环境•农林最新文献

The strategy to reduce agricultural ammonia (NH₃) emissions is a focus of attention for governments and scientists around the world. However, the effect of different irrigation and fertilization management practices on NH₃ emission in alkaline soil and the underlining mechanisms are poorly understood. An experiment with drip fertigation (a combination of fertilizing and irrigation), sprinkler fertigation, and traditional furrow irrigation with chemical fertilizer spraying was conducted in potato fields with alkaline soil in arid areas of Northwest China. The objective of this study was to investigate the effect of three irrigation and fertilization management practices on NH₃ emissions using the static box-venting method in a three-year in situ trial. There are significant seasonal difference for NH₃ emission fluxes in alkaline soils under different fertilization and irrigation management practices. The accumulative NH₃ emissions in the alkaline soil from drip fertigation and sprinkler fertigation was 55.93% and 54.05% lower than that from traditional furrow irrigation, respectively. The dynamic changes of NH₄⁺-N and NO₃⁻-N in alkaline soil were the most important factors controlling the differences of NH₃ emissions under different irrigation and fertilization methods. Drip fertigation significantly reduced NH₃ emission intensity in alkaline soil, and were important measures for reducing agricultural NH₃ emissions and ensuring potato yield in alkaline soil farmland in arid regions.

The aim of this study is to propose a new catalyst for catalytic ozonation of acid orange 7 (AO7) dye in aqueous solutions. CoFe₂O₄@Biochar catalyst was synthesized, prepared, and used in a heterogeneous catalytic ozonation process (COP) for AO7 removal. The characteristics of synthetized nanoparticles were investigated through the following equipment: x-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), fourier transform infrared (FTIR) spectroscopy, vibrating sample magnetometer (VSM), transmission electron microscopy (TEM), Brunauer, Emmett and Teller (BET) and energy dispersive x-ray (EDX) analyses. The results showed that the process offered a sufficient efficiency for removal of 150 and 200 mg/L concentrations of AO7. Moreover, CO₃^2-, NO₃^-, Cl^- and PO₄^3- anions had a decreasing effect on the efficiency. The results of the scavenger experiments showed that the hydroxyl radical and ozone oxidants played the primary role for decomposition of the pollutants. The removal efficiency of total organic carbon (TOC) was 99% after 120 min by COP which was 44% more than the Single Ozonation Process (SOP). COP also caused the removal of chemical oxygen demand (COD) by 92% after 360 min. Based on the results, the COP with CoFe₂O₄@Biochar catalyst can be an effective and efficient process for treating textile wastewaters.

Settleability is vital important for the stability of effluent quality from the widely used activated sludge (AS) process in wastewater treatment plants. In this study, filamentous algae and seawater condition were used to build a microalgae-bacteria (MB) consortia system with the objective of improving the settleability of AS. Filamentous algae were found to flourish more in aeration seawater reactor (R2) than non-aeration (R1). During 90 days, large contents of N, P were firstly released from the biomass, but were absorbed by the algae to relatively low concentrations (N 1.1 mg/L, P 1.4–2.3 mg/L). Meanwhile, the settleability of the two types of MB consortia both significantly increased, but was superiorly enhanced in aeration condition to a low 5-min sludge volume (SV₅) (11.5%, 55 d). Filamentous algae Leptolyngbya, as the most dominant part (9.8%) of microbial community in R2, could tightly bind the bacteria cells and extracellular polymeric substances (EPS) to form larger particles, which greatly accelerated the sedimentation. This study is of interest for the potential use of sludge settleability promotion in wastewater treatment plants, which has promising prospects for preventing the sludge bulking or biomass loss in AS systems.

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Manganese (Mn) concentrations in many groundwater supplies exceed the national drinking water limit of 0.05 mg/L, exacerbating regional water scarcity and potential ecological issues. Adsorption, as an efficient process for wastewater treatment. For the adsorption process, the adsorbent was the key parameter. Manganese oxides have strong specific adsorption and catalytic oxidation capacity for Mn(II). Serpentine loading was an effective way to improve the dispersion of manganese oxides and the adsorption efficiency of heavy metals. This study aimed to remove dissolved Mn(II) from groundwater using a raw serpentine modified with manganese oxide (Srp/MO). SEM, EDS, XRD, BET and XPS were used to characterize the physicochemical properties and characteristic groups of the serpentine before and after loading. Response surface methodology (RSM) based on Box-Behnken method was used to design the experiment to optimize the effects of dosage, oscillation rate and reaction time on manganese removal. The results show that after modification, the pores of serpentine become larger, the surface becomes smooth and loose, the basic skeleton has no obvious change, the specific surface area increases, and the total pore volume decreases. The adsorption behavior of Mn(II) by Srp/MO follows Langmuir isotherm model and pseudo-second-order kinetic model. The maximum adsorption rate of Mn(II) in water by Srp/MO was 34.88 mg/g, which was 7.6 times that of the raw serpentine. The primary mechanism for Mn(II) removal by Srp/MO was based on physical adsorption and mediated by Mn³⁺/Mn⁴⁺ species. The optimal manganese removal conditions were as follows: Srp/MO dosage 80 mg/L, oscillation rate 180 r/min, reaction time 104 min. At this time, the manganese removal rate was 99.3%, which was basically consistent with 100% predicted by the model. A regeneration study over three cycles indicated that Srp/MO possessed promising reusability potential. In conclusion, Srp/MO was an excellent adsorption material for the removal of Mn(II) in groundwater, which provides a new solution for the purification treatment of manganese containing groundwater.

