有机无机配施下西北旱区麦田土壤N2O的排放特征及微生物特性

有机无机配施可为作物提供长效持续的营养物质来源,研究旱地农田有机无机配施带来的环境效应和土壤酶活性及微生物特性,对减少化肥面源污染,改善生态环境有重要意义.本试验以3个梯度氮水平(NO、N1、N2):0、150、300 kg·hm-2为主处理,单施化肥和有机无机配施(+M)为副处理,有机肥施用量为30 t·hm-2;测定了小麦生长季的温室气体N2O排放通量和土壤酶活性,硝态氮及铵态氮含量和土壤物理性质.结果表明,土壤N2O排放通量最高的为N2+M处理,排放通量达到0.190 4 mg·(m2·h)-1,N2+M处理较NO累计排放量提高了 255％;N2和N2+M处理N2O的排放通量和增温潜势高于N1和N1+M处理,而产量低于N1和N1+M处理;微生物量碳氮以N2+M处理分蘖期最多,分别为346.31 mg·kg-1和33.36 mg·kg-1;N2+M处理的土壤酶活性较高,其次是N2处理,NO和NO+M处理土壤酶活性较低;通径分析表明,铵态氮(NH4+-N)、土壤磷酸酶(AKP)和微生物量氮(MBN)对N2O排放通量的直接影响较大,其他间接影响较小可不予以考虑.研究旱地麦田有机无机配施的环境效益,与多方面因素相关,合理地配施有机肥可以平衡产量与土壤环境的综合效益.     

邻苯二甲酸二甲酯对典型细菌生长和氧化应激酶系的影响

邻苯二甲酸二甲酯(DMP)是一种在环境中广泛存在的有毒有机化合物,已被中国列为优先控制污染物之一。为研究邻苯二甲酸二甲酯(DMP)对典型细菌的影响,将Bacillus subtilis B19(G+)和Escherichia coli K12(G-)暴露于含不同浓度DMP(0,5,10,20,40和80 mg·L-1)的培养基中,监测它们的生长状态以及氧化应激酶系的变化。结果表明:DMP能抑制细菌生长,且其抑制作用随DMP的浓度增大而增强。在相同的实验条件下,DMP对Escherichia coli K12的抑制作用比Bacillus subtilis B19更为显著,且会使菌体的长度增加。随着DMP浓度的逐渐增高,菌体内的SOD、CAT和GST的活性也随之上升。这一现象表明菌体内的ROS浓度有所升高。通过观察DMP的作用浓度及对时间的效应过程,发现菌体内的酶活性呈现低浓度促进,高浓度抑制的趋势,并伴随出现氧化应激反应,该研究结果为进一步研究DMP对微生物的影响提供了重要基础。     

环草隆对城市绿地重金属污染土壤有机氮矿化、基础呼吸及相关酶活性的影响

城市土壤重金属和有机污染物复合污染广泛存在,而城市草坪除草剂的应用使城市绿地土壤的农药污染问题成为了新的关注点。为了准确评价城市绿地重金属污染土壤的农药污染生态风险,选择不同重金属污染程度的土壤为研究对象,以土壤有机氮矿化量、基础呼吸以及土壤酶活性为指标,采用室内模拟试验方法,探讨了草坪除草剂环草隆污染对土壤微生物的生态毒理效应。结果表明:(1)土壤有机氮矿化、基础呼吸、芳基硫酸酯酶和碱性磷酸酶对重金属和环草隆污染响应较为敏感,脲酶和蔗糖酶对重金属和环草隆污染不敏感。(2)环草隆浓度为0~1 000 mg·kg~(-1)范围内,和污染较轻的样点N土壤的碱性磷酸酶活性抑制(激活)率的线性相关关系显著,和污染较为严重的样点D和G土壤的芳基硫酸酯酶活性抑制(激活)率的线性关系显著。(3)土壤中环草隆对样点D和G土壤芳香硫酸酯酶活性、对样点N土壤碱性磷酸酶活性抑制(激活)率的EC10分别为568 mg·kg~(-1)、1 306 mg·kg~(-1)(抑制值)和56 mg·kg~(-1)(激活值)、99 mg·kg~(-1),EC50分别为1 901 mg·kg~(-1)、3 806 mg·kg~(-1)、2 321 mg·kg~(-1)。以上研究结果能够为城市土壤重金属和农药复合污染生态风险评价提供基础数据和技术方法。     

