Urea is considered as the most widely used nitrogen (N) fertilizer. Unfortunately, its application is associated with losses such as emissions of ammonia (NH₃) and nitrous oxide (N₂O) in a gas form. In addition to the economic loss, such N losses may threaten atmospheric quality. Application of both urease and nitrification inhibitors is advocated as an approach to mitigate these gaseous losses. Thus, laboratory studies were carried out to evaluate the effects of urease inhibitor-coated urea, nitrification inhibitor-coated urea, and other modified urea fertilizers on NH₃ volatilization and N₂O gas emissions in selected anaerobic rice soils. Copper (Cu) and Zinc (Zn) were selected as urease inhibitors and DMPP (3,4-dimethylpyrazole phosphate) as nitrification inhibitor. Nitrogen fertilizer treatments used were urea, Cu-coated urea (CuU), Zn-coated urea (ZnU), Cu + Zn-coated urea (CuZn), DMPP-coated urea (DMPPU), DMPP + Cu + Zn-coated urea (DMPPCuZn), OneBaja, sulfur-coated urea (SU), and dolomite-coated urea (DU). Results demonstrated that CuU, ZnU, DMPPCuZn, SU, and OneBaja were effective in reducing NH₃ volatilization by 12.12–37.48 % compared to urea, while DMPPU had no effect on NH₃ volatilization. Meanwhile, sulfur-coated urea (SU), CuU, ZnU, CuZn, OneBaja, DMPPU, and DMPPCuZn reduced N₂O emission over urea by 14.86, 17.57, 21.62, 29.73, 29.73, 33.78, and 48.64 %, respectively. These results suggest that using Cu, Zn, or combinations of DMPP, Cu, and Zn is recommended as an alternative to mitigate both NH₃ volatilization and N₂O emission, in addition to providing positive impact to environment.

From 2010 to 2012, the Yangtze River and Hanjiang River (Wuhan section) were monitored for estrogenic activities during various water level periods. Using a recombinant yeast estrogen screen (YES) assay, 54 water samples were evaluated over the course of nine sampling campaigns. The mean 17β-estradiol equivalent (EEQ) value of raw water from the Yangtze River was 0–5.20 ng/L; and the EEQ level from the Hanjiang River was 0–3.22 ng/L. In Wuhan, drinking water treatment plants (DWTPs) using conventional treatments reduced estrogenic activities by more than 89 %. In general, water samples collected during the level period showed weaker estrogenic activities compared to those collected during the dry period. The samples collected in 2010 showed the strongest estrogenic activities of the 3-year period. The lack of correlations between estrogenic activities and selected common water quality parameters showed that estrogenic activity cannot be tied to common water quality parameters.

Tropical forests play an important role in carbon cycle. However, the temporal and spatial variation in soil carbon dioxide (CO₂) emission of tropical forest remains uncertain, especially near the Tropic of Cancer. In this research, we studied the annual soil CO₂ fluxes from three tropical montane rainforests on the Hainan Island of China (pristine montane rainforest, PF; secondary montane rainforest, SF; and Podocarpus imbricatus plantation, PP). The results showed a lower annual average soil CO₂ flux as 6.85 ± 0.52 Mg C-CO₂ ha⁻¹ (9.17 Mg C-CO₂ ha⁻¹ in the wet season and 4.50 Mg C-CO₂ ha⁻¹ in the dry season). The CO₂ fluxes exhibited obviously seasonal variation during the study period. Among the three forest types, PF had the highest average CO₂ flux rate of 317.77 ± 147.71 mg CO₂ m⁻² h⁻¹ (433.08 mg CO₂ m⁻² h⁻¹ in the wet season and 202.47 mg CO₂ m⁻² h⁻¹ in the dry season), followed by PP of 286.84 ± 137.48 mg CO₂ m⁻² h⁻¹ (367.12 mg CO₂ m⁻² h⁻¹ in the wet season and 206.56 mg CO₂ m⁻² h⁻¹ in the dry season) and SF of 255.09 ± 155.26 mg CO₂ m⁻² h⁻¹ (351.48 mg CO₂ m⁻² h⁻¹ in the wet season and 155.71 mg CO₂ m⁻² h⁻¹ in the dry season). We found between CO₂ fluxes and soil temperature a highly significant linear relation (P < 0.01) at 5 cm depth and a highly significant exponential correlation (P < 0.01) at 10 cm depth for all three forest types; a significant linear relation (P < 0.05) between CO₂ fluxes and soil moisture content was found for SF and PF, but not for PP (P > 0.05). The CO₂ flux was significantly correlated (P < 0.05) with water-filled pore space only for PF. In conclusion, our results suggested soil CO₂ fluxes in the three forest types that exhibit obviously spatial and temporal variation, and the temperature is the major factor affecting soil CO₂ fluxes from this region.

