荧光假单胞菌产铁载体对油麦菜吸收砂基和水基中镉的影响

选取荧光假单胞菌(Pseudomonas fluorescence)作为代表微生物菌种,考察了菌体产铁载体的规律,并研究了添加菌体对水培油麦菜吸收砂基和水基中Cd2+的影响。在此基础上分析了根际微生物与重金属之间的相互作用机理,为典型微生物在重金属污染治理中的作用提供了可借鉴的理论基础。通过平板实验证实荧光假单胞菌菌体代谢能够产生铁载体,且产铁载体量随着菌体培养时间的增加而增大。铁载体能够与Cd2+络合,将Cd2+固定,使得油麦菜对Cd2+的吸收减少。添加菌体后,采用砂基和水基方式培养的油麦菜中Cd的含量分别减少了27.23%~50.74%和10.57%~45.53%,表明菌体形成的根际微生物能抑制油麦菜对Cd的吸收。因此,微生物代谢产生的铁载体可在重金属污染的植物修复中起到重要作用。     

超滤法回收PVA并回用于生产的扩大实验

本工作采黑由美国引进的超滤装置,在湖南湘潭纺织印染厂进行了从退浆废水中回收pVA的生产性扩大试验,探讨了料液温度、浓度,操作压力等因素对超滤性能的影响,并简单介绍了回收浆料回用于浆纱,织布及印染生产的情况。     

油气田污泥无害化处理途径探讨

我国污泥处理和处置研究起步较晚,大部分为农田堆肥处置,这对环境保护有不良的影响。在室内进行了油田污泥固化试验研究。研究结果表明:水泥固化污泥可用于制作筑路材料,以水泥、石灰、水玻璃为主要固化剂的污泥可进行填埋处理,含油污泥可制成煤球,可将含油污泥焚烧处理,可以用污泥焚烧灰制砖。这些方法都是污泥后续无害化、资源化处理的有效手段。     

Morphology and composition of particles emitted from conventional and alternative fuel vehicles

Size, morphology, and composition of airborne particles strongly affect human health and visibility, precipitation, and the kinetic characteristics of particles. In this study, the morphology and chemical composition of particles emitted from conventional (diesel and gasoline) and alternative (CNG and methanol) fuel vehicles were characterized through scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX). The SEM images revealed that the size of primary particles (without agglomeration) was approximately 10 nm in the exhaust from all the tested vehicles. The particles emitted from gasoline vehicle (GV), CNG vehicle (CNGV), and methanol vehicle (MV) had the same median diameter, 62 nm, which was smaller than those from heavy diesel vehicle (HDV) and light diesel vehicle (LDV). Soot was observed in the HDV, LDV, and GV samples but not in the CNGV and MV. The fractal dimension, which was used to quantify the degree of irregularity of soot, was 1.752 ± 0.014, 1.789 ± 0.076, and 1.769 ± 0.006 in the exhaust from HDV, LDV, and GV samples, respectively. The particles discharged by all tested vehicles contained the elements C, O, Fe, and Na. The main element in the samples of HDV, LDV, and GV was C, while O was the main element in the samples of alternative fuel vehicles. The profiles of minor elements were more complex in the emissions of alternative fuel vehicles than those in the emissions of conventional fuel vehicles. The results improved our understanding of the morphology and elemental composition of particles emitted from vehicles powered by diesel, gasoline, CNG, and methanol.

     

Field investigation into unsaturated flow and transport in a fault: model analyses

Results of a fault test performed in the unsaturated zone of Yucca Mountain, Nevada, were analyzed using a three-dimensional numerical model. The fault was explicitly represented as a discrete feature and the surrounding rock was treated as a dual-continuum (fracture-matrix) system. Model calibration against seepage and water-travel-velocity data suggests that lithophysal cavities connected to fractures can considerably enhance the effective fracture porosity and therefore retard water flow in fractures. Comparisons between simulation results and tracer concentration data also indicate that matrix diffusion is an important mechanism for solute transport in unsaturated fractured rock. We found that an increased fault-matrix and fracture-matrix interface areas were needed to match the observed tracer data, which is consistent with previous studies. The study results suggest that the current site-scale model for the unsaturated zone of Yucca Mountain may underestimate radionuclide transport time within the unsaturated zone, because an increased fracture-matrix interface area and the increased effective fracture porosity arising from lithophysal cavities are not considered in the current site-scale model.     

