In this study, graphene-based adsorbent was successfully prepared following a thermal treatment method. The prepared material, named as graphene-coated sand (GCS), was used as an adsorbent for the removal of Hg(II) ions from aqueous solutions. Structure, composition, and morphology of the GCS were characterized by Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), X-ray diffractometer (XRD), Raman spectroscopy, electron diffraction (ED) measurements, energy dispersive X-ray spectroscopy (EDX), surface area measurements, particle size, and zeta potential measurements, respectively. A batch adsorption method was used to assess the ability of GCS towards removal of Hg(II) ions from aqueous solutions. The results of batch studies revealed that the GCS required a pH value 6.0, contact time 120 min, and adsorbent dose of 200 mg to attain adsorption equilibrium. Langmuir, Freundlich, Temkin, and D-R adsorption isotherm models were employed to evaluate the isotherm constants and other parameters related to the adsorption process. The Hg(II) ions uptake by the GCS was found to follow Freundlich isotherm model with R ² value of 0.97695, under optimized conditions and at 40 °C with a maximum adsorption capacity of 299.40 mg/g. The adsorption process followed the second-order kinetic path. The thermodynamic parameters such as ΔH°, ΔS°, and ΔG° were also calculated which suggested that the adsorption processes of Hg(II) ions onto the GCS was endothermic and entropy favored. The values of ΔG° at 283, 303, and 313 K were − 1.10, − 0.025, and − 4.55 kJ, respectively, and ΔH°, ΔS° were calculated to be 26.60 kJ mol⁻¹ and ΔS° 1.35 J mol⁻¹ K⁻¹, respectively. The obtained results revealed that the prepared materials could be effectively and economically beneficial.

A unique test chamber system, which enables experiments with plants under highly controlled environmental conditions, was used to examine the pollutant removal efficiency of plants. For this purpose, the removal of two different volatile organic compounds (VOC) (toluene, 2-ethylhexanol) from the air by aerial plant parts of two common indoor plant species (Dieffenbachia maculata and Spathiphyllum wallisii) was monitored. While the control over environmental conditions (temperature, relative humidity, CO₂ content, and light condition) worked very well in all experiments, control experiments with the empty chamber revealed high losses of VOC, especially 2-ethylhexanol, over the test duration of 48 h. Nonetheless, compared to the empty chamber, a significantly stronger and more rapid decline in the toluene as well as in the 2-ethylhexanol concentrations was observed when plants were present in the chamber. Interestingly, almost the same VOC removal as by aerial plant parts could be achieved by potting soil without plants. A comparative literature survey revealed substantial heterogeneity in previous results concerning the VOC removal efficiency of plants. This can be mainly attributed to a high diversity in experimental setup. The experimental setup used in the current study offers an excellent opportunity to examine also plant physiological responses to pollutant exposure (or other stressors) under highly controlled conditions. For the analysis of VOC removal under typical indoor conditions, to obtain data for the assessment of realistic VOC removal efficiencies by plants in rooms and offices, a guideline would be helpful to achieve more coherent findings in this field of research.

In this investigation, the photocatalytic activity of α-Bi₄V₂O₁₁ in the degradation of 2-naphthol under simulated solar light was evaluated. Bismuth vanadate α-Bi₄V₂O₁₁ was synthesized by the solid-state reaction method and by co-precipitation in aqueous media, with the aim of comparing their performance in the photodegradation of the aromatic pollutant. The latter method (co-precipitation) has not been previously reported for the synthesis of α-Bi₄V₂O₁₁. Structural evolution of the oxides precursors was determined by X-ray diffraction. Morphology and optical properties of the solids were analyzed by scanning electron microscopy (SEM) and UV-vis diffuse reflectance spectroscopy (UV-vis), respectively. The results showed that at 800 °C, only α-Bi₄V₂O₁₁ was formed in both preparations. The SEM micrographs revealed that the powders were composed of agglomerates with sizes between 0.8–2 μm for those synthesized by co-precipitation and 2–10 μm for those obtained by solid-state reaction. The optical properties indicated that α-Bi₄V₂O₁₁ was activated with visible light during the photocatalytic process. The photocatalytic degradation of 2-naphthol was largely influenced at basic pH, degrading 79% of the contaminant in 240 min, with the powder obtained by co-precipitation; meanwhile, for the solid-state preparation, the degradation reached only 55%.