TiO₂-graphene (TiO₂-GR) composites were successfully prepared by a two-step solvothermal method using titanium dioxide and natural graphite powder. X-ray diffraction (XRD) patterns showed that graphene oxide (GO) was prepared from natural flake graphite by a modified hydrothermal pressurized oxidation method. The results of Fourier transform infrared spectroscopy (FTIR) proved that TiO₂-GR composites were synthesized during the process of hydrothermal reaction while GO was changed into graphene. X-ray photoelectron spectroscopy (XPS) demonstrated that TiO₂ particles contacted closely with graphene via Ti–O–C bonds. The results of Raman spectra confirmed the existence of graphene in the TiO₂-GR composite. Scanning electron microscopy (SEM) images showed that TiO₂ particles were oval and grafted on the graphene sheet which was smooth with ripples. UV-visible diffuse reflectance spectra demonstrated that there was a red shift in the absorption edge of TiO₂-GR composite. The experimental results indicated that the TiO₂-GR composite had significantly adsorption-photocatalytic activity for the degradation of methylene blue (MB) dyes. The adsorption capacity (q ₘₐₓ) of TiO₂-6%GR-4h for MB was 41.32 mg ⋅ g⁻ ¹ calculated based on the Langmuir adsorption model, which was about 3.3 times the adsorption capacity of TiO₂. Adsorption kinetics studies showed that the adsorption process fit well with the pseudo-second-order model. It proved that the TiO₂-GR composites were more efficient than the pure TiO₂ in the field of environmental protection.

As increased greenhouse gas concentrations (GHG: N₂O, CO₂, CH₄) in our atmosphere remain a major concern, better quantifying GHG fluxes from natural systems is essential. In this study, we investigate GHG concentrations in saturated riparian sediments (dry, wet, mucky), streambed hyporheic zone sediments (pools, riffles), and stream water in a New York mountain stream for summer baseflow conditions, and attempt to identify the primary drivers (e.g., DO, DOC, NO₃⁻, and NH₄⁺, temp) of GHG concentrations at these locations. Although DO, DOC, NO₃⁻, and NH₄⁺ concentration patterns certainly explained some of the observed trends, the overall differences in GHG abundance in riparian water vs. hyporheic pool water vs. hyporheic riffle water strongly suggest that water velocity/mixing with the atmosphere is a key control on GHG concentration across locations. When all floodplain locations are considered, in-stream pools are hot spots of CO₂ and CH₄ concentrations relative to other in-stream locations. On the other hand, riparian areas are hot spots of CH₄ and CO₂ concentrations relative to stream locations. No clear patterns are observed for N₂O.

Herbaspirillum chlorophenolicum strain FA1, a gram-negative bacterium isolated from activated sludge, was found to be able to use pyrene as sole carbon and energy sources. During biodegradation, the contribution of biosorption to the whole pyrene removal mattered in the early reaction stage, and biodegradation was the predominant process. Pyrene biodegradation was significantly enhanced with the presence of a typical carboxylated aromatic metabolite (phthalic acid) at concentrations of 30–50 mg l⁻¹, and the metabolite itself could also be efficiently biodegraded. For the purpose of practical application, immobilization of strain FA1 was carried out, and polyvinyl alcohol (PVA)-diatomite carrier by chemical method was proved to be the most efficient, with a PYR biodegradation of 92.8 % in 10 days. Investigation on the pyrene biodegradation kinetics by both free and immobilized cells showed that the experimental data fitted well to the first-order kinetic model. Besides, the PVA-diatomite carrier (chemical method) could be reused in at least eight consecutive biodegradation processes of PYR without any significant decrease in biodegradation efficiency. Further storage stability tests revealed that the ability to degrade pyrene using immobilized cells remained stable after storage at 4 °C for 45 days. Moreover, strain FA1 exhibited a relative broad substrate profile, including naphthalene, fluorene, phenanthrene, anthracene, fluoranthene, benzo[b]fluoranthene, benzene, toluene, and Tween 80. Taken together, results indicate that strain FA1 might be high potential in the development of treatment technologies for PAHs contamination.

