永定河流域(北京段)不同生态护岸形式坡面侵蚀及面源污染特征

永定河是北京市的防洪安全屏障和供水河道,河道生态系统修复问题亟待解决.选择河北省廊坊市永定河沙质河道,建立13个野外标准径流小区,设置2个岸坡坡比,选取5种材料复合得9种护岸配置形式,研究3个放水流量下不同护岸形式的减流减沙效果以及对于总氮(TN)、总磷(TP)、氨氮(NH4+-N)、化学需氧量(COD)、生化需氧量(...     

北京市房山区开发建设项目水土保持方案中的植物措施设计

植物措施是开发建设项目水土保持方案中非常重要的一部分,对防治水土流失、恢复植被、改善生态环境都起着重要的作用。总结了北京市房山区常见的房地产、道路工程和河道整治工程三大类开发建设项目水土保持方案中的植物措施设计,指出现有植物措施设计中存在重视程度不够、设计不具有典型性、不能科学合理地选择和配置树种等问题,并提出了一些合理化建议与对策。     

木兰科植物在都匀市园林绿化中的应用现状分析

木兰科植物具有树形优美,花大艳丽,花香袭人,适应性广,抗污能力强等优点,是现代园林绿化及景观生态建设的重要选择。但是,在园林城市的建设中还有许多品种仍未广泛应用。本文通过对贵州都匀市的木兰科资源及其园林应用现状的调查分析,探索其在园林造景上的植物配置方法,以期为开发和利用木兰科植物资源提供依据。     

观花藤蔓植物在立体绿化中的应用

介绍了观花藤蔓植物的类型,在立体绿化中的应用原则和形式,推荐了一些适宜在重庆地区应用的观花藤蔓植物品种及其园林配置。     

HEC-RAS在河道生态治理中的应用——以滦平县兴洲河路南营段河道治理工程为例

在河道生态治理中,充分认识河道治理前后河床断面及河道植被等对水流、水位的影响,有利于更合理地进行河道生态治理综合措施的配置。以滦平县兴洲河路南营段河道治理为例,参照水面线计算公式,采用HEC-RAS软件对该段河道治理前后的水面线进行了分析计算,然后根据治理前后河底糙率系数的差异及不同断面的水位变化分析了河道治理效果。采用HEC-RAS软件进行水面线计算的结果显示:治理前随着河底纵坡的变化,水面线变化不平稳,水流流速在不同断面间发生变化;与治理前相比较,治理后的水面线(设计值)变化平缓,水深变化平稳。在河道治理中,采用河道清淤、设置护堤坝和生态护岸等措施,同时进行湿地恢复、河岸绿化等工程的建设可以达到生态治理目的,即使在遇到10年一遇洪水时也能够防治或者消除洪水对两岸的威胁。参考不同河段通过HEC-RAS推求的河道水面线成果,提出了在河道治理过程中滨水植物的选择和配置方案。     

长江下游典型生态河道水土保持措施调查分析及对策

为明确生态河道建设中面临的水土保持问题，指导生态河道建设中的水土保持措施配置及管护，以江苏省生态河道建设工程为研究对象，采用资料收集、无人机航摄、野外实测及现场座谈等方法，开展了典型生态河道水土保持措施调查。基于因素空间分异特征，综合考虑河道工程断面和措施配置，确定宜兴洑西河、宝应大溪河和宿迁黄河故道宿城段为典型生态河道建设工程，统计分析了生态河道建设工程中实施的措施类型及种类，结果表明，具有水土保持功能的措施有21种，其中16种界定为水土保持措施，且典型生态河道建设工程的水土保持措施数量和投入在初步设计和验收阶段存在较大差异。针对生态河道建设中存在的不重视水土保持方案编制、植物种类选择不合理、河道边坡耕垦现象及面源污染问题突出、文化挖掘和植被多样性以及与环境景观的协调性不足等问题，提出了相应的对策与建议。     

生态清洁小流域建设中植物措施的作用及建议

水土保持植物措施是"生态修复、生态治理、生态保护"三道防线建设内容的重要组成部分,对于防治水土流失、净化水质和改善环境起着重要作用。水土保持植物措施在北京市生态清洁小流域建设中得到了广泛应用,主要措施有水保林、矿山植被恢复、农村产业结构调整、村庄绿化美化、库滨植被缓冲带建设、河道生态护岸以及河库湿地建设。建议在今后的工作中加强水源保护和生态修复技术研究,合理选择植物品种,完善"三道防线"理论与技术。     

