Probing the effects of silicon amendment on combined stressors on rice: Lead pollution and blast fungus (Magnaporthe oryzae) infection.

As agroecology deteriorates, agricultural production is threatened by the combined stressors of exposure to environmental pollutants and pathogenic microbes. Proper agronomic practices for crop growth management and fertilization require understanding plant tolerance strategies. Both rice blast and heavy metals substantially impair rice crops, while silicon (Si) is an effective amendment to alleviate the combined stressors. Herein, this study was conducted to investigate the rice physiology and pathology perspective on the mechanism of Si alleviation against both lead (Pb) toxicity and Magnaporthe oryzae infection, utilizing pot experiments with inoculation of the virulent Magnaporthe oryzae strain. Exogenous Si reduced the phyto-availability and plant absorption of Pb, resulting in a 73.5% reduction in exchangeable Pb concentration in soil and a 40.23% reduction in rice plants. Furthermore, Si addition boosted the plant antioxidant system by increasing the activities of related enzymes, as the activities of catalase, superoxide dismutase, and polyphenol oxidase were significantly improved while the activity of peroxidase in rice panicles decreased. As a result, an improvement in dry matter quantity by 19.19% was observed compared to treatments without Si application, and the panicle blast severity (PBS) was reduced by 0.4-37.52%. Notwithstanding the interaction between the combined stressors, this study revealed that the speciation of Pb formation in the rhizosphere was the primary contributor to the alleviation of abiotic stresses, whereas the regulation of oxidative stress by enzymatic antioxidants played a dominant role in alleviating Magnaporthe oryzae colonization and impairments. The regulation process may reveal the mechanism of siliceous fertilizer functioning in the paddy system. Thereby the role of exogenous Si in anti-fungal, heavy metal toxicology, and plant physiology needs further study to fully elucidate the role of Si amendment, which is proposed to be considered from the perspective of soil chemistry and plant physiology.

In-depth insights into Fe(III)-doped g-C3N4 activated peracetic acid: Intrinsic reactive species, catalytic mechanism and environmental application.

In this study, we demonstrate that Fe(III)-doped g-C3N4 can efficiently activate peracetic acid (PAA) to degrade electron-rich pollutants (e.g., sulfamethoxazole, SMX) over a wide pH range (3-7). Almost ∼100% high-valent iron-oxo species (Fe(V)) was generated and acted as the dominant reactive species responsible for the micropollutants oxidation based on the analysis result of quenching experiments, 18O isotope-labeling examination and methyl phenyl sulfoxide (PMSO) probe method. Electrochemical testing (e.g., amperometric i-t and linear sweep voltammetry (LSV)) and density functional theory (DFT) calculations illustrated that the main active site Fe atom and PAA underwent electron transfer to form Fe(V) for attacking SMX. Linear free energy relationship (LFER) between the pseudo-first-order rates of different substituted phenols (SPs) and the Hammett constant σ+ depicted the electrophilic oxidation properties. The selective oxidation of Fe(V) endows the established system remarkable anti-interference capacity against water matrices, while the Fe(V) lead to the formation of iodinated disinfection by-products (I-DBPs) in the presence of I-. Fe(III)-doped g-C3N4/PAA system showed excellent degradation efficiency of aquaculture antibiotics. This study enriches the knowledge and research of high-valent iron-oxo species and provides a novel perspective for the activation of PAA via heterogeneous iron-based catalysts and practical environmental applications.

Dispersed cobalt embedded nitrogen-rich carbon framework activates peroxymonosulfate for carbamazepine degradation: cobalt leaching restriction and mechanism investigation.

