Titania/silica nanomaterials have many possible applications; however, they can be toxic to living organisms, particularly if the material accumulates in niche environments, e.g. areas colonised by actinomycetes. This study therefore investigated the effect of non-activated and UV light-activated titania/silica nanospheres on an environmental Streptomyces strain. The bacteria were incubated with the nanospheres and subsequently cultured on solid medium. The morphology and elemental composition were analysed using optical and electron microscopy (TEM, STEM) and energy-dispersive X-ray spectroscopy (EDX). The appearance of Streptomyces sp. in the experimental and control samples demonstrated that the nanospheres did not have bactericidal properties in the used dose. Furthermore, the observed strain not only survived in the presence of the nanomaterial but also appeared to play a role in its dissolution with an accumulation of the titanium in the intracellular globules of polyphosphate (volutin). Additionally, it was discovered that the UV light-activated titanium dioxide altered the ability of the bacteria to secrete humic acid. The reported phenomenon might be made possible through an accumulation of titanium in the volutin compounds. These findings suggest that streptomycetes could be employed to participate in the dissolution of nanomaterials which enter the natural environment.

As concentrations of greenhouse gases (GHG: N₂O, CO₂, CH₄) continue to increase in the earth’s atmosphere, there is a need to further quantify the contribution of natural systems to atmospheric GHG concentrations. Within this context, characterizing GHG contributions of riparian zones following storms events is especially important. This study documents soil GHG effluxes in a North Carolina riparian zone in the days following both a natural 2.5-cm precipitation event, and that same event associated with the addition of 8.7 cm artificial rainwater in select static chambers. No significant differences in CO₂, CH₄, and N₂O fluxes in response to increased moisture were observed between a depression, a sand bar, and an upland forested area. However, in this water-limited riparian zone, less negative CH₄ fluxes (i.e., methane oxidation decreased) and higher CO₂ fluxes (i.e., aerobic respiration increased) were observed following precipitation. A short-term burst in N₂O emission was observed in the hours after precipitation occurred, but elevated N₂O emissions did not persist long enough to turn the site from the N₂O sink to a N₂O source in the 3 days following the beginning of the experiment. Our results are in contrast with riparian GHG studies in wetter environments and illustrate the importance of water limitation in regulating riparian soil response to precipitation with respect to GHG emissions. More studies should be conducted in water-limited environments (e.g., US southeast/southwest) before management strategies commonly applied in wetter environments (e.g., US Northeast/Midwest) are applied in these regions.

Zeolitic imidazole frameworks (ZIFs), a new adsorbent with a high chemical and thermal stability and a high adsorption capacity, are used for adsorptive removal of azo dyes. The synthesized ZIF-67 was characterized with Fourier transform infrared spectroscopy (FTIR), thermogravimetric–differential thermal analysis (TG–DTA) and zeta potential instrument. The adsorption of some azo dyes on ZIF-67 in the single dye systems showed that the removal efficiencies are congo red > methyl orange > methyl red > methyl blue. The highest adsorption capacity of congo red and methyl orange were 3900 and 1340 mg/g, respectively. In a binary dye system the adsorption capacity of congo red decreased, while the removal efficiency of methyl orange increased in comparison with the single systems, indicating that a competitive adsorption of congo red and methyl orange over the ZIF-67 occurred. The experimental data indicate that the electrostatic attraction between ZIF-67 and congo red is the major driving force and the π–π stacking is also responsible for dye adsorption. After 5 cycles of ZIF-67 adsorption and desorption, the congo red removal efficiency maintained more than 95%. Graphical Abstract The adsorption of Congo red and Methyl orange on the ZIF-67

Long-term irrigation with recycled water (RW) that contains high salt may pollute groundwater. The HYDRUS-1D model was texted against soil water content and electrical conductivity (ECe) observed in a summer maize and winter wheat rotational field irrigated with ground water (GW) and RW; then, the risk for polluting groundwater in two regions of Beijing was evaluated. The comparisons indicated that the simulated soil water content and ECe values were generally in agreement with the field observations, indicating the reliability of HYDRUS-1D in soils irrigated with GW and RW. The regional prediction results of the proposed simulation model indicated that the average soil ECe at the bottom of vadose zones ranged from 0.400 to 0.896 dS m⁻¹, and the values in the Tongzhou and Daxing Districts irrigated with RW were 1.40 and 1.09 times, respectively, higher than that irrigated with GW over the next 50 years. Five risk indicators represent salt transporting time and values were used. The results of the proposed evaluation model showed that the risk scores ranged from 3.04 to 9.32. In the Tongzhou and Daxing Districts, the risk scores of RW irrigation for polluting groundwater were 1.06 and 1.08 times, respectively, higher than that GW irrigation. The risk scores of GW or RW irrigation for polluting groundwater in the Tongzhou District were 1.75 or 1.72 times, respectively, higher than that in the Daxing District. Considering the small risk difference between GW and RW irrigations, RW can be used in both regions. Due to the different vadose zone structures, the Daxing District is more suitable for RW irrigation. The long-term use of RW for irrigation should consider the salt content of RW and vadose zone structure.

