Nitrogen cycling of atmosphere-plant-soil system in the typical Calamagrostis angustifolia wetland in the Sanjiang Plain, Northeast China

The nitrogen (N) distribution and cycling of atmosphere-plant-soil system in the typical meadow Calamagrostis angustifolia wetland (TMCW) and marsh meadow Calamagrostis angustifolia wetland (MMCW) in the Sanjiang plain were studied by a compartment model. The results showed that the N wet deposition amount was 0.757 gN/(m2·a), and total inorganic N (TIN) was the main body (0.640 gN/(m2·a)). The ammonia volatilization amounts of TMCW and MMCW soils in growing season were 0.635 and 0.687 gN/m2, and the denitrification gaseous lost amounts were 0.617 and 0.405 gN/m2, respectively. In plant subsystem, the N was mainly stored in root and litter. Soil organic N was the main N storage of the two plant-soil systems and the proportions of it were 93.98% and 92.16%, respectively. The calculation results of N turnovers among compartments of TMCW and MMCW showed that the uptake amounts of root were 23.02 and 28.18 gN/(m2·a) and the values of aboveground were 11.31 and 6.08 gN/(m2·a), the re-translocation amounts from aboveground to root were 5.96 and 2.70 gN/(m2·a), the translocation amounts from aboveground living body to litter were 5.35 and 3.38 gN/(m2·a), the translocation amounts from litter to soil were larger than 1.55 and 3.01 gN/(m2·a), the translocation amounts from root to soil were 14.90 and 13.17 gN/(m2·a), and the soil (0-15cm) N net mineralization amounts were 1.94 and 0.55 gN/(m2·a), respectively. The study of N balance indicated that the two plant-soil systems might be situated in the status of lacking N, and the status might induce the degradation of C. angustifolia wetland.     

Sulfur cycle in the typical meadow Calamagrostis angustifolia wetland ecosystem in the Sanjiang Plain, Northeast China

The sulfur cycle and its compartmental distribution within an atmosphere-plant-soil system was studied using a compartment model in the typical meadow Calamagrostis angustifolia wetland in the Sanjiang Plain Northeast China. The results showed that in the typical meadow C. angustifolia wetland ecosystem, soil was the main storage compartment and current hinge of sulfur in which 98.4% sulfur was accumulated, while only 1.6% sulfur was accumulated in the plant compartment. In the plant subsystem, roots and litters were the main storage compartment of sulfur and they remained 83.5% of the total plant sulfur. The calculations of sulfur turnover through the compartments of the typical meadow C. angustifolia wetland ecosystem demonstrated that the above-ground component took up 0.99 gS/m2 from the root, of which 0.16 gS/m2 was translocated to the roots and 0.83 gS/m2 to the litter. The roots took in 1.05 gS/m2 from the soil, subsequent translocation back to the soil accounted for 1.31 gS/m2, while there was 1.84 gS/m2 in the litter and the net transfer of sulfur to the soil was more than 0.44 gS/(m2·a). The emission of H2S from the typical meadow C. angustifolia wetland ecosystem to the atmosphere was 1.83 mgS/(m2·a), while carbonyl sulfide (COS) was absorbed by the typical meadow C. angustifolia wetland ecosystem from the atmosphere at the rate of 1.76 mgS/(m2·a). The input of sulfur by the rainfall to the ecosystem was 4.85 mgS/m2 during the growing season. The difference between input and output was 4.78 mgS/m2, which indicated that sulfur was accumulated in the ecosystem and may cause wetland acidify in the future.     

模拟湿地水分变化对小叶章枯落物分解及氮动态的影响

2005年5月-2006年9月,利用三江平原典型碟形洼地的自然水分梯度作为水分变化研究的替代系统,结合分解袋法,模拟研究了湿地水分变化对典型草甸小叶章(TMC)和沼泽化草甸小叶章(MMC)枯落物分解及氮动态的可能影响.试验沿水分梯度设漂筏苔草群落(PF)、毛果苔草群落(MG)、乌拉苔草群落(WL)、沼泽化草甸小叶章群落(XII)、典型草甸小叶章群落(XI)和岛状林群落(DZL)6个分解小区.研究表明.水分条件对枯落物分解有重要影响,当未来降水格局变化导致小叶章湿地形成积水环境后,TMC和MMC枯落物的失重率分别将增加4.33%-16.76%和24.84%-53.97%.分解速率将增加10.51%-32.73%和77.85%-93.92%,95%分解时间将减少0.72-1.85 a和3.67-4.05 a;TMC和MMC枯落物的氮含量及氮积累指数的变化较为一致.但不同小区间的变化模式差异较大.二者枯落物的氮在DZL、XI、WL、MG和PF小区整体上均表现处出释放累积的交替变化特征.但仍以释放过程为主.在XII小区,氮在整个时期一直表现为释放.C/N分解过程中氮养分的调控作用更为重要;TMC和MMC枯落物的氮现存量分别为12.75 g·m-2和8.29 g·m-2.氮年归还量分别大于1.95 g·(m2·a)-1和2.25g·(m2·a)-1;温度对枯落物相对分解速率具有促进作用,水分条件对其具有抑制作用.当分解环境的养分状况不发生较大变化时,相对分解速率取决于枯落物基质质量,当养分状况发生较大改变时,相对分解速率取决于环境养分供给状况.     

