In this article, a comparison will be made concerning the advantages and disadvantages of five kinds of coal mine methane (CMM) deoxygenation method, including pressure swing adsorption, combustion, membrane separation, non-metallic reduction, and cryogenic distillation. Pressure swing adsorption has a wide range of application and strong production capacity. To achieve this goal, adsorbent must have high selectivity, adsorption capacity, and adequate adsorption/desorption kinetics, remain stable after several adsorption/desorption cycles, and possess good thermal and mechanical stabilities. Catalytic combustion deoxygenation is a high-temperature exothermic redox chemical reaction, which releases large amounts of thermal energy. So, the stable and accurate control of the temperature is not easy. Meanwhile partial methane is lost. The key of catalytic combustion deoxygenation lies in the development of high-efficiency catalyst. Membrane separation has advantages of high separation efficiency and low energy consumption. However, there are many obstacles, including higher costs. Membrane materials have the requirements of both high permeability and high selectivity. The development of new membrane materials is a key for membrane separation. Cryogenic distillation has many excellence advantages, such as high purity production and high recovery. However, the energy consumption increases with decreasing CH₄ concentrations in feed gas. Moreover, there are many types of operational security problems. And that several kinds of deoxygenation techniques mentioned above have an economic value just for oxygen-bearing CMM with methane content above 30%. Moreover, all the above methods are not applicable to deoxygenation of low concentration CMM. Non-metallic reduction method cannot only realize cyclic utilization of deoxidizer but also have no impurity gases generation. It also has a relatively low cost and low loss rate of methane, and the oxygen is removed thoroughly. In particular, the non-metallic reduction method has good development prospects for low concentration oxygen-bearing CMM. This article also points out the direction of future development of coal mine methane deoxygenation.

Cadmium (Cd) transport in overland flow from agricultural soils is potentially important when trying to predict future soil Cd concentrations, but at present there is little information on the magnitude of loss from this pathway. This study measured Cd concentrations and fluxes in overland flow from a catchment where cattle winter-grazed a forage crop (kale) (Brassica oleracea) in year one and measurements continued in year two when the catchment was returned to pasture and grazed by sheep. Flow-weighted mean concentrations (FWMC) of total, particulate and dissolved Cd in overland flow events from the forage crop were 0.49, 0.41 and 0.08 μg L⁻¹, respectively. In contrast, no dissolved Cd was detected in overland flow from pasture, with a FWMC of total Cd of 0.09 μg L⁻¹. In line with the Cd concentrations, total Cd fluxes were greater from the forage crop (0.06 g Cd ha⁻¹ year⁻¹) than from pasture (0.04 g Cd ha⁻¹ year⁻¹). Cadmium losses in overland flow were relatively minor compared with those reported for other pathways such as plant uptake or subsurface flow. Further, compared to the amount of Cd that is currently added to soil in a maintenance application of phosphate fertiliser (30 kg P ha⁻¹ year⁻¹) which is on average 5.5 g Cd ha⁻¹, Cd losses in overland flow represented < 1% of inputs. Measurement of Cd losses in overland flow should be undertaken at other sites to confirm the low Cd losses found in this study, along with the distribution between dissolved and particulate fractions.

Eggshells are good bioindicators of environmental contamination, and therefore, the concentrations of 17 trace elements in 87 eggshells of black-headed gulls, Chroicocephalus ridibundus, were determined in five breeding colonies in an area dominated by farmland in northern Poland. The intra-clutch variability in the eggshell concentrations of heavy metals and other elements was also investigated, and the concentrations of the elements showed the following pattern: Ca > Mg > Sr > Fe > Zn > Al > Cr > Se > Mn > Cu > Pb > As > Ni > Mo = V > Sc > Cd. The concentrations of Fe, Al, and Mn decreased with the order in which the eggs were laid, but Sr concentrations increased. In contrast, the concentration of Cu significantly increased with the laying date. The concentrations of all elements significantly differed among the studied colonies; the highest concentration of eight elements was found in the eggshells from the Kusowo colony, which may have resulted from the intensive use of fertilizers, manure, and slurry in the surrounding agricultural region. The concentrations of Mg, Sr, and Zn in the eggshells from Skoki Duże were higher than those of the other studied colonies, which may have occurred because the gulls were nesting in a functioning gravel pit; soil and the parent rock are natural reservoirs of these elements. The observed element levels indicate that the environment where the black-headed gull eggs were formed, i.e., primarily near the breeding colonies, remains in a relatively unpolluted state, which was reflected by the low levels of Cd, Ni, and Pb and the lack of measurable levels of Hg.

