Heavy metal (Pb,Zn) uptake and chemical changes in rhizosphere soils of four wetland plants with different radial oxygen loss

Lead and Zn uptake and chemical changes in rhizosphere soils of four emergent-rooted wetland plants;Aneilema bracteatum,Cyperus alternifolius,Ludwigia hyssopifolia and Veronica serpyllifolia were investigated by two experiments：（1） rhizobag filled with ＂clean＂ or metal-contaminated soil for analysis of Pb and Zn in plants and rhizosphere soils;and （2） applied deoxygenated solution for analyzing their rates of radial oxygen loss （ROL）.The results showed that the wetland plants with different ROL rates had significant effects on the mobility and chemical forms of Pb and Zn in rhizosphere under flooded conditions.These effects were varied with different metal elements and metal concentrations in the soils.Lead mobility in rhizosphere of the four plants both in the ＂clean＂ and contaminated soils was decreased,while Zn mobility was increased in the rhizosphere of the ＂clean＂ soil,but decreased in the contaminated soil.Among the four plants,V.serpyllifolia,with the highest ROL,formed the highest degree of Fe plaque on the root surface,immobilized more Zn in Fe plaque,and has the highest effects on the changes of Zn form （EXC-Zn） in rhizosphere under both ＂clean＂ and contaminated soil conditions.These results suggested that ROL of wetland plants could play an important role in Fe plaque formation and mobility and chemical changes of metals in rhizosphere soil under flood conditions.

Stable Oxygen and Deuterium Isotope Techniques to Identify Plant Water Sources

There is still very little information on the sources of water absorbed by oil palm plant. This information is very important for water management system in oil palm plantation. Thus, this study was carried out to determine current water sources absorbed by the oil palm roots using oxygen (δ18O) and deuterium isotopes (δD) techniques. Sketches of oxygen and deuterium isotope were total rainfall, throughfall, runoff, measurement at 5 soil depths (namely: 20 cm, 50 cm, 100 cm, 150 cm, and 200 cm), and oil palm stem. Results of this study showed huge variance in the values of oxygen and deuterium isotope. Based on Least Significant Difference (LSD) test, there was no significant value in the oxygen and deuterium isotope of stem water and others;however, a similar value was obtained at the depths of 0 - 20 cm and 20 - 50 cm with the stem water. This indicated that oil palm absorbed water from 0 - 50 cm depth. This result agreed with the oil palm rooting system, which has verified that the root quarter is the most active root of oil palm.

增氧条件下粉绿狐尾藻的氮磷吸收特征

为探明增氧处理下粉绿狐尾藻植株的氮磷吸收特征,该研究以粉绿狐尾藻为研究材料,设置5个不同增氧水平(增氧时长),即CK (0 min)、JO1(4 min)、JO_(2)(6 min)、JO3(8 min)、JO4(10 min),系统分析了不同增氧水平下粉绿狐尾藻幼苗期(7月10日—9月15日)、生长旺盛期(9月16日—12月22日)生理指标的变化规律,明确了植株N、P含量、N/P和叶绿素含量、底泥各形态氮磷含量之间的关系。结果表明:增氧8 min时,t_(1)、t_(2)取样时期(9月15日、10月10日)粉绿狐尾藻的氮、磷吸收量及t5取样时期(12月22日)的氮吸收量最高;增氧6 min时,t_(3)、t4取样时期(10月27日、11月16日)粉绿狐尾藻的氮、磷吸收量及t5取样时期的磷吸收量最高;增氧有利于粉绿狐尾藻在t_(1)、t_(2)、t_(3)时期对氮的吸收,t4时期对磷的吸收,表现为t_(1)、t_(2)、t_(3)时期粉绿狐尾藻的植株氮磷比分别增加5.27%~36.57%、9.04%~63.07%、3.50%~73.45%,t4时期的N/P降低1.38%-34.05%;增氧使t_(2)、t5时期粉绿狐尾藻叶片叶绿素a、b及叶绿素总含量降低,t4时期叶绿素含量增加同时,使t_(1)、t_(2)时期底泥氮磷比值(sediment total nitrogen/phosphorus,STN/P)分别降低64.84%、54.76%,t4、t5时期STN/P分别增高138.97%、47.02%;层次聚类分析及多元线性回归分析结果进一步表明,增氧6 min是增氧促进粉绿狐尾藻氮磷吸收利用的理论满意方案,增氧降低t_(1)时期叶绿素a、b含量、t5时期底泥碱解氮含量(sediment alkali-hydro nitrogen,SAHN)和t4时期铁结合态磷(Fe-P)含量同时,促进了粉绿狐尾藻t5时期氮磷的吸收。增氧调控粉绿狐尾藻叶片叶绿素形成和底泥氮磷的形态转化,促进其对底泥氮磷吸收,同时提高了粉绿狐尾藻氮磷的吸收利用效果,可抑制甲烷和氧化亚氮、CO_(2)等温室气体的排放。

