Improved Microbial and Chemical Reduction of Direct Blue 71 Using Anthraquinone-2,6-disulfonate Immobilized on Granular Activated Carbon

The aim of this study was to evaluate the redox mediating capacity of anthraquinone-2,6-disulfonate (AQDS) immobilized on granular activated carbon (GAC) during the reductive decolorization of direct blue 71 (DB71) under microbial and chemical conditions. The immobilization of AQDS on GAC was conducted by adsorption, and it has obtained an uptake capacity of 0.227 mmol g^?1. The anchorage of AQDS on GAC improved its electron transfer capacity (ETC) up to 2.05 times higher than the raw material. Similarly, the addition of GAC-AQDS increased up to 1.75- and 1.16-fold the rate of decolorization (k _d ) of DB71 under microbial and chemical conditions, respectively, in comparison to the unmodified GAC. Surprisingly, a higher k _d value was achieved in incubations without either GAC or GAC-AQDS because of the generation of aromatic amines, from the reduction DB71, taking into account that these species may act as a catalyst in the DB71 reduction process. In contrast, adsorption of aromatic amines on either GAC or GAC-AQDS decreased its redox mediating capacity as evidenced by spectrophotometric screenings of the decolorized solution and the supporting material. The development of materials with enhanced both redox and adsorption properties, as the GAC used in this study, offers a promising way to increase the redox conversion of recalcitrant pollutants commonly found in industrial wastewaters.     

Anaerobic Dechlorination of Tetrachlorobisphenol A in River Sediment and Associated Changes in Bacterial Communities

Tetrachlorobisphenol A (TCBPA) is a widely used flame retardant and a potential endocrine disruptor. We estimated the role of the microbial community in degradation of TCBPA in river sediment from the vicinity of an E-waste processing facility. The effects of different anaerobic conditions on degradation efficiency of TCBPA were investigated, and differences in bacterial communities among these conditions were analyzed by 16S ribosomal RNA (rRNA) gene sequencing. The most effective dechlorination of TCBPA occurred under methanogenic conditions followed by electron donor-enhanced conditions and sulfate-reducing conditions with initial sulfate concentrations of 1, 10, and 20 mM. The extent of TCBPA removal under these conditions mentioned above was 65, 44, 43, 23, and 23%, respectively. 16S rRNA gene sequence analysis indicated that five dominant genera in the phylum Chloroflexi and another five species of Bacteroidetes, Chlorobi, and Firmicutes in these five systems were largely involved in TCBPA dechlorination. The initial sample had a total relative abundance of autochtonous potential dechlorinating bacteria of 12%. After 160 days, these values increased to 29–43% under above conditions. Addition of TCBPA decreased bacterial diversity. Efficiency of TCBPA degradation depends on the abundance and metabolism of dechlorinating bacterial guilds. The effectiveness of dechlorinating microbes in degradation of TCBPA was reduced by high sulfate concentrations.     

Physiological Responses of <Emphasis Type="Italic">Rosa rubiginosa</Emphasis> to Saline Environment

The aim of this work was to analyse the response of Rosa rubiginosa to salinity induced by different concentrations of sodium chloride and calcium chloride (0, 25, 50, 100, 150 and 200 mM). Besides salt accumulation and pH changes, other parameters were investigated including photosynthetic activity, leaf water content, the dynamics of necrosis and chlorosis appearance and leaf drying. The study was complemented with microscopic analysis of changes in leaf anatomy. R. rubiginosa was more sensitive to the salinity induced by calcium chloride than by sodium chloride. Plant response to salinity differed depending of the salt concentration. These differences were manifested by higher dynamics of necrosis and chlorosis appearance and leaf drying. CaCl₂ showed greater inhibition of the photosynthetic apparatus and photosynthetic activity. Treatment with CaCl₂ caused more visible deformation of palisade cells, reduction in their density and overall reduction in leaf thickness. The study demonstrated higher accumulation of CaCl₂ in the soil, and thus greater limitations in water availability resulting in reduced leaf water content and quicker drying of leaves as compared with NaCl-treated plants.     

