华北山区核桃液流变化特征及对不同时间尺度参考作物蒸散量的响应

核桃是华北山区重要的经济树种,但该地区水资源紧缺,因此研究核桃液流耗水变化及其对气象因子的响应对于加强核桃水分管理、确定水分承载力具有指导意义。2008—2010年连续3个生长季节观测分析了华北山区核桃单株液流变化特征,研究了不同时间尺度(日尺度、月尺度)核桃液流与气象因子、参考作物蒸散量(ET0)的关系,并利用2009—2010年数据建立了拟合方程,在此基础上用拟合方程的估算值与2008年液流实测值进行了对比验证。结果表明:核桃液流具有明显的时间变化特征,最大液流量出现在5、6月份,2008—2010年生长季节(4—9月份)核桃液流量分别为893.23 L、854.88 L和841.77 L,日平均液流量分别为4.96 L、4.75 L和4.68 L。液流年际差异主要是由年降雨量引起。核桃液流与不同时间尺度下气象因子、ET0均有较好的相关性,且随着时间尺度的增加,二者间的相关性变大。利用2009—2010年液流实测值与气象因子、ET0建立的拟合方程,对2008年液流值进行了拟合,并与实测值进行了对比验证,发现不同时间尺度下液流拟合值与实测值均具有较好的一致性。在不能实现对液流进行连续观测的情况下,可以结合当地的气象资料、ET0等因子,利用建立的拟合方程对树木液流进行估算,弥补缺失的数据,具有较高的精确性,可用于指导当地核桃水分管理。     

Modelling pollutant removal in a pilot-scale two-stage subsurface flow constructed wetlands

The hydraulic behaviour and effluent pollutant concentrations in a pilot-scale two-stage subsurface flow constructed wetland for treatment of municipal wastewater have been simulated. The experimental pilot plant is located in San Michele di Ganzaria (Eastern Sicily) and consists of four lines of two-stage subsurface flow constructed wetlands for secondary or tertiary treatment of municipal wastewater. The first stage, for each line, consists of a horizontal flow bed, while in the second stage a vertical flow bed operates for two lines and a horizontal flow bed for the other two. Phragmites sp. was used as vegetation in two lines while the other two lines are without plants. The HYDRUS-2D software was applied to describe flow and single-solute transport, while the multi-component reactive transport module CW2D was used to model the transformation and elimination processes of organic matter, nitrogen and phosphorus. Tracer studies and chemical wastewater analyses were carried out to calibrate and validate the transport model. In general, the simulation results obtained show a good match with the measured data for water flow, tracer experiments and pollutant removal processes.     

基于茎流-蒸渗仪法的荒漠草原带人工灌丛群落蒸散特征

中国西北地区通过大量种植中间锦鸡儿(Caragana liouana)进行生态治理, 在荒漠草原带上形成人工灌丛景观, 改变了生态系统的结构和功能, 影响到地-气水汽循环过程, 研究该人工灌丛群落的蒸散特征, 对揭示其生态水文效应和指导地方生态治理实践具有重要意义。该文以宁夏盐池荒漠草原带上的人工灌丛群落为例, 利用茎流-蒸渗仪法测定了2018年5-8月的灌木蒸腾和丛下蒸散, 并分析了环境因子对人工灌丛群落蒸散的影响。结果表明: (1)茎流-蒸渗仪法所测的群落蒸散与水量平衡法、涡度相关法得到的群落蒸散有较好的一致性, 茎流-蒸渗仪法能适用于荒漠草原带人工灌丛群落蒸散及其组分结构的测定; (2)观测期内晴天的灌木蒸腾速率和丛下蒸散速率日变化趋势相近, 均为单峰曲线, 群落蒸散主要发生在日间, 但灌丛最大蒸腾速率的出现时间比丛下蒸散最大速率的出现时间晚1 h; (3) 5-8月间灌木累积蒸腾为83.6 mm, 日平均蒸腾量为0.7 mm·d^-1, 季节变化呈抛物线状; 同期丛下累积蒸散为182.5 mm, 日平均蒸散量为1.5 mm·d^-1; 丛下蒸散明显大于灌木蒸腾; (4)观测期间人工灌丛群落累积蒸散266.1 mm, 而同期的降水量为222.6 mm, 陆面水分收支处于亏缺状态; (5)净辐射是影响蒸散最主要、最直接的驱动因素, 且能够影响其他因子进而对人工灌丛群落蒸散产生作用。综上, 人工灌丛引发荒漠草原地带陆面水分收支亏缺的现象, 在生态恢复与重建中须引起注意。     

