonstrate that the availability of endocrine disruptors may be directly related to the presence of organic material in sediment samples. Studies of this kind provide an important means of understanding the mobility, transport, and/or reactivity of this type of emergent contaminant in aquatic systems.

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.