江南地区乡土植物在生态河道护岸中的试验及应用

近年来人们越来越重视将植物措施应用于生态河道的建设。以浙江省安吉县为代表地区,在生态河道护坡建设中,筛选出7种适合生长于江南地区生态河道护坡的乡土植物,探索出2种科学合理的乡土植物空间配置模式,集成1项江南地区乡土植物在生态河道护岸建设中应用的技术体系,并设立了技术体系的示范区域。据观测,示范区域采取此技术体系后减流效益大约为70%,减沙效益在90%以上,可以十分明显地降低坡面水土流失量。     

植物在弃土场水土流失防治中的作用与配置

通过研究植被的水土保持机理和水土流失对植被的影响,并以"生产建设项目弃土场植物品种的选择及植物措施配置"为例讨论植物在生产建设项目弃土场水土流失治理中的应用,结合弃土场立地条件及实际需求,筛选优良的水土保持植物品种,提出适合江西省生产建设项目弃土场植物措施配置模式.     

北京市朝阳区立交桥立体绿化植物配置模式

为提高有限空间范围内的绿化率,实施立体绿化是一条有效的途径.北京市朝阳区立交桥区是立体绿化的主要载体,通过对区内已经进行立体绿化的立交桥进行全面的调查及资料收集,经研究分析,提出适宜立交桥立体绿化的植物品种;并区分桥壁式、立柱式、边坡式3种类型,对现有立交桥立体提出绿化的植物配置模式的改进方案,同时对光明桥的立体绿化改造提出了具体的实施方案.     

硫酸根自由基高级氧化技术对污染场地多环芳烃的修复效果研究

硫酸根自由基高级氧化技术(sulfate radical(SO₄^·–)based advanced oxidation processes,SR-AOPs)是一种被广泛应用于降解土壤有机污染物的原位氧化修复技术。然而,关于SR-AOPs降解土壤多环芳烃(polycyclic aromatic hydrocarbons,PAHs)的报道相对较少。本研究以南京某炼钢厂附近土壤作为试验样本,通过设置不同比例混合体系的过硫酸钠(Na₂S₂O₈)和亚铁离子(Fe²⁺)以及反应不同时间,探究SR-AOPs对土壤中16种PAHs的修复效果以及最佳技术方案。结果表明:Na₂S₂O₈和Fe²⁺的配比会显著影响土壤PAHs的降解效果,当两者比例达到10︰1时,即Na₂S₂O₈用量为5 mmol/g,Fe²⁺     

A method for estimating coefficients of soil organic matter dynamics based on long-term experiments

The one-compartment C model C_t=C₀e^−k₂t+k₁A/k₂(1−e^−k₂t) is being long used to simulate soil organic C (SOC) stocks. C_t is the SOC stock at the time t; C₀, the initial SOC stock; k₂, the annual rate of SOC loss (mainly mineralization and erosion); k₁, the annual rate to which the added C is incorporated into SOC; and A, the annual C addition. The component C₀e^−k₂t expresses the decay of C₀ and, for a time t, corresponds to the remains of C₀ (C_0 remains). The component k₁A/k₂(1−e^−k₂t) refers, at time t, to the stock of SOC derived from C crops (C_crop). We herein propose a simple method to estimate k₁ and k₂ coefficients for tillage systems conducted in long-term experiments under several cropping systems with a wide range of annual C additions (A) and SOC stocks. We estimated k₁ and k₂ for conventional tillage (CT) and no-till (NT), which has been conducted under three cropping systems (oat/maize −O/M, vetch/maize −V/M and oat + vetch/maize + cowpea −OV/MC) and two N-urea rates (0 kg N ha⁻¹ −0 N and 180 kg N ha⁻¹ −180 N) in a long-term experiment established in a subtropical Acrisol with C₀ = 32.55 Mg C ha⁻¹ in the 0–17.5 cm layer. A linear equation (C_t = a + bA) between the SOC stocks measured at the 13th year (0–17.5 cm) and the mean annual C additions was fitted for CT and NT. This equation is equivalent to the equation of the model C_t=C₀e^−k₂t+k₁A/k₂(1−e^−k₂t), so that a=C₀e^−k₂t and bA=k₁A/k₂(1−e^−k₂t). Such equivalences thus allow the calculation of k₁ and k₂. NT soil had a lower rate of C loss (k₂ = 0.019 year⁻¹) than CT soil (k₂ = 0.040 year⁻¹), while k₁ was not affected by tillage (0.148 year⁻¹ under CT and 0.146 year⁻¹ under NT). Despite that only three treatments had lack of fit (LOFIT) value lower than the critical 5% F value, all treatments showed root mean square error (RMSE) lower than RMSE 95% indicating that simulated values fall within 95% confidence interval of the measurements. The estimated SOC stocks at steady state (C_e) in the 0–17.5 cm layer ranged from 15.65 Mg ha⁻¹ in CT O/M 0 N to 60.17 Mg ha⁻¹ in NT OV/MC 180 N. The SOC half-life (t_1/2 = ln 2/k₂) was 36 years in NT and 17 years in CT, reflecting the slower C turnover in NT. The effects of NT on the SOC stocks relates to the maintenance of the initial C stocks (higher C_0 remais), while increments in C_crop are imparted mainly by crop additions.     