基于SVAT模型的冬小麦光合作用和蒸散过程研究

在已建立的土壤－植被－大气传输（SVAT）模型中,冠层光合作用／气孔导度耦合子模型可区分遮荫叶和受光叶光合作用强度的差异;作物生长模型考虑了生长呼吸和维持呼吸,模拟与实测结果对比发现,日总蒸散量实测和模拟的根均方差（RMSD）为0.65mm,平均绝对差（MAPD）为14％;对冠层上部净光合作用率日变化过程而言,实测和模拟结果具有较好的一致性。利用模型模拟了冬小麦全生育争光合作用率和蒸散的演变过程。最后,分析了冬小麦蒸散和水分利用效率对不同最大叶面积指数,大气CO2浓度和叶片N含量的响应。     

A hydrologic assessment of the Everglades Nutrient Removal Project, a subtropical constructed wetland in South Florida (USA)

The Everglades Nutrient Removal Project (ENRP), a 1544-ha constructed wetland in south Florida, was intensively monitored throughout its five-year operational history. Water budgets for the ENRP and each of its interior treatment cells were dominated by surface flows (≥85% of inflows; ≥68% of outflows) with smaller contributions from precipitation, evapotranspiration, groundwater flux, and change in storage. The mean water depth, hydraulic loading rate for surface water, and nominal hydraulic retention time for the entire wetland were 0.6 m, 3.1 cm d⁻¹ and 17.7 d, respectively, and were comparable to values anticipated in design. The east flow-way was slightly shallower (0.2 m) and received proportionately more flow (61%) than the west flow-way. The hydrology of other treatment wetlands is often driven by surface flows. All treatment cells in the ENRP were to some extent hydraulically short-circuited. There was net groundwater inflow to the ENRP from Water Conservation Area 1 (WCA-1) resulting from significant head differences between these wetlands. Groundwater outflow to the adjacent farmlands was greatest in Cell 2 and substantially exceeded groundwater inflow. All hydrologic parameters exhibited seasonality to some extent; fluctuation in water depth and groundwater inflows corresponded with the seasonal change in stage in WCA-1. Errors in the ENRP and individual cell water budgets were generally less than 10% and within the range of errors for water budgets from other wetlands.     

气候变化与人类活动对青藏高原湿地的影响研究进展

青藏高原是中国湿地分布最多的区域,其独特的高寒湿地对区域生态环境安全有着不可或缺的作用。梳理了青藏高原湿地变化的时空特征,基于此,重点分析了气候变化与人类活动对不同类型湿地的影响和作用机制。研究发现：(1)主导不同类型湿地变化的气候因素有差异,影响存在区域异质性。湖泊湿地主要受降水量影响,湖泊湿地在北部扩张、南部缩小的趋势与降水量的空间差异存在较强的一致性;沼泽湿地主要受气温影响,气温升高导致水分蒸发、植被群落演替,沼泽湿地向草地转化,江河源区和若尔盖高原等主要分布区域呈现退化趋势;河流湿地主要受气温影响,气温升高加速河源冰川消融、同时也增大河流蒸散发量,共同作用下河流湿地呈现北部减少、南部增加的趋势。(2)过度放牧、泥炭开采、水利建设等是影响湿地变化的主要人类活动。若尔盖高原同时存在过度放牧、泥炭开采和沟渠建设多重人类活动影响,当地沼泽湿地退化明显;柴达木盆地的人工湿地由于盐业开采迅速扩张。(3)当前研究存在数据可对比性不足、大区域尺度和野外定点持续监测数据缺乏等问题,导致对气候变化与人类活动影响机制研究不够深入。未来应加强高寒湿地定期监测与风险评估,完善高寒湿地生态系统与环境变化和...     