The construction materials industry faces major challenges since 2013 when the European Construction Products Regulation was implemented, especially in the sector of environmentally friendly construction products. This study determined concentrations of leachable inorganic and organic compounds from microfine cement paste with and without superplasticiser addition. Furthermore, the leached superplasticiser amounts were detected via LC-MS. The multi-method approach was supplemented by ecotoxicological assays. Phytotoxicity was tested with white mustard (Sinapis alba) and cress (Lepidium sativum). The mutagenic and genotoxic potential of the leachates was tested with the Ames fluctuation assay and the umuC assay. As leaching protocol, the European horizontal dynamic surface leaching test was used. The cement paste samples with superplasticiser followed the wash-off effect with a total organic carbon release up to 43 mmol/m², whereas the release of samples without superplasticiser was driven by diffusion. The ecotoxicological assays showed a clear time depending behaviour. No cytotoxicity and mutagenicity could be observed; anyhow some leachates show minor genotoxic potential. In all tests, a clear difference between the samples with and without superplasticiser could be detected.This study clearly demonstrates the importance of further studies in the field of leaching of construction products.

Ecological remediation is one of the most practical methods for removing nutrients from river ecosystems. In this study, transformation and fate of nitrate and ammonium among four different ecological restoration treatments were investigated by stable ¹⁵N isotope pairing technique combined with quantitative polymerase chain reaction and high-throughput sequencing technology. The results of ¹⁵N mass-balance model showed that there were three ways to the fate of nitrogen: precipitated in the sediment, absorbed by Elodea nuttallii (E. nuttallii), and consumed by microbial processes (denitrification and anaerobic ammonium oxidation (anammox)). The results shown that the storage of ¹⁵NH₄ ⁺ in sediments was about 1.5 times as much as that of ¹⁵NO₃ ⁻. And much more ¹⁵NH₄ ⁺ was assimilated by E. nuttallii, about 2 times as much as ¹⁵NO₃ ⁻. Contrarily, the rate of microbial consuming ¹⁵NO₃ ⁻ was higher than converting ¹⁵NH₄ ⁺. As for the group with ¹⁵NO₃ ⁻ added, 29.61, 45.26, 30.66, and 51.95 % were accounted for ¹⁵N-labeled gas emission. The proportions of ¹⁵NH₄ ⁺ loss as ¹⁵N-labeled gas were 16.06, 28.86, 16.93, and 33.09 % in four different treatments, respectively. Denitrification and anammox were the bacterial primary processes in N₂ and N₂O production. The abundances of denitrifying and anammox functional genes were relatively higher in the treatment with E. nuttallii-immobilized nitrogen cycling bacteria (E-INCB) assemblage technology applied. Besides, microbial diversity increased in the treatment with E. nuttallii and INCB added. The ¹⁵NO₃ ⁻ removal rates were 35.27, 49.42, 50.02, and 65.46 % in four different treatments. And the removal rates of ¹⁵NH₄ ⁺ were 24, 34.38, 48.84, and 57.74 % in treatments A, B, C, and D, respectively. The results indicated that E-INCB assemblage technology could significantly promote the nitrogen cycling and improve nitrogen removal efficiency.

A standard method for the detection and isolation of microplastics is required to adequately investigate plastic ingestion by juvenile fish. Dissections of juvenile fish guts require precise handling, which can affect the processing time if sample numbers are high. To investigate the efficacy of nitric acid (HNO₃) in aiding the isolation of microplastics using whole fish, we digested juvenile glassfish, Ambassis dussumieri (Cuvier, 1828), at room temperature and at 80 °C. For a complete digestion, overnight incubation in 10 mL of 55% analytical-reagent (AR) HNO₃ was sufficient for a whole fish of 1 g at room temperature. When coupled with elevated temperature, the digestion time is shortened to a few minutes and larger fish of 3 g can be digested in 30 min. Four of the five types of plastic survived the process, with nylon being the exception. This is a shortfall to the method; however, until a better method replaces it, we still value the use of HNO₃ for its simple, inexpensive, swift and complete digestions of whole fish. Four fish species from two feeding guilds were digested using this method to validate its use. The number of plastic particles ingested did not differ between benthic and pelagic species and microplastic fibres comprised the majority of the plastic types found.

This study aimed to quantify the water balance components at a grassland and a forest site representative of the Atlantic Forest biome in southern Brazil using drainage lysimeters. Since it was not possible to place mature trees on the forest lysimeter, it was planted with young trees and understory vegetation. Data from this lysimeter and computations with the water balance and the Penman-Monteith equation were then used to assess the values of the water balance components for the mature forest.Total precipitation during the study period was 2308 mm. In the forest environment, 46% thereof was intercepted by the canopy from where it later evaporated. Hence, much less rain reached the ground than under grassland. Runoff from both sites was <1% of precipitation and therefore not a significant factor in the water balance. Cumulative drainage amounted to 1136 mm from grassland: from the mature forest, it was estimated to be 389 mm. There were two reasons for this low value under forest: Interception prevented a lot of water from reaching the ground, and the actual evapotranspiration from the mature forest was much higher than from grassland (1231 mm compared to 1964 mm).

