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.

Synechocysis sp. PCC6803 is a unicellular blue alga which ubiquitously exists in aquatic system and is considered to play a role in arsenic cycling. Our results showed that Synechocysis can accumulate arsenic as much as 1.0 and 0.9 g kg−1 DW when exposed to 0.5 mM arsenate and arsenite for 14 days, respectively. In addition, arsenic species in cells were assayed under different exposure conditions and it was found that inorganic arsenic, including arsenate and arsenite, is the dominant species. Organic methylated arsenicals can only be detected exposed to higher arsenic concentration range (100–500 μM). Arsenate is the dominant arsenic species and presents more than 80% of the total arsenic in cells. Efflux of both arsenate and arsenite was observed. When treated with 2.67 μM arsenite, Synechocysis can rapidly oxidize arsenite to arsenate and accumulate As rapidly. The observed arsenic oxidation in solute is solely caused by cellular oxidation. Given the robust ability of As accumulation, it can serve as a phytoremediation organism to efficiently remove arsenic from aquatic environments.

A Gram-negative bacterium strain LWD09, capable of growing aerobically on 3,4-dichloroaniline (DCA) as the sole carbon and energy source, was isolated from the farm field. This bacterium was identified as Myroides odoratimimus strain by morphological, physiological, and biochemical characteristics as well as 16S rDNA sequence. Analysis of culture pH, temperature, cells growth, and DCA concentration demonstrated that strain LWD09 could effectively degrade DCA without a lag phase. The kinetics of DCA degradation was well described using the Andrews equation, and the kinetic parameters were as follows: q max = 1.74 h−1, K s = 43.5 mg L−1, and K i = 230.3 mg L−1. In addition, strain LWD09 was found to be moderately halophilic and showed the highest power of DCA degradation in 5% NaCl (w/w, %). With initial concentrations of 30, 100, and 200 mg L−1, 100%, 80.4%, and 33.2% of DCA were transformed after 96 h in 5% NaCl, respectively. These results suggest that strain LWD09 has the potential to degrade DCA in saline wastewater. To date, this is the first report on the degradation of DCA by a M. odoratimimus strain with moderate salinity tolerance.

The selection of control measures for reducing metal contamination in rivers has targeted point sources such as wastewater treatment plants (WWTPs) and industrial discharges without a proper evaluation of their relative contribution to metal loads at the catchment level. The necessity of controlling pollutant inputs in a sound and cost-effective way to prevent the deterioration of chemical and ecological quality of receiving waters has highlighted the need for appropriate source assessment. As metals in rivers emanate from a wide range of sources, it is necessary to understand their relative contribution in order to reduce effectively the concentrations in receiving waters. This study presents a simple method for calculating the relative contribution of WWTPs to levels of metals in receiving waters as applied to the Aire–Calder catchment in the UK. In this catchment, the apportionments to WWTP effluents of metal levels in rivers were 37, 31, 36 and 60 % of total cadmium (Cd), lead (Pb), mercury (Hg) and nickel (Ni), respectively. Spatial metal distribution in rivers with maximum concentrations of 0.47 μg L⁻¹ for Cd, 8.54 μg L⁻¹ for Pb, 0.05 μg L⁻¹ for Hg and 10.17 μg L⁻¹ for Ni caused by the discharge of WWTP effluents was estimated. The findings demonstrate that the proposed approach using quantification of metal loads and estimation of concentrations in receiving waters could adequately calculate the relative contribution of WWTP effluents to metal levels in receiving waters. Applications to various river catchments using site-specific data would further validate the effectiveness of the approach proposed.

The soil dynamics of hexavalent Cr, a particularly mobile and toxic metal, is of a great environmental concern, and its availability to plants depends on various soil properties including soil organic matter. Thus, in a pot experiment, we added 50 mg Cr(VI) kg⁻¹ soil and studied Cr(VI) soil extractability and availability to spinach, where we applied both natural (zeolite), synthetic adsorptive materials (goethite and zeolite/goethite) and organic matter with farmyard manure. We found that, compared to the unamended control plants, dry matter weight in the Cr(VI)-added soil was greatly decreased to 17 % of the control, and height was decreased to 34 % of the control, an indication of Cr toxicity. Also, exchangeable Cr(VI) levels in soil decreased back to the unamended control even in the first soil sampling time. This was much faster than the exchangeable Cr(VI) levels in the mineral-added soil, where Cr(VI) levels were decreased to the levels of the unamended control in the third sampling time. The positive effect of organic matter was also indicated in the Cr quantity soil-to-plant transfer coefficient (in grams of Cr in plant per kilogram of Cr added in soil), a phyto-extraction index, which was significantly higher in the manure-amended (1.111 g kg⁻¹) than in the mineral-added treatments (0.568 g kg⁻¹). Our findings show that organic matter eliminates the toxicity of added Cr(VI) faster than the mineral phases do and enhances the ability of spinach to extract from soil greater quantities of Cr(VI) compared to mineral-added soils.