羟基氧化铝吸附去除六价铬

以水合氧化铝和氢氧化铝聚团微球作为前躯体制备羟基氧化铝,并研究自制羟基氧化铝对水中六价铬的吸附性能。实验考察了吸附过程中溶液pH、羟基氧化铝投加量、吸附时间、温度以及离子强度对吸附效果的影响。研究结果表明,在pH=7,温度25℃,吸附剂剂量为2 g/L、初始浓度为10 mg/L的六价铬最大去除率为97.6%,吸附平衡时间为60 min。同时羟基氧化铝吸附六价铬的吸附符合Freundlich和Temkin吸附模型,吸附动力学适合伪二级动力学模型。     

Arsenic sorption by red mud-modified biochar produced from rice straw

Red mud-modified biochar (RM-BC) has been produced to be utilized as a novel adsorbent to remove As because it can effectively combine the beneficial features of red mud (rich metal oxide composition and porous structure) and biochar (large surface area and porous structure properties). SEM-EDS and XRD analyses demonstrated that red mud had loaded successfully on the surface of biochar. With the increasing of pH in solution, arsenate (As(V)) adsorption on RM-BC decreased while arsenite (As(III)) increased. Arsenate adsorption kinetics process on RM-BC fitted the pseudo-second-order model, while that of As(III) favored the Elovich model. All sorption isotherms produced superior fits with the Langmuir model. RM-BC exhibited improved As removal capabilities, with a maximum adsorption capacity (Q_max) for As(V) of 5923 μg g^?1, approximately ten times greater than that of the untreated BC (552.0 μg g^?1). Furthermore, it has been indicated that the adsorption of As(V) on RM-BC may be strongly associated with iron oxides (hematite and magnetite) and aluminum oxides (gibbsite) by X-ray absorption near-edge spectroscopy (XANES), which was possibly because of surface complexation and electrostatic interactions. RM-BC may be used as a valuable adsorbent for removing As in the environment due to the waste materials being relatively abundant.     

超声波强化污水厌氧生物处理综述

通过对超声波辐射促进微生物活性以及超声波强化污水好氧生物处理、厌氧污泥减量化处理等作用机制的分析研究,探讨将超声波应用于强化污水厌氧生物处理的可行性.同时对超声波强化污水厌氧生物处理的应用前景进行了展望.     

我国粮食安全保障中改善农业环境的途径

本文分析了我国粮食安全及粮食持续生产所依托的农业环境状况。从我国粮食生产状况与经济发展水平看,全国粮食生产处于结构性过剩与低水平安全中,区域性粮食安全与不安全并存;耕地资源、水资源以及农民的经济收入状况等均不容乐观,加之自然灾害加重,粮食生产的环境成本将随之增加,这将影响我国未来粮食安全。为此,本文提出了走农业集约化道路是解决我国粮食安全与改善环境的基本途径。     

微塑料对双齿围沙蚕生理代谢的影响研究

为探讨微塑料对双齿围沙蚕生理代谢的影响,本文研究了聚丙烯(PP)、聚酰胺(PA)和聚氯乙烯(PVC)3种微塑料在不同浓度(0.1％、1％和5％)和暴露时间下对双齿围沙蚕体内过氧化氢酶(CAT)、乙酰胆碱酯酶(AchE)活性以及代谢指标排氨率和呼吸速率的影响.结果表明,随微塑料浓度的升高,双齿围沙蚕体内CAT活性显著提升,5％浓度下双齿围沙蚕体内CAT活性最高;PVC对双齿围沙蚕体内AchE活性表现为低浓度(0.1％)抑制、高浓度(5％)促进的作用;PP和PA在不同浓度下对双齿围沙蚕体内AchE酶活性均表现为促进作用;随着微塑料浓度的升高,双齿围沙蚕的排氨率和呼吸速率显著升高(P<0.05).综上,微塑料在高浓度条件下,在一定时间内可以对双齿围沙蚕产生氧化胁迫作用,并一定程度上影响其排氨率和呼吸速率.