Inter-basin water transfer and source water switching will be increasingly launched due to significant population increase and the shortage of the local water resources in cities around the world. Source water switch may cause physiochemical and microbiological de-stabilization of pipe material, biofilms, and loose deposits in drinking water distribution system (DWDS). Great sulfate alteration during source water switch had been deemed as the main cause of a red water case that occurred in a northern China city. To ascertain the relationship between water quality changing and bacterial communities of biofilms in DWDS and possible bacteria risk in a red water case, water quality changing experiments in simulated DWDSs were conducted for approximately 2 years. Twenty-five corrosion scale samples and eight water samples collected from pipe harvest sites or during experimental periods were analyzed for their bacterial community composition by 454-pyrosequencing technology. Taxonomy results together with redundancy analysis (RDA) or canonical correspondence analysis (CCA) and hierarchical cluster analysis all indicated that bacterial community of samples with groundwater (GW) or surface water (SW) supply history and their variations under high sulfate water were rather different owing to different water source histories and the original pipe scale characteristics. Potential opportunistic pathogens: Burkholderia, Escherichia-Shigella, Mycobacterium, Serratia, Ralstonia, Novosphingobium, Flavobacterium, Sphingomonas, and Sphingopyxis were observed in scale or water samples.

The mechanisms by which complex products released from the organic matrix of cattle manure impact phosphorus (P) behavior and transport are largely undefined. Effects of a dairy slurry isolate on sorption characteristics of three benchmark soils and the breakthrough of phytate-P were determined in short soil columns of Mattapex loam (fine-silty, mixed, active, mesic Aquic Hapludults) under saturated flow conditions. The manure liquid isolate was obtained after a 7-day incubation of reconstituted dairy manure (1.6:1, feces-to-urine) at 37 °C and centrifugation at 16,000×g. The liquid isolate, at dilutions of 20:1 to 4:1 water-to-isolate, decreased soil sorption of phytate-P, with reduction in logₑ K averaging 30%. Whether the influent contained artificial rainwater or the manure isolate at a water-to-isolate ratio of 20:1, P retention and breakthrough curves were differentially impacted. Only inorganic phosphate-P was eluted in a multiple-stage process, and breakthrough occurred after 16 pore volumes of rainwater. Both inorganic- and enzyme-labile P (TBIOP) appeared in the effluent when either a dilute solution of 0.05 M EDTA (ethylenediamine-N, N, N′, N′-tetraacetate) or one containing 5% of manure liquid isolate was used as influent. The polydentate ligand-like substances reduced (i) the soil’s affinity for phytate and (ii) the hydrolysis rate in soil, allowing phytate to be eluted. Therefore, dissolved components of the manure matrix played critical roles in controlling transport and dispersion of phytate-derived P forms in soil and may hold the key to the understanding of biogeochemical bases of persistent effects of legacy P in agricultural watersheds.

Microbial fuel cell (MFC) is a sustainable technology to treat cattle manure slurry (CMS) for converting chemical energy to bioelectricity. In this work, two types of allochthonous inoculum including activated sludge (AS) and domestic sewage (DS) were added into the MFC systems to enhance anode biofilm formation and electricity generation. Results indicated that MFCs (AS + CMS) obtained the maximum electricity output with voltage approaching 577 ± 7 mV (~ 196 h), followed by MFCs (DS + CMS) (520 ± 21 mV, ~ 236 h) and then MFCs with autochthonous inoculum (429 ± 62 mV, ~ 263.5 h). Though the raw cattle manure slurry (RCMS) could facilitate electricity production in MFCs, the addition of allochthonous inoculum (AS/DS) significantly reduced the startup time and enhanced the output voltage. Moreover, the maximum power (1.259 ± 0.015 W/m²) and the highest COD removal (84.72 ± 0.48%) were obtained in MFCs (AS + CMS). With regard to microbial community, Illumina HiSeq of the 16S rRNA gene was employed in this work and the exoelectrogens (Geobacter and Shewanella) were identified as the dominant members on all anode biofilms in MFCs. For anode microbial diversity, the MFCs (AS + CMS) outperformed MFCs (DS + CMS) and MFCs (RCMS), allowing the occurrence of the fermentative (e.g., Bacteroides) and nitrogen fixation bacteria (e.g., Azoarcus and Sterolibacterium) which enabled the efficient degradation of the slurry. This study provided a feasible strategy to analyze the anode biofilm formation by adding allochthonous inoculum and some implications for quick startup of MFC reactors for CMS treatment.