夏季红碱淖水化学特征及影响因素分析

以陕北红碱淖为研究对象,2020年6月对其湖泊水体选取9个采样点采样,分析阴阳离子的空间分布,并利用Piper三线图及离子比例关系分析离子来源及影响因素,探讨红碱淖水化学特征及其影响因素。结果表明：红碱淖水体阳离子测定值为Na+＞Mg2+ ＞Ca2+ ＞K+,阴离子测定值为HCO-3＞Cl-＞SO42-,水化学类型现状为HCO3·Cl-Na型,水化学特征主要受碳酸盐岩和蒸发盐岩共同作用。红碱淖主要受岩石风化溶解作用控制,人类活动对水化学特征也有一定的影响。     

SBAR反应器生物膜生长特性

采用载体吸附法的自固定化方式培养出活性良好的颗粒污泥———悬浮载体生物膜颗粒,并建立了生物膜物化特性和生化特性的系统分析方法。试验装置采用SBAR反应器,投加人工配水,裸载体为陶粒(湿视密度1 310 kg/m3、平均粒径0.55 mm)。试验运行了110 d,反应器内最大污泥浓度12.4 g/L,最大附着污泥浓度9.52 g/L。     

Effect of chemical dose on phosphorus removal and membrane fouling control in a UCT-MBR

Phosphorus removal was enhanced effectively by dosing aluminum sulfate and effluent phosphorus concentration was lower than 0.5 mg/L. Sludge activity was not inhibited but improved slightly with addition of aluminum sulfate. EPS concentrations both in mixed liquid and on membrane surface were decreased, contributing to the effective mitigation of membrane fouling. To enhance phosphorus removal and make the effluent meet the strict discharge level of total phosphorus (TP, 0.5 mg/L), flocculant dosing is frequently applied. In this study, the performance of aluminum sulfate dosing in a University of Cape Town Membrane Bioreactor (UCT-MBR) was investigated, in terms of the nutrients removal performance, sludge characteristics and membrane fouling. The results indicated that the addition of aluminum sulfate into the aerobic reactor continuously had significantly enhanced phosphorus removal. Moreover, COD, NH₄⁺-N and TN removal were not affected and effluent all met the first level A criteria of GB18918-2002. In addition, the addition of aluminum sulfate had improved the sludge activity slightly and reduced trans-membrane pressure (TMP) increase rate from 1.13 KPa/d to 0.57 KPa/d effectively. The membrane fouling was alleviated attributed to the increased average particle sizes and the decreased accumulation of the small sludge particles on membrane surface. Furthermore, the decline of extracellular polymeric substance (EPS) concentration in mixed sludge liquid decreased its accumulation on membrane surface, resulting in the mitigation of membrane fouling directly.     

Field tests to study the dynamics of weed inhibition of allelopathic rice and microbial physiological traits of rice rhizospheric soils北大核心CSCD

The weed inhibition of allelopathic rice PI312777 and nonallelopathic rice Lemont, allelopathic potential of rice rhizospheric soils, as well as the microbial physiological traits of rice rhizospheric soils, were studied by field tests after weedremoving and weed treatments. The results showed that the inhibitory rate of PI312777 at the 7-leaf stage on paddy weeds was 85.82%. Results of the Soil-Agar Sandwich method revealed that the allelopathic potential of PI312777 rhizospheric soils on the inhibitory rate of plant dry weight of barnyard grass was significantly higher at the 5-leaf stage than that at the 3-leaf stage, and increased by 20.16% from the 3-leaf stage to the 5-leaf stage after weed treatment. When at the same leaf stage, the soil microbe biomass carbon and soil respiration, the number of soil bacteria, and activity of soil enzymes (urease, protease, and sucrase) were significantly higher in PI312777 rhizospheric soils than in Lemont rhizospheric soils; they were also higher after the weed-removing treatment than after weed treatment. The largest increase of soil allelopathic potentials and soil microbial physiological indexes in PI312777 rhizospheric soils appeared from the 3-leaf stage to the 5-leaf stage. In case of weed treatment, the allelopathic potential of PI312777 rhizospheric soils on the soil microbe biomass carbon, soil respiration, the number of soil bacteria, activity of urease, activity of protease, and activity of sucrase increased by 53.11%, 51.56%, 38.97%, 44.83%, 60.00%, and 41.92%, respectively, from the 3-leaf stage to the 5-leaf stage. These results indicated that rice allelopathy had a close relationship with the activity of rhizospheric soils. Rice allelochemicals lead to the change of soil microbes; rice allelopathy is a process based on plant-soil interaction. © 2018 Science Press. All rights reserved.     