植物改善密闭环境空气质量研究进展

针对空间密闭环境的空气质量问题,对密闭环境中存在的微量有害气体、微小颗粒物、高浓度二氧化碳等不利因素进行分析,比较了物理和化学处理方法改善空气质量的优缺点。重点讨论了植物净化方法对空气质量的改善效益,以及植物吸收微量有害气体、释放负氧离子和吸收二氧化碳三个方面的研究进展,提出目前研究存在的问题,为后续利用植物改善密闭环境空气质量提供新的研究思路。

不同氧气条件下红枫湖流域典型陆源植物有机质降解特征

植物残体有机质降解是生态系统中养分循环的主要过程。本研究选取红枫湖流域典型陆源植物开展了为期1年的不同氧气条件下有机质降解模拟实验,利用Power模型刻画有机质降解变化特征,并对影响植物残体有机质降解的主要因素进行了分析。研究结果表明,缺氧环境和富氧环境下,C3植物残体分解剩余生物量比例分别为64%~77.3%和59.5%~76.8%,不同环境下的差异较小;C4植物残体分解剩余生物量比例分别为42.6%~57.4%和31.2%~43.5%,呈现出富氧环境降解程度高于缺氧环境的特征,且降解程度显著高于C3植物。C4植物具有较高的半纤维素、纤维素含量和较低的木质素含量,这是导致其具有较高降解程度和降解速率的主要原因。其中,半纤维素含量对降解速率的影响最显著,半纤维素含量越高,植物降解速率常数越大。不同C3植物残体的降解速率常数具有一定差异,在不同氧气条件下均呈现出马尾松>梧桐>水稻的变化规律。不同环境条件下C4植物降解速率显著不同,缺氧环境和富氧环境下,降解速率常数分别呈现出玉米>狗牙根>茅草和玉米>茅草>狗牙根的变化规律。

氢液化装置防固氧累积及安全消除固氧的流程优化

氢液化过程中氧含量超标可能导致固氧累积并导致氢氧爆炸风险。分析了由此引发的爆炸事故,并阐述了预防固氧累积的重要性。综述了近年来防止固氧累积的研究成果,包括使用超纯氢作为原料气、增加固氧洗涤器、将固氧累积调整为固空累积等,这些方法在一定程度上增加了成本或能耗。提出了一种新的解决方案,通过安装两道节流阀来防止固氧累积并安全地消除累积的固氧。通过流程模拟计算,证明了这种优化流程更易获得过冷液氢。该优化流程方案在实际应用中不会增加额外设备和能耗,具有广泛的适用性。

富氧/烟气再循环对锅炉热效率及二氧化碳捕集的影响研究

本文对火力发电厂烟风系统进行计算研究,对烟气系统进行处理之后,回收其中氧气,作为空气的补充助燃剂,回到锅炉参与燃烧,提高空气中所含氧量,从而减少烟气量,进而减少排烟热损失,提高锅炉燃烧效率。同时,随着烟气量的减少,二氧化碳浓度升高,可以在处理烟气之时,减少二氧化碳捕集成本。烟气再循环则是充分利用烟气中的氧气参与燃烧,从而提高二氧化碳的浓度。

变频器在污水处理厂风机上的应用

介绍了变频器在污水处理厂离心鼓风机上的应用和实践途径,并结合实例对变频器的效果应用进行了比较和分析。

海拔对生活污水处理厂生化池曝气量影响探讨

我国地域广阔,平均海拔跨度大,海拔越高氧气越稀薄、气压越低,对污水处理厂标准传氧速率和曝气量具有明显影响。本文结合相关工程实例,对0、500、1000、1500、2000、2500、3000、3500、4000、4500、5000 m海拔下生化池实际需氧量、标准传氧速率和曝气量相关参数进行计算和校核。结果表明,考虑氧分压修正工况下曝气量与未考虑修正工况下差值随着海拔增加逐渐增大;实际需氧量不受海拔影响;标准传氧速率、供气量与海拔呈现一定指数关系,高海拔地区标准传氧速率和曝气量成倍增长,与平原地区差距显著。该研究结果也可为相关高原地区生化池曝气量的计算和设备选型提供参考。