To evaluate the effects of ocean acidification (OA) on the shell morphology of the gastropods, three different populations of Planaxis sulcatus (Born) in the South China Sea (Coast of Borneo) were investigated. All sites are natural rocky shores sharing a very similar geologic setting of the intertidal zone including, water depth, beach topography, and wave energy. The population densities observed during sampling were similar across all three study sites. However, one population lives under low pH due to geochemical discharge from acidic soils (site E), while the other two populations live under higher pH levels (T and U sites). Quantitative analyses of the shell shape using geometric morphometrics demonstrated that OA had a significant effect on the shell morphology, demonstrating that both allometric growth and the calcification process were affected. Shells from the acidified sites were more rounded and had smaller apertures. Moreover, shell size was significantly reduced as a response to OA stress. These shell changes may have arisen to reduce the cost of shell maintenance. As there is also a significant salinity difference among sites, salinity may have influenced the shell shape of the gastropod Planaxis sulcatus and therefore, the role of OA should be examined in areas where all other physicochemical variables are the same.

Since their inception in 2011, MXenes have attracted significant attention from a range of industries due to their fascinating architectures and alluring features. Given its two-dimensional multilayered structures, high mechanical strength, outstanding electrical conductivity, and customizable surface chemistry, MXene, a new family of two-dimensional (2D) multifunctional nanomaterials, has demonstrated exceptional performance in water treatment technologies. The most recent developments in the field of MXene-based membranes, from synthesis to fabrication and application, are reviewed in this article. The manufacture of MXene membranes and their applications in membrane separation were explored in detail. The discovery and properties of MXene were briefly reviewed first, and then new developments in MXene production methods were discussed. Subsequently, the properties and methods of manufacture and integration of versatile membranes based on MXene were explored. The most recent developments in water treatment applications, such as wastewater purification, oil/water separation, and desalination, were also covered in-depth. The durability and stability of membranes based on MXene were thoroughly discussed from many perspectives, revealing that these membranes can achieve filtration efficiency of over 99% for various contaminants, such as heavy metals and organic pollutants. Additionally, Durability tests demonstrate that these membranes retain their structural integrity and performance even after extended exposure to harsh chemical environments and many filtration cycles. Comparative studies demonstrate that MXene membranes surpass unmodified membranes, in terms of both flux and pollutant removal efficiency. Lastly, research directions and prospects were discussed to enhance the use of MXene-based membranes in a variety of water treatment applications. The literature analyses revealed that, after addressing several shortcomings and challenges related to their use, MXene-based membranes could revolutionize nanostructured composite membranes.

Sodium lauryl sulfate (SLS) is an anionic surfactant used as an emulsifying detergent in personal care products (PCPs). As a pseudo-persistent pollutant, it accumulates in aquatic ecosystems with consequent adverse effects on the whole ecosystem. Most of the studies about the toxicity of SLS on non-target species were conducted before 2010, and just a bunch of recent studies focus on this topic. Due to the COVID-19 pandemic, there has been a rise in the use of PCPs, thus increasing SLS release in aquatic environments. Therefore, the present study aims to assess the impact of SLS on non-target organisms Danio rerio, Cyprinus carpio, and Xenopus laevis, through embryotoxicity tests. Embryos were exposed to different concentrations of SLS (0.1, 0.5, 1, 5, 10, 15 mg/L) for 96 h and relevant toxicity endpoints (mortality, hatching rate, and malformations) were monitored each 24 h. Additionally, heart rates along with animal length were measured. The study highlights the high sensitivity of D. rerio and X. laevis when exposed to SLS concentrations comparable to the one detected in the environment. Specifically, relevant results have been observed in the endpoint of mortality (D. rerio showed 100% mortality in the highest concentrations), hatching and malformations in both animals. Heart rate measurements showed significant differences in C. carpio and D. rerio in all the concentrations tested.

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