臭氧污染对不同品种小麦干物质与生物量碳积累与分配的影响

近地层臭氧(O3)污染对陆地生态系统及植物生长的危害备受关注.本研究利用开放式臭氧污染(Free-air O3concentration enrichment,O3FACE)研究平台,研究了大气O3浓度增加(比周围大气高50%)对长江三角洲地区5个冬小麦(Tritcium aestivum L.)品种(扬麦15、扬麦16、烟农19、扬幅麦2号和嘉兴002)的干物质与生物量碳的积累与分配以及作物残体C/N比的影响.结果表明,不同品种小麦的干物质积累和分配对O3升高的响应差异明显;O3升高具有降低扬麦15、嘉兴002和增加扬幅麦2号总生物量的趋势,但对扬麦16和烟农19几乎无影响,其中嘉兴002达到显著水平.O3升高显著增加了扬麦15、嘉兴002和显著降低了烟农19和扬幅麦2号的根/冠比,而对品种扬麦16无影响,导致干物质在地上和地下分配呈现品种差异.高O3环境下扬麦15、扬麦16和嘉兴002穗重降低,而烟农19和扬幅麦2号无明显变化;小麦籽粒占穗的比重在高O3条件下嘉兴002、烟农19和扬幅麦2号显著降低8.2%～15.5%,扬麦15呈增加趋势而扬麦16变化不大;表明O3升高将致嘉兴002、烟农19、扬幅麦2号和扬麦16不同程度减产.O3升高导致烟农19和扬幅麦2号秸秆碳量显著增加14.1%～22.9%和C/N比显著降低10.9%～29.1%,JX002秸秆碳量显著减少和C/N比显著增加,扬麦16和扬麦15的秸秆碳量与C/N比则分别呈增加和降低趋势.O3升高显著降低了扬麦16、烟农19和扬幅麦2号品种的根茬碳量和C/N比,对嘉兴002的根茬碳量无显著影响却显著降低了C/N比,但对扬麦15根茬碳数量与质量均影响不大.评价小麦干物质的形成与分配、根茬和秸秆固碳的质与量对O3污染的响应需考虑品种差异影响.     

氮素调控对冻融过程中土壤N2O排放的影响

应用室内冰柜模拟冻融过程,研究了不同氮素形态(铵态氮、硝态氮和酰胺态氮)和浓度(40、200和800 mg/L)对潮土N2O排放通量的影响.结果表明,随土壤冻结时间的延长N2O排放通量缓慢降低,土壤融化初期出现一个土壤N2O排放通量高峰,而后随土壤逐渐融化的进行N2O排放通量缓慢升高.3种氮素浓度条件下,铵态氮、硝态氮和酰胺态氮冻融过程中土壤平均N2O排放通量分别为119.01、205.28、693.95μg.(m2.h)-1,611.61、1 084.40、1 820.02μg.(m2.h)-1和148.22、106.13、49.74μg.(m2.h)-1,而对照处理仅为100.35μg.(m2.h)-1.随氮素浓度的增加,铵态氮、硝态氮源土壤N2O累积排放通量分别比对照增加17.49%、40.09%、425.67%和563.38%、915.28%、1458.6%,且施加的浓度越高累积排放量越大,但达到稳定N2O排放通量的时间向后推移.随浓度增加酰胺态氮处理土壤N2O排放通量随浓度增加而降低.建议潮土越冬水中铵态氮和硝态氮浓度应分别小于200 mg/L和40 mg/L,酰胺态氮的浓度不限,从而减少土壤N2O的排放.     

