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131.
132.
Xiaoyang Zou Wenquan Niu Jingjing Liu Yuan Li Bohui Liang Lili Guo Yahui Guan 《Water, air, and soil pollution》2017,228(2):71
The quantities of residual mulch film in the soil will further increase with the wide application of agricultural plastic mulch film, and the pollution of residual mulch film, which is a continuous pollutant and the one that is difficult to degrade, is a major limiting factor for the sustainable development of agriculture in China. Residual mulch film in the soil inevitably affects soil hydrodynamic parameters, destroys the homogeneity of the soil texture, seriously impedes the movement of soil water and solutes, and thus greatly influences crop growth and fruit quality. To unravel the effects of residual mulch film on tomato growth and fruit quality, pot experiments in the greenhouse were carried out in 2015 and 2016 in Northwest China. Six levels of residual mulch film were applied: 0 kg ha?1 (CK), 80 kg ha?1 (T1), 160 kg ha?1 (T2), 320 kg ha?1 (T3), 640 kg ha?1 (T4), and 1280 kg ha?1 (T5). Plant height, stem diameter, dry biomass, yield, root length, root surface area, fruit shape index (FSI), soluble sugar content (SSC), organic acid (OA), vitamin C (VC), lycopene, and nitrate content (NC) were measured. Plant height, stem diameter, dry biomass, and yield of tomato had a downward trend as the residual mulch film amount increased. Root length and root surface area were significantly decreased with an increasing amount of residual mulch film, but root volume and root diameter showed an inconspicuous decrease. When the amount of residual mulch film was more than 80 kg ha?1, growth indexes, dry biomass, and yield of tomato showed a sharp decline. FSI, OA, and lycopene decreased as the residual mulch film amount increased, whereas SSC, VC, and NC showed an increase trend. With the increase in residual mulch film amount, the F and membership function values (X μ ) all showed a declining trend in comparison to the CK. Therefore, residual mulch film can aggravate the negative effects on the comprehensive fruit quality of tomato. 相似文献
133.
Treated wastewater (TWW) is an imperative nonconventional water resource for reuse in irrigation to cope with the water shortage and agricultural expansion in Egypt. The Bahr El-Baqar drain in Sharqia, Egypt, is one of the main drains in the Nile Delta that receives various types of wastewater. Monitoring and assessing the drain’s water quality were achieved by collecting georeferenced water samples along the drain during the 2015 summer and winter cropping seasons. Chemical, microbial, and parasitic analyses were performed. Additionally, surface soil samples irrigated with the drain water were gathered from the adjacent area to quantify the main physicochemical properties. Water analysis results revealed that the concentrations of most trace elements were within international standards and the Egyptian allowable levels for TWW reuse in agriculture. Oxygen depletion was observed for all samples collected. The microbial analysis indicated that there was fecal coliform contamination (>1000 per 100 mL) in the summer and winter samples. Concentrations of PO4 and SO4 were within the permissible level for irrigation use, whereas NH4, NO3, and MoO4 concentrations were higher than the recommended values for reusing Bahr El-Baqar water in irrigation. Based on the soil analysis results, Cd contamination was observed, whereas the Pb concentration in soils was slightly higher than its normal range. Mixing Bahr El-Baqar water with freshwater and implementing appropriate on-farm treatment before the reuse are recommended as a prerequisite for reusing Bahr El-Baqar water for irrigation. Bio-diesel fuel and energy oil crops are recommended for the studied region. 相似文献
134.