潜流人工湿地中氮磷污染物净化的分层效应研究

选定芦苇、小叶章为湿地植物,土壤、炉渣为基质,构建3个小型潜流人工湿地系统,通过间歇运行方式,考察了模拟系统上层、下层中N、P和pH值等指标的变化.结果表明,当水力停留时间为10 d时,小叶章和芦苇湿地上层总氮的去除负荷分别为0.771 g·(m2·d)-1和1.481 g·(m2·d)-1,分别是下层的1.15倍和1...     

三江平原小叶章湿地H2S和COS排放动态

利用静态箱/气相色谱法，观测了生长季（5～9月）三江平原小叶章沼泽化草甸H₂S和COS的释放动态，结果表明，H₂S、COS的排放通量具有季节和日变化规律，小叶章沼泽化草甸H2S的平均释放通量为0.34 μg·(m²·h)^-1，COS的平均释放通量为－0.29μg·(m²·h)^-1；在生长季，小叶章沼泽化草甸表现为H₂S的源，COS的汇。小叶章的生长过程对H₂S、COS的排放影响显著，在小叶章生长旺盛期，H₂S出现排放峰值，COS出现吸收高峰，H₂S和COS的释放通量呈负相关。     

三江平原不同类型小叶章湿地土壤细菌群落功能多样性

为全面了解三江平原小叶章湿地土壤细菌功能多样性的变化规律,采用Biolog-ECO微平板法对三江平原内不同类型小叶章湿地(草甸化小叶章湿地、沼泽化草甸小叶章湿地和沼泽化小叶章湿地)的土壤细菌群落功能多样性变化规律和特点进行分析.结果表明:不同类型小叶章湿地土壤理化性质差异显著(P<0.05).土壤细菌群落平均颜色变化率(AWCD)随培养时间的延长而增加,不同类型湿地土壤细菌群落代谢活性表现为草甸化小叶章湿地>沼泽化草甸小叶章湿地>沼泽化小叶章湿地;土壤细菌群落多样性之间差异显著(P<0.05),草甸小叶章湿地土壤微生物的Shannon-Wiener多样性指数和McIntosh指数最高,分别为3.30和64.03;沼泽化草甸小叶章湿地次之,分别为3.23和60.63;沼泽化小叶章湿地最低,分别为3.19和54.21.Shannon-Wiener多样性指数和McIntosh指数与平均颜色变化率变化规律一致,说明土壤细菌群落结构受到土壤理化性质的影响,并且随着土壤含水量的升高,土壤细菌群落的平均颜色变化率和多样性均呈下降趋势.土壤细菌群落对不同碳源的利用强度上存在明显差异,其中对碳水化合物类、氨基酸类碳源的利用强度差异不大(P>0.05),但是对羧酸类、胺类、酚酸类、多聚物类碳源的利用强度差异显著(P<0.05).主成分分析(PCA)表明,两个主成分累计贡献率为80%,能够很好地解释不同湿地土壤细菌在碳源利用上有明显的空间分异这一现象.碳水化合物类碳源对土壤细菌群落多样性的影响最高,其次是氨基酸类和羧酸类碳源.研究显示,土壤理化性质及植被群落组成是影响小叶章湿地土壤细菌群落组成和功能活性的重要因素.      

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 di ering in nitrogen supply (0, 5 and 15 g N/m2) and CO2 levels (350 and 700 mol/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 di ered 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.     