纳米金属氧化物对土壤酶活性的影响研究进展

纳米金属氧化物的大量生产和广泛应用使其不可避免地进入环境中,土壤是其释放到环境中主要的汇。纳米颗粒由于尺寸效应,具有许多独特的物理化学性质,其进入环境后潜在的生态和健康风险问题日益受到研究者的关注。土壤酶是土壤生物化学过程的主要参与者,也是生态系统物质循环和能量流动过程中最活跃的生物活性物质。土壤酶活性的变化能反映土壤中生化反应的情况,可作为评价土壤中纳米材料污染状况的生物学指标。本文较系统地回顾和总结了纳米金属氧化物对土壤酶活性的影响及可能的影响途径,探讨了纳米金属氧化物作用于土壤酶的主要影响途径,并展望了未来研究主要发展方向。     

磁场强化曝气生物滤池处理高浓度氨氮废水的研究

本研究采用普通陶粒、普通陶粒外加静态磁场（50 mT）和磁性陶粒（2.5 mT和5 mT）曝气生物滤池处理高浓度氨氮废水,对比研究了不同类型和强度的磁场强化下曝气生物滤池的硝化反硝化效果,并通过分子生物学手段系统分析了磁场强化硝化反硝化的微生物学机理.结果表明,随着氨氮浓度增加,磁场强化下曝气生物滤池硝化反硝化效果显著高于普通陶粒曝气生物滤池.当氨氮浓度提高到400 mg·L^-1时,磁场强化曝气生物滤池（磁性陶粒和外加静态磁场）的氨氮去除率大于97%,高于普通陶粒曝气生物滤池的氨氮去除率（88%）;磁场强度为2.5 mT的磁性陶粒曝气生物滤池的总氮去除率达到67%,显著高于其他3个曝气生物滤池（p<0.05）（分别为55%、54%和55%）.分子生物学检测结果表明,2.5 mT磁场强度的磁性陶粒上生物膜的硝化反硝化酶活性和功能基因丰度大幅提高,硝化反硝化细菌的丰度及多样性显著增加.     

炭化苹果枝通过减少土壤DTPA-Cd降低苹果砧木镉积累和镉伤害

为探究炭化苹果枝对苹果砧木镉积累和镉伤害的影响,以盆栽苹果砧木（平邑甜茶）实生苗为试材,在施有0.5%和1%（质量分数）的炭化苹果枝的盆土中灌入含镉（CdSO₄）营养液,分析盆土中二乙烯三胺五乙酸（diethylenetriamine pentaacetic acid,DTPA）所提取镉（DTPA-Cd）及根茎叶镉含量,检测根系和叶片抗氧化酶活性和根系细胞死亡情况以及叶片光合速率.结果表明,施用炭化苹果枝的盆土DTPA-Cd含量显著低于未施用炭化苹果枝的,其中施用0.5%和1%的炭化苹果枝使盆土DTPA-Cd含量在处理第12 d分别比未施的降低17.50%和25.55%;施入炭化苹果枝明显降低苹果砧木根茎叶镉积累量,提高根系和叶片超氧化物歧化酶（SOD）、过氧化物酶（POD）和过氧化氢酶（CAT）活性,降低根系和叶片·O₂^-生成速率、H₂O₂和MDA含量,还降低根系细胞死亡比率,提高叶片光合速率,其中施用（ω）0.5%和1%的炭化苹果枝使根系镉含量在处理第12 d分别比未施的降低29.49%和37.18%,使根细胞死亡比率分别比未施的降低22.73%和29.09%.这些说明施用炭化苹果枝可通过降低土壤DTPA-Cd含量,减少苹果砧木对镉的吸收和积累,减轻根系细胞以及叶片光合性能所受到的伤害,施用1%的比施用0.5%的效果更显著.     