The stable isotopes of δ¹⁸O, δ²H, and ⁸⁷Sr/⁸⁶Sr and dissolved major ions were used to assess spatial and seasonal water chemistry variability, chemical weathering, and hydrological cycle in the Pangani River Basin (PRB), Tanzania. Water in PRB was NaHCO₃ type dominated by carbonate weathering with moderate total dissolved solids. Major ions varied greatly, increasing from upstream to downstream. In some stations, content of fluoride and sodium was higher than the recommended drinking water standards. Natural and anthropogenic factors contributed to the lowering rate of chemical weathering; the rate was lower than most of tropical rivers. The rate of weathering was higher in Precambrian than volcanic rocks. ⁸⁷Sr/⁸⁶Sr was lower than global average whereas concentration of strontium was higher than global average with mean annual flux of 0.13 × 10⁶ mol year⁻¹. Evaporation and altitude effects have caused enrichment of δ¹⁸O and δ²H in dry season and downstream of the river. Higher d-excess value than global average suggests that most of the stations were supplied by recycled moisture. Rainfall and groundwater were the major sources of surface flowing water in PRB; nevertheless, glacier from Mt. Kilimanjaro has insignificant contribution to the surface water. We recommend measures to be taken to reduce the level of fluoride and sodium before domestic use.

Variations in the composition of stable isotopes of mercury contained in tissues (root, stem, leaf, and hypocotyl or flower) of three typical mangrove plants (Kandelia candel, Aegiceras corniculata, and Bruguiera gymnorhiza), collected from the mangrove wetland of Jiulong estuary, SE China, were used to investigate the sources and transformation of mercury in the mangrove plants. Tissue samples from the plants were digested and mercury in the solution was pre-concentrated with purge-trap method and then analyzed by multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS). The results showed that the mass dependent fractionation (MDF) of mercury ranged from −2.67 to −0.87 ‰ for δ ²⁰²Hg while the mass independent fractionation (MIF) of mercury isotopes ranged from −0.16 to 0.09 and −0.19 to 0.05 ‰ for Δ¹⁹⁹Hg and Δ²⁰¹Hg, respectively, relative to the standard NIST SRM 3133. The ratio of Δ¹⁹⁹Hg/Δ²⁰¹Hg was 0.991, indicating that the mercury had been photo-reduced before being accumulated in mangrove plants. Analyses of the data from MIF studies revealed that the major portion of the mercury measured in leaves (∼90 %) originated from the atmosphere while the source of over half of the mercury present in roots was the surficial sediment. This study, the first of its kind investigating the variations in isotopic composition of mercury in the tissues of mangrove plants, could be helpful to identify the source of mercury contamination in mangroves and understand the biogeochemical cycle of mercury in the estuarine mangrove wetlands.

For the treatment of high-strength pyridine containing wastewater, a bioaugmented continuous-flow self-forming dynamic membrane bioreactor (CSFDMBR), which was consisted of a continuous flow airlift reactor (CFAR) and a dynamic membrane bioreactor (DMBR), was developed in this study. The results indicated that through the bioaugmentation by Rhizobium sp. NJUST18, CSFDMBR could be successfully started, which was confirmed by complete removal of pyridine, efficient nitrification, and significant increase of biomass. Pyridine could be effectively degraded in the CSFDMBR even at influent pyridine loading rate as high as 9.0 kg m⁻³ day⁻¹, probably due to the efficient biomass retention in the CSFDMBR, which could be attributed to the formation of aerobic granules and the key role of dynamic membrane. CSFDMBR presented good polishing performance in treating pyridine wastewater, with effluent total organic carbon (TOC) and turbidity as low as 22.5 ± 6.8 mg L⁻¹ and 3.8 ± 0.5 NTU, respectively. Membrane fouling could be effectively controlled, as indicated by backwash period as long as 60 days. The observed efficient performance highlights the potential for the full-scale application of the bioaugmented CSFDMBR, particularly for highly recalcitrant pollutant removal.

In this article, Cr(OH)₃ nanoparticle-modified cellulose nanocrystal (CNC) as a novel hybrid nanocomposite (Cr(OH)₃-NPs-CNC) was prepared by a simple procedure and used as a sorbent for adsorptive removal of methylene blue (MB) and malachite green (MG) from aqueous solution. Different kinetic models were tested, and the pseudo-second-order kinetic model was found more suitable for the MB and MG adsorption processes. The BET and Langmuir models were more suitable for the adsorption processes of MB and MG. Thermodynamic studies suggested that the adsorption of MB and MG onto Cr(OH)₃-NPs-CNC nanocomposite was a spontaneous and endothermic process. The maximum adsorption capacities for MB and MG were reached 106 and 104 mg/g, respectively, which were almost two times higher than unmodified CNC. The chemical stability and leaching tests of the Cr(OH)₃-NPs-CNC hybrid nanocomposite showed that only small amounts of chromium were leached into the solution.

In a previous study, we found that rice-straw biochar degraded and removed hydrophobic organic contaminants (HOCs) through coupled adsorption-biodegradation. However, few studies have determined whether biochar affects HOC isomer degradation and isomer-selective biodegradation or whether biochar can alter HOC isomer features, resulting in changes to HOC isomer residues in water environments. In this study, the effects of biochar at two dosages (0.001 and 0.01 g) on the biodegradation of ten isomers of a typical xenoestrogen of nonylphenol (NP) were evaluated. The results revealed that there were no effects of biochar on the adsorption of NP isomers. However, biochar addition affected the biodegradation of a specific isomer without altering the features of the NP isomers. The treatment of NP isomers with Pseudoxanthomonas sp. yielded degradation ratios ranging from 60.7 to 100%. At 0.001 g biochar treatment, the degradation of eight NP isomers was enhanced (except for NP₁₉₄ and NP₁₉₃ₐ₊b) due to their bulky structures. The degradation of the ten NP isomers was inhibited when 0.01 g biochar was added. These findings characterized the effects of biochar on NP isomer contaminants and provided basic information for the application of biochar for the remediation of NP isomer contaminants.