Characteristics of evapotranspiration in planted shrub communities in desert steppe zone based on sap flow and lysimeter methods

中国西北地区通过大量种植中间锦鸡儿(Caragana liouana)进行生态治理, 在荒漠草原带上形成人工灌丛景观, 改变了生态系统的结构和功能, 影响到地-气水汽循环过程, 研究该人工灌丛群落的蒸散特征, 对揭示其生态水文效应和指导地方生态治理实践具有重要意义。该文以宁夏盐池荒漠草原带上的人工灌丛群落为例, 利用茎流-蒸渗仪法测定了2018年5-8月的灌木蒸腾和丛下蒸散, 并分析了环境因子对人工灌丛群落蒸散的影响。结果表明: (1)茎流-蒸渗仪法所测的群落蒸散与水量平衡法、涡度相关法得到的群落蒸散有较好的一致性, 茎流-蒸渗仪法能适用于荒漠草原带人工灌丛群落蒸散及其组分结构的测定; (2)观测期内晴天的灌木蒸腾速率和丛下蒸散速率日变化趋势相近, 均为单峰曲线, 群落蒸散主要发生在日间, 但灌丛最大蒸腾速率的出现时间比丛下蒸散最大速率的出现时间晚1 h; (3) 5-8月间灌木累积蒸腾为83.6 mm, 日平均蒸腾量为0.7 mm·d^-1, 季节变化呈抛物线状; 同期丛下累积蒸散为182.5 mm, 日平均蒸散量为1.5 mm·d^-1; 丛下蒸散明显大于灌木蒸腾; (4)观测期间人工灌丛群落累积蒸散266.1 mm, 而同期的降水量为222.6 mm, 陆面水分收支处于亏缺状态; (5)净辐射是影响蒸散最主要、最直接的驱动因素, 且能够影响其他因子进而对人工灌丛群落蒸散产生作用。综上, 人工灌丛引发荒漠草原地带陆面水分收支亏缺的现象, 在生态恢复与重建中须引起注意。     

玉米农田蒸散过程及其对气候变化的响应模拟

应用基于生理生态学过程的EALCO模型,对玉米农田生态系统的蒸散(ET)过程进行了模拟,在模型检验基础上,使用该模型模拟了玉米农田生态系统ET过程对未来气候变化的响应。结果表明,EALCO模型中能量与水过程的动态耦合机制使模型能够较好地模拟农田蒸散过程,基于涡度相关法的观测值与模型模拟值在小时、日尺度上均吻合较好,模型可以解释67%的日蒸散的变化特征。对土壤蒸发与冠层蒸腾的分别模拟显示,生长季土壤蒸发约占ET的36%。温度的升高会引起ET与冠层蒸腾的增加,同时土壤蒸发减少;ET对降水减少的响应较为敏感,主要表现在土壤蒸发的下降。大气CO2浓度升高对冠层蒸腾影响显著,该情景下冠层蒸腾下降幅度最大。研究所假设的2100年气候情景下,该农田生态系统生长季蒸散将减少,然而相对于降水的减少而言,蒸散的减少量较小,即水分支出项相对增加,因此,发生土壤水分匮乏的可能性加大,这可能会加剧该地区的暖干化趋势,给作物产量及生态环境带来威胁。     

Reliability, repeatability and accuracy of the falling head method for hydraulic conductivity measurements under laboratory conditions

The aim of this study was to verify under lab conditions the reliability, repeatability and accuracy of the falling head method (FHM) for hydraulic conductivity measurements. The FHM is a reliable procedure that has slight variations (less than 10%) in repeated measurements and turns out to be a reliable technique to record the hydraulic conductivities typically described for clogged and unclogged subsurface-flow constructed wetlands (from 4 to ca. 360 m/day). The accuracy of the method is acceptable considering difficulties in the measurement of hydraulic conductivity in highly conductive media. Accordingly, results show measurement deviations of 20% when compared with a laboratory constant head method for highly conductive media (higher than 250 m/day), and 80% for media with low hydraulic conductivity (lower than 50 m/day). The main conclusion of the present paper is that of the FHM is a reliable and repeatable technique for hydraulic conductivity measurements and it is accurate enough for on-site clogging assessment in full-scale constructed wetlands.     

