中华绒螯蟹在不同pH值环境下的氮排泄

研究不同pH值环境对中华绒螯蟹（Eriocheir sinensis）氮排泄的影响。本研究采用直接浸浴法测定中华绒螯蟹在pH值4．5,6．0,7．5,9．0和10．5条件下的氮排泄。结果表明,在pH值9．0及其以下时,氨氮排泄无显著变化,当pH值升高到10．5时,氨氮排泄急剧下降,其排泄过程具有不连续性;亚硝酸氮、尿素氮和有机氮的排泄随pH值的升高而增加;硝酸氮的排泄同亚硝酸氮类似,但在pH值10．5时,呈下降状态;总氮的排泄随pH值升高而降低。在pH值4．5时,中华绒螯蟹的氨氮排泄量占总氮排泄量的91．0％,随着pH值上升,氨氮占总氮排泄的比例下降,而包括有机氮在内的其它形式的含氮化合物的排泄比例上升。因此．我们认为当环境pH值在9．0以下的范围波动时,不会对中华绒螯蟹的氨氮排泄带来不利影响,但过高的pH值可能会阻碍氮排泄。     

不同土壤肥力条件下施氮量对小麦氮肥利用和土壤硝态氮含量的影响

在土壤肥力不同的两块高产田上,利用15N示踪技术,研究了高产条件下施氮量对冬小麦氮肥吸收利用、籽粒产量和品质的影响,及小麦生育期间土壤硝态氮含量的变化.结果表明：1.成熟期小麦植株积累的氮素73.32%～87.27%来自土壤,4.51%～9.40%来自基施氮肥,8.22%～17.28%来自追施氮肥;随施氮量增加,植株吸收的土壤氮量减少,吸收的肥料氮量和氮肥在土壤中的残留量显著增加,小麦对肥料氮的吸收率显著降低;小麦对基施氮肥的吸收量、吸收率和基施氮肥在土壤中的残留量、残留率均显著小于追施氮肥,基施氮肥的损失量和损失率显著大于追施氮肥;较高土壤肥力条件下,植株吸收更多的土壤氮素,吸收的肥料氮量较少,土壤中残留的肥料氮量和肥料氮的损失量较高,不同地块肥料氮吸收、残留和损失的差异主要表现在基施氮肥上.2.当施氮量为105 kg/hm2时,收获后0～100cm土体内未发现硝态氮大量累积,随施氮量增加,0～100cm土体内硝态氮含量显著增加;施氮量大于195 kg/hm^2时,小麦生育期间硝态氮呈明显的下移趋势,土壤肥力较高地块,硝态氮下移较早,下移层次深.3.随施氮量增加,小麦氮素吸收效率和氮素利用效率降低,适量施氮有利于提高成熟期小麦植株氮素积累量、籽粒产量和蛋白质含量;施氮量过高籽粒产量和蛋白质含量不再显著增加,甚至降低;较高土壤肥力条件下,获得最高籽粒产量和蛋白质含量所需施氮量较低.     

内蒙古高原湖滨湿地优势植物功能性状特征及其适应性

受人类活动和气候变化的影响,湖泊湖滨带退化速度显著加快。植物功能性状的方法可以量化植物特征,预测植物对外界环境干扰的反应,有助于理解退化湖滨带湿地植物应对环境变化所表现出的适应机制,对湖泊湖滨湿地生态系统植被的恢复与重建具有重要意义。在内蒙古高原典型湖泊湖滨湿地选取芦苇（Phragmites australis）、赖草（Leymus secalinus）、毛茛（Ranunculus japonicus）、鹅绒委陵菜（Potentilla anserina）、碱蓬（Suaeda glauca）、盐角草（Salicornia europaea）和拂子茅（Calamagrostis epigeios）7种优势植物的叶片和根系作为研究对象,对不同湿地植物的11种功能性状变化规律及其与环境因子的关系进行研究。旨在探究环境变化影响下湖滨带湿地植物的物种分布和功能性状的差异,以及湿地植物在不同湖滨带湿地生境下的适应策略。在评估植物功能性状差异基础上,采用环境矩阵连接性状矩阵（RLQ）结合第四角分析（Fourth-Corner）的方法分析环境因子对植物功能性状的影响。结果表明,内蒙古湖滨带湿地中7种优势植物为了适应不同的环境的影响,植物的功能性状均产生不同程度的种间与种内变异,在湖滨带湿地中植物的植株高度、叶片碳含量、叶片氮含量、叶片碳氮比、比根长、根组织密度、根氮含量对环境变化的响应比较敏感,土壤pH与叶片干物质含量呈显著负相关;土壤盐分与植株高度、叶片碳含量和叶碳氮比显著负相关,与叶片氮含量、根组织密度显著正相关;土壤的总氮含量与植株高度显著正相关,与比根长显著负相关;土壤碳氮比与植株高度和叶片碳含量显著负相关,与植物比根长显著正相关;土壤容重与根氮含量显著负相关。研究表明内蒙古高原湖滨带湿地植物的功能性状受环境的作用强烈,植物采取了不同的性状策略来适应环境。     