Interpreting the dependence of soil respiration on soil temperature and water content in a boreal aspen stand

Continuous half-hourly measurements of soil CO₂ efflux made between January and December 2001 in a mature trembling aspen stand located at the southern edge of the boreal forest in Canada were used to investigate the seasonal and diurnal dependence of soil respiration (R_s) on soil temperature (T_s) and water content (θ). Daily mean R_s varied from a minimum of 0.1 μmol m⁻² s⁻¹ in February to a maximum of 9.2 μmol m⁻² s⁻¹ in mid-July. Daily mean T_s at the 2-cm depth was the primary variable accounting for the temporal variation of R_s and no differences between Arrhenius and Q₁₀ response functions were found to describe the seasonal relationship. R_s at 10 °C (R_s10) and the temperature sensitivity of R_s (Q_10Rs) calculated at the seasonal time scale were 3.8 μmol m⁻² s⁻¹ and 3.8, respectively. Temperature normalization of daily mean R_s (R_sN) revealed that θ in the 0–15 cm soil layer was the secondary variable accounting for the temporal variation of R_s during the growing season. Daily R_sN showed two distinctive phases with respect to soil water field capacity in the 0–15 cm layer (θ_fc, 0.30 m³ m⁻³): (1) R_sN was strongly reduced when θ decreased below θ_fc, which reflected a reduction in microbial decomposition, and (2) R_sN slightly decreased when θ increased above θ_fc, which reflected a restriction of CO₂ or O₂ transport in the soil profile.Diurnal variations of half-hourly R_s were usually out of phase with T_s at the 2-cm depth, which resulted in strong diurnal hysteresis between the two variables. Daily nighttime R_s10 and Q_10Rs parameters calculated from half-hourly nighttime measurements of R_s and T_s at the 2-cm depth (when there was steady cooling of the soil) varied greatly during the growing season and ranged from 6.8 to 1.6 μmol m⁻² s⁻¹ and 5.5 to 1.3, respectively. On average, daily nighttime R_s10 (4.5 μmol m⁻² s⁻¹) and Q_10Rs (2.8) were higher and lower, respectively, than the values obtained from the seasonal relationship. Seasonal variations of these daily parameters were highly correlated with variations of θ in the 0–15 cm soil layer, with a tendency of low R_s10 and Q_10Rs values at low θ. Overall, the use of seasonal R_s10 and Q_10Rs parameters led to an overestimation of daily ranges of half-hourly R_s (ΔR_s) during drought conditions, which supported findings that the short-term temperature sensitivity of R_s was lower during periods of low θ. The use of daily nighttime R_s10 and Q_10Rs parameters greatly helped at simulating ΔR_s during these periods but did not improve the estimation of half-hourly R_s throughout the year as it could not account for the diurnal hysteresis effect.     

Genetic diversity and differentiation of cultivated ginseng (<Emphasis Type="Italic">Panax ginseng</Emphasis> C. A. Meyer) populations in North-east China revealed by inter-simple sequence repeat (ISSR) markers

