烧失量法测定土壤有机质含量的实验条件探究

烧失量法是测定有机质含量的可靠手段,以其方便、快捷、经济等优点被广泛应用于土壤学、地质学、湖泊学等研究中。但由于对煅烧过程的研究较少,煅烧条件的选择不统一,使得不同实验条件下测定结果的可比性较差。本研究使用带烧失称重系统的马弗炉,对中国北方有机质含量不同的三种类型土壤进行了烧失量测定实验,通过观察土壤重量随温度和时间变化的连续失重过程,对煅烧温度、煅烧恒温时长、样品量及升温速率等实验条件进行了系统研究,确立了烧失量法适宜的实验条件组合。实验结果表明:升温速率宜选择3℃/min;样品量建议选用3~5 g,有机物含量低的样品可适量增加;不同类型土壤的适宜煅烧温度略有差别,黑土和栗钙土建议选用550℃,而黑垆土选用500℃或550℃;恒温2h可获得较为稳定的烧失量结果。     

吹扫捕集／气相色谱－质谱法测定水中挥发性有机物的质量控制研究

影响吹扫捕集／气相色谱－质谱法测定水中挥发性有机物的因素很多,如空气中的挥发性有机物可能通过采样瓶的扩散,使准确性和可靠性降低。结合环境监测工作实际,按分流比20∶1分流进样,选择11＃捕集阱,样品解析时选择解析时间0．5 min,选择吹扫管支座温度为40℃,选择与目标化合物相比相对保留时间在0．8～1．20之间内标物,同时样品采集、保存、运输和器皿清洗等条件严格按照国标方法进行,可以确保吹扫捕集／气相色谱－质谱法测定的精密度和准确度。     

炼油行业泄漏检测与修复技术实践研究

炼油行业排放的大气污染物主要是挥发性有机物,是形成二次污染物的重要前体物,也是引发大气环境问题的重要污染物.以天津某炼油企业泄漏检测与修复技术的工作实践为例,结合炼油行业生产装置的工艺特点,介绍在该行业开展泄漏检测与修复技术时的工作流程,包括设备和管线组件密封点位的建档、检测、泄漏点位的修复、复测以及泄漏量核算方法,对炼油行业开展泄漏检测与修复工作减少挥发性有机物无组织的排放起到借鉴作用.     

微生物调控对有机废物堆肥的理化性质影响研究

研究了微生物调控对有机生活废物堆肥的理化性质影响,结果表明:添加微生物处理比对照处理提前1 d进入高温分解期,且高温(>50℃)持续时间为6 d,较对照处理的长3 d;pH呈先升高后降低的趋势,微生物处理的pH值对照处理的偏低;EC值呈"M"型变化规律,微生物处理的EC值较对照高;在整个堆肥过程中微生物处理的胡敏酸E 4/E 6值都低于对照,表明添加菌剂有利于生活垃圾腐殖化;以发芽指数GI均大于80%这一标准评判,微生物处理比对照提前8d腐熟.     

Volatile organic compound emissions from straw-amended agricultural soils and their relations to bacterial communities: A laboratory study

A laboratory study was conducted to investigate volatile organic compound(VOC) emissions from agricultural soil amended with wheat straw and their associations with bacterial communities for a period of 66 days under non-flooded and flooded conditions. The results indicated that ethene, propene, ethanol, i-propanol, 2-butanol, acetaldehyde, acetone,2-butanone, 2-pentanone and acetophenone were the 10 most abundant VOCs, making up over 90% of the total VOCs released under the two water conditions. The mean emission of total VOCs from the amended soils under the non-flooded condition(5924 ng C/(kg·hr)) was significantly higher than that under the flooded condition(2211 ng C/(kg·hr)). One "peak emission window" appeared at days 0–44 or 4–44, and over 95% of the VOC emissions occurred during the first month under the two water conditions. Bacterial community analysis using denaturing gradient gel electrophoresis(DGGE) showed that a relative increase of Actinobacteria, Bacteroidetes, Firmicutes and γ-Proteobacteria but a relative decrease of Acidobacteria with time were observed after straw amendments under the two water conditions. Cluster analysis revealed that the soil bacterial communities changed greatly with incubation time, which was in line with the variation of the VOC emissions over the experimental period. Most of the above top 10 VOCs correlated positively with the predominant bacterial species of Bacteroidetes, Firmicutes and Verrucomicrobia but correlated negatively with the dominant bacterial species of Actinobacteria under the two water conditions. These results suggested that bacterial communities might play an important role in VOC emissions from straw-amended agricultural soils.     

Fate and transport of the β-adrenergic agonist ractopamine hydrochloride in soil–water systems

The feed additive ractopamine hydrochloride was fortified at four concentrations into batch vials containing soils that differed in both biological activity and organic matter(OM).Sampling of the liquid layer for 14 days demonstrated that ractopamine rapidly dissipated from the liquid layer. Less than 20% of the fortified dose remained in the liquid layer after 4 hr,and recoveries of dosed ractopamine ranged from 8 to 18% in the liquid layer at 336 hr. Sorption to soil was the major fate for ractopamine in soil:water systems, i.e., 42%–51% of the dose at14 days. The major portion of the sorbed fraction was comprised of non-extractables; a smaller fraction of the sorbed dose was extracted into water and acetone, portions which would be potentially mobile in the environment. Partitioning coefficients for all soils suggested strong sorption of ractopamine to soil which is governed by hydrophobic interactions and cation exchange complexes within the soil OM. Ractopamine degradation was observed, but to mostly non-polar compounds which had a higher potential than ractopamine to sorb to soil. The formation of volatiles was also suggested. Therefore, despite rapid and extensive soil sorption,these studies indicated a portion of ractopamine, present in manures used to fertilize soils,may be mobile in the environment via water-borne events.     