火电厂废水处理过程中氧腐蚀问题的应对策略研究

在火电厂废水处理过程中,特别是在曝气池和滤池处理环节容易出现氧腐蚀问题,导致设备损坏和效率下降。基于此,研究火电厂废水处理过程中的氧腐蚀问题,并探索缓蚀阻垢剂的用量,提高废水处理系统的处理效率和使用寿命。分析了共聚物缓蚀阻垢剂的制备过程,并进行性能测试实验,验证其缓蚀阻垢效果。结果表明,该缓蚀阻垢剂配方在实验条件下表现出了良好的缓蚀性能和阻垢性能,且旋转挂片法实验和碳酸钙沉积法实验结果均符合规范要求。

基于碳氢氧同位素的桉树人工林水循环过程研究进展

桉树是我国南方地区重要的速生用材树种,在我国人工林资源中具有十分重要的地位。然而,桉树种植带来的生态环境问题日益受到关注,尤其在对桉树是否为“抽水机”、桉树大面积种植是否导致土壤干旱和地下水位下降等问题上一直存在诸多争议。碳氢氧稳定同位素为陆地生态系统水循环过程定量研究提供了有效和便捷的方法,能系统和定量地阐明桉树人工林生态系统水文过程、不同水体转化关系和桉树水分利用效率等。系统归纳了碳氢氧同位素在桉树人工林生态系统水循环过程(包括大气降水、林冠穿透水、地表水、土壤水、植物水、地下水及蒸发水等)和植物水分利用效率中的应用研究进展,指出了当前研究中存在的不足,展望了其未来研究和应用前景。研究结果可为我国桉树人工林可持续经营理念下的水资源优化管理提供科学依据。

Stable isotope techniques in plant water sources:a review

The stable hydrogen and oxygen isotopes widely exist in various kinds of natural water.Plants have to cope with various water sources:rainwater,soil water,groundwater,sea water,and mixtures.These are usually characterized by different isotopic signatures (18O/16O and D/H ratios).Because there are relative abundance variations in water,and plant roots do not discriminate against specific water isotopes during water uptake,hydrogen and oxygen stable isotope ratios of water within plants provide new information on water sources,interactions between plant species and water use patterns under natural conditions.At present,the measurement of δD,δ18O composition of various potential water sources and stem water has become significant means to identify plant water sources.Based on previous studies,this review highlights recent advances such as theory basis,methodology,as well as different spatial and temporal scales,and existed questions and prospects.Stable isotope techniques for estimating plant water sources have provided valuable tools for conducting basic and applied research.Future studies emphasize the modification of preparing methods,isotope technique combined with other measurements,and aerial organs of plant water source should be en-couraged.

Screening of Antioxidant Potential of Selected Barks of Indian Medicinal Plants by Multiple in vitro Assays

Objective To evaluate the antioxidant potential in herbal extract barks of five therapeutically important medicinal plants native to India, i.e. Crataeva nurvala Buch.-Ham., Buchanania lanzan Spreng., Aegle marmelos Corr., Dalbergia sissoo Roxb. ex DC., and Cedrela toona Roxb. Methods Standardized aqueous alcoholic extracts from the selected barks having different target radicals, such as superoxide radical, nitric oxide, ABTS radical, and peroxidative decomposition of phospholipids, were prepared and screened by multiple in vitro assays. These extracts were also tested for total phenolic and tannin content and correlated with antioxidant capacity. Results Total phenolic and tannin contents were found to be the highest in C. nurvala （195 GAE mg/g and 218.3 mg/g CE）. SOD mimetic activity was found to be the highest in Crataeva nurvula, although all barks showed activity more than IO3 units/mg extract. Lipid peroxidation inhibitory potential was found to be the highest in Crataeva nurvala （83.4% inhibition of MDA formation/10 μg extract）, and also showed a comparatively high NO quenching capacity （45.5% per 10 μg extract）. The highest NO quenching potential was found in Aegle marmelos （47.3% per 10 μg extract）. Cedrela toona showed the lowest LPO inhibitory potential and NO quenching capacity （50.5% and 30.5%, respectively）. Buchanania lanzan, a medicinal plant extensively used for inflammatory disorders and Dalbergia sissoo also showed 72.5% and 69.1% LPO inhibitory potential/10 μg extract. Trolox equivalent antioxidant capacity ranged from 0.24 to 0.39 mmol/L TEAC/mg extract, indicating that all the barks tested had ABTS^＋ radical quenching capacity. Conclusion Bark of Crataeva nurvula has the highest antioxidant capacity and a positive correlation between antioxidant activity and their plendic content was found.