Panax ginseng C. A. Meyer is a medicinally important herb with a long history of cultivation, and includes three cultivated types, viz. garden ginseng (GGS), forest ginseng (FGS) and transplanted wild ginseng (TGS). In the present study, inter-simple sequence repeat (ISSR) markers were employed to investigate the genetic variability in 282 individuals, which corresponded to 16 cultivated ginseng populations. Genetic diversity was high at the species level (h = 0.2886; I = 0.4382; PPB = 98.96%), but relatively lower at the cultivated-type level (GGS: h = 0.2294, I = 0.3590, PPB = 85.42%; FGS: h = 0.1702, I = 0.2559, PPB = 57.29%; TGS: h = 0.2021, I = 0.3125, PPB = 76.04%). The hierarchical analysis of molecular variance (AMOVA) revealed pronounced genetic differentiation among populations (Φ _ST = 53.94%), which was confirmed by the gene differentiation coefficient (G _ST = 0.4910) and low gene flow (N _m = 0.5184). Both Principal Coordinates Analysis (PCoA) and UPGMA cluster analysis supported the clustering of all 16 populations into three groups, corresponding to the three cultivated types, among which there occurred remarkable genetic differentiation (Φ _ST = 37.43%). Pronounced genetic differentiation was also detected among populations within the three cultivated types (GGS: Φ _ST = 40.83%, G _ST = 0.3187, N _m = 1.0691; FGS: Φ _ST = 22.85%, G _ST = 0.2328, N _m = 1.6480; TGS: Φ _ST = 30.68%, G _ST = 0.2540, N _m = 1.4686). Mantel test indicated no significant correlation between geographic and genetic distances at both species and cultivated-type levels (P > 0.05). These findings have profound implications for the sustainable utilization of this precious medicinal herb.     

Perchlorate Depositional History as Recorded in North American Ice Cores from the Eclipse Icefield, Canada, and the Upper Fremont Glacier, USA

Temporal depositional rates are important in order to understand the production and occurrence of perchlorate (ClO₄⁻) as limited information exists regarding the impact of anthropogenic production or atmospheric pollution on ClO₄⁻ deposition. Perchlorate concentrations in discrete ice core samples from the Eclipse Icefield (Yukon Territory, Canada) and Upper Fremont Glacier (Wyoming, USA) were analyzed using ion chromatography tandem mass spectrometry to evaluate temporal changes in the deposition of ClO₄ ⁻ in North America. The ice core samples cover a time period from 1726 to 1993 and 1970 to 2002 for the Upper Fremont Glacier (UFG) and Eclipse ice cores, respectively. The average ClO₄ ⁻ concentration in the Eclipse ice core for the time period from 1970 to 1973 was 0.6 ± 0.3 ng L⁻¹, with higher values of 2.3 ± 1.7 and 2.2 ± 2.0 ng L⁻¹ for the periods 1982–1986 and 1999–2002, respectively. All pre-1980 ice core samples from the UFG had ClO₄ ⁻ concentrations <0.2 ng L⁻¹, and the post-1980 samples ranged from <0.2 ng L⁻¹ to a maximum of 2.6 ng L⁻¹ for the year 1992. A significant positive correlation (R = 0.75, N = 15, p < 0.001) of ClO₄⁻ with SO₄²⁻ was found for the annual UFG ice core layers and of ClO₄ ⁻ with SO₄²⁻ and NO₃⁻ in sub-annual Eclipse ice samples (R > 0.3, N = 121, p < 0.002). The estimated yearly ClO₄⁻ depositional flux for the Eclipse ice core ranged from 0.6 (1970) to 4.7 μg m⁻² year⁻¹ (1982) and the UFG from <0.1 (pre-1980) to 1.4 μg m⁻² year⁻¹ (1992). There was no consistent seasonal variation in the ClO₄⁻ depositional flux for the Eclipse ice core, in contrast to a previous study on the Arctic region. The presence of ClO₄⁻ in these ice cores might correspond to an intermittent source such as volcanic eruptions and/or any anthropogenic forcing that may directly or indirectly aid in atmospheric ClO₄⁻ formation.     

Estimating the component of soil respiration not dependent on living plant roots: Comparison of the indirect y-intercept regression approach and direct bare plot approach

Distinguishing between root and non-root derived CO₂ efflux is important when determining rates of soil organic matter turnover, however, in practice they remain difficult to separate. Our aim was to evaluate two methods for determining the component of below-ground respiration not dependent on plant roots (i.e., basal soil respiration; R_b). The first approach estimated R_b indirectly from the y-intercept of linear regressions between below-ground respiration (BGR) and root biomass. The second approach involved direct measurements of soil respiration from bare plots. To compare the contrasting approaches, BGR and crop biomass measurements were collected throughout the year in a range of agricultural systems. We found that both methods were very closely correlated with each other. Values of R_b determined by the intercept approach, however, were slightly higher than those determined by measurement of bare plots. Both approaches showed a seasonal trend with estimates of R_b lowest in winter months at 0.02 t C ha⁻¹ month⁻¹ for the y-intercept approach and 0.11 t C ha⁻¹ month⁻¹ for the bare plots approach, even after the data had been corrected for the influence of soil temperature. Highest rates of R_b occurred from the height to the end of the crop growing season (0.8-1.5 t C ha⁻¹ month⁻¹). The annual CO₂ efflux due to R_b was estimated to be 8.1 t C ha⁻¹ y⁻¹ from the y-intercept approach and 6.8 t C ha⁻¹ y⁻¹ from bare plots. Annual BGR was 12.1 t C ha⁻¹ y⁻¹. We conclude that both methods provide similar estimates of R_b, however, logistically the bare plots approach is much easier to undertake than the y-intercept approach.     