Selenium (Se) has long been known as an effective antagonist for counteracting mercury (Hg) and arsenic (As) toxicity in many animal and plant species. This study is the first to assess a low-dose Se additive as an in situ remediation tool for As- and Hg-contaminated gold mine tailing material. Mine tailing material from an 1860s gold mine stamp mill site was treated with different concentrations of sodium selenite (0, 0.5, 1, 3, 8, and 15 mg Se/kg). Reclamation grass seeds planted in each treatment showed significantly decreased plant toxicity with increasing [Se], as measured by increases in biomass, % emergence, and root lengths. Leachate was collected from each pot after the grass was harvested. The lowest Hg and As concentrations measured in the leachate were associated with the 1 mg Se/kg treatment (94 and 71 % lower than concentrations in leachate from untreated tailing material) and increased with lower and higher Se treatments. Finally, earthworms (Eisenia andrei) were introduced to the experimental treatments. Earthworm [Hg] decreased with increasing [Se], but this effect was confounded by differing [Hg] in the tailing material. Earthworm [As] decreased with [Se] up to 3 mg Se/kg, then earthworm [As] increased with tailing [Se]. This experiment confirms that low-dose selenium additions (up to 3 mg Se/kg tailing material) can have beneficial effects by limiting toxicity and mobility of As and Hg from the tailing material for both grass and earthworms.

Within the last few years, the presence of bentazone herbicide has been observed in many water resources. For the first time, removal of bentazone using mesoporous silica was investigated revealing reversible adsorption. The adsorption isotherm was well described using the Freundlich model. The affinity towards bentazone is strongly affected by pH in the range of 2–7, decreasing with the increase of the pH, becoming negligible at the neutrality. Regeneration of the adsorbent was possible, and a recovery as high as 70 % was obtained using CH₃OH-NaOH solution. Furthermore, appreciable recovery (47 %) was also obtained using water. Applications on the purification of lake water and wastewaters, both characterized by a significant organic carbon load, spiked with 2 mg L⁻¹ bentazone were tested, observing removal yields in the range of 61–73 %. Taking advantage of the fast adsorption kinetics observed, an in-flow purification treatment was set-up, with quantitative removal of bentazone from polluted water.

The development of shirasu balloons (SB) modified with polydopamine (PDA) has been conducted. The aim of this research is to increase the performance of shirasu balloons in the adsorption of methylene blue (MB). The SB modified with PDA (SB/PDA) was prepared by immersing SB in the dopamine solution in the aerobic alkaline condition. The prepared material was characterized using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy with energy dispersive X-ray spectrometry (SEM-EDS), specific surface area N₂ sorption, and zeta potential analysis. The adsorption behavior of SB and SB/PDA was investigated by studying the effect of the pH, adsorption kinetics, and effect of salt concentration. The adsorption kinetics of SB before and after modification was analyzed using two kinetics models, i.e., pseudo-first order and pseudo-second order. The adsorption isotherm was analyzed using Langmuir and Freundlich models. The adsorption study results showed that the adsorption isotherm fitted to Langmuir isotherm with a maximum capacity that could reach up to 26.17 mg g⁻¹ for SB and 36.23 mg g⁻¹ for SB/PDA. The adsorption kinetics showed that adsorption behavior followed the pseudo-second-order kinetic model and the equilibrium time for each material can be obtained at 5 min shaking time.

Textile wastewater was treated by adsorption in batch and column systems using electrochemically modified montmorillonite clay and activated carbon. Textile wastewater was obtained from a denim manufacturing process; according to the characterization of wastewater, non-biodegradable organic matter was found and it limits the application of biological treatments, and then an alternative method was evaluated. The adsorption process was performed with natural and modified materials; iron-modified montmorillonite was prepared at pH 7 using iron electrodes and activated carbon was treated with copper electrodes at pH 2, and 10–12 % of iron and copper respectively were found in the modified materials. Adsorption kinetics and isotherms of chemical oxygen demand (COD), color, and total organic carbon (TOC) were evaluated; the adsorption capacities for color were 50, 37, and 44 U PtCo/g for natural clay, activated carbon, and iron-modified clay, respectively. Adsorption kinetics of COD, color, and TOC data were best adjusted to Elovich model and isotherms data to Freundlich model, indicating chemisorption on heterogeneous materials. The regeneration of materials was performed in the presence and absence of hydrogen peroxide. Continuous systems were evaluated for color and TOC. Fe-modified clay was the best adsorbent, and data were best adjusted to Thomas and Yoon-Nelson models.