TiO 2 and SiO 2 Nanoparticles Combined with Surfactants Mitigate the Toxicity of Cd 2+ to Wheat Seedlings Abstract Engineered nanoparticles (NPs) could be coated by surfactants and modify the bioavailability and toxicity of heavy metals. In this study, the single and combined effect of sodium dodecyl benzene sulfonate (SDBS) and NPs on the toxicities of Cd2+ to wheat seedlings was investigated by a root elongation, and the underlying influence mechanism was further discussed. The results showed that the presence of SDBS improved the Cd2+ adsorption capacity of TiO2 and SiO2 NPs. The reaction of SDBS and TiO2 and SiO2NPs could increase TiO2 and SiO2 NPs dispersion stability and produced more available adsorption sites. The adsorption coefficients of Cd2+ on TiO2 and SiO2 NPs were enhanced from 3.84 to 4.52 mg/g and from 4.51 to 7.16 mg/g after SDBS coating. Both SDBS-coated TiO2 and SDBS-coated SiO2 NPs reduced Cd2+ phytotoxicity. The presence of bare TiO2 and SiO2 NPs at 1000 mg/L promoted root length of the wheat seedlings by 31.2% and 39.3%; however, SDBS-coated TiO2 and SiO2 NPs increased the root length by 41.2% and 51.4%, which demonstrated that SDBS-coated NPs had a much better effect on reducing the toxicity of Cd2+ than bare NPs. The results indicated the mitigation of Cd2+ toxicity was due to a decrease in bioavailable soluble Cd2+ which was adsorbed by NPs through electrostatic attraction.

Increased Mortality, Delayed Hatching, Development Aberrations and Reduced Activity in Brown Trout ( Salmo trutta ) Exposed to Phenethyl Isothiocyanate Abstract Plants of the order Brassicaceae have evolved a chemical defence against herbivory: the glucosinolate-myrosinase system. Mechanical damage to plant tissues, such as grazing, initiates the production of phenethyl isothiocyanate (PEITC), a compound toxic to invertebrates. Mechanical damage caused during biofumigation and the harvesting and washing of watercress presents routes for PEITC release into waterbodies, such as the chalk stream spawning sites of brown trout (Salmo trutta). This laboratory study exposed developing S. trutta embryos to PEITC at concentrations of 0.01, 0.1 and 1 μg/L. S. trutta exposed to 1 μg/L PEITC during embryonic development resulted in 100% mortality after four dose days. Exposure to 0.1 μg/L PEITC resulted in an approximate fourfold increase in mortality relative to the controls, while exposure to 0.01 μg/L PEITC had a negligible effect on embryo mortality. Embryos exposed to 0.1 μg/L PEITC showed a significant delay in hatching and produced alevins with significantly shorter total lengths, lighter body weights and an approximate threefold increase in spinal deformities relative to those exposed to the controls and 0.01 μg/L PEITC. The results of a motor activity assay demonstrate that alevins exposed to PEITC showed a significant decrease in swimming activity compared with control animals during periods of illumination. The increased mortality, teratogenic effects and impaired behaviour in S. trutta following embryonic exposure to relatively low concentrations of PEITC highlight a need to accurately quantify and monitor environmental levels of PEITC.

Catalytic Degradation of Humic Acid by Mn-Cu/Al-MCM-41 Catalyst in Electro-Fenton/Chlorine Processes: Influencing Factors, Mechanisms, and Kinetics Abstract Degradation of humic acid (HA) in heterogeneous electro-Fenton/chlorine processes was investigated using a catalyst of Mn-Cu bimetallic oxides supported on Al-containing MCM-41. The catalyst was synthesized by co-precipitation method and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), N2 adsorption–desorption, and X-ray photoelectron spectroscopy (XPS) techniques. The bimetallic oxide catalyst exhibited a higher activity compared to monometallic one. Adding Al in the bimetallic oxide catalyst enhanced the stability of the catalyst, reduced metal ion leaching, increased the initial ratio of Mn3+/Mn4+ and Cu+/Cu2+, and slightly enhanced the degradation efficiency of HA and corresponding chemical oxygen demand (COD). The effect of Mn and Cu content in MCM-41, catalyst dosage, pH value, and initial concentration of HA and salinity on degradation efficiency were investigated. A high COD reduction about 91.5% and general current efficiency (GCE) about 41.7% have been achieved under the optimal conditions of pH 6, salinity 1000 mg/L, catalyst dosage 0.5 g/L, HA sodium salt concentration 200 mg/L, and reaction time 60 min. A possible mechanism for the reaction was suggested. Kinetic analysis showed that HA degradation in the electro-Fenton/chlorine processes was fit with first-order kinetics.