Metal leaching is a key issue in cobalt-based catalysts/PMS systems, which results in the decline of catalytic ability and serious secondary pollution. Hence, a nitrogen-rich carbon framework with cobalt node (Co-NC-920) with low cobalt leaching was synthesized based on zeolite imidazole framework (ZIF) and g-C3N4 to activate peroxymonosulfate (PMS) for the degradation of carbamazepine (CBZ). With the restriction of nitrogen-rich carbon framework, cobalt can disperse better and form stable cobalt-nitrogen bonds, thus only 0.09 mg/L cobalt ions were leached in the solution. More than 99.9% of CBZ can be removed within 30 min of PMS addition. Further investigation revealed that 1O2, SO4•- and high-valent cobalt species were primarily responsible for CBZ degradation in the Co-NC-920/PMS system and different reactive oxygen species (ROS) were distinguished and quantified, finding 1O2 was predominant. The degradation process was realized by the coexistence of free radicals and non-free radicals. Moreover, CBZ degradation capacity of the catalyst was evaluated under the influence of common anions and in actual waterbody. Finally, the possible degradation pathways of CBZ were proposed and the toxicity of the intermediates was analyzed. This work provides a new approach for the synthesis of cobalt-based nitrogen-rich carbon catalysts with low leaching and high efficient.

An endeavor of "deep-underground agriculture": storage in a gold mine impacts the germination of canola (Brassica napus L.) seeds.

Exploring and utilizing the agronomic potential of deep-underground is one of the ways to cope with the challenges of sudden environmental change on agriculture. Understanding the effects of environmental stresses on the morphological and physiological indicators of crop seeds after their storage deep-underground is crucial to developing and implementing strategies for agriculture in the deep-underground space. In this study, we stored canola seeds in tunnels with horizontal depths of 0, 240, 690, and 1410 m in a gold mine. Seeds in envelopes were retrieved at 42, 66, 90, and 227 days of storage, whereas seeds in sealed packages were retrieved at 66 and 227 days of storage. The germination tests were conducted to investigate the effects of storage depth, duration, and packing method on stored and non-stored seeds. Results showed that increased depth and duration reduced seed germination rate, with the germination and vigor indexes also descending to varying degrees. Increased hypocotyl length and biomass accumulation suggested that deep-underground environment had a more significant compensatory effect on seed germination. For all indicators, the performance of seeds sealed in packages was superior to those stored in envelopes. Regression analysis showed that it was difficult to obtain the optimal value of each indicator simultaneously. The successful germination experiment foreshadowed the possibilities of deep-underground agriculture in the future.

Optimal segmentation scale selection and evaluation of cultivated land objects based on high-resolution remote sensing images with spectral and texture features.

As the remote sensing technology develops, there are increasingly more kinds of remote sensing images available from different sensors. High-resolution remote sensing images are widely used in the detection of land cover/land change due to their plenty of characteristics of a specific feature in terms of spectrum, shape, and texture. Current studies regarding cultivated land resources that are the material basis for the human beings to survive and develop focus on the method to accurately obtain the quantity of cultivated land in a region and understand the conditions and the trend of change of the cultivated land. Pixel-based method and object-oriented method are the main methods to extract cultivated land in remote sensing field. Pixel-based method ignores high-level image information, while object-oriented method takes the image spot after image segmentation as the basic unit of information extraction, which can make full use of spectral features, spatial features, semantic features, and contextual features. Image segmentation is a key step of object-oriented method; the core problem is how to obtain the optimal segmentation scale. Traditional methods for determining the optimal segmentation scale of features (such as the homogeneity-heterogeneity method, the maximum area method, and the mean variance method), in which only the spectral and geometrical characteristics are considered, while the textural characteristics are neglected. Based on this, the Quickbird and unmanned aerial vehicle (UAV) images obtained in Xiyu Village, Pengzhou City, Sichuan Province, China, were selected as experimental objects, and the texture mean and spectral grayscale mean method (MANC method based on GLCM), which comprehensively considered the spectrum, shape, and texture features, was proposed to calculate the optimal segmentation scale of cultivated land in the study area. The error segment index (ESI) and centroids distance index (CDI) were adopted to evaluate image segmentation quality based on the method of area and position differences. The experimental results show that the MANC method based on GLCM can obtain higher segmentation precision than the traditional methods, and the segmentation results are in good agreement with the cultivated land boundary obtained by visual interpretation.

N/Fe/Zn co-doped TiO2 loaded on basalt fiber with enhanced photocatalytic activity for organic pollutant degradation.