湿地生物地球化学过程研究进展

1　湿地生物地球化学过程的概念及内涵营养物质在生态系统之间的输入和输出以及在生物各圈层之间进行的物质和能量交换称为生物地球化学循环 (ｂｉｏｇｅｏｃｈｅｍｉｃａｌｃｉｒｃｕｌａｔｉｏｎ) [4 ] ,它实质上是指生物有机体及其产物与无机环境之间进行的物质交换和能量转换过程。湿地是介于陆地生态系统和水生生态系统之间的过渡地带[3 ] ,它是一种特殊的生态系统 ,其独特多样的生物条件显著影响着生物地球化学过程。这些过程不仅改变了物质的化学组成 ,而且使它们在湿地内发生空间位移以及生物地球化学转化。湿地生物地球化学过程是…     

Solute exclusion from cellulose in packed columns: experimental investigation and pore volume measurements

A packed column approach was used in this investigation to determine pore volume and surface area distributions of several celluloses. Specific surface areas for Avicel PH 102, Solka Floc BW 300, and two size fractions of corn cobs that have been pretreated to remove lignin and hemicellulose were measured using this technique. In addition to measuring pore volume and specific surface area, the molecular diameters of several PEGs (polyethylene glycol) were estimated using viscosity measurements. Also, the influence of cellulose particle size, molecular diameter of PEGs, and PEG solution velocity on dispersion and tailing were investigated. Molecular diameter estimates from this investigation were 30%-35% lower than those reported in the literature. This discrepancy is due to earlier investigators using an inappropriate relationship for estimating molecular diameter from viscosity measurements. The precision of the column approach to solute exclusion was higher than that obtained by investigators using a batch approach. Dispersion increased with increasing particle size. Tailing of the elution curve was increased with increasing solute molecular diameter and elution rate. For a cellulase with a molecular diameter of 5.1 nm, estimated specific surface area ranged from 7.2 to 10.5 m(2) g(-1).     

湿地土壤种子库与地上植被相似性关系研究评述

土壤种子库与地上植被的关系是土壤种子库研究的重要组成部分。当前,湿地生态系统面临严重威胁,研究湿地土壤种子库和地上植被关系既可以加强对土壤种子库和植物群落特征的认识,又可以为湿地保护与管理提供理论指导。检索了科学引文索引扩展版(SCIE)数据库中收录的1900—2012年间研究湿地土壤种子库与地上植被关系的文献,通过分析土壤种子库与地上植被的Srensen相似性系数,结果发现:不同湿地类型的土壤种子库和地上植被的相似性存在显著差异,河流湿地中两者的相似性最小;不同植被类型中土壤种子库与地上植被的相似性差异显著:草本群落的相似性大于乔木群落;不同气候带的湿地中两者的相似性也存在显著差异,其中亚热带地区相似性最小。总结了湿地种子库与地上植被相似性关系的时空变化特征。二者的相似性通常随着植物群落的演替而减小,在空间上也随着环境梯度而变化。分析了两者关系的影响因素,如种子传播、环境条件和繁殖策略等。对研究中存在的问题及发展方向提出建议。     

Yield and nitrogen uptake of rapessed (Brassica campestris L.) with ammonium and nitrate

Water culture, growth chamber, greenhouse and field experiments were conducted to compare the effect of NH₄−N and NO₃−N on yield and N uptake of rapeseed (Brassica campestris L.). In water culture, the yields of 28-day old rapeseed plants grown at 14 μg N ml⁻¹ were double with NO₃ compared to NH₄, but N uptake was little affected. There was no such effect when concentration was reduced to 3.5 or 7 μg N ml⁻¹. The yield and N uptake of 26-day old rapeseed grown on six soils (pH 4.6 to 6.5) in pots in a growth chamber were much greater with NO₃ than with NH₄, although N concentration was more in the NH₄- than the NO₃-grown plants. In a greenhouse experiment with rapeseed grown on 12 potted soils, the N uptake of applied N was greater with NO₃ than with NH₄ on all soils. Averages were 63% with NH₄ and 78% with NO₃. However, NH₄-fixation capacities of the soils were only weakly correlated with yield from the two sources of N (r=0.48) and the relation was similar with N uptake. In contrast to the behavior of water culture, growth chamber and greenhouse experiments, the 33 field experiments did not show consistent difference in seed yield with NH₄ and NO₃ applied at time of seeding. In nine field experiments where band application was used for Ca(NO₃)₂, (NH₄)₂ SO₄, NH₄ NO₃, yield tended to be greatest for (NH₄)₂SO₄. However, in 19 experiments on acid soils with and without lime, yields in most cases were similar with (NH₄)₂SO₄ and NH₄ NO₃. Nitrification inhibitors were added to spring banded NH₄-based fertilizers in five experiments, but the yields were not influenced. Scientific Paper No. 558, Lacombe Research Station, Agriculture Canada.     