南京地区蒸散发降尺度研究--基于增强型时空自适应反射融合模型

蒸散发是水文循环的重要组成部分,获取高时空分辨率的数据能够更加精细化蒸散发的时空变化规律,对于水资源管理、生态水文过程量化具有重要意义。由于单一传感器反演的蒸散发无法同时具有高空间和高时间分辨率,以南京地区为例,首先结合Landsat-8遥感影像数据和气象数据,采用基于能量平衡原理的SEBS模型估算日蒸散量。在此基础上,选取典型区域采用基于增强型时空自适应反射融合模型(ESTARFM)将估算的蒸散发结果与低空间分辨率的MOD16A2蒸散发产品数据进行时空融合降尺度研究,并评价模型的融合精度。结果表明：(1)SEBS模型估算的蒸散发结果与蒸发皿折算后的数据、MOD16A2产品数据的平均相对误差分别为0.14 mm/d和0.22 mm/d。(2)南京地区蒸散量季节差异明显,表现为夏季>秋季>冬季;各区在夏季的日平均蒸散量差异也较大,六合区蒸散量最大,秦淮区最小;另外,蒸散量分布受土地利用类型的影响,总体上表现为水域>林地>耕地>草地>其他,且植被覆盖度较高的区域蒸散量较大。(3)基于ESTARFM模型融合的蒸散发结果与基于Landsat-8遥感影像反演的...     

Implementing plant hydraulic architecture within the LPJ Dynamic Global Vegetation Model

Aim To implement plant hydraulic architecture within the Lund–Potsdam–Jena Dynamic Global Vegetation Model (LPJ–DGVM), and to test the model against a set of observational data. If the model can reproduce major patterns in vegetation and ecosystem processes, we consider this to be an important linkage between plant physiology and larger‐scale ecosystem dynamics. Location The location is global, geographically distributed. Methods A literature review was carried out to derive model formulations and parameter values for representing the hydraulic characteristics of major global plant functional types (PFTs) in a DGVM. After implementing the corresponding formulations within the LPJ–DGVM, present‐day model output was compared to observational data. Results The model reproduced observed broad‐scale patterns in potential natural vegetation, but it failed to distinguish accurately between different types of grassland and savanna vegetation, possibly related to inadequate model representations of water fluxes in the soil and wildfire effects. Compared to a version of the model using an empirical formulation for calculating plant water supply without considering plant hydraulic architecture, the new formulation improved simulated patterns of vegetation in particular for dry shrublands. Global‐scale simulation results for runoff and actual evapotranspiration (AET) corresponded well to available data. The model also successfully reproduced the magnitude and seasonal cycle of AET for most EUROFLUX forests, while modelled variation in NPP across a large number of sites spanning several biomes showed a strong correlation with estimates from field measurements. Main conclusions The model was generally confirmed by comparison to observational data. The novel model representation of water flow within plants makes it possible to resolve mechanistically the effects of hydraulic differences between plant functional groups on vegetation structure, water cycling, and competition. This may be an advantage when predicting ecosystem responses to nonextant climates, in particular in areas dominated by dry shrubland vegetation.     

基于树干液流及涡动相关技术的葡萄冠层蒸腾及蒸散发特征研究

针对西北干旱区绿洲经济作物葡萄树冠层蒸腾及蒸散发特征的相关问题,在甘肃省敦煌市南湖绿洲开展无核白葡萄树液流速率及蒸散发观测试验,采用基于热平衡原理的包裹式茎流计,详细分析了典型生长季7—9月份葡萄树蒸腾耗水规律,使用"单位叶面积上的平均液流速率SF×叶面积指数LAI"的方法,实现了从单株到林分冠层蒸腾的尺度扩展,并通过与涡动相关技术所测蒸散发数据对比,详细研究了葡萄地冠层蒸腾及蒸散发规律。结果表明:典型生长季中葡萄树液流速率日变化为单峰型曲线,日均耗水量从2.76 kg到10 kg不等,胸径越大的葡萄树日均耗水量越大;冠层蒸腾及蒸散发日变化曲线亦为单峰型,白天8:00—12:00与17:00—20:00期间,葡萄冠层蒸腾与蒸散发曲线均比较吻合,该时间段葡萄地蒸散发绝大部分来源于葡萄冠层蒸腾,而12:00—17:00之间由于午后太阳辐射强烈土壤蒸发量增加,葡萄蒸散发大于冠层蒸腾;典型生长季3个月中,葡萄冠层蒸腾量的变化范围在1.88—8.12 mm/d之间,日均冠层蒸腾量为6.12 mm/d,蒸散发在1.74 mm/d至10.78 mm/d之间,日均蒸散发量为7.13 mm/d;日均土壤蒸发量约为1.01 mm/d,只占总蒸散发量的14.2%,日均冠层蒸腾占日均蒸散发的比重达到85.8%,说明该生长阶段冠层蒸散发以作物蒸腾为主。     