水位梯度对小叶章湿地土壤微生物活性的影响

通过3 a野外控制试验,研究了不同水位梯度(-10~30 cm)条件下,小叶章湿地植物地上生物量和0~15 cm以及15~50 cm土壤总有机碳(TOC)、微生物量碳(MBC)、基础呼吸(BR)、微生物商(Cmic/Corg)、代谢商(qCO2)的变化规律.结果表明,不同水位条件下植物地上生物量差异显著(p0.05),积水水位10 cm的植物地上生物量最高,且积水水位0~20 cm保持较高的生产力;积水水位变化对土壤TOC、MBC、BR、Cmic/Corg、qCO2影响显著(p0.05).土壤TOC和BR对积水水位变化的响应趋势一致,0~15 cm土壤TOC和BR在零积水水位最高;15~50 cm土壤TOC和BR随着积水水位的升高而降低,与土壤MBC和Cmic/Corg的变化趋势相同,其中MBC变化最为明显;而qCO2随着积水水位的增加而增大.随着积水水位的增加,土壤微生物群落发生改变和土壤微生物活性降低,其中积水水位30 cm的土壤微生物活性最低,对有机碳的累积与分解过程产生影响.     

三江平原不同土地利用方式下凋落物对土壤呼吸的贡献

运用Li-6400土壤呼吸配套系统研究了三江平原沼泽湿地不同土地利用方式下保留和去除凋落物的土壤呼吸特征,进而分析了不同土地利用方式下凋落物对土壤呼吸的贡献及其与凋落物输入量和环境因子(温度、降水等)之间的相互关系.结果表明,整个生长季4种土地利用方式下凋落物对土壤呼吸的平均贡献量在-0.21~0.64μmol/(m2.s)之间,贡献率表现为小叶章草甸湿地(14%)人工林地(12%)大豆田(8%)退耕还湿地(-5%).其中,退耕还湿后凋落物对土壤呼吸的贡献表现为负值,减少了土壤呼吸的排放,表明凋落物对土壤呼吸的贡献可能最终取决于凋落物分解与屏蔽作用之间的平衡.除大豆田外,不同土地利用方式下凋落物对土壤呼吸的贡献均与10 cm地温达到了极显著相关关系(p0.01).另外,降雨的影响与凋落物输入密切相关,表明凋落物除自身分解外,还可能参与到气候变化的生态效应中.     

三江平原沼泽湿地N2O浓度与排放特征初步研究

2001年8月到9月在三江平原沼泽湿地进行N₂O的原位静态箱观测.结果发现近地气层N₂O平均浓度为281.7×10^-9m³/m³,低于大气背景浓度,说明沼泽湿地可能是人类目前了解较少但很重要的N₂O汇.选取积水状况和地表植被不同的毛果苔草沼泽、小叶章湿草甸(Ⅰ,Ⅱ)以及作为对照的小麦休耕地进行观测,发现4个地点的N₂O排放日变化形式不完全相同,除小麦田全天持续排放N₂O外,其余各点一天当中均出现排放与吸收交替出现的情况.温度是影响排放模式的主要因素.观测期内毛果苔草沼泽、小叶章湿草甸(Ⅰ,Ⅱ)和小麦休耕地N₂O的平均排放强度分别为0.22μg/(m²·h),1.75μg/(m²·h),1.31μg/(m²·h)和4.86μg/(m²·h).氧化还原电位是决定沼泽湿地N₂O排放特征的关键因子,地表积水情况和土壤水分状况则是影响N₂O排放的另一重要因素.     

Fluxes of CH4 and N2O from soil under a tropical seasonal rain forest in Xishuangbanna, Southwest China

CH4 and N2O fluxes from soil under a tropical seasonal rain forest in Xishuangbanna, Southwest China were measured for one year using closed static chamber technique and gas chromatography method. Three treatments were set in the studied field: (A) litter-free,(B) with litter, and (C) with litter and seedling. The results showed that the soil in our study was a sink of atmospheric CH4 and source of atmospheric N2O. The observed mean CH4 fluxes from treatments A, B, and C were -50.0±4.0, -35.9±2.8,-31.6±2.8 μgC/(m2·h),respectively,and calculated annual fluxes in2003 were -4.1,-3.1,and -2.9kgC/hm2,respectively.The observed mean N2O fluxes from treatments A,B,and C were 30.9±3.1,28.2±3.5,50.2±3.7μgN/(m2·h),respectively,and calculated annual fluxes in 2003 were 2.8, 2.6, and 3.7 kgN/hm2, respectively. Seasonal variations in CH4 and N2O fluxes were significant among all the three treatments. The presence of litter decreased CH4 uptake during wet season (P ＜ 0.05), but not during dry season. There was a similar increase in seedlings-mediated N2O emissions during wet and dry seasons, indicating that seedlings increased N2O emission in both seasons. A strong positive relationship existed between CH4 fluxes and soil moisture for all the three treatments, and weak relationship between CH4 fluxes and soil temperature for treatment B and treatment C. The N2O fluxes correlated with soil temperature for all the three treatments.     