Cristina E. Almeida-Naranjo Patricio J. Espinoza-Montero Marcelo I. Muñoz-Rodríguez Cristina A. Villamar-Ayala 《Water, air, and soil pollution》2017,228(7):253
Hydraulic retention time (HRT) influence improving sludge flocculation with adding the polyelectrolytes (non-ionic, anionic, and cationic) was studied on an activated sludge (AS) system fed with synthetic domestic wastewater (SDW), dairy industry wastewater (DIW), and caramel industry wastewater (CIW). The sludge volumetric index, food/microorganism ratio (F/M), and mixed liquor volatile suspended solids at different HRTs (6, 8 and 10 h) were monitored on an experimental model. Results showed that both SDW and IW had the best sludge flocculation conditions at 8 h and 100 mL of non-ionic polyelectrolyte (0.2 mg L?1). In addition, this phenomenon reached the organic matter removal efficiencies of 95.9, 95.7, and 94.2% for SDW, DIW, and CIW, respectively. Therefore, optimum HRT increased the organic matter removal efficiencies by 10%, sludge concentration by 37% (22–55%), and F/M ratio by 70%. Moreover, the polyelectrolytes used in AS improved the sludge flocculation by 2.9 times. 相似文献
135.
Daniel E. León Henry Zúñiga-Benítez Gustavo A. Peñuela Héctor D. Mansilla 《Water, air, and soil pollution》2017,228(9):361
This study presents the main results about the removal of the antibiotic cefotaxime (CTX) under simulated sunlight radiation using heterogeneous photocatalysis with titanium dioxide (TiO2) and zinc oxide (ZnO) in aqueous solutions. The effects of pH and catalyst initial load on pollutant removal were assessed considering the response surface methodology and a central composite circumscribed experimental design, which allowed to determine the optimized conditions that lead to a higher substrate elimination. Experimental results indicated that evaluated parameters have a significant effect on antibiotic removal in both TiO2 and ZnO suspensions. In addition, the role of photogenerated holes, hydroxyl, and superoxide anion radicals on CTX degradation was evaluated to clarify the reaction mechanism. Finally, analysis of the dissolved organic carbon content in solutions and the antibacterial activity of treated samples showed that photocatalytic treatments were able to reduce a considerable portion of the organic matter present in the systems and its antimicrobial activity. 相似文献
136.
Ni Yan Mengjiao Li Yali Liu Fei Liu Mark L. Brusseau 《Water, air, and soil pollution》2017,228(12):453
The efficacy of two oxidant systems, iron-activated hydrogen peroxide (H2O2) and iron-activated hydrogen peroxide coupled with persulfate (S2O8 2?), was investigated for treatment of two chlorinated organic compounds, trichloroethene (TCE) and 1,2-dichloroethane (DCA). Batch tests were conducted at multiple temperatures (10–50 °C) to investigate degradation kinetics and reaction thermodynamics. The influence of an inorganic salt, dihydrogen phosphate ion (H2PO4 ?), on oxidative degradation was also examined. The degradation of TCE was promoted in both systems, with greater degradation observed for higher temperatures. The inhibition effect of H2PO4 ? on the degradation of TCE increased with increasing temperature for the iron-activated H2O2 system but decreased for the iron-activated hydrogen peroxide-persulfate system. DCA degradation was limited in the iron-activated hydrogen peroxide system. Conversely, significant DCA degradation (87% in 48 h at 20 °C) occurred in the iron-activated hydrogen peroxide-persulfate system, indicating the crucial role of sulfate radical (SO4 ??) from persulfate on the oxidative degradation of DCA. The activation energy values varied from 37.7 to 72.9 kJ/mol, depending on the different reactants. Overall, the binary hydrogen peroxide-persulfate oxidant system exhibited better performance than hydrogen peroxide alone for TCE and DCA degradation. 相似文献
137.
Karel Folens Marie-Christine Van Labeke Gijs Du Laing 《Water, air, and soil pollution》2017,228(12):457
Urban horticulture is gaining more and more attention in the context of sustainable food supply. Yet, cities are exposed to (former) industrial activities and traffic, responsible for emission of contaminants. Trace elements were monitored in soils located in the urban environment of Ghent (Belgium) and 84 samples of Lactuca satica L. lettuce grown on it. The effects of cultivation in soil versus trays, neighbouring traffic and washing of the lettuce before consumption were studied. The 0–30 cm top layer of soils appeared heterogenic in composition and enriched in Co, Cd, Ni and Pb within 10 m from the nearest road. Yet, no similar elevated concentrations could be found in the crops, except for As. Besides uptake from the roots, the presence of trace elements in the plants is also caused by the atmospheric deposition of airborne particulate matter on the leaf surface. Correlation analysis and principal component analysis (PCA) revealed that this latter transport pathway might particularly be the case for Pt, Pd and Rh. Concentrations of Cd did not exceed the 0.2 mg kg?1 (fresh weight) threshold for Cd in leafy vegetables set by the European Commission. Measurements to reduce the health risks include the washing of lettuce, which effectively reduced the number of samples trespassing the maximum Pb level of 0.3 mg kg?1 (fresh weight). Also, cultivation in trays resulted in a lower As content in the plants. Taking into account a vigilance on crop selection, cultivation substrate and proper washing before consumption are considered essential steps for safe domestic horticulture in urban environments. 相似文献
138.