Phytoremediation of domestic wastewater using a hybrid constructed wetland in mountainous rural area

The purpose of this study is to evaluate the efficiency of hybrid constructed wetlands (HCWs) in a rural mountainous area. The experiment was set up in small rural community named Tidili within the region of Marrakech, Morocco. The wastewater treatment plant was composed of three vertical flow constructed wetlands (VFCWs) working in parallel, followed by two parallel horizontal-subsurface flow constructed wetlands (HFCWs), with hydraulic loading rates of 0.5 and 0.75 m³/m².d, respectively. The two units were planted with Phragmites australis at a density of 4 plants/m². Wastewater samples were collected at the inlet of the storage tank and at the outlet of the whole system (VFCWs, HFCWs) stages. The main removal percentages of total suspended solids (TSS), biochemical oxygen demand measured in a 5-day test (BOD₅), chemical oxygen demand (COD), total nitrogen, and total phosphorus were respectively 95%, 93%, 91%, 67%, and 62%. The system showed a very high capacity to remove total coliforms, fecal coliforms, and fecal streptococci (4.46, 4.31, and 4.10 Log units, respectively). Artificial neural networks (ANNs) were used to model the quality parameters (TSS, BOD₅, COD) and total coliforms and fecal streptococci. Based on the obtained results, the ANN model could be considered as an efficient tool to predict the studied phytoremediation performances using HCWs.     

Adaptation of wastewater surface flow wetland formulae for application in constructed stormwater wetlands

Over the past 30 years, the use of constructed wetlands for wastewater treatment has been a topic of significant research culminating in a good data base from which simplistic equations have been derived to aid in the design of these facilities to meet long term water quality treatment performance criteria. Over the past decade, the use of treatment wetlands has extended to stormwater and combined sewer overflow (CSO) management applications. Designing constructed wetlands for stormwater and CSO applications have unique challenges stemming from the highly stochastic nature of the hydraulic and pollutant loading on a stormwater wetland compared with wastewater treatment systems. This paper explores the possibility of adapting the simplistic models for wastewater wetlands for interim use in developing design guidelines for stormwater wetland systems. A procedure that takes into account the unsteady intermittent nature of stormwater inflows to these wetlands has been incorporated into one of these simplistic models and a case study presented to demonstrate the application of the procedure.     

石羊河流域干旱荒漠绿洲区不同滴灌模式下葡萄茎液流变化及其与环境因子的关系

研究了石羊河流域干旱荒漠绿洲区交替滴灌（ADI）、固定滴灌（FDI）和常规滴灌（CDI）模式下葡萄茎液流的变化规律及其与气象因子和土壤含水率的相关关系.结果表明：研究区葡萄茎液流表现出与太阳辐射同步的昼夜变化节律;新梢生长期和开花期CDI处理的茎液流量显著大于其它两个处理;影响瞬时茎液流的主要气象因子是太阳辐射和气温,日茎液流量与平均气温和风速具有线性相关关系;不同灌溉方式下葡萄茎液流与气象因素的相关程度依次为：CDI>ADI>FDI;葡萄日茎液流量与参考作物蒸发蒸腾量（ET₀）呈显著线性相关关系.与CDI相比,ADI节省50%水量,而茎液流总量仅降低6.56%,且其葡萄茎液流和水分传导具有明显的补偿效应.     

Influence of Plants and Organic Matter on the Nitrogen Removal in Laboratory‐Scale Model Subsurface Flow Constructed Wetlands Inoculated with Anaerobic Ammonium Oxidizing Bacteria