波形潜流湿地处理低浓度生活污水

本文主要研究不同水力负荷条件下,波形潜流人工湿地对低浓度生活污水中有机物、氮和磷的去除效果及其影响因素。低、中、高水力负荷分别为0·2、0·4、0·8m3/(m2·d),处理低浓度生活污水试验研究表明:水力负荷对CODCr和TP的去除率有一定的影响,都是随着水力负荷的增大而下降;对NH3-N和TN的去除效果几乎没有影响。     

不同水分条件下小叶章湿地表土有机碳及活性有机碳组分季节动态

通过野外试验与室内分析,考察了三江平原生长季内不同水分条件小叶章(Calamagrostis anguatifolia)湿地表层0～20cm土壤有机碳(SOC)、轻组有机碳(LFOC)与微生物生物量碳(MBC)的季节变化动态.结果表明,不同水分条件小叶章湿地表土SOC及各组分含量季节变化明显.季节性积水条件对表土活性有...     

Nitrogen cycle of a typical Suaeda salsa marsh ecosystem in the Yellow River estuary

The nitrogen (N) biological cycle of the Suaeda salsa marsh ecosystem in the Yellow River estuary was studied during 2008 to 2009. Results showed that soil N had significant seasonal fluctuations and vertical distribution. The N/P ratio (15.73±1.77) of S. salsa was less than 16, indicating that plant growth was limited by both N and P. The N absorption coefficient of S. salsa was very low (0.007), while the N utilization and cycle coefficients were high (0.824 and 0.331, respectively). The N turnover among compartments of S. salsa marsh showed that N uptake from aboveground parts and roots were 2.539 and 0.622 g/m2, respectively. The N translocation from aboveground parts to roots and from roots to soil were 2.042 and 0.076 g/m2, respectively. The N translocation from aboveground living bodies to litter was 0.497 g/m2, the annual N return from litter to soil was far less than 0.368 g/m2, and the net N mineralization in topsoil during the growing season was 0.033 g/m2. N was an important limiting factor in S. salsa marsh, and the ecosystem was classified as unstable and vulnerable. S. salsa was seemingly well adapted to the low-nutrient status and vulnerable habitat, and the nutrient enrichment due to N import from the Yellow River estuary would be a potential threat to the S. salsa marsh. Excessive nutrient loading might favor invasive species and induce severe long-term degradation of the ecosystem if human intervention measures were not taken. The N quantitative relationships determined in our study might provide a scientific basis for the establishment of effective measures.     

Influence of environment and substrate quality on the decomposition of wetland plant root in the Sanjiang Plain, Northeast China

The litterbag method was used to study the decomposition of wetland plant root in three wetlands along a water level gradient in the Sanjiang Plain,Northeast China.These wetlands are Calamagrostis angustifolia(C.aa),Carex meyeriana(C.ma)and Carex lasiocarpa (C.la).The objective of our study is to evaluate the influence of environment and substrate quality on decomposition rates in the three wetlands.Calico material was used as a standard substrate to evaluate environmental influences.Roots native to each we...     

滇西北纳帕海高原湿地区域退化草甸土壤有机碳含量特征

为了解气候变化和人类活动双重影响下纳帕海高原湿地区域有机碳含量特征,采用空间格网状抽样调查方法,对区域内退化系列下湿地草甸w（SOC）（SOC为土壤有机碳）特征进行研究.结果表明:① 随着草甸的退化及土壤深度的增加,土壤含水量呈下降趋势,土壤容重呈增加趋势;② 从无退化草甸到重度退化草甸,植被地上生物量从321.4 g/m2降至142.1 g/m2;③ 在地表至地下50 cm深度范围内,从无退化到重度退化草甸,w（SOC）分别为28.21、20.59、18.01、14.81 g/kg,湿地草甸退化导致w（SOC）下降了近50%,ρ（SOC）从40.92 kg/m3降至25.23 kg/m3;④ 狼毒草甸的w（SOC）、ρ（SOC）等均表现出相对较高的水平,仅次于无退化样地;⑤ w（SOC）与土壤含水量呈显著正相关（P < 0.05）、与土壤容重呈显著负相关（P < 0.01）.湿地草甸植被退化所形成的地上植被盖度及生物量的下降,以及土壤含水量的下降和土壤容重的增加,最终导致近50%左右的w（SOC）发生流失;此外,若从同类研究中季节性淹水的沼泽或沼泽化草甸转变为该研究中常年出露于水面的草甸景观后,在20 cm土壤深度内将导致45%以上的w（SOC）损失.      