不同氮污染特征河流N2O浓度、释放通量与排放系数

以铁岭市22条河流为研究对象,分析了河流N_2O溶存浓度、释放通量及排放系数.根据氮素的主要赋存形态及氮素浓度,22条河流可分为铵态氮污染(铵态氮平均浓度5.86 mg·L~(-1))、硝态氮污染(硝态氮平均浓度3.05 mg·L~(-1))和氮限制(溶解性无机氮平均浓度1.04 mg·L~(-1))河流这3种.总体上,N_2O溶存浓度介于17.03~9 028.60 nmol·L~(-1),均值为546.75nmol·L~(-1),饱和度均值为6 256%;河流水-气界面N_2O释放通量介于17.21~15 655.3μg·(m~2·h)~(-1),均值为949.36μg·(m~2·h)~(-1).铵态氮污染河流断面N_2O浓度和释放通量显著高于硝态氮污染和氮限制断面(LSD,P0.05).根据IPCC方法计算了河流N_2O排放系数(EF_(5r)),结果表明3种类型河流EF_(5r)呈现极为明显的差异,EF_(5r)变异系数达到445%.硝态氮污染河流EF_(5r)均值为0.000 5,显著低于IPCC建议值(0.002 5);但铵态氮污染河流硝态氮浓度较低,导致EF_(5r)计算均值高达0.445 6,为IPCC建议值的180倍;氮限制河流EF_(5r)均值为0.005 0,为IPCC建议值的2倍.因此,在计算EF_(5r)时应充分评估河流的氮污染状况.本文根据河流氮污染特征,结合不同类型河流N_2O产生机制,对EF_(5r)进行了分类计算,探讨了EF_(5r)的修正计算方法.建议针对氨氮污染和氮限制河流采用[N_2O]/[NH_4~+]方法计算EF_(5r);如不考虑河流氮污染特征,建议采用[N_2O]/[DIN]方法计算EF_(5r).     

开放式臭氧浓度升高对2个冬小麦品种光合损伤的研究

在开放式臭氧浓度升高（ozone-free air controlled enrichment,O₃-FACE）平台上,观测了高浓度臭氧（正常大气臭氧浓度的基础上增加50%）对2个冬小麦(Tritcium aestivum L.)品种（烟农19和扬麦16）在灌浆期内功能叶片光合损伤的情况．观测显示,整个灌浆期内2个小麦品种有关参数响应的趋势表现一致:①净光合速率（P_n）逐渐下降,在臭氧处理35 d时,烟农19和扬麦16降幅分别达到56.21%和21.82%．②荧光动力学参数F_v/F_m（最大光化学量子产量）、q_p（光化学淬灭系数）、Φ_exc（PSⅡ有效光化学量子产量）、Φ_PSⅡ（PSⅡ实际光化学量子产量）呈下降趋势,NPQ（非光化学淬灭系数）逐渐上升;在能量分配方面,吸收的光能在PSⅡ天线色素的耗散部分（%D）升高、用于PSⅡ光化学反应的部分（%P）降低,而不属于前两者的其它消耗部分（%X）变化不明显．在臭氧处理35　d时,烟农19和扬麦16的Φ_PSⅡ分别下降24.42%和9.97%.③光合色素参数Chla/Chlb(叶绿素a/叶绿素b）比值上升,而Chlt/Car(叶绿素/叶黄素)的比值下降.④叶绿体内依赖Mg²⁺、Ca²⁺的ATP_ase(ATP酶)活性和ATP含量均增加．上述参数随臭氧处理时间延长,变化幅度和品种间的差异趋于显著,当臭氧处理35 d时,变幅最大,且烟农19变幅显著大于扬麦16．结果表明,在臭氧浓度升高环境下,作物通过增加热耗散、改变色素含量和结构、提高ATP_ase活性等进行防御和损伤修复．随着处理时间的增加,臭氧对冬小麦的光合损伤具有累积效应,且2个品种表现出较大的差异性．     

城市河流水生植物氮含量和氮同位素记录及其对水体氮污染的响应

城市生产和生活活动排放大量含氮污染物到城市河流中,造成水质下降、水体富营养化。河流水生植物已被广泛用于水体氮污染的评价和去除,但目前水生植物氮利用的过程机制并不十分清楚,这阻碍了利用水生植物的氮素地球化学指标去评价河流水体氮污染状态。本研究采集西南地区流经贵阳市区的南明河河水和水生植物样本,通过分析氮浓度和同位素组成,探讨在不同水体氮浓度条件下水生植物的氮利用机制。在受城市污染的河段,水体铵根（NH₄⁺）、硝酸根（NO₃^-）、溶解有机氮（DON）浓度均显著升高（n=13,p<0.05）,其水生植物的总氮含量随河水无机氮含量升高而升高。但是,受城市污染河段的水生植物总氮的δ¹⁵N值却无显著变化,说明除了水体氮源的δ¹⁵N特征,水生植物的氮利用策略是影响其δ¹⁵N记录的重要因素。在河流低氮浓度下植物主要利用水中的NO₃^-,在下游高氮浓度下植物氮利用机制较复杂,过程中会发生分馏,但具体的利用形态还无法确定。本研究揭示了水生植物氮利用策略对河流氮污染状态的响应机制和对塑造其地球化学记录的重要性,为城市河流废水氮污染评价及其植物修复措施提供基础科学依据。     