Anaerobic oxidation of ammonium has become an alternative for the treatment of wastewater with high ammonium loads, and it was also suggested to be involved in the nitrogen removal process in constructed wetlands. Nonetheless, its role has not been well evaluated as yet. In this paper, results of a lab‐scale study are presented focusing on the evaluation of the role of Anammox bacteria, plants, applied ammonia, nitrite nitrogen loads, and the presence of organic matter in nitrogen transformation processes in subsurface‐flow constructed wetlands. The inoculation of the experimental model wetlands with active Anammox biomass increased the total nitrogen and ammonium removal rates to values up to 5.7 g N/m² d, which is almost 10 times higher than those values reported for subsurface flow constructed wetlands. Although the presence of plants caused a higher removal rate, the role of the plants became less important with high nitrite influent concentration. Because the unplanted experimental system without the addition of any organic carbon source showed also high nitrogen removal rates, it can be concluded that beside the potential for “conventional” denitrification in the planted systems the main mechanism for explaining the high nitrogen removal rates obtained during the experiments was the anaerobic ammonia oxidation. The assay of the formation of hydrazine from hydroxylamine and the findings of the molecular biology tests fitted with the positive results for potential Anammox activity obtained in the bottle test. The addition of organic carbon, specifically acetate, apparently had no great influence on Anammox activity, which is in agreement with the findings reported by other authors. Nevertheless, the addition influenced the redox potential. Some questions are still left open, which are mainly associated with the scaling up of these results and the inoculation of Anammox biomass in full‐scale systems.     

Ecohydrology of the Venezuelan páramo: water balance of a high Andean watershed

ABSTRACT

Background: The páramo provides key ecosystem services, including regulation and provision of water. To understand the underlying functions, an ecosystem approach is necessary.

Aims: We quantified the combined effect of vegetation and soils (integrated topographic and vegetation units – TVU) on the hydrological balance of a Venezuelan páramo micro-watershed and analyse its hydrological response to intra- and interannual rainfall variability.

Methods: Data (2008–2016) from meteorological stations of TVUs and of a streamflow station was used to calculate watershed level hydrologic balances. We quantified the impact of the TVUs outputs by calculating evapotranspiration under non-standard conditions (ETc adj).

Result: Evapotranspiration of wetlands and tarns was high, exceeding annual precipitation. Shrubland had low evapotranspiration. Recharge of páramo reservoirs (soils, wetlands, tarns) occurred when monthly rainfall exceeded 90 mm. In dry years there were lower water yields with less effective hydrological regulation. In average years the differences between input and output in watershed balances were very small.

Conclusions: The high and constant evapotranspiration of the wetlands and tarns (due to permanent water availability) suggests they could maintain streamflow during dry periods. Their high evapotranspiration rates are compensated by low rates in shrublands units, reducing the mean total evapotranspiration of the watershed. The watershed balances suggest a limited regulatory capacity in these relatively dry páramos with no volcanic soils.     

华北平原冬小麦农田蒸散量

以华北平原冬小麦农田为研究对象,采用涡度相关技术和热红外遥感技术,研究了不同环境条件下土壤含水量与农田蒸散量及作物冠层温度的关系.结果表明,冬小麦在农田郁闭(LAI≥3)、晴天和土壤相对含水量低于田间持水量65%的情况下,蒸发比值日变化正午前后出现相对较低且平稳的变化趋势.在晴天情况下,农田潜热通量与作物冠层温度日变化和季节变化均呈极显著的非线性相关关系,而冠气温差、农田相对蒸散量则与0～100 cm土层的土壤相对含水量密切相关.以13:30～14:00的平均冠层温度值T_c、日最高气温T_{a max}和日净辐射总量Rn_d为统计数据,确立了冬小麦农田日蒸散量ET_d （mm）估算简化模式参数.     

Impact of climatic change on eco-hydrology: a case study for Poland

The impact of climatic change on variables of concern to eco-hydrology was examined. Long time series of records of temperature, precipitation and river flow for Poznan were analyzed and forecasts of tendencies were made. Spatial distribution of runoff and of the ratio of evapotranspiration to precipitation was obtained for the country. It was found likely that the dynamics of the hydrological cycle will accelerate. Annual precipitation, runoff and evapotranspiration will increase. The joint effect, including estimated growth in water demand, is likely to be a decrease in the amount of soil moisture.     

人工湿地去污模型的统一结构特征

通过对典型人工湿地去污模型的分析比较,提出了基于各模型微分方程而建立的统一去污模型。该模型能够将典型去污模型作为特例而导出,并能很好地解释这些模型之间的过渡关系。以潜流湿地中NH4^＋和BOD5的降解为例,对统一去污模型的应用情况进行了简单探讨,表明利用统一去污模型结构有助于深入揭示去污机理,从而提出更为精确的去污模型。