The behavior of estrone (E1) and 17β-estradiol (E2) in relatively closed water environment was studied by continuous flow experiment using sediments from a freshwater reservoir. For this, four sediment columns (two oxic ones and two anoxic ones) were employed, which were structured by packing 30 cm of undisturbed sediment and 60 cm of overlying water collected from two sites within a reservoir. A mass balance model that considered the influent flux, the effluent flux, mass transfer, sorption, and biodegradation was proposed to describe the behavior of E2 and E1 in the columns. The results indicated that the water–sediment partition coefficient of E1 [Formula: see text] was higher than E2 [Formula: see text]. The degradation rate of E1 (k E1) was smaller than E2 (k E2). Under both oxic and anoxic conditions, E1 was formed from E2. Furthermore, to clarify the impact of the model parameters such as the hydraulic retention time (HRT), K d, and k on the behavior of E2 and E1, variance analysis was performed based on the results of model simulations. The results showed that the concentrations of E2 and E1 in the column effluent were controlled most significantly by the sorption capacity of the natural estrogens onto sediment particles, with the determined contributory ratios changing in the order of sorption > HRT > degradation.

The removal of nutrients in wastewater is a critical issue in water treatment because released nutrients can cause serious adverse effects in water systems or the aquatic environment. In this study, a high-performing polymeric anion-exchange resin was developed for the removal of nutrients from wastewater. The resins were prepared by chloromethylation followed by amination under preferred conditions. The resins were investigated for the removal of nutrients such as phosphate, nitrate, and fluoride from water. The density of functional groups on the synthesized resin was approximately 33 % higher than on commercialized resins, and the specific surface area of synthesized resin was increased by approximately tenfold compared with commercialized resins. The adsorption capacity of synthesized resins (AMP16-FeCl₃) for anions was 285.8 mg/g, which was approximately three times higher than the capacity of commercialized resin (AMP16-OH). A study of the effects of the types of counterions and functional groups found that resins having hydroxide ion as a counterion showed higher capacity and selectivity for phosphate ion and that dimethylethanolamine as a resin functional group of resin was more efficient than trimethylamine.

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 %.

We investigated the potential application of pyrolysis treatment to a mixture of woody biomass and a metal-contaminated soil as an alternative eco-friendly option to stabilize metals in soils. Our specific objective was to test the optimum combination of high heating temperature (HHT) and heating time to effectively encapsulate metals in a contaminated soil into a biochar. For this purpose, we used a laboratory bench batch reactor to react a mixture of multi-element metal contaminated soil with 0% (control) 5%, 10%, and 15% (w/w) sawdust. Each mixture was reacted at 200°C and 400°C HHT for 1 and 2 h heating times. Physicochemical and morphological characterization along with standard EPA Synthetic Precipitation Leaching Procedure (SPLP) test were conducted to assess the effectiveness of the heat treatment to immobilize the metals in the contaminated soil. Compared to controls, we recorded up to 93% reduction in Cd and Zn leachability after 1 h heat treatment at 400°C, with the addition of 5–10% biomass. Pb leaching was reduced by 43% by the same treatment but without the addition of biomass. At lower pyrolysis temperature (200°C), however, there was a substantial increase in both As and Zn leaching compared to the untreated controls. Our study suggests that several factors such as the type of metal, heating temperature, heating period, and the addition of biomass influence the efficiency of pyrolysis to immobilize metals in the contaminated soil.

The use of azo dyes is popular in different branches of industry. Discharge of colourants to surface water cause harmful environmental effects. The aim of the present study was evaluation of effectiveness of diazo Evans blue decolourization by two Pseudomonas strains and estimation of process byproducts toxicity. In static conditions, both tested strains removed more than 85 % of dye after 48 h and completely decolorized samples after 120 h. Agitation had negative impact on Evans blue removal (less than 70 % of dye removed after 120 h). Ecotoxicological effects were different for both studied strains beside comparable decolourization effectiveness. Increase of zootoxicity was noticed for strain Sz6 and decrease from IV to III class was noticed for strain SDz3. Optimization of process conditions for the most promising strain SDz3 should be deeply examined.