沉积盆地地下水无机氮来源示踪及其演化模式

以我国沉积型盆地三江平原的典型农业区抚远地区为例，采用水化学法和GIS技术分析区域水化学成因作用及无机氮素的污染特征，利用氮氧双稳定同位素分布特征及稳定同位素解析模型（SIAR）确定氮素来源及各污染源贡献比，基于对影响氮素浓度变化的多项因素的认识，建立区域氮素的水化学演化模式.结果表明：研究区地下水中氨氮超标率为56.52%，毫克当量百分数平均值占无机氮总量的55.50%，是地下水无机氮素中污染影响程度最大的指标；土壤有机氮、厩肥污水和氨态化肥是径流补给区氮素的主要污染来源，各污染端元贡献比由大到小依次为40.49%、30.24%和29.27%.地下水补给区是氨氮污染最重的区域，排泄区是硝酸盐氮污染相对严重的区域，氧化还原条件是影响氮素浓度的关键因素；在氮素的时空演化过程中，除二级阶地仍保持天然水化学状态外，一级阶地和漫滩区的氮素浓度均有不同程度的升高.     

基于δ15N和δ18O的农业区地下河硝酸盐污染来源

为研究岩溶区农业活动为主导的地下河流域硝酸盐污染来源,于2017年5~10月每24 d左右对重庆青木关流域6个采样点进行监测,利用~(15)N和~(18)O同位素技术对示踪硝酸盐来源进行解译,应用IsoSource模型计算出不同端元硝酸盐的贡献率.结果表明:(1)青木关农业区地下河系统存在较大的硝酸盐污染风险,大部分采样点出现不同程度NO_3~--N浓度超标现象.(2)空间上,青木关地下河中NO_3~--N浓度整体呈现由上游向下游升高的趋势.时间上,上游鱼塘和岩口落水洞以及下游姜家泉样点NO_3~--N浓度在5~6月因受农业施肥的影响,均呈上升趋势,6~9月受降水影响而出现不同程度升高或降低,9月之后随着农业活动减少而逐渐降低;中游土壤点NO_3~--N浓度保持较高值;中下游大鹿池NO_3~--N浓度较低且变幅不大.(3)通过硝酸盐~(15)N和~(18)O同位素分析,表明上游鱼塘和岩口落水洞的硝酸盐源于土壤有机氮、动物粪便及污废水混合;中游土壤点硝酸盐源于土壤有机氮、降水和肥料中NH_4~+;中下游大鹿池中硝酸盐来源于动物粪便及污废水、土壤有机氮、降水和肥料中NH_4~+的混合作用.地下河出口处姜家泉硝酸盐污染严重,其源于土壤有机氮、降水和肥料中NH_4~+、动物粪便及污废水、大气沉降的综合作用.(4)基于IsoSource模型对地下河出口处硝酸盐来源进行定量分析,发现动物粪便及污废水贡献率占46.4%,土壤有机氮占32.6%,降水与肥料中NH_4~+占18.6%,大气沉降仅占2.4%.     

底泥曝气对城市污染河道内源氮变化过程的影响

以城市重污染河道上覆水和沉积物为研究对象,采用模拟实验方法,探讨了底泥曝气对城市污染河道内源氮变化过程的影响.结果表明：底泥曝气促进内源氮去除和有机质分解,泥水系统氮素去除率比对照组高出5%,对照组有机质升高35.1%,而底泥曝气组有机质却基本维持不变;底泥曝气促进氨氮的迁移与转化,曝气阶段上覆水、表层底泥间隙水和吸附态氨氮浓度分别降低了99.5%、94.4%和75.6%;底泥曝气时有机质分解促使有机氮浓度升高,曝气结束后有机氮的矿化作用与有机质的分解作用共同影响内源无机氮的含量;底泥曝气直接改变了底泥的理化性质,继而在一定程度上改变底泥氮素的赋存情况,含水率与表层间隙水和底泥的有机氮、无机氮均呈显著相关,表层无机氮与亚铁显著相关,内源氮变化与有机质无显著相关性.     

