Effects of mowing plus waterlogging on germination and seedling growth of Spartina alterniflora

互花米草(Spartina alterniflora)是我国危害最严重的外来入侵植物之一,探索环保、经济、有效地防治互花米草的技术对保护我国海滩生态环境具有重要意义。本研究通过人工气候室(20~25℃)的盆栽实验,研究刈割与淹水对互花米草萌发和幼苗生长的影响。实验持续4个月,对互花米草地上部分进行了2次刈割,首次刈割是在互花米草生长季结束时,3个月后进行第二次刈割。首次刈割后持续淹水至实验结束,淹水处理设计0、5、10、20 cm四个淹水深度。首次刈割后各淹水处理互花米草根茎上迅速萌发克隆苗,种子的萌发比克隆苗晚约3个月。不同淹水深度对克隆苗的萌发和生长均有抑制作用,克隆苗株数、株高和地上生物量均随淹水深度增加而减少。第二次刈割后各淹水处理均没有再萌发克隆苗,但有少量种子实生苗,其中20 cm水深处理的实生苗数量最少。刈割加淹水可以很好地抑制互花米草的萌发和幼苗生长,据此建议互花米草防治方案为:在春季萌芽前,修筑堤坝,保持淹水20 cm,在营养生长期后期贴地刈割互花米草,继续淹水,第二年重复同样的刈割和淹水。为防止二次入侵,需要在邻近的互花米草分布区同时进行治理。&nbsp;</p

煤粉流态化预热气态组分CO/CO_2生成转化特性研究

基于循环流化床预热的燃烧系统是一种新型的清洁燃烧技术,其流态化预热后煤气中CO/CO_2比值对后续燃烧和排放影响较大,研究正确反映CO/CO_2比值的焦炭燃烧模型有助于进一步了解该流态化预热过程。笔者基于燃料流态化预热转化过程,研究典型的预热空气富氧气氛(O_2/N2)、富氧气氛(O_2/CO_2)以及燃料种类变化对预热后气态组分中CO/CO_2生成转化特性的影响,分析现有焦炭燃烧模型与流态化预热过程的匹配程度。试验数据和模型预测对比分析表明,空气富氧气氛下,氧气浓度从21%增至28.2%的过程中,神木半焦流态化预热过程产生的预热气体中CO_2占比减少,CO占比增多,CO/CO_2比值从0.81增至1.45;神木烟煤在该气氛预热时,各参数与神木半焦呈现同样的变化趋势,且随氧气浓度从21.0%增至24.4%,CO/CO_2比值从0.51增至0.76。富氧气氛时神木半焦预热产生的CO与神木烟煤相比产量更高,CO/CO_2比值随氧气浓度增大而增大,但与空气富氧气氛下相比递增幅度较小。神木烟煤预热气体组分CO/CO_2的试验数据与Tognotti提出的焦炭燃烧模型预测值吻合度最高,富氧气氛下试验与预测结果误差在9%以内

Biomass Changes of Suaeda glauca and Suaeda salsa under Reciprocal Companion and Different Additive Amount of Extraneous Nitrogen: A Field Simulation Experiment

To reveal the biomass changes of Suaeda glauca and Suaeda salsa as reciprocal companion under different additive amount of extraneous nitrogen, a field simulation experiment was conducted in the Yellow River Delta ecology research station of coastal wetland from May 2 to June 27, 2017. The two species were transplanted in to PVC pipe, with overall 108 PVC pipes laid. There were 3 planting densities (4 plants of dominant with 1 plant of companion, 2 plants of dominant with 1 plant of companion, and only 1 plant of dominant) were set in the experiment. Considering the situation of nitrogen deposition in the Yellow River Delta, 3 kinds of additive amount of extraneous nitrogen (0 g/m~2 nitrogen, 15 g/m~2 nitrogen, 30 g/m~2 nitrogen) were set, urea was as the nitrogen resource of extraneous nitrogen. The results showed that the average biomass accumulation of Suaeda salsa and Suaeda glauca both enhanced significantly along with increasing extraneous nitrogen input when planted 4 plants of dominant and 2 plants of dominant in each PVC pipe. When the additive amount of extraneous nitrogen were 15 g/m~2 nitrogen and 30 g/m~2 nitrogen, the biomass of Suaeda glauca was (58.0502.560) g per plant and (58.7403.170) g per plant, which were both significantly higher than that [(20.8500.640) g per plant] without extraneous nitrogen addition. The biomass of Suaeda salsa was (82.6401.330) g per plant and (111.9606.400) g per plant separately when the additive amount of extraneous nitrogen was 15 g/m~2 nitrogen and 30 g/m~2 nitrogen, which were also both significantly higher than that [(37.5001.750) g per plant] without extraneous nitrogen addition. Increasing additive amount of extraneous nitrogen promoted the biomass accumulation of Suaeda glauca and Suaeda salsa with an higher increase degree of the biomass of Suaeda salsa, indicating that increasing extraneous nitrogen promoted the growth of Suaeda salsa more strongly.</p

