Research and application of method of oxygen isotope of inorganic phosphate in Beijing agricultural soils

Phosphorus (P) in agricultural ecosystems is an essential and limited element for plants and microorganisms. However, environmental problems caused by P accumulation as well as by P loss have become more and more serious. Oxygen isotopes of phosphate can trace the sources, migration, and transformation of P in agricultural soils. In order to use the isotopes of phosphate oxygen, appropriate extraction and purification methods for inorganic phosphate from soils are necessary. Here, we combined two different methods to analyze the oxygen isotopic composition of inorganic phosphate (δ¹⁸O_P) from chemical fertilizers and different fractions (Milli-Q water, 0.5 mol L^?1 NaHCO₃ (pH = 8.5), 0.1 mol L^?1 NaOH and 1 mol L^?1 HCl) of agricultural soils from the Beijing area. The δ¹⁸O_P results of the water extracts and NaHCO₃ extracts in most samples were close to the calculated equilibrium value. These phenomena can be explained by rapid P cycling in soils and the influence of chemical fertilizers. The δ¹⁸O_P value of the water extracts and NaHCO₃ extracts in some soil samples below the equilibrium value may be caused by the hydrolysis of organic P fractions mediated by extracellular enzymes. The δ¹⁸O_P values of the NaOH extracts were above the calculated equilibrium value reflecting the balance state between microbial uptake of phosphate and the release of intracellular phosphate back to the soil. The HCl extracts with the lowest δ¹⁸O_P values and highest phosphate concentrations indicated that the HCl fraction was affected by microbial activity. Hence, these δ¹⁸O_p values likely reflected the oxygen isotopic values of the parent materials. The results suggested that phosphate oxygen isotope analyses could be an effective tool in order to trace phosphate sources, transformation processes, and its utilization by microorganisms in agricultural soils.     

Preparation and performance characterization of a new dust suppressant with a cross-linked network structure for use in open-pit coal mines

Environmental Science and Pollution Research - In an effort to control dust pollution in open-air environments such as pit coal mines and coal transportation systems, a new dust suppressant with a...     

废弃风机叶片非金属粉末热解产物增强环氧树脂复合材料的制备与性能探究

针对风机叶片大量报废后处理处置的问题,将废弃风机叶片非金属粉末 (retired wind turbine blades,RWTBs) 热解后的产物 (记作P-RWTBs) 作为填料,三乙烯四胺 (triethylenetetramine,TETA) 为固化剂,环氧树脂 (epoxy resin,EP) 为基体,陶瓷粉 (ceramic powder,CP) 和KH-560偶联剂为添加剂制备复合材料样条,实现了废弃风机叶片的回收及再利用。通过浇筑成型法制备了复合材料,探究了热解条件对RWTBs 热解失重率的影响及CP添加量、KH-560的质量分数对复合材料的力学性能、耐热性能和耐腐蚀性能的影响。结果表明,当升温速率为10 ℃·min⁻¹时,热解的最佳条件为600 ℃停留6 h,此时RWTBs 表面的热固性树脂被彻底热解。当以TETA为固化剂、20% CP为添加剂、P-RWTBs为填料时,通过2% KH-560处理后制备的P-RWTBs-2%KH-560/20% CP/EP 复合材料具有较好的力学性能,拉伸强度、弯曲强度和冲击强度可分别达到55.59 MPa、86.43 MPa和23.99 kJ·m⁻²,相较于TETA/EP,分别提高了23.1%、77.1%和35.3%。当温度达到360.7 ℃时,P-RWTBs-2%KH-560/20% CP/EP复合材料的热解失重率为30%,相较于TETA/EP提高了15.9 ℃。经过48h酸浸后的P-RWTBs-2%KH-560/20% CP/EP复合材料拉伸强度、弯曲强度和冲击强度分别降低了10%、2.4%和5.4%,相较于RWTBs/20% CP/EP,具有更强的耐腐蚀性能。P-RWTBs-2%KH-560/20% CP/EP复合材料性能的提升主要是由于KH-560接枝在P-RWTBs表面形成了一层硅烷分子覆盖层,其中亲水基团与EP基体中的羟基发生氢键作用,增强了填料与基体之间的相互作用力,加强了复合材料的界面结合强度,同时提升了复合材料的亲水性和亲油性,使其表面更加稳定光滑,能有效减缓腐蚀速度。该研究可为废弃风机叶片的资源回收再利用提供一个新的思路。     

Field crops (Ipomoea aquatica Forsk. and Brassica chinensis L.) for phytoremediation of cadmium and nitrate co-contaminated soils via rotation with Sedum alfredii Hance

Environmental Science and Pollution Research - Phytoremediation coupled with crop rotation (PCC) is a feasible strategy for remediation of contaminated soil without interrupting crop production....     

Treatment of drilling fluid waste during oil and gas drilling: a review

Environmental Science and Pollution Research - Oil and gas exploration and development provide important energy sources for the world, and drilling fluid is an essential engineering material for...     

Treatment of fluorine-containing pharmaceutical wastewater by VUV/UV process

Environmental Science and Pollution Research - As an advanced oxidation process, vacuum ultraviolet/ultraviolet (VUV/UV) has been intensively studied for drinking water treatment, but assessment of...     

Immobilization of Cd2+ and Pb2+ by biomineralization of the carbonate mineralized bacterial consortium JZ1

Environmental Science and Pollution Research - Microbially induced carbonate precipitation (MICP) has been proven to effectively immobilize Cd2+ and Pb2+ using a single bacterium. However, there is...     

Harvesting of Chlorella sp. using hollow fiber ultrafiltration

Introduction

The suitability of the application of ultrafiltration (UF) to harvest Chlorella sp. from the culture medium was examined. We investigated the effects of two improved UF system, forward air?Cwater flushing and backwash with permeate, on the concentration process.

Materials and methods

Backwash with permeate was selected as an optimization of the improved UF system, which was more effective for permeate flux recovery. Moreover, the hollow fiber UF system by adding periodical backwash with permeate was examined for Chlorella sp. harvesting.

Results and discussion

It was found that Chlorella sp. could be concentrated with high recovery in a lab-scale experiment. An overall algal biomass recovery of above 90% was achieved when the volume concentration factor was 10. For an original biomass of 1.3?±?0.05?g/L, 1?min backwash followed by 20?min forward concentrating was more effective, which resulted in a recovery of 94% and a high average flux of 30.3?L/m²/h. In addition, the algal recovery was highly correlated to the volume concentration factor and the initial biomass. A high concentration factor or a high initial biomass resulted in a low biomass recovery.