模拟氮沉降和CO2浓度增加对三江平原小叶章群落土壤总有机碳和氮素含量的影响

利用开顶气室(Open-Top Chamber,OTC),设置当前大气CO2浓度(370μmol.mol-1)、中等CO2浓度(550μmol.mol-1)和高CO2浓度(700μmol.mol-1)3个CO2浓度水平和不施氮(N1,0g N.m-2.a-1)、常氮(N2,5g N.m-2.a-1)、高氮(N3,10g N.m-2.a-1)3个氮素水平。研究了不同N沉降水平下,大气CO2浓度升高对以三江平原小叶章群落土壤有机碳和氮素含量的影响。结果表明:CO2浓度升高结合氮沉降连续运行两个生长季后,湿地土壤总有机碳含量没有显著变化,说明较短时间内大气CO2浓度升高和氮沉降不会使三江平原土壤有机碳含量产生变化。氮沉降引起各个土层的土壤全氮、铵态氮和硝态氮的含量增加,施氮水平越高土壤氮增加越多,但是全氮增加量不明显,铵态氮随施氮量的增加呈现极显著差异水平(P<0.01)。0～10cm,10～20cm土层土壤全氮、铵态氮的含量随着CO2浓度升高呈现出先增大后减小的趋势。土壤硝态氮含量在10～20cm土层含量变化与土壤全氮、铵态氮的变化趋势相同。说明大气CO2浓度一定程度的增加可以增加土壤的氮素含量,但是过量的大气CO2浓度反而会使得土壤氮素含量减少。     

常规施肥条件下农田不同途径氮素损失的原位研究:以长江中下游地区夏玉米季为例

为了解农田常规施肥条件下的不同途径氮素损失特征,本文通过田间原位试验同步研究了长江中下游地区夏玉米生长季氮肥施用后的农田N2O排放、NH3挥发、氮渗漏和地表径流的变化.结果表明,在复合肥为基肥,尿素为追肥,基追肥氮素水平均为150 kg·hm-2的条件下,整个玉米生长季N2O排放系数为3.3%,NH3挥发损失率为10.2%,氮渗漏和地表径流损失率分别为11.2%和5.1%.此外,基肥施用以氮素渗漏损失为主,而追肥氮素损失以氨挥发和渗漏为主,表明不同途径化肥氮素损失主要受氮肥品种影响,玉米季追肥可改用低氨挥发氮肥品种以减少氮素损失.     

Functional traits of poplar leaves and fine roots responses to ozone pollution under soil nitrogen addition

Concurrent ground-level ozone（O₃） pollution and anthropogenic nitrogen（N） deposition can markedly influence dynamics and productivity in forests.Most studies evaluating the functional traits responses of rapid-turnover organs to O₃ have specifically examined leaves,despite fine roots are another major source of soil carbon and nutrient input in forest ecosystems.How elevated O₃ levels impact fine root biomass and biochemistry remains to be resolved.This study was...     

地表臭氧污染与其他环境因子复合胁迫对中国城市森林的影响研究进展

地表臭氧污染（O₃）和气候变化加剧成为当今威胁城市森林可持续发展的关键环境要素.目前对于O₃单一因子对城市树木的影响研究已很难用于准确评估自然城市环境条件下由多种环境因子交互作用而产生的复杂生态效应.本文综述了O₃与二氧化碳（CO₂）、干旱、氮（N）沉降和升温的两两交互以及三因子交互作用对中国城市树木生理生化和生长的影响,探讨了O₃与其他环境因子对树木的交互作用机制过程.CO₂升高在光合代谢、抗氧化系统以及生长发育等方面能一定程度缓解O₃升高对树木的负效应.O₃和干旱的交互影响存在复杂的作用过程,可能协同加重植物损伤,也可能拮抗减轻植物伤害,或者无交互效应.O₃和N沉降对树木无交互效应.增温和O₃对树木存在显著的交互作用,增温减缓了O₃对树木生长和光合作用的不利影响.最后,还提出了未来研究的发展方向,为我国应对未来气候变化和空气污染下的城市森林管理及可持续发展提供科学指导.     

Elevated CO2 facilitates C and N accumulation in a rice paddy ecosystem

Elevated CO₂ can stimulate wetland carbon (C) and nitrogen (N) exports through gaseous and dissolved pathways, however, the consequent influences on the C and N pools are still not fully known. Therefore, we set up a free-air CO₂ enrichment experiment in a paddy field in Eastern China. After five year fumigation, we studied C and N in the plant–water–soil system. The results showed: (1) elevated CO₂ stimulated rice aboveground biomass and N accumulations by 19.1% and 12.5%, respectively. (2) Elevated CO₂ significantly increased paddy soil TOC and TN contents by 12.5% and 15.5%, respectively in the 0–15 cm layer, and 22.7% and 26.0% in the 15–30 cm soil layer. (3) Averaged across the rice growing period, elevated CO₂ greatly increased TOC and TN contents in the surface water by 7.6% and 11.4%, respectively. (4) The TOC/TN ratio and natural δ¹⁵N value in the surface soil showed a decreasing trend under elevated CO₂. The above results indicate that elevated CO₂ can benefit C and N accumulation in paddy fields. Given the similarity between the paddies and natural wetlands, our results also suggest a great potential for long-term C and N accumulation in natural wetlands under future climate patterns.     