仿酶配合物四苯基卟啉铁(Ⅱ)的制备及模型油催化脱硫特性的研究

以四苯基卟啉为原料和氯化亚铁合成了仿酶配合物-四苯基卟啉铁(Ⅱ)(TPPFe),产物结构通过红外(IR)、紫外(UV)和元素分析得到验证。在H2O2氧化脱硫体系中考察了不同反应条件下产物对含二苯并噻吩(DBT)的模型油氧化脱硫的催化效果。结果显示,在催化剂四苯基卟啉铁(Ⅱ)用量为0.04 g、氧化剂H2O2用量为0.20 m L、反应温度为50℃及反应时间3 h的较优条件下,DBT的氧化脱除率可达62.0%,展现了产物较好的催化活性。     

镉致背角无齿蚌消化腺组织损伤及调节消化腺和斧足的抗氧化酶活性

采用酶学和组织学方法,研究了镉(Cd)对背角无齿蚌(Anodonta woodiana)消化腺和斧足组织中超氧化物歧化酶(SOD)和过氧化氢酶(CAT)活性和组织形态结构的影响.Cd浓度设置为4.22、8.43、16.86、33.72和67.45 mg·L-1,处理时间为24 h、48 h、72 h和96 h.结果显示,与对照组相比,同一时间随着Cd浓度的增加,消化腺中SOD和CAT活性,在24 h呈现升高的趋势;96 h消化腺中SOD活性逐渐升高,差异极显著(p0.01);48 h和72 h呈现先升后降的趋势.斧足中SOD和CAT在72 h和96 h时活性升高明显,差异显著或极显著(p0.01,p0.05).Cd浓度67.45 mg·L-1处理24 h,消化腺组织细胞结构变化不明显;在48 h以后,消化管间结缔组织松散,腺体结构损伤严重,上皮细胞形态结构异常,细胞界限模糊,甚至消失;细胞膜肿胀、变形;有的细胞核碎裂、明显肿胀甚至消失,上皮细胞部分与基膜分离、脱落;斧足组织未出现显著变化和损伤.研究表明,消化腺在酶活性和组织结构上对镉的反应较快且更具规律性,而且具有明显的时间和剂量效应关系.但是,斧足对镉的胁迫反应与消化腺相比较为迟缓,说明组织之间对重金属的敏感性具有差异性.     

地膜覆盖对农田土壤养分和生态酶计量学特征的影响

生态酶计量比可以用来衡量土壤微生物能量和养分资源限制状况.为明确地膜覆盖后农田土壤生态酶计量学特征,选取地膜覆盖下不同残膜积累量的农田土壤,利用荧光分析法测定其碳氮磷循环关键过程中的β-1,4-葡萄糖苷酶（BG）、β-1,4-N-乙酰氨基葡萄糖苷酶（NAG）和磷酸酶（ACP）的活性.探讨地膜覆盖对农田土壤养分循环和供应的影响.结果表明,施用化肥的土壤,覆膜使Olsen-P和NO^-₃-N分别降低至不覆膜土壤的48%～62%和16%～24%;而有机-无机配施的土壤,两者在覆膜条件下分别提高了144%～203%和1.9～5.1倍.覆膜下SOC∶TN在有机-无机配施土壤中降低了6.6%～25.8%,而SOC∶TP和TN∶TP却显著增加.覆膜土壤中MBC含量均显著低于不覆膜的土壤,然而由于MBN和MBP也随之降低,MBC∶MBN和MBC∶MBP无显著差异;覆膜使MBN∶MBP在S1和S2分别降低了36.6%和23.8%,而在S3和S4中分别提高了5.4和1.3倍.土壤中NAG∶ACP计量比与微生物生物量中相对应的元素的计量比趋势相似;而覆膜下BG∶NA...     

Effect of Florasulam on soil residues and enzyme activity of wheat in drylands北大核心CSCD

Florasulam is a three azole and pyrimidine sulfonamide herbicide, mainly used for weeds prevention and control in winter wheat fields. The main purpose of this experiment was to study the effects of different doses of Florasulam on soil residues and on the enzymatic activity of wheat cultivated in drylands, and to provide the theoretical basis for a scientific use of florasulam. Five doses (0, 15, 30, 45, and 60 mL/667 m2) of Florasulam were applied in order to detect differences in soil residue content and enzymatic activities. Soil residues and enzymatic activities (catalase, phosphatase, urease, dehydrogenase) were measured and analyzed after the 5 different doses of Florasulam were processed. The residual amount of Florasulam in the soils decreased gradually with the growth phase of wheat, and was lower than that of 0.01 mg/kg. The residual amount of Florasulam in different soil layers gradually decreased with the increase of soil thickness. The enzymatic activity of soils treated with Florasulam was basically T3 > T2 > T1 > CK > T4, where T3 was the highest, whereas T4 could inhibit the enzymatic activity. Under these experimental conditions, in order to decrease soil pollution and lower Florasulam residues, it is recommended to apply Florasulam at a concentration range of 30 to 45 mL/667 m2 © 2018 Science Press. All rights reserved.     