Chen Meng Jianzhi Niu Xiang Li Ziteng Luo Xiaoqing Du Jie Du Xingna Lin Xinxiao Yu 《Journal of Soils and Sediments》2017,17(9):2357-2370
Purpose
Macropores have important effects on the movement of soil water, air, and chemical substances. However, the quantitative relationship between complex 3D soil macropore networks and forest communities remains unclear in the northern mountainous area in China. The objectives of this study were to (1) use industrial computed tomography (CT) scanning and image analysis to quantitatively analyze macropore networks in intact soil columns and (2) identify characteristics of soil macropore networks in different forest communities.Materials and methods
Intact soil columns (100-mm diameter, 300 mm long) were taken from six local forest communities with three replicates for a total of 18 samples. Industrial X-ray CT was used to scan soil samples; then, the scanned images were used to obtain the 3D images of rock fragments and macropore structures. Next, the macropore structure was quantified, including volume, diameter, surface area, length, angle, tortuosity, and number of macropores. This technique provided an accurate method to quantify the structure of macropores.Results and discussion
The analysis and results revealed that different forest communities influence soil macropore 3D structure significantly and in different ways. Macropores in mixed Pinus tabulaeformis, Castanea mollissima, and Ulmus pumila forest had the largest diameter, surface area, network density, and length density of macropores as well as the smallest mean tortuosity of soil macropores. This is caused by the fact that mixed forest soils had more complex root systems, better soil structure, and more biotic activity. Within the soils of a single forest community, macropore porosity, network density, surface area density, and length of macropores decreased with increased soil depth, because more roots and more biological activity were present in the surface soil.Conclusions
Advanced industrial CT technology can allow an accurate quantification of soil macropore structure. This is important because this type of structure has significant effects on soil water, air, and chemical transport. The results suggest that mixed forest is the best afforestation model in the northern mountainous area in China because of its ability to improve soil structure.139.
Yuanchun Yu Jingyu Yang Shucai Zeng Daoming Wu Douglass F. Jacobs Joshua L. Sloan 《Journal of Soils and Sediments》2017,17(9):2230-2238
Purpose
Chinese fir (Cunninghamia lanceolata (Lamb.) Hook) is an important native tree species in China. Consecutive cropping traditionally occurs in Chinese fir plantations (CFPs), but this practice has resulted in productivity declines in subsequent rotations. This study was designed to better understand the change of soil properties in the continuous cropping CFPs.Materials and methods
We investigated soil pH, soil organic matter (SOM), and nutrient contents in different soil layers and in rhizosphere soil (RS) and non-rhizosphere soil (NRS) under CFPs of different ages and in different rotations.Results and discussion
In the upper (0–20 cm) soil layer, soil pH decreased, while SOM increased, beneath mature CFPs with consecutive rotations. Total nitrogen (TN), available potassium, and available phosphorus contents in the upper soil layers did not differ significantly with consecutive rotations. Soil pH in RS was significantly lower than in NRS under mature plantations of the third rotation. Soil organic matter, TN, and available nitrogen did not differ between RS and NRS. Available phosphorus in RS was consistently lower than in NRS, and was highly deficient in the third rotation.Conclusions
We conclude that no severe soil nutrient degradation occurred in the continuous cropping CFPs examined in this study, with soil acidification and phosphorus deficiency being two primary problems observed.140.