A novel indicator of reducing conditions and water-table depth in mires

1. Direct measurements of water-table depth in a mire were compared with depth to discolouration of polyvinyl chloride (PVC) tape left in situ for 15 months. Discolouration depth was highly correlated with positions of highest and lowest water tables; estimates were systematically biased but generally within 5 cm of measured values.
2. The annual range in water-table position indicated by discolouration depth varied 10-fold along a 30 m transect. Discolouration of PVC tape is an indicator of reducing conditions that could be applied in extensive surveys at very low cost.     

Book reviews

Wetlands have been widely applied for water quality amelioration. Enzymatic analysis was applied in a study of decomposition in constructed wetlands. We hypothesise that soil enzyme activities would be lower in wetland sediment than adjacent upland and that the lower soil enzyme activities are partly responsible for the water quality amelioration. Four soil enzyme activities (β-glucosidase, β-N-acetylglucosaminidase, phosphatase, and arylsulfatase) and microbial activity (electron transport system activity) were measured across a transect from a upland soil to a wetland sediment in two constructed wetland sites in the USA. Along with the activities, hydrochemistry was determined in inflow and outflow of the wetlands. In both wetlands, the enzyme activities in the sediments were significantly lower than the adjacent upland soils. For hydrochemistry, significant decreases were observed in phosphate and nitrate concentrations in outflow water compared to inflow water. However, there were no significant changes in other anions (F^-, Cl^-, SO ₄ ^2- . For dissolved organic carbon, it seems that the wetlands would be a source rather than a sink. The results suggest that the enzymatic approach represents a valuable method to assess decomposition processes in wetland sediments, and that characteristically low enzyme activities in the sediments may be important in the water quality amelioration function. This revised version was published online in July 2006 with corrections to the Cover Date.     

长江口九段沙湿地不同生境中大型底栖动物群落结构特征分析

2004年10月至2005年1月对九段沙湿地大型底栖动物的群落分布特征及环境因子进行了调查。选取6种主要生境的57个样方,分析大型底栖动物的种类、密度、生物量、多样性指数及均匀度指数等群落特征。共记录到28种大型底栖动物,主要由甲壳动物、环节动物、软体动物及昆虫幼体组成,优势种为谭氏泥蟹(Ilyrplaxdeschampsi)、光滑狭口螺(Stenothyraglabra)、堇拟沼螺(Assimineaviolacea)、绯拟沼螺(A.latericea)和霍甫水丝蚓(Limnodriuhoffmeisteri)。6种生境类型中以低潮位光滩大型底栖动物种类最为丰富,但其密度最低;海三棱藨草(Scirpusmariqueter)带底栖动物密度最高,并且其均匀度与其他生境存在显著差异;互花米草(Spartinaalterniflora)带下底栖动物的种类组成与其他生境有一定差异,但种类数、密度和多样性处于平均水平,总体群落结构没有显著差异。     