The physiological response and iron and potassium contents in the hairy roots of Brassica rape L. Under cadmium stress北大核心CSCD

The experiments were conducted to investigate the tolerance and enrichment capabilities by elucidating the physiological response and cadmium impact on iron and potassium accumulation amounts of brassica rape hairy roots under different cadmium concentrations by using liquid suspension culture method. The results showed the following. (1) The growth of hairy roots was not significantly different under low cadmium concentrations (below 100 μmol/L), whereas it was obviously inhibited under high cadmium concentrations (more than 100 μmol/L). Further, the maximum fresh weight of brassica rape hairy roots reached 4.34 g under 25 μmol/L cadmium stress after 7 days. (2) The content of ROS in brassica rape hairy roots increased with increasing concentrations of cadmium; the antioxidant enzyme activities of brassica rape hairy roots (SOD, POD, and CAT) decreased first and then increased with increasing cadmium concentrations under 1-day stress, whereas showed an opposite trend under 7-day stress. (3) PI staining and MDA content indicated that cellular damage was more serious with increasing cadmium concentrations. (4) With the increase of cadmium concentrations, cadmium content of hairy roots increased and reached maximum of 2.97 mg/g under 400 μmol/L cadmium stress after 7 days. The iron content also increased significantly with the maximal weight of 14.52 mg/g after 1-day cadmium stress, whereas no significant difference was noted under 7-day cadmium stress. The potassium content under 7-day cadmium stress was 1.6 times of that after 1-day stress (15.73 mg/g). The study showed that the physiological response of Brassica rape hairy roots was correlated with the concentration and time of cadmium stress. Moreover, cadmium stress caused metabolic disorders of iron and potassium in the hairy roots, but the hairy roots of Brassica rape had better enrichment effect on cadmium. © 2018 Science Press. All rights reserved.     

超顺磁性纳米材料对镉污染稻田土壤微生物和酶的影响

以磁性纳米Fe₃O₄和羟基磷灰石等为原料,制备出超顺磁性纳米Fe₃O₄-磷酸盐功能化材料（MFH）,通过在镉污染稻田土壤中投加MFH,对土壤进行磁选修复.选择对Cd具有高、低富集两种水稻,在修复后土壤中进行盆栽试验,研究MFH磁选修复对土壤微生物和酶的影响,探究该材料应用于农田镉污染修复的可能性.结果表明,施用MFH修复镉污染土壤,对Cd污染土壤有较好的修复效果,土壤中总Cd和有效态Cd浓度有了明显降低,总镉去除率为38.9%,有效镉下降率为27.3%,并且两种水稻籽粒中Cd含量均显著降低.采用MFH磁选修复土壤镉后,在两种水稻拔节期、抽穗期和成熟期土壤微生物群落多样性、群落丰富度均有所降低;栽培Cd高富集的玉针香水稻品种的处理在拔节期和抽穗期稻田土壤优势细菌Firmicutes丰度显著增加.采用MFH磁选修复土壤镉后,在两种水稻拔节期、抽穗期和成熟期土壤脲酶活性、过氧化氢酶活性以及土壤过氧化物酶活性均得到了提高;栽种Cd高富集品种玉针香的土壤POD酶活性比栽种低富集品种湘晚籼13号的土壤POD酶活性要略高,而脲酶活性则相反.     

不同UV-C辐射时间对豌豆幼苗光合特性及抗氧化酶活性的影响

研究了不同UV-C辐射时间对豌豆幼苗光合特性及抗氧化酶活性的影响。结果表明,UV-C辐射增强使叶片光合速率减弱,气孔导度、胞间CO2浓度、蒸腾速率和羧化效率明显降低,CO2补偿点升高。随着UV-C辐射时间的延长,POD和CAT活性先升高随后降低,SOD活性、叶绿素含量则逐渐降低,但丙二醛含量逐渐增加。这说明UV-C辐射增强引起抗氧化酶活性降低,使膜脂过氧化,导致光合作用减弱。