Large variability in ambient ozone sensitivity across 19 ethylenediurea-treated Chinese cultivars of soybean is driven by total ascorbate

The sensitivity of Chinese soybean cultivars to ambient ozone(O3) in the field is unknown,although soybean is a major staple food in China. Using ethylenediurea(EDU) as an O3 protectant, we tested the gas exchange, pigments, antioxidants and biomass of 19 cultivars exposed to 28 ppm·hr AOT40(accumulated O3 over an hourly concentration threshold of40 ppb) over the growing season at a field site in China. By comparing the average biomass with and without EDU, we estimated the cultivar-specific sensitivity to O3 and ranked the cultivars from very tolerant( 10% change) to highly sensitive( 45% change), which helps in choosing the best-suited cultivars for local cultivation. Higher lipid peroxidation and activity of the ascorbate peroxidase enzyme were major responses to O3 damage, which eventually translated into lower biomass production. The constitutional level of total ascorbate in the leaves was the most important parameter explaining O3 sensitivity among these cultivars. Surprisingly, the role of stomatal conductance was insignificant. These results will guide future breeding efforts towards more O3-tolerant cultivars in China, while strategies for implementing control measures of regional O3 pollution are being implemented. Overall, these results suggest that present ambient O3 pollution is a serious concern for soybean in China, which highlights the urgent need for policy-making actions to protect this critical staple food.     

Effects of elevated CO2 concentration and nitrogen supply on biomass and active carbon of freshwater marsh after two growing seasons in Sanjiang Plain, Northeast China

An experiments were carried out with treatments differing in nitrogen supply (0, 5 and 15 g N/m²) and CO₂ levels (350 and 700 μmol/mol) using OTC (open top chamber) equipment to investigate the biomass of Calamagrostis angustifolia and soil active carbon contents after two years. The results showed that elevated CO₂ concentration increased the biomass of C. angustifolia and the magnitude of response varied with each growth period. Elevated CO₂ concentration has increased aboveground biomass by 16.7% and 17.6% during the jointing and heading periods and only 3.5% and 9.4% during dough and maturity periods. The increases in belowground biomass due to CO₂ elevation was 26.5%, 34.0% and 28.7% during the heading, dough and maturity periods, respectively. The responses of biomass to enhanced CO₂ concentrations are differed in N levels. Both the increase of aboveground biomass and belowground biomass were greater under high level of N supply (15 g N/m²). Elevated CO₂ concentration also increased the allocation of biomass and carbon in root. Under elevated CO₂ concentration, the average values of active carbon tended to increase. The increases of soil active soil contents followed the sequence of microbial biomass carbon (10.6%) > dissolved organic carbon (7.5%) > labile oxidable carbon (6.6%) > carbohydrate carbon (4.1%). Stepwise regressions indicated there were significant correlations between the soil active carbon contents and plant biomass. Particularly, microbial biomass carbon, labile oxidable carbon and carbohydrate carbon were found to be correlated with belowground biomass, while dissolved organic carbon has correlation with aboveground biomass. Therefore, increased biomass was regarded as the main driving force for the increase in soil active organic carbon under elevated CO₂ concentration.     

Yield formation of CO2-enriched inter-subspecific hybrid rice cultivar Liangyoupeijiu under fully open-air field condition in a warm sub-tropical climate