城市绿地固碳释氧效益对植物群落特征因子响应分析

【目的】在城市自然地表破碎化程度加剧的背景下,在现有的城市环境和资源限制下最大化植物群落固碳释氧效益,是缓解城市气候变化问题、响应“双碳”目标的关键途径之一。【方法】以天津市典型百年城市公园——人民公园为研究区域,选取60个典型植物群落,分别测算日固碳释氧量,分析植物群落典型特征因子(层次结构、平均胸径、平均树高、平均冠幅、三维绿量和群落密度)与固碳释氧量之间的关系。【结果】研究表明:1)层次结构越复杂的植物群落,固碳释氧能力越强;2)具备特定规格的植物群落(平均胸径为0~0.2 m、平均树高<6.0 m、平均冠幅为0~2.0 m)具有更强的固碳释氧能力;3)0.2~0.4株/m^(2)是实现群落高固碳释氧效益的最适种植密度区间;4)各植物群落特征因子中,三维绿量对固碳释氧效益的正向影响最显著。并进一步提出提升植物群落固碳释氧效益的优化设计策略。【结论】探究植物群落特征因子对固碳释氧量的影响可为城市绿地高固碳释氧能力的植物群落设计提供理论支撑与指导。

Plant water use strategies in the Shapotou artificial sand-fixed vegetation of the southeastern margin of the Tengger Desert, northwestern China

Stable oxygen and hydrogen isotopic compositions(δ^(18)O and δD) of plant xylem water and its potential water sources can provide new information for studying water sources, competitive interactions and water use patterns of plants. The contributions of different water sources to three plants, Hedysarum scoparium(HS), Caragana Korshinskii(CK) and Artemisia ordosica(AO), were investigated in the artificial sand-fixed vegetation of Shapotou, the southeastern margin of the Tengger Desert of northwestern China, based on meteorological data and δ^(18)O and δD values of precipitation, groundwater, soil water and xylem water of HS, CK and AO. Our results indicated that soil water infiltration through precipitation was the main water source of the artificial sand-fixed vegetation. Obvious differences in soil water content and in δ^(18)O of soil water and xylem water were found among different seasons. No relationship was found between the δ^(18)O in plant xylem water and in soil water in January. The same water use patterns were found in CK, HS and AO in May, suggesting they have the same water sources. The different water sources of CK, HS and AO in August indicate that water competition occurred. In addition, the main water sources of CK, HS and AO in August mainly come from shallow soil water, while they use relatively deep soil water in May. This phenomenon is related to the differences of soil water content throughout soil profile, precipitation, transpiration and water competition under different growth periods. The water use patterns of CK, HS and AO respond to soil water content throughout the soil profile and their competition balance for water uptake during different growth season. The results indicate that these sandfixed plants have developed into a relatively stable stage and they are able to regulate their water use behavior as a response to the environmental conditions, which reinforces the effectiveness of plantation of native shrubs without irrigation in degraded areas.

Tomato Plants Overexpressing a Celery Mannitol Dehydrogenase (MTD) Have Decreased Susceptibility to <i>Botrytis cinerea</i>

The oxidative burst is a critical early event in plant-pathogen interactions that leads to a localized, programmed cell death (PCD) called the hypersensitive response (HR). The HR and associated PCD retard infection by biotrophic pathogens, but can, in fact, enhance infection by necrotrophic pathogens like Botrytis cinerea. In addition to signaling the induction of the HR, reactive oxygen species (ROS) produced during the oxidative burst are?antimicrobial. We hypothesize that pathogens such as B. cinerea survive the antimicrobial effects of ROS, at least partially by secreting the antioxidant mannitol during infection. This is supported by the previous observation that overexpression of the catabolic enzyme mannitol dehydrogenase (MTD) can decrease a plants susceptibility to mannitol-secreting pathogens like B. cinerea. To extend the above hypothesis, and test the general utility of this approach in an important horticultural crop, we overexpressed celery MTD in tomato (Solanum lycopersicum cv. “Moneymaker”). In these studies, we observed a significant increase (up to 90%) in resistance to B. cinerea in transgenic tomatoes expressing high amounts of MTD.