Experimental Study of Tidal Effects on Coastal Groundwater and Pollutant Migration

The problem of current urban groundwater pollution is very serious, which has influenced social development and people’s daily life. Around the land-sea interface, tide obviously changes nearshore the groundwater flow regime and makes the pollutant migration process become more complex. In the present study, the effect of tide-induced groundwater table fluctuations and on the pollutants migration in beach aquifers is investigated by constructing a two-dimensional sand trough physical experimental model. The model considered brackish-water density differences and the tide by controlling experimental medium properties and boundary conditions. The results showed that the groundwater table fluctuation cycle is the same as the tidal cycle and the fluctuation lag time increases linearly with the increase of the offshore distance. Tidal fluctuation flattens brackish-freshwater interface, widens the dispersion zone, and generates the upper saline and the freshwater belt. Time lag corresponding relationships between saline water and tidal fluctuation was observed. With the pollutant approaching the saline water area, the profile of the pollutant migration is gradually developed into a spindle shape until the strip shape, and the pollutant enters the saline water body along the curved edge of the upper part of the saline water. The transverse dispersion of pollutants is larger than the longitudinal dispersion in a tidal cycle and its outline presents a strip shape development. No mixing or exchange between the pollutants and the saline water body happened during the whole process. This study can provide scientific references for nearshore groundwater pollution prevention and control in the future.     

Ecotoxicological Assessment of Chemical Fumigants Utilising an Earthworm (<Emphasis Type="Italic">Eisenia andrei</Emphasis>) Bioassay and Soil Microbial Communities

Fumigation is an important crop protection practice employed to control soil pathogens and diseases. Metham sodium and cadusafos are two commonly used soil fumigants for this purpose. However, little information is available on their effects on non-target soil organisms. The aim of the study was to determine the ecotoxicity of these chemical fumigants on earthworms (organismal responses and DNA damage) and soil microbial communities. Changes in soil microbial community function and structure were evaluated by means of Biolog? Ecoplates and phospholipid fatty acid (PLFA) analyses, respectively. Both fumigants had a significant (p < 0.05) negative impact on all earthworm endpoints. Earthworms did not reproduce; biomass was affected negatively and manifested significant DNA damage with metham sodium causing more pronounced effects in comparison to cadusafos. The fumigants had an inhibitory effect on microbial growth. No lasting effects were observed in the community structure but cadusafos had a pronounced effect on the microbial community functional diversity. Metham sodium and cadusafos had varying effects on earthworm and microbial endpoints. This illustrates the importance of using different bioindicators to get a better understanding of the overall effects on the soil ecosystem.     

Radioactivity of Selected Agricultural Soils in Croatia: Effects of Soil Properties,Soil Management,and Geological Parameters

We present a study on the radioactivity of selected Croatian agricultural soils that vary considerably with respect to geological background; physical, chemical, and biological characteristics; soil type; land use; and soil management. Our investigation is focused on the main naturally occurring radionuclides (⁴⁰K, ²³⁸U, ²²⁶Ra, ²³²Th, ²³⁵U) and ¹³⁷Cs as the most threatening long-lived anthropogenic radionuclide. We find that the radioactivity level is not influenced by the application of different soil amendments, at least in moderate quantities, and that no effect of soil management can be detected as well. In contrast, geological and location-specific properties influence radionuclide content in soil, especially regarding the naturally occurring ones. Moreover, physical and chemical soil properties such as texture and soil adsorption complex, respectively, seem to be the main factors regarding fixation of ¹³⁷Cs in soil. Calculated dose rates for external exposure to the gamma radiation originating from soil have been found to be generally low, except for two locations where they are higher but not at a level that would lead to health problems for workers on the field.     