The possibility of using different densities of cherry tomato as a bio-filter in a simple media-based aquaponic system to recycle nutrients from pearl gourami intensive culture wastewater was evaluated. Water quality parameters including total ammonia nitrogen (TAN), nitrite (NO₂ ⁻), nitrate (NO₃ ⁻), phosphate (PO₄ ³⁻), pH, and dissolved oxygen (DO) were determined in outlet of the aquaponic system during a 60-day experimental period. Cherry tomato was planted at four densities of 0 (control), 3 (T1), 6 (T2), and 9 (T3) plants per aquaponic unit with a constant fish stock density. Each treatment was equipped with aquaponic systems containing fish tank and plant growing bed. Productivity of the system was measured by recording the fish and plant growth indices. The potential in removing nitrogen of the water was the highest in T3 (with nine plants) compared to other treatments (p < 0.05). The highest concentrations of TAN (6.59 ± 0.241 mg/L), nitrite (0.42 ± 0.005 mg/L), nitrate (0.45 ± 0.162 mg/L), and phosphate (30.47 ± 0.371 mg/L) were obtained in control group, while the lowest concentrations of TAN (0.05 ± 0.091 mg/L), NO₂ ⁻ (0.11 ± 0.008 mg/L), NO₃ ⁻ (29.77 ± 0.205 mg/L), and phosphate (18.59 ± 0.185 mg/L) were detected in T3 (p < 0.05). The maximum fish weight gain was recorded in T3 (26 ± 0.014%) with 1.26 ± 0.059 FCR, and the lowest fish weight gain was measured in the control group (15 ± 0.024%) with 2.19 ± 0.446 FCR (p < 0.05). Total plant length gain was reached at the maximum value in T3 (74.70 ± 1.153 cm) in comparison to other groups (p < 0.05). It was concluded that small-scale aquaponic growing bed system can be created a sustainable ecosystem which both the plant and fish can thrive and suitable for home-made production system.

Nitrogen fertilizer availability to plants is strongly linked with water availability. Excessive or insufficient use of nitrogen can cause reduction in grain yield of wheat and environmental issues. The per capita per annum water availability in Pakistan has reduced to less than 1000 m³ and is expected to reach 800 m³ during 2025. Irrigating crops with 3 or more than 3 in. of depth without measuring volume of water is not a feasible option anymore. Water productivity and economic return of grain yield can be improved by efficient management of water and nitrogen fertilizer. A study was conducted at post-graduate agricultural research station, University of Agriculture Faisalabad, during 2012–2013 and 2013–2014 to optimize volume of water per irrigation and nitrogen application. Split plot design with three replications was used to conduct experiment; four irrigation levels (I₃₀₀ = 300 mm, I₂₄₀ = 240 mm, I₁₈₀ = 180 mm, I₁₂₀ = 120 mm for whole growing season at critical growth stages) and four nitrogen levels (N₆₀ = 60 kg ha⁻¹, N₁₂₀ = 120 kg ha⁻¹, N₁₈₀ = 180 kg ha⁻¹, and N₂₄₀ = 240 kg ha⁻¹) were randomized as main and sub-plot factors, respectively. The recorded data on grain yield was used to develop empirical regression models. The results based on quadratic equations and economic analysis showed 164, 162, 158, and 107 kg ha⁻¹ nitrogen as economic optimum with I₃₀₀, I₂₄₀, I₁₈₀, and I₁₂₀ mm water, respectively, during 2012–2013. During 2013–2014, quadratic equations and economic analysis showed 165, 162, 161, and 117 kg ha⁻¹ nitrogen as economic optimum with I₃₀₀, I₂₄₀, I₁₈₀, and I₁₂₀ mm water, respectively. The optimum irrigation level was obtained by fitting economic optimum nitrogen as function of total water. Equations predicted 253 mm as optimum irrigation water for whole growing season during 2012–2013 and 256 mm water as optimum for 2013–2014. The results also revealed that reducing irrigation from I₃₀₀ to I₂₄₀ mm during 2012–2013 and 2013–2014 did not reduce crop yield significantly (P < 0.01). The excessive nitrogen application ranged from 31.2 to 55.4% at N₁₈₀ and N₂₄₀ kg ha⁻¹ for different levels of irrigation. It is concluded from study that irrigation and nitrogen relationship can be used for efficient management of irrigation and nitrogen and to reduce nitrogen losses. The empirical equations developed in this study can help farmers of semi-arid environment to calculate optimum level of irrigation and nitrogen for maximum economic return from wheat.