Predicting Naphthenic Acid Migration Through the Foundation of Oil Sands Tailing Pond Abstract In this paper, a conceptual model was developed to predict the seepage of oil sands process-affected water with capabilities of evaluating the transport and attenuation of naphthenic acids through the dykes and the foundations of oil sands tailings pond. The model incorporates naphthenic acid diffusion, adsorption, dispersion, advection, and biodegradation, and was modeled through the commercial software tools to predict naphthenic acid fate in both spatial and time scales. The tailing pond of the Muskeg River Mine in the Athabasca oil sands deposit was investigated in the case study. The comparison between the onsite monitoring data and the simulation results was in good agreement. In addition, limiting factors for migration of naphthenic acid were also discussed based on a parametric sensitivity study.

Correction to: Tracking the Limnoecological History of Lake Hiidenvesi (Southern Finland) Using the Paleolimnological Approach Erroneous information considering Chironomidae and Chaoboridae accumulation was given in Figure 4 published in Luoto et al. (2017).

Rainfall-Runoff Simulation of Radioactive Cesium Transport by Using a Small-Scale Portable Rainfall Simulator Abstract Soil pollution with radioactive cesium (134Cs and 137Cs) has been considered one of the major environmental issues of agricultural farmlands after the nuclear power station incident which occurred in Fukushima Prefecture on 11th March 2011. A small-scale portable rainfall-runoff simulator was developed to conduct the rainfall-runoff experiments in the laboratory using the radiocesium contaminated soil in Fukushima. This study describes and demonstrates the operation method and performance of a portable rainfall simulator as well as runoff, sediment discharge, radioactivity, and contaminant transport. The rainfall simulator is able to produce the rainfall intensity from 30 to 70 mm h−1 with Christiansen’s Uniformity varied from 72 to 91%. The simulated rainfall kinetic energy rates were accounted for about 45, 58, and 74% of the kinetic energy of the natural precipitation for different rainfall intensities of 30, 50, and 70 mm h−1, respectively. The applicability of a small-scale portable rainfall simulator for the rainfall impacts on runoff, soil erosion, and the transport of radioactive cesium is investigated. The total radioactive cesium (134 + 137Cs) measured in runoff sediments ranged up to 6847 Bq kg−1 and they were in the ranges that have been reported in the literature. The results revealed that the average total radioactivity average of cesium in the discharged sediments was found to be higher (up to three times) than the average rates determined in initial soil in lysimeters of all Fukushima sites before the experiment. The results have proved that a small-scale portable rainfall-runoff simulator system is a useful tool for investigating rainfall-runoff phenomena and contaminant transport in the laboratory.

Native Plants for Revegetation of Mercury- and Arsenic-Contaminated Historical Mining Waste—Can a Low-Dose Selenium Additive Improve Seedling Growth and Decrease Contaminant Bioaccumulation? Abstract Highly contaminated exposed legacy gold mine tailings from the late 1800s are present in many locations throughout North America and other parts of the world that experienced gold rushes at that time. Those tailing fields can pose risks to human health and the environment. Revegetation of tailing fields can reduce dust generation and other risks associated with these sites. The objective of this study was to investigate if native rapid-growing plants could be successfully germinated in mercury (Hg) and arsenic (As) contaminated legacy mine tailings, both untreated and treated with a low dose of sodium selenite (Na2SeO3) to promote growth and decrease bioaccumulation of contaminants. After screening many candidates, four wide-spread North American native plant species were selected, Juncus tenuis, Anaphalis margaritacea, Symphotrichum novi-belgii, and Panicum virgatum for their tolerance, presence near legacy gold mine sites, and ability to germinate rapidly in harsh conditions. Three of these species germinated and grew well in untreated tailings except for S. novi-belgii. The selenite treatment increased biomass, emergence, shoot height, and root length in J. tenuis; emergence in A. margaritacea; and root lengths in P. virgatum. This treatment also decreased shoot [Hg] and [As] in P. virgatum by 36% and 40%. Low-dose selenite treatments hold promise for supporting germination and growth of native plants in Hg- and As-contaminated tailing fields.