融雪对土壤溶解性有机质溶析作用的影响

利用土壤浸提实验和土柱淋洗实验,考察了化学离子的种类与浓度对进入融雪径流的土壤溶解性有机物(DOM)的含量和光谱学特性的影响,以及不同化学特征的积雪融化过程中土壤DOM的释放规律.土壤浸提实验结果表明,随着Na~+、Mg~(2+)和Ca~(2+)浓度的升高,土壤浸提液中的溶解性有机碳(DOC)浓度显著降低;随着Cl~-、SO_4~(2-)、Mg~(2+)和Ca~(2+)浓度的升高,土壤浸提液中波长254 nm处的紫外吸光度(UV-254)逐渐降低;随着Na~+和Mg~(2+)浓度的升高,土壤浸提液中单位浓度DOC的紫外吸收值(SUVA)值逐渐升高.NO_3~-、SO_4~(2-)和Na~+的浓度过高或过低时,土壤浸提液中DOM的类腐殖酸和类富里酸荧光峰强度较低;随着Cl~-、Mg~(2+)和Ca~(2+)浓度的升高,土壤浸提液中DOM的类腐殖酸荧光峰强度逐渐降低.土柱淋溶实验结果表明,类腐殖酸和类富里酸荧光物质是土壤淋滤液中的主要荧光物质.与纯水相比,融雪水作为淋洗液导致土壤淋滤液中DOC浓度的降低,以及类微生物代谢产物荧光峰强度的增高.冻融交替抑制DOM自土壤解吸进入淋滤液,并且导致土壤淋滤液中芳香族化合物相对含量的降低.     

铜绿微囊藻培养过程中氨基酸的释放特征及其对水体有机质的贡献

为深入分析铜绿微囊藻水华暴发对水体有机质、氨基酸含量及组成的影响,进一步揭示蓝藻水华暴发对湖泊内源氨基酸和有机质的贡献及养分循环机制,采集太湖北部富营养化区域梅梁湾中的水样,用于在室内培养太湖蓝藻水华优势种——铜绿微囊藻(Microcystis aeruginosa),采用邻苯二甲醛(OPA)柱前衍生-反相高效液相色谱法(HPLC)分析铜绿微囊藻生长、衰亡过程中氨基酸的摩尔浓度及其组成特征的变化,探讨藻类产生的氨基酸和有机质对湖泊水体中有机质、TC(总碳)及DTN(溶解性总氮)的贡献. 结果表明:铜绿微囊藻在生长过程中产生的氨基酸对水体中TC、DTN、TOC(总有机碳)的贡献率分别为23%~37%、46%~93%和46%~83%;在衰亡期,水体中难降解氨基酸(如甘氨酸、丝氨酸、丙氨酸和赖氨酸)的摩尔浓度(c)为60.4 μmol/L,显著高于同时期易降解氨基酸(如酪氨酸、苯丙氨酸、谷氨酸和精氨酸)的摩尔浓度(40.9 μmol/L);c(D-氨基酸)/c(L-氨基酸)由初始的0.28降至0.09,表明在铜绿微囊藻对数生长至衰亡期间,水体中有机质的降解程度逐渐降低. 研究显示,在水体有机质降解程度降低的同时,氨基酸摩尔浓度逐步增加,因此大量未降解的氨基酸沉积下来成为水体有机质来源之一.      

有机肥施用对盐渍土富里酸荧光特性的影响

为探讨有机肥长期培肥盐渍土后土壤富里酸(FA)结构组成及土壤环境的变化特征,对黑龙江西北部盐渍土壤连续5 a采取不同施肥处理,设置CK(对照)和TR1(处理1,施用有机肥8 000 kg/hm2)、TR2(处理2,施用有机肥4 000 kg/hm2及化肥N 80 kg/hm2、P₂O₅ 50 kg/hm2、K₂O 35 kg/hm2)、TR3(处理3,施用化肥N 160 kg/hm2、P₂O₅ 100 kg/hm2、K₂O 70 kg/hm2) 4个处理组,分析土壤中富里酸荧光光谱特征的变化情况. 结果表明:与CK比较,TR1、TR2处理可明显增加土壤中ρ(富里酸),增幅分别为98.24%、72.16%;二维荧光参数分析显示,各处理下富里酸腐殖化程度均表现为TR1>TR2>TR3>CK;三维荧光光谱区域积分比值分析结果进一步证实,TR1、TR2处理通过增加可见区类富里酸的荧光响应比值和减少紫外区类富里酸的荧光响应比值来提高富里酸的腐殖化程度. 根据三维荧光光谱结合平行因子分析结果,可将富里酸分为C1组分(生物可利用富里酸组分)、C2组分(陆生来源富里酸组分)及C3组分(类蛋白组分);施用有机肥主要增加C1组分的比例,其次为增加C2组分的比例,说明施用有机肥可提高盐渍土供肥能力,对盐渍土生态环境改善具有积极作用. 传统荧光图谱解析手段结合统计分析结果显示,施用有机肥可明显提高盐渍土富里酸含量并增加其腐殖化程度.