镨对镉胁迫下水稻幼苗根系生长和根系形态的影响

为了解稀土镨对镉胁迫下水稻(Oryza sativa L.)根系毒害的缓解效应,以水稻幼苗为实验材料,采用溶液培养方法,研究了50μmol·L-1镉胁迫下不同浓度镨对水稻幼苗根系鲜质量、形态和根系活力的影响。结果表明,50μmol·L-1镉胁迫下,水稻根系生长受到明显的抑制,根系鲜质量、根长、根表面积、根体积和根系活力明显降低,且随镉处理时间的延长,抑制程度加重。但镉对根系平均直径无明显影响。23～184μmol·L-1的镨对水稻镉毒害有一定的缓解效果,可不同程度的减轻镉对幼苗的伤害,促进了镉胁迫下根系鲜质量、根系长度、根系表面积和根系体积的增加,提高了根系活力,且随着处理时间的延长,缓解效应愈加明显,与单镉毒害相比,镨处理5天后根系鲜质量、根长、根表面积、根体积和根系活力分别提高了0.92%～14.8%、1.61%～16.3%、2.57%～20.3%、1.52%～17.2%和3.71%～32.8%,处理10d后根系鲜质量、根长、根表面积、根体积和根系活力分别提高了2.55%～31.2%、1.44%～21.4%、1.78%～27.2%、2.16%～23.4%和8.14%～52.9%;此外,23～184μmol·L-1的镨处理对直径≤1.0mm的根长和根表面积、直径0.5mmD≤1.0mm的根体积影响较大,其分别提高了0.9%～24.3%、1.9%～32.6%、0.4%～33.2%,其中以92μmol·L-1镨缓解效果最好。但随着镨浓度的进一步加大,当镨浓度达到230μmol·L-1时,反而会使水稻根系受到更严重的毒害。     

三种典型纳米颗粒物造成的人体肺细胞氧化应激和炎症效应(Oxidative Stress and Inflammatory Effect on A549 Cell Line Induced by Three Typical Nano-Particles )

采用体外细胞暴露实验研究了人肺腺癌细胞系(A549)单层细胞暴露于50和500μg·mL-1两种浓度纳米氧化钛、纳米氧化硅、碳纳米管和晶体石英砂等四种颗粒物后产生的氧化应激和炎症反应.用细胞活度、细胞内活性氧总量和细胞上清液中白细胞介素8(IL-8)表达量表征暴露效应.研究结果表明,纳米氧化钛、纳米氧化硅和碳纳米管在体外暴露实验过程中均发生不同程度的聚集;细胞暴露48h后,三种纳米颗粒物均使A549细胞活度下降,诱导细胞产生过量活性氧,同时刺激细胞IL-8表达量增高;三种纳米颗粒物中,纳米氧化钛和纳米氧化硅对细胞活度影响较大,碳纳米管诱发的炎症效应较另两种纳米材料强.     

Release of elements from municipal solid waste incineration fly ash

The element-release behavior of municipal solid waste incineration fly ash was explored through leaching test with continuous set-point pH (pH_stat test) and serial single reaction cell (SSRC) tests. First, the relationship between element release and acid neutralizing capacity (ANC) consumption was examined with a pH_stat test. Four types of release behaviors were identified which are characteristic for different elements: (1) release curves that were almost linear with ANC consumption (Ca, Zn, and Cd); (2) release that was significantly faster than ANC (Na, K, and Cl); (3) curves that featured a strong increase with ANC consumption, after a transient release, followed by an almost equal decrease (Si and S); and (4) release that is strongly retarded compared with ANC consumption (Cr, Cu, and Pb). In the SSRC system, it the existence of a pH front and a wash-out phenomenon is demonstrated. Combining the results from the SSRC test with the kinetic analysis of the ANC system in the pH_stat test, it was inferred that less than one-third of the ANC measured from a batch pH titration plays a neutralization role in a field situation. The methodologies described may provide a powerful set of tools for systematic evaluation of element release from solid wastes.