水氮耦合对冬小麦氮肥吸收及土壤硝态氮残留淋溶的影响

在高肥力条件下,大田试验采用裂区设计,主区为不同灌水频次(0～3次),裂区为不同施氮量(0～240 kg/hm2),结合15N微区示踪技术,研究了水氮耦合对冬小麦氮肥的吸收利用及生育后期土壤硝态氮累积迁移的影响.结果表明,在一定氮肥水平下,不灌水处理的氮肥利用率高于各灌水处理,各灌水处理的氮肥利用率随灌水次数增加呈上升趋势;增加灌水次数,氮肥耕层残留量和残留率显著降低,氮肥损失量和损失率则明显增加.在一定的灌溉水平上,随施氮量(0～240 kg/hm2)增加,植株总吸氮量、氮肥吸收量、氮肥耕层残留量、氮肥损失量以及损失率均呈上升趋势,而氮肥利用率和耕层残留率呈下降趋势.氮肥水平一定时,在灌0至灌2水范围内,籽粒产量随灌水次数增加呈上升趋势,灌3水处理中施氮处理(N168、N240)的籽粒产量较灌2水处理显著降低;灌水生产效率随灌水次数增加显著下降.在一定灌溉水平上,施氮量由168 kg/hm2增至240 kg/hm2,氮素收获指数和氮肥生产效率显著降低,各灌水处理的生物产量、籽粒产量和籽粒蛋白质含量均无显著变化,不灌水处理的生物产量、籽粒产量显著降低.灌水促进了施氮处理(N168,N240)中土壤硝态氮向下迁移,从开花到收获0～100 cm土层中部分硝态氮迁移到了100～200 cm土层.灌水次数是导致收获期0～100 cm土层残留NO-3-N累积量变化的主导因素;水氮互作效应是决定收获期100～200 cm土层残留NO-3-N累积量变化的主导因素,且灌水效应大于施氮效应.     

Effects of Decreasing Mitochondrial Volume on the Regulation of the Permeability Transition Pore

The permeability transition pore (PTP) is a Ca²⁺-sensitive mitochondrial inner membrane channel involved in several models of cell death. Because the matrix concentration of PTP regulatory factors depends on matrix volume, we have investigated the role of the mitochondrial volume in PTP regulation. By incubating rat liver mitochondria in media of different osmolarity, we found that the Ca²⁺ threshold required for PTP opening dramatically increased when mitochondrial volume decreased relative to the standard condition. This shrinkage-induced PTP inhibition was not related to the observed changes in protonmotive force, or pyridine nucleotide redox state and persisted when mitochondria were depleted of adenine nucleotides. On the other hand, mitochondrial volume did not affect PTP regulation when mitochondria were depleted of Mg²⁺. By studying the effects of Mg²⁺, cyclosporin A (CsA) and ubiquinone 0 (Ub₀) on PTP regulation, we found that mitochondrial shrinkage increased the efficacy of Mg²⁺ and Ub₀ at PTP inhibition, whereas it decreased that of CsA. The ability of mitochondrial volume to alter the activity of several PTP regulators represents a hitherto unrecognized characteristic of the pore that might lead to a new approach for its pharmacological modulation.     

The effect of delignification of forest biomass on enzymatic hydrolysis

The effect of delignification methods on enzymatic hydrolysis of forest biomass was investigated using softwood and hardwood that were pretreated at an alkaline condition followed by sodium chlorite or ozone delignification. Both delignifications improved enzymatic hydrolysis especially for softwood, while pretreatment alone was found effective for hardwood. High enzymatic conversion was achieved by sodium chlorite delignification when the lignin content was reduced to 15%, which is corresponding to 0.30-0.35 g/g accessible pore volume, and further delignification showed a marginal effect. Sample crystallinity index increased with lignin removal, but it did not show a correlation with the overall carbohydrate conversion of enzymatic hydrolysis.     

三峡水库消落带优势植物不同配置对土壤结构稳定性的影响

土壤结构稳定性是衡量退化生态系统功能恢复和维持的关键指标。探究优势植物配置对土壤结构稳定性的影响,对于三峡水库消落带的植被恢复与岸线稳定具有重要意义。选择三峡水库消落带优势植物狗牙根(G)、香附子(X)和苍耳(C),设置空白(CK)、单种(G、X、C)、两两混种(GX、CX、CG)三种不同处理,利用Yoder湿筛法和计算机断层扫描技术(Computed Tomography,CT)对土壤团聚体粒径分布和土壤孔隙特征进行测定,对比分析了不同植物配置对土壤团聚体粒径分布与稳定性及土壤孔隙结构的影响。结果表明:1)相比于CK处理,不同植物配置处理下土壤团聚体(>0.25 mm)的质量百分比均有增加。植物根系的生长促进了土壤团聚体的形成与稳定,但并未达到显著水平。2)香附子单种及其与狗牙根的混种均抑制了土壤大孔隙的形成,可能由于香附子根系不发达,且其膨大的根结在生长过程中压缩了周围的土壤孔隙。然而,对于狗牙根和苍耳,无论是单种还是混种都会促进土壤大孔隙的发育。3)植物根系性状与土壤团聚体稳定性和土壤孔隙结构具有显著相关性,根长(RL)和根表面积(RSA)是影响土壤团聚体稳定性的关键根系性状,根长(RL)、根表面积(RSA)和根体积(RV)是控制土壤孔隙结构的关键性状。因此,为了有效提升土壤结构的稳定性,可以基于植物的根长、根表面积等根系功能性状,筛选出适合脆弱生态系统植被恢复的先锋或优势植物,并进行合理配置。该结果可为三峡水库消落带及相似区域的水土保持和生态恢复中的植物遴选与群落配置提供基础数据和理论支持。     