Methane fluxes from three ecosystems in tropical peatland of Sarawak, Malaysia

Methane fluxes were measured monthly over a year from tropical peatland of Sarawak, Malaysia using a closed-chamber technique. The CH₄ fluxes in forest ecosystem ranged from −4.53 to 8.40 μg C m⁻² h⁻¹, in the oil palm ecosystem from −32.78 to 4.17 μg C m⁻² h⁻¹ and in the sago ecosystem from −7.44 to 102.06 μg C m⁻² h⁻¹. A regression tree approach showed that CH₄ fluxes in each ecosystem were related to different underlying environmental factors. They were relative humidity for forest and water table for both sago and oil palm ecosystems. On an annual basis, both forest and sago were CH₄ source with an emission of 18.34 mg C m⁻² yr⁻¹ for forest and 180 mg C m⁻² yr⁻¹ for sago. Only oil palm ecosystem was a CH₄ sink with an uptake rate of −15.14 mg C m⁻² yr⁻¹. These results suggest that different dominant underlying environmental factors among the studied ecosystems affected the exchange of CH₄ between tropical peatland and the atmosphere.     

Effects of nitrite toxicity on soil bacteria under aerobic and anaerobic conditions

Isolates of a soil Pseudoimonas, as well as other soil bacteria, showed a different sensitivity towards NO^?₂ when grown under aerobic or anaerobic conditions. The tolerance to NO^?₂ was increased in the presence of O₂: for instance, a concentration of $\text{200parts}\text{10}{}^6$ of NO^?₂-N proved to be toxic to a Pseudomonas sp. under anaerobic conditions, whereas over $\text{400 parts}\text{10}{}^6$ were needed aerobically to suppress its growth completely. The addition of NO^?₃ as an electron acceptor for anaerobic respiration did not overcome the inhibitive effect of NO^?₃. The pH range, at which NO^?₂ was utilized anaerobically, was narrowed with increasing NO^?₂ concentration (pH 6.8–8.8 at $\text{70 parts}\text{10}{}^6$ of NO^?₂-N and 7.4–8.5 and $\text{140 parts}\text{10}{}^6$ of NO^?₂-N).Tolerance to nitrite varied considerably among the bacteria tested. Each species was able to overcome the inhibitory effect of NO^?₂ up to a certain concentration, while the length of the lag phase was related to NO^?₂ concentration.     

Emissions of CO2, CH4 and N2O from Southern European peatlands

Peatlands play an important role in emissions of the greenhouse gases CO₂, CH₄ and N₂O, which are produced during mineralization of the peat organic matter. To examine the influence of soil type (fen, bog soil) and environmental factors (temperature, groundwater level), emission of CO₂, CH₄ and N₂O and soil temperature and groundwater level were measured weekly or biweekly in loco over a one-year period at four sites located in Ljubljana Marsh, Slovenia using the static chamber technique. The study involved two fen and two bog soils differing in organic carbon and nitrogen content, pH, bulk density, water holding capacity and groundwater level. The lowest CO₂ fluxes occurred during the winter, fluxes of N₂O were highest during summer and early spring (February, March) and fluxes of CH₄ were highest during autumn. The temporal variation in CO₂ fluxes could be explained by seasonal temperature variations, whereas CH₄ and N₂O fluxes could be correlated to groundwater level and soil carbon content. The experimental sites were net sources of measured greenhouse gases except for the drained bog site, which was a net sink of CH₄. The mean fluxes of CO₂ ranged between 139 mg m⁻² h⁻¹ in the undrained bog and 206 mg m⁻² h⁻¹ in the drained fen; mean fluxes of CH₄ were between −0.04 mg m⁻² h⁻¹ in the drained bog and 0.05 mg m⁻² h⁻¹ in the drained fen; and mean fluxes of N₂O were between 0.43 mg m⁻² h⁻¹ in the drained fen and 1.03 mg m⁻² h⁻¹ in the drained bog. These results indicate that the examined peatlands emit similar amounts of CO₂ and CH₄ to peatlands in Central and Northern Europe and significantly higher amounts of N₂O.