考虑光热电站及富氧燃烧捕集技术的电热气综合能源系统低碳运行优化

针对传统机组的运行约束及环境污染问题,引入富氧燃烧捕集技术对燃气机组进行改造,配置含热回收器的光热电站实现热电解耦与辅助供能,并结合电转气设备、燃气锅炉等能量转换设备组成综合能源系统,提出一种电热气综合能源系统低碳优化方法。首先,构建系统架构,并建立富氧燃烧捕集机组的电碳特性方程与光热电站模型;其次,计及反应余热利用与氧气回收,建立电转气设备模型;然后,引入奖惩阶梯型碳交易机制以限制碳排放量,建立以系统运行成本最小为目标的电热气综合能源系统低碳经济调度模型;最后,进行算例仿真,由仿真结果可知,该方案可兼顾减碳效果与运行效益,不仅可以提高燃气机组的运行调节能力与电转气设备的运行潜力,提升系统的运行效益,而且可以有效降低环境污染与制氧能耗。

溶解氧含量对国产化锻造主管道316LN不锈钢环境促进疲劳寿命的影响

在模拟核电厂一回路高温高压水环境中,对国产化锻造主管道用316LN不锈钢开展了疲劳试验,分析了应变速率和溶解氧(DO)含量对不锈钢环境促进疲劳(EAF)寿命的影响。结果表明:在不同DO含量下,试样EAF断口均呈典型的多裂纹源疲劳开裂特征,疲劳辉纹明显;断口上覆盖的腐蚀产物主要为富Fe、Cr、Ni的尖晶石氧化物,随着DO含量的增加,氧化物颗粒数量增加、尺寸变大;在不同DO含量下EAF寿命偏差不超过30%,无明显统计差别;结合不同的统计模型可知,在低应变速率(0.1×10^(-4)~0.1×10^(-3) s^(-1))下DO含量对316LN不锈钢EAF寿命的影响才会比较明显;在建立较为精确的统计模型时,需要细分应变速率范围,并考虑DO含量的影响。

660 MW超超临界机组CO-O_(2)控制技术的应用

利用火力发电厂烟气排放连续监测系统(CEMS),实现锅炉烟气中一氧化碳(CO)、氧气(O_(2))的测量,设计完善风量氧量串级控制系统,实现CO-O_(2)联合控制。实际应用结果表明:该系统投入后可以有效监控CO含量,减少锅炉燃烧中产生的CO,为锅炉燃烧调整提供数据支持,提高锅炉效率,减少水冷壁高温腐蚀,进而提高锅炉运行的安全性、经济性。

百色干热河谷地区降雨氢氧稳定同位素特征及芒果树水分来源研究

百色市右江河谷是我国著名的干热河谷之一,干旱是该地区最严重的气象灾害。芒果是该地区地理标志农产品,但其水分利用策略尚不清楚。本文基于氢氧稳定同位素示踪技术研究该地区降雨同位素特征及影响因素,利用多元线性混合模型方法量化不同来源水分对芒果树根系吸水的贡献比例,揭示芒果树生育期内水分利用策略。结果表明:(1)研究区氢氧稳定同位素具有明显的季节变化,δ值和氘盈余(d)具有旱季富集、雨季贫化的规律,建立了研究区的大气降水线方程:δD=8.2587δ^(18)O+12.308,δD和δ^(18)O值有极显著相关性(r=0.9968,n=35,P<0.001);(2)季风气候影响下大气降水稳定同位素值具有显著的降雨量效应和反温度效应(P<0.05);(3)在芒果花期、幼果期、果实膨大期和成熟期,土壤水氢氧稳定同位素总体上随土壤深度的增加而变贫;在花期和幼果期,芒果树对各层次土壤水分及地下水利用比例较为均匀,果树膨大期和成熟期则主要利用深层次土壤水及地下水,表明该地区芒果树主要以深层次土壤水及地下水为水源,说明芒果树更接近于保守型水分利用策略。降雨氢氧稳定同位素特征反映了该地区干热的气候特征,芒果树主要以深层土壤水和地下水为水源。研究结果可为百色干热河谷地区芒果园种植结构调整及芒果产业的可持续发展提供科学依据。