Effects of <Emphasis Type="Italic">Carex rostrata</Emphasis> on soil oxygen in relation to soil moisture

Many wetland plants are faced with severe edaphic problems. Long term flooding effects a sequence of chemical processes that result in soil anoxia and production of several phytotoxic compounds. In order to maintain an aerobic root respiration wetland plants produce aerenchyms that enable oxygen conduction through the plant body to underground organs. Moreover wetland plants are able to release oxygen into the soil. This aeration effect of wetland plants in turn can influence soil chemistry considerably and protects roots by an aerobic rhizosphere. Oxygen release by underground organs of aerenchymous plants has been well documented in laboratory investigations but not under field conditions. In this study, dynamics of oxygen saturation were measured together with soil water content and microclimatic parameters. Measurements were carried out on some lowland peat covered by Carex rostrata Stokes from July to October 2001. Oxygen saturation was quantified using novel optical sensors (microoptrodes). The presence of C. rostrata significantly increased oxygen content in the soil. Mean oxygen saturation under Carex rostrata (56.0%) was significantly higher than in a control plot without vegetation (26.6%). Due to fluctuating water content, oxygen saturation in both plots was characterized by pronounced time variation. Increasing soil water content caused an extreme decline of oxygen saturation in both plots and led to anoxia in the control plot. In the presence of C.rostrata, the decline in soil oxygen took place at significantly higher water content (68.5% compared to 67.5% in the control plot) which is substantial as the mean water contents varied between 67 and 69% during the measurement period.     

三江平原典型环型湿地土壤-植被-动物系统的结构及功能研究

环型湿地是三江平原沼泽湿地的主要景观类型之一。由于微地貌的变化 ,形成了相应的高势能区和低势能区。随着势能的变化 ,形成了不同的水热分布带 ,因而也产生了不同的土壤、植物、动物的环型水平结构和垂直结构的特点。在水平结构上 ,环型湿地由中心向外缘 ,地势由低到高 ,水分由多渐少 ,温度由低到高分布。因此 ,也带来了土壤和动植物的变化 ,土壤由泥炭土向沼泽土和白浆土过渡 ;植物由沉水的小狸藻向浮水的漂筏苔草、挺水的大穗苔草 睡菜群丛、毛果苔草 -狭叶甜茅群丛、小叶章 -沼柳 -越菊柳以及外缘分布的蒙古栎 白桦岛状林发展。动物的水平结构也就有相应的变化。环型湿地每个水平分布带又都具有各自不同的垂直结构。环型湿地的特殊结构 ,使其有着巨大的储水功能和调节温度的功能。即使在高温干旱的季节 ,由于湿地表面的须根层有隔离的空间 ,阻止了温度的传导 ,减少了下层水的蒸发 ,在下层的泥炭中仍有大量的水分保持。同时 ,这里也是一个太阳能储存库和遗传基因库。深入了解环型湿地的结构与功能 ,对研究湿地生态系统的功能及其保护湿地 ,实现湿地资源的可持续利用都具有重要的意义     

接种蚯蚓对有机茶园土壤结构及有机碳库的影响

为探讨接种蚯蚓对有机茶园土壤团聚体、孔隙分布及有机碳库的影响,设置375条/m²,250条/m²,125条/m²三种蚯蚓投放密度,将威廉腔环蚓接种于信阳有机茶园土壤中。结果表明：接种蚯蚓能显著提升>2mm大团聚体的比例而降低<0.25mm粒径的微团聚体的比例;提高水稳性小团聚体(0.25mm≤d≤2mm)比例,但对水稳性大团聚体d>2mm的影响不显著;高密度蚯蚓处理平均重量直径(MWD),平均几何直径(NWD)以及分型维数(D),团聚体破坏率(PAD)显著高于其他密度处理及对照(CK)。接种蚯蚓使得结构性孔隙(土壤颗粒间和团聚体间孔隙)所占比重增加,其中以团聚体间孔隙增加最为显著,其次为颗粒间孔隙,对由粘粒及矿物层间形成的毛管孔隙分布无显著影响;随着接种密度的增加,颗粒间孔隙度变化不显著而团聚体间孔隙度的相对值和绝对值均显著增加。添加蚯蚓能显著增加土壤活性有机库总量。接种密度的增加对活性有机碳库总量影响不大,但对土壤呼吸速率提升较多,故从温室气体排放角度考虑低接种密度更合适。可见,有机茶园中少量接种蚯蚓...