Potential Alternative Reuse Pathways for Water Treatment Residuals: Remaining Barriers and Questions—a Review Abstract Water treatment residuals (WTRs) are by-products of the coagulation and flocculation phase of the drinking water treatment process that is employed in the vast majority of water treatment plants globally. Production of WTRs are liable to increase as clean drinking water becomes a standard resource. One of the largest disposal routes of these WTRs was via landfill, and the related disposal costs are a key driver behind the operational cost of the water treatment process. WTRs have many physical and chemical properties that lend them to potential positive reuse routes. Therefore, a large quantity of literature has been published on alternative reuse strategies. Existing or suggested alternative disposal routes for WTRs can be considered to fall within several categories: use as a pollutant and excess nutrient absorbent in soils and waters, bulk land application to agricultural soils, use in construction materials, and reuse through elemental recovery or as a wastewater coagulant. The main concerns and limitations restricting current and future beneficial uses of WTRs are discussed within. This includes those limitations linked to issues that have received much research attention such as perceived risks of undesirable phosphorous immobilisation and aluminium toxicity in soils, as well as areas that have received little coverage such as implications for terrestrial ecosystems following land application of WTRs.

Bioethanol Mill Wastewater Purification by Combination of Coagulation-Flocculation and Microbial Treatment of Trametes versicolor INACC F200 Abstract Black liquor is generated from the pretreatment process of biomass-based bioethanol production and due its environmental impact, should be treated effectively before discharged to the water body. Chemical treatment using coagulation-flocculation method was commonly used for wastewater treatment. In the case of black liquor, chemical treatment is often insufficient and further treatment was needed to degrade lignin in order to reduce its black coloration. This present study investigated the two-step treatment to decolorize black liquor using chemical coagulation-flocculation and biological treatment using white-rot fungus Trametes versicolor INACC F200. The biological treatment was optimized by applying a response surface methodology (RSM) of the utilization of CuSO4 concentration, Tween 80 concentration, and agitation. Furthermore, lignin degradation was also confirmed using FTIR and LC-MS. Initial chemical treatment using ferrous sulfate and polyacrylamide as coagulant-flocculant with a ratio of 3:3, resulted in black liquor decolorization at 80.9% and reduced the COD up to 90.77%. A full quadratic stepwise model was utilized with CuSO4 inducer, Tween 80 mediator, and agitation speed as the independent variables. Optimum decolorization of 96.188% was predicted when using 2 mM CuSO4, 2% Tween 80, and an agitation speed of 150 rpm. The highest enzyme activity during the decolorization process was lignin peroxidase (LiP). FT-IR and LC-MS profile showed that lignin-associated bond was eliminated and the molecular weight of lignin was decreased after the treatment. This study concludes the effective decolorization and delignification of black liquor by the two-step chemical and biological treatment.

Seasonality of E. coli and Enterococci Concentrations in Creek Water, Sediment, and Periphyton Abstract Environmental reservoirs of fecal indicator bacteria (FIB) are attracting increasing attention because of the ambiguity they present when assessing the microbial quality of water. FIB can survive and even grow in various environmental reservoirs which means FIB measured in the water column may not have originated directly from a fecal source. Sediment and periphyton, i.e., aquatic biofilms growing on submerged rocks, have been shown to harbor large populations of FIB in the environment. However, little is known about the spatial and temporal dynamics of FIB in periphyton. The objective of this work was to determine levels of the common FIB, Escherichia coli and enterococci, in creek water, sediment, and periphyton during the summer and winter. FIB were measured during two summer and winter sampling dates at five locations along a 2.8-km stretch of creek in Beltsville, Maryland. Significant differences in FIB by location were only observed for E. coli in water at one time point. Levels of FIB significantly declined from summer to winter in all media. FIB concentrations in periphyton ranged from 102 to 104 gdw−1 in the summer and from 100 to 104 CFU gdw−1 in the winter. When compared on a dry weight basis, periphyton contained higher concentrations of FIB than the sediment. Variability of FIB was in the order of water < sediment < periphyton. Levels of E. coli and enterococci measured in the same sample showed significant positive correlation in all media (rs = 0.87, 0.48, 0.70, for water, sediment, and periphyton, respectively). Results from this work show that fecal bacteria can persist in creek periphyton which may act as both a reservoir for fecal pathogens as well as a probable source of fecal bacteria to the water column.