燃料流态化预热后NO_x生成路径及详细机理研究

为进一步控制污染物排放和实现碳中和的目标,富氧燃烧技术作为一种清洁燃烧技术受到广泛关注,将其与基于循环流化床预热的新型燃烧技术结合后,有利于进一步降低NO_x排放以及增强燃料的适应性。为探究不同燃料在预热富氧燃烧技术中NO_x的迁移规律,基于循环流化床预热的O_2/CO_2燃烧技术,采用神木烟煤与半焦2种对比燃料,利用CHEMKIN反应动力学软件的完全搅拌反应器(PSR),以预热燃料为输入条件,通过生成速率分析法(ROP)和敏感性分析法(SA) 2种分析方法对下行燃烧室内气相燃烧过程中NO_x迁移路径进行探究。将模拟计算与前人试验进行对比,结果表明:两段PSR模型能够对下行燃烧室的气相燃烧进行较好的计算模拟,模型适应性较好且输入参数设置方法可行。在O_2/CO_2气氛下,下行燃烧室内的燃烧产物CO_2以生成反应为主,主燃区CO_2分压的增大对NO生成有一定的促进作用。烟煤与半焦在整个燃烧过程中含氮物质发生气相反应的基本途径一致。在主燃区,NH_3转化的主要路径为:NH_3→NH_2→NH→HNO→NO,烟煤燃烧中,NH_3转化出现NH→N→NO反应,而HCN除消耗反应外,还可以由烃基与NO反应生成。对于半焦而言,烃基浓度增大对于NH_3和HCN的生成均起到促进作用

环境和生物因子对黄河三角洲滨海湿地净生态系统CO_2交换的影响

通过涡度相关和微气象观测技术,对黄河三角洲滨海湿地净生态系统CO_2交换(NEE)以及环境、生物因子进行了观测,探究湿地NEE变化规律及环境和生物因子对NEE的影响.结果表明:在日尺度上,生长季NEE呈明显"U"型曲线,非生长季变幅较小;在季节尺度上,NEE生长季波动较大,表现为碳汇,非生长季波动较小,表现为碳源;在年尺度上,滨海湿地生态系统表现为碳汇,总净固碳量为-247 g C·m~(-2).白天NEE主要受控于光合有效辐射(PAR),且生态系统表观量子产量(α)与白天生态系统呼吸(R_(eco,d))均于8月达到最大值,最大光合速率(A_(max))于7月达到最大值;夜间NEE随气温(T..

Effects of elevated temperature on soil respiration in a coastal wetland during the nongrowing season in the Yellow River Delta, China

冬季土壤呼吸能释放生长季所固存的碳,因而在陆地碳循环中占有重要地位。随着全球气候变暖,平均地表温度将升高0.3&ndash;4.8℃,且冬季增温更加明显,而温度的升高会促进更多CO2的释放。另外,滨海湿地地下水位浅,淡咸水交互作用明显,增温能引起土壤表层盐分升高,从而影响土壤呼吸。该研究以黄河三角洲滨海湿地为研究对象,采用红外辐射加热器模拟增温,研究了该地区非生长季土壤呼吸的日动态及季节动态,同时探讨了土壤呼吸对环境因子的响应机制。结果显示:日动态中,增温与对照的土壤呼吸速率变化趋势一致,为单峰曲线;在平均日变化中,整个非生长季不同处理的土壤呼吸速率无显著差异,而土壤温度和土壤盐分均为增温大于对照,并且土..

Effects of Spartina alterniflora Invasion on Soil Carbon, Nitrogen, Phosphorus and Their Ecostoichiometric Characteristics in the Yellow River Estuary Wetlands

Spartina alterniflora invasion has severely threatened the ecological integrity of coastal wetland ecosystems. The carbon, nitrogen, phosphorus and ecostoichiometric characteristics of soils in different layers were investigated under different stages of S. alterniflora invasion in the Yellow River Estuary wetlands. Using the method of substituting space for time, 0-100 cm soil samples were collected in wetlands of different stages of S. alterniflora invasion (SA3, invaded in 2016;SA8, invaded in 2011;SA13, invaded in 2006)and uninvaded bare flats (SA0). The contents of total carbon (TC), total nitrogen (TN)and total phosphorus (TP), were then measured and analyzed by the stoichiometric ratios of carbon, nitrogen and phosphorus. Results showed that (1)S. alterniflora invasion increased the content of TC and TN in surface soils, but had little effects on TP. (2)TC contents in the 0-10 cm soil layer of SA16, SA11 and SA06 were 18.9%, 27.6% and 57.6% higher than that of SA0, respectively, and TN contents were 1.39, 2.37 and 3.66 times higher than that of SA0, respectively. (3)S. alterniflora invasion didn't significantly affect soil w(C)/w(N), but increased w(C)/w(P)and w(N)/w(P)in shallow soils, and decreased w(C)/w(P)and w(N)/w(P)in deep soils. The order of soil w(C)/w(P)and w(N)/w(P)in the 0-10 cm soil layer was SA13>SA8>SA3>SA0. In the 0-100 cm soil layer, the order of soil w(C)/w(N)was SA0>SA8>SA13>SA3, that of soil w(C)/w(P)was SA13>SA8>SA0>SA3, and that of soil w(N)/w(P)was SA13>SA0>SA3>SA8. In the 0-100 cm soil layer, soil pH, electrical conductivity, bulk density and water content were important environmental factors affecting the contents of carbon, nitrogen and phosphorus. There were no significant correlations between w(C)/w(N)and soil environmental factors, but w(C)/w(P)and w(N)/w(P)were significantly correlated with environmental factors. In conclusion, S. alterniflora invasion changed the contents of soil carbon and nitrogen in the salt marsh wetlands of the Yellow River Estuary and affected the balance of soil nutrient resources