Ammonia (NH₃) volatilization is one of the main pathways of N loss from farmland soil. Saline water irrigation can have direct or indirect effects on soil NH₃ volatilization, N leaching, and crop N uptake. This study was conducted to evaluate the effects of irrigation water salinity and urea-N application rate on NH₃ volatilization and N use efficiency in a drip-irrigated cotton field. The experiment consisted of three levels of irrigation water salinity: fresh water, brackish water, and saline water (electrical conductivities of 0.35, 4.61, and 8.04 dS/m, respectively). The N application rates were 0, 240, 360, and 480 kg/ha. The results showed that soil salinity and soil moisture content were significantly higher in the saline water treatment than in either the fresh or brackish water treatments. Irrigation water salinity significantly increased soil NH₄-N concentration, but NO₃-N concentration decreased as water salinity increased. The amount of N leaching varied from 5.0 to 25.5 kg/ha, accounting for 1.81 to 4.79 % of the urea-N applied under different water salinity and N application rate treatments. Both the amount of N leaching and the proportions of applied N lost through leaching significantly increased as water salinity increased. N application increased the amounts of N leaching, but the ratios of applied N were not affected by N application rate. Soil NH₃ volatilization increased rapidly after urea fertigation, and peaked at 1–2 days after N application, then decreased rapidly. The amount of NH₃ volatilization varied from 9.0 to 33.7 kg/ha, accounting for 3.2 to 3.8 % of the N applied in all treatments. Soil NH₃ volatilization was significantly higher in the saline water treatment than that in either the fresh or the brackish water treatments. Cotton N uptake increased significantly as N application rate increased, but decreased with irrigation water salinity increased. In conclusion, saline water irrigation with high N application rate induced high N leaching and NH₃ volatilization losses, thereby dramatically reducing the apparent N recovery (ANR) of cotton.

The use of poultry waste (without proper treatment) as a potential fertilizer in agricultural soils have great concern to environment and human health, due to high levels of organic and inorganic toxicants, including heavy metals. Thus, the aim of this study was to monitor and assess bio-accumulation of heavy metals, cadmium (Cd), copper (Cu), Iron (Fe), lead (Pb), and zinc (Zn) contained in soil amended with poultry waste (SPW) and compared with controls. The physico-chemical parameters and heavy metal concentration in control soil (CS), poultry waste (PW), and SPW samples was also determined. The comparison study between the test vegetables and controls showed that the concentrations of Cd, Cu, Fe, Pb, and Zn in edible parts of chili pepper were found to be 0.057, 38.0, 61.9, 1.02, and 51.1 mg kg⁻¹, respectively, while the levels of Cd, Cu, Fe, Pb, and Zn were 0.14, 28.7, 138, 3.67, and 64.7 mg kg⁻¹, respectively, in coriander grown on SPW. The uptakes of heavy metals in test vegetables were found to be 35.7 to 95.6 % higher as compared with control vegetables. Soil-to-vegetable transfer factor values for all heavy metals in test samples were higher than control samples (p < 0.05). The enrichment factor values were >1.05, which indicated that the source of heavy metal contamination in the studied area was anthropogenic. Graphical Abstract Fate of heavy metals from poultry manure to agricultural soil

The Cumberland Marsh Region (CMR), located on the coast of the Bay of Fundy, is a major feeding ground for waterfowl and contains significant coastal wetland systems. In this study, concentrations of lead (Pb) and arsenic (As) were assessed in the bottom sediments of various open water wetlands across the CMR, and gastropods were sampled from the same wetlands to assess bioaccumulation of these non-essential trace elements and the potential for transfer to higher trophic level species. It was predicted that gastropods would have higher concentrations of Pb and As from wetlands with higher concentrations of these elements in sediments. Although wetland sediments and gastropods had elevated Pb and As concentrations, in some cases above the Canadian Sediment Quality Guidelines for the protection of aquatic life, there were no significant correlations between sediment and gastropod trace element concentrations. Gastropod to sediment ratios of Pb and As concentrations were highest in the brackish wetlands, but overall, levels were not of toxicological concern. Wetland chemistries and gastropod physiologies are hypothesized to be driving factors in determining the level to which Pb and As will bioaccumulate and merit careful consideration when developing wetland management strategies.

The Tagus Estuary is one of the most Hg-contaminated estuaries in SW Europe. Sediment cores were sampled at two low Hg-contaminated sites inside the natural park, Alcochete (ALC) and Vale Frades (VF), and analyzed for mercury and methylmercury. Concentrations of Hg and MeHg in sediments were below 1 μg g⁻¹ and 4.4 ng g⁻¹, respectively. While in summer organic matter and/or excess SO₄ ²⁻ promotes Hg methylation, in winter, Hg availability is the sole driver for methylation. Diffusive fluxes in the sediment/water interface show a sink of Hg species in the ALC site (ca. 170 mg year⁻¹ of Hg and 60 mg year⁻¹ of MeHg), while in the VF area, a sink of MeHg (ca. 1900 mg year⁻¹) as well as a source of Hg (ca. 2000 mg year⁻¹) is observed. The morphology and hydrodynamic regime of the Tagus Estuary seem to influence Hg dynamics even in areas with low levels of Hg contamination.

The present work investigates the potential of two experimental field columns (FC-2 and FC-4) to reduce volatile organic compound (VOC) emissions from a municipal solid waste (MSW) landfill located in Quebec, Canada. The FC-2 and FC-4 were fed by raw biogas coming from the landfill site. The VOC were identified and quantified in emitted biogas and raw biogas. The emitted biogas was collected at the surface of FC-2 and FC-4, and the raw biogas was obtained directly from the well. The main groups of the VOC in the landfill biogas are BTEX (66 %), alkanes (19 %), cyclic compounds (10 %), and halogenated compounds (5 %). The concentration of VOC in the landfill raw biogas varies from below the limit of detection (BLD) to 22 ppmv, and that of the emitted biogas varies from BLD to 3.1 ppmv. The result of this study showed that the experimental field columns had a very high potential to reduce the VOC emissions from the investigated landfill. The effectiveness of the VOC emission removal for the FC-2 and FC-4 was shown to be practically 100 % for many compounds. The experimental field column elimination capacity of VOC emissions is in the range of 0.1 to 4.6 mg m⁻³ h⁻¹.