Comparison of Iodide and Iodate Accumulation and Volatilization by Filamentous Fungi during Static Cultivation

Five common fungal strains, Cladosporium cladosporioides, Aspergillus clavatus, Penicillium citrinum, Fusarium oxysporum, and Alternaria alternata, were cultivated in presence of iodide and iodate to evaluate their efficiency in iodine biovolatilization and bioaccumulation. Our results suggest that iodide and iodate bioaccumulation by microscopic filamentous fungi is similar although the biological transformation into volatile iodine compounds is driven by various pathways resulting in higher volatilization efficiency of iodate. Thus, the mobilization of iodate by filamentous fungi is superior to iodide mobilization. Our paper is also the first to compare the iodide and iodate volatilization efficiency by microorganisms. Our results highlight the significant role of filamentous fungi in biogeochemistry of iodine, especially in formation of environmentally reactive volatile forms that may contribute to ozone layer destruction.     

Multitrophic Assessment of Copper Contamination Using Watercress (<Emphasis Type="Italic">Nasturtium officinale</Emphasis>) and the Mustard Beetle (<Emphasis Type="Italic">Phaedon viridis</Emphasis><Emphasis Type="Bold">)</Emphasis>

Copper is an active component of some commercial algaecides and is commonly found in low concentrations in contaminated aquatic systems. Unintended consequences of algaecide application include macrophyte bioaccumulation and possible trophic level bioamplification especially by specialist herbivores. Trophic level effects of copper contamination were observed through feeding trials using the mustard beetle (Phaedon viridis). Several metals, including copper, interfere with the myrosinase enzyme system responsible for the watercress (Nasturtium officinale) allelopathic defense against herbivory. The mustard beetle is a specialist herbivore that has evolved a detection system that is stimulated by the products of the glucosinolate-myrosinase system. Because copper interferes with myrosinase enzymes, mustard beetles were expected to avoid copper-contaminated plants. While larvae exhibited a slight preference for contaminated plants, adult mustard beetles in this experiment exhibited a statistically significant preference for plants uncontaminated with copper.     

Trials of Treating Decentralized Domestic Sewage from a Residential Area by Potassium Ferrate(VI)

The present study aims to investigate the performance of potassium ferrate(VI) in treating decentralized domestic sewage from a rural scattered residential area. Major results were that around 90% of total phosphorus (TP) and 40% of chemical oxygen demand (COD) could be reduced when 25 mg L^?1 of ferrate(VI) was applied. The removal of ammonia and total nitrogen (NH₃–N and TN) was also monitored. However, the nitrogen removal during the chemical dosing was rather low. Big fluctuations of removal rates were observed against shock pollutants concentrations. Considering its strong ability in removing emerging organic pollutants and P, ferrate(VI) is competitive in the treatment of decentralized domestic sewage as an advanced treatment unit following some traditional treatment units.     

Response of Winter Manure Application on Surface Runoff Water Quantity and Quality from Small Watersheds in South Dakota

Manure application on frozen soil, which is a common practice in the upper Midwest of USA, results in degraded soil and water quality. During snowmelt or precipitation events, water runoff carries nutrients into nearby streams and impairs the water quality. There is a need, therefore, to identify improved management of manure application in the soils. This study was conducted to assess water quality impacts associated following manure application during winter months when soil is completely covered with snow. The study site included three watersheds, named south (SW), east (CW), and north (NW) managed with a corn (Zea mays L.)-soybean (Glycine max L.) rotation located in South Dakota. The SW and NW were used as treatment, and CW as the control watershed. The treatments included manure application on the upper half of the SW and lower half of the NW, and CW received no manure application. This study showed that manure improved soil properties including infiltration rate and organic matter. Nitrogen and phosphorus losses in the surface runoff were higher from NW compared to that of SW. The CW had similar nutrient losses compared to the NW with slight differences. It can be concluded that maintaining a setback distance can help in improving the environmental quality as well as managing the agricultural wastes during the winter months.