Hybrid rice (Oryza sativa L.) cultivars play an important role in rice production due to its heterosis, resistance to environmental stress and high yield potential. However, no attention has been given to its yield responses to rising atmospheric CO₂ concentration ([CO₂]). To address this need, we conducted a Free Air CO₂ Enrichment (FACE) experiment at Yangzhou, Jiangsu, China, in 2004–2006. A two-line inter-subspecific hybrid rice variety Liangyoupeijiu, recently bred in China, was grown at ambient or elevated (c. 570 μmol mol^?1) [CO₂] under two levels of nitrogen (N) application (12.5 and 25 g N m^?2). Elevated [CO₂] slightly accelerated phenological development (1–2 days), and substantially enhanced grain yield (+30%). The magnitude of yield response to [CO₂] was independent of N fertilization, but greatly varied among years. On average, elevated [CO₂] increased panicle number per unit land area by 8%, due to an increase in maximum tiller number under FACE, while productive tiller ratio remained unaffected. Spikelet number per panicle showed an average increase of 10% due to elevated [CO₂], which was also supported by increased plant height and dry weight per stem. Meanwhile, Elevated [CO₂] caused a significant enhancement in both filled spikelet percentage (+5%) and individual grain mass (+4%). Compared with previous rice FACE studies, this hybrid cultivar appears to profit much more from elevated [CO₂] than inbred japonica cultivars (c. +13%), not only due to its stronger sink generation, but also enhanced capacity to utilize the carbon sources in a high [CO₂] environment. As sufficient intraspecific variation in yield response exists under field conditions, there is a pressing need to identify genotypes which would produce maximum grain yield under projected future [CO₂] levels.     

林州-安阳地区地下水三氮分布特征及其影响因素

本文分析了林州-安阳地区地下水的三氮分布特征,探讨了氮污染来源。运用Piper三线图、SPSS20软件,综合分析地下水化学特征,揭示氮循环作用机理。结果表明,研究区西北部主要为HCO_3-Ca-Mg型水,东部平原主要为HCO_3-Ca-Mg型水,其次为HCO_3-SO_4-Ca-Mg型、HCO_3-Cl-Ca型和HCO_3-Cl-Mg-Ca型水;氮污染源主要分布于林州市北部、安阳县北部、安阳市的东南部地区,其中农事活动、附近养殖场的畜禽排泄及污水排放是主要来源;地下水中存在着反硝化作用等氮的迁移转化现象,但是氮主要来源于附近的污染源。     

奥运前期与奥运期间北京市大气细颗粒物特征比较分析

利用城市生态系统研究站对北京市奥运前后(2008年6～9月)大气中细颗粒物(PM2.5)进行连续监测,获得不同阶段PM2.5日平均浓度的动态特征,分析气象因素、人为控制管理措施对颗粒物浓度的影响.结果表明,近北五环的生态中心站点(RCEES)颗粒物日均浓度平均值为0.067 mg.m-3,奥运期间的颗粒物浓度(0.060 mg.m-3)比奥运前期(0.081 mg.m-3)减少了约26%.而位于南二环市中心的教学植物园站点(JX)颗粒物浓度平均含量为0.078 mg.m-3.JX站点奥运期间的颗粒物浓度(0.069 mg.m-3)比奥运前期(0.095 mg.m-3)减少了约27%.各个阶段PM2.5的日变化都基本呈现双峰态势.第一个峰值出现在08:00～10:00左右,RCEES站点颗粒物浓度为0.068 mg.m-3,JX站点浓度值为0.089 mg.m-3;另一个峰值出现在晚20:00～22:00左右,RCEES和JX站点颗粒物浓度为0.079 mg.m-3和0.083 mg.m-3,这主要与上班交通高峰导致的尾气排放污染和道路扬尘污染等有关.研究气象参数发现奥运期间与奥运前期气象条件无显著差异,属于高温高湿风力不大的典型北京夏季天气条件.奥运期间颗粒物浓度与温度呈显著正相关(P<0.01),而与风速、相对湿度及降水相关性不显著(P>0.05).而连续多年大气污染综合治理措施和奥运空气质量保障措施的实施,产生了显著环境效益.在自然因素相差不大的条件下,人为控制因素对奥运期间颗粒物的下降起到主导作用.     

碳源和氮源对异养硝化好氧反硝化菌株Y1脱氮性能的影响

从焦化废水活性污泥中筛选到一株高效脱氮细菌,命名为Acinetobacter sp.Y1.本实验对菌株Y1在不同碳源、氮源、碳氮比及底物浓度下的脱氮特性进行了研究,结果表明,菌株Y1可以利用氨氮、亚硝氮和硝氮生长,不能利用羟胺;以氨氮为唯一氮源进行硝化作用时,柠檬酸钠和乙酸钠是最佳碳源,最佳碳氮比为15,菌株Y1可降解高浓度氨氮,在36h内将400 mg·L-1氨氮全部去除,1600 mg·L-1氨氮的去除率可达21.3％,最大降解速率随着初始氨氮浓度的升高而增大.以硝氮或亚硝氮为唯一氮源进行反硝化时,菌株Y1可以适应高浓度氮源但不能完全去除氮源,当碳氮比为20,经36h培养硝氮和亚硝氮的去除率均达到100％.