To avoid the loss of catalytic material powder, a loaded catalytic material of TiO2 with basalt fiber as the carrier (TiO2@BF) was synthesized by an improved sol-gel method. The TiO2@BF was doped with different contents of N, Fe and Zn elements and was used to degrade rhodamine B (RhB) under ultraviolet light. The physical characterization analysis indicated that the co-doping of the N, Fe and Zn elements had the effects of reducing grain size, increasing sample surface area, and narrowing the electronic band gap. The electronic band gap of nitrogen-iron-zinc co-doped TiO2@BF (N/Fe/Zn_TiO2@BF) was 2.80 eV, which was narrower than that of TiO2@BF (3.11 eV). The degradation efficiency of RhB with N/Fe/Zn_TiO2@BF as a photocatalyst was 4.3 times that of TiO2@BF and its photocatalytic reaction was a first-order kinetic reaction. Quenching experiments suggested that the reactive species mainly include photoinduced holes (h+), superoxide radicals (˙O2 -) and hydroxyl radicals (˙OH). In brief, this study provides a prospective loaded catalytic material and routine for the degradation of organic contaminants in water by a photocatalytic process.

Response of Plant Rhizosphere Microenvironment to Water Management in Soil- and Substrate-Based Controlled Environment Agriculture (CEA) Systems: A Review.

As natural agroecology deteriorates, controlled environment agriculture (CEA) systems become the backup support for coping with future resource consumption and potential food crises. Compared with natural agroecology, most of the environmental parameters of the CEA system rely on manual management. Such a system is dependent and fragile and prone to degradation, which includes harmful bacteria proliferation and productivity decline. Proper water management is significant for constructing a stabilized rhizosphere microenvironment. It has been proved that water is an efficient tool for changing the availability of nutrients, plant physiological processes, and microbial communities within. However, for CEA issues, relevant research is lacking at present. The article reviews the interactive mechanism between water management and rhizosphere microenvironments from the perspectives of physicochemical properties, physiological processes, and microbiology in CEA systems. We presented a synthesis of relevant research on water-root-microbes interplay, which aimed to provide detailed references to the conceptualization, research, diagnosis, and troubleshooting for CEA systems, and attempted to give suggestions for the construction of a high-tech artificial agricultural ecology.

[Organic Distribution Characteristics and Influence on Drinking Water Quality in the Typical Water Sources for Towns in the Southwest Hilly Area of China].

This study analyzed the organic distribution characteristics of original and treated water and their impacts on drinking water quality using a conventional water treatment process in the typical water supply sources for towns in the southwest hilly area of China. The results showed that the water supply source in this area is micro-polluted water. Dissolved organics of low molecular weight accounted for the great majority of the organics, with the proportion ranging from 50% to 80%. There were 53 kinds and 14 classes of organics, including alkanes, esters, phenolic compounds, and benzenes, with the proportion from 80% to 90%. The amounts of organic acid, alkene, alcohols, and aldehyde were small, while the amounts of dichloromethane, phenol, and dibutyl-phthalate were relatively high. Herbicides, food additives, and antibiotics were detected, such as terbuthylazine, 2,6-di-tert-butyl-p-cresol, and nalidixic acid. The conventional water treatment process could efficiently remove the compounds with molecular weights higher than 10×103 and organic acid; however, it was limited greatly in its removal of alkanes, esters, phenolic compounds, and benzenes.

Effects of sodium polyacrylate on water retention and infiltration capacity of a sandy soil.

Based on the laboratory study, the effects of sodium polyacrylate (SP) was investigated at 5 rates of 0, 0.08, 0.2, 0.5, and 1%, on water retention, saturated hydraulic conductivity(Ks), infiltration characteristic and water distribution profiles of a sandy soil. The results showed that water retention and available water capacity effectively increased with increasing SP rate. The Ks and the rate of wetting front advance and infiltration under certain pond infiltration was significantly reduced by increasing SP rate, which effectively reduced water in a sandy soil leaking to a deeper layer under the plough layer. The effect of SP on water distribution was obviously to the up layer and very little to the following deeper layers. Considering both the effects on water retention and infiltration capacity, it is suggested that SP be used to the sandy soil at concentrations ranging from 0.2 to 0.5%.