持续放牧和围封对科尔沁退化沙地草地碳截存的影响

研究了科尔沁退化沙地草地持续放牧和围封恢复下土壤-植物系统的碳(C)贮存,以揭示草地管理对C动态的影响.结果表明,0～15cm土壤OC和植物系统贮存的C(包括初级生产固定的C,立枯和地表凋落物C和根系C)贮量大小为:围封10年草地(584g·m^-2和309 g·m^-2)＞围封5年草地(524g·m^-2和146g·m^-2)＞持续放牧草地(493g·m^-2和95 g·m^-2).在围封10年,围封5年和持续放牧草地中,0～15cm土壤贮存C分别占各自土壤-植物系统C的65.3%,78.2%和83.9%.在风蚀严重的科尔沁沙地,持续放牧对植被,土壤及其周围环境有极严重的恶化作用.采取围封恢复措施后,植被恢复和凋落物积累使土壤免遭风蚀,也显著增加了土壤有机质的输入,因而显著作用于大气C的截存.但排除家畜放牧的长期围封使植物C向土壤C的再循环受到限制,截存的大部分C以凋落物的形式积存在土壤表面,需进一步深入研究围封的时间尺度.研究结果表明,退化沙地草地在采取有效的保护措施后,可以由C源变为C汇.     

不同水文情势下环形湿地土壤铁的时空分布特征

通过分季节原位采集三江平原环形湿地不同深度的土壤和土壤溶液,调查了土壤总铁的空间分布和土壤溶液中可溶性铁的时间变化,分析了水文情势对这种铁时空分异的影响.结果表明,环形湿地0～60 cm土层总铁的平均含量为（2.54±0.73）×10⁴mg·kg^-1,且随地表积水深度的增加由小叶章群落和乌拉苔草群落的（2.91±0.51）×10⁴ mg·kg^-1和（2.60±0.35）×10⁴mg·kg^-1逐渐下降到毛苔草和漂筏苔草群落的（2.48±0.31）×10⁴mg·kg^-1和（2.17 ± 0.31）×10⁴mg·kg^-1;常年积水土壤中铁的可溶性高于季节性积水土壤;从春季化冻开始,土壤溶液中的可溶性铁含量随积水时间的延长而逐渐增加,从6月的（0.35±0.086） mg·L^-1增加到10月上冻前的（12.67±2.92） mg·L^-1;以Fe³⁺/Fe²⁺表征的土壤还原性随积水深度或浸没时长的增加而增加;土壤溶液中的可溶性铁与pH、总有机碳、总氮和磷酸盐都具有显著或极显著相关,表明铁的分布还受土壤理化性质的影响,并与土壤碳、氮、磷的迁移转化相耦合.     

Response of soil fauna to simulated nitrogen deposition： A nursery experiment in subtropical China

We studied the responses of soil fauna to a simulated nitrogen deposition in nursery experimental plots in Subtropical China. Dissolved NH4NO3 was applied to the soil by spraying twice per month for 16 months, starting January 2003 with treatments of 0, 5, 10, 15 and 30 gN/(m2·a). Soil fauna was sampled after 6, 9, 13 and 16 months of treatment in three soil depths (0-5 cm, 5-10 cm, 10-15 cm). Soil available N increased in correspondence with the increasing N treatment, whereas soil pH decreased. Bacterial and fungal densities were elevated by the N treatment. Soil fauna increased in the lower nitrogen treatments but decreased in the higher N treatments, which might indicate that there was a threshold around 10 gN/(m2·a) for the stimulating effects of N addition. The N effects were dependent on the soil depth and sampling time. The data also suggested that the effects of the different N treatments were related to the level of N saturation, especially the concentration of NO3- in the soil.     

水翁(Cleistocalyx operculatus)在人工湿地的生长特性及对污染物的去除效果

研究了水翁在人工湿地的生长特性及其对污水的净化效果.结果表明:生长在人工湿地的水翁具有发达的侧根系,能保持正常的净光合速率((19.2±2.1)μmol/(m2·s))、蒸腾速率((23.5±2.3)mmol/(m2·s))、气孔传导率((657.5±53)mmol/(m2·s))、根系活力((20.9±3.2)μg/(g·min))和生长速率((9.9±0.5)mg/(g·d)).水翁人工湿地对TN,TP,C0D_cr和BOD₅的去除率分别为55.6%,44.2%,75.7%和73.2%.其中水翁对N,P的吸收量分别占人工湿地对N,P去除量的16.4%和12.6%.水翁为常绿乔木,可考虑与灌木和草本植物结合起来,建立乔、灌、草自然湿地系统,达到改善水质的目的.