Assessing the Value of Using a Remote Sensing-Based Evapotranspiration Map in Site-Specific Management

ABSTRACT

In the glaciated regions of the northern Great Plains, water - either too much or too little - influences soil development, carbon storage, and plant productivity. Integrating site-specific water variability information directly into management is difficult. Simulation models that employ remotely sensed data can generate hard to measure values such as evapotranspiration (ET). This information can be used to identify management zones. The objective of this study was to determine if the METRIC (Mapping Evapotranspiration at High Resolution and with Internalized Calibration) model, which uses weather station and remote sensing data can be used as a tool in site-specific management. This study was conducted on a 65 ha corn (Zea mays L.) field located in east central South Dakota. The METRIC model used Landsat 7 data collected on August 4, 2001 to calculate ET values with spatial resolution of 30 m. ET values were correlated with corn yield (r = 0.85??), apparent electrical conductivity (EC_a; r = 0.71??), soil organic carbon (SOC; r = 0.32?), and pH (r = 0.28?). In the footslope positions, high ET values were associated with high corn yields, SOC, EC _a , and pH values, while in the summit/shoulder areas low ET values were associated with low yields, SOC, EC_a, and pH values. The strong relationship between ET and productivity was attributed to landscape processes that influenced plant available water, which in turn influenced productivity. Cluster analysis of the ET and EC data showed that these data bases complimented each other. Remote sensing-based ET data was most successful in identifying areas where water stress reduced corn yields, while EC_a was most successful in identifying high yielding management zones. Findings from this study suggest that remote sensing-based ET estimates can be used to improve management zone delineation.     

Modeling Water Quality Impacts of Petroleum Contaminated Soils in a Reservoir Catchment

Soil contamination due to spills or leaks of crude oils andrefined hydrocarbons is a common problem. Estimation of spillvolume is a crucial issue in order to determine the expectedcontaminating life span of contaminated soils. The directprocedure to determine the amount of hydrocarbon in soil is to measure the concentration of total petroleum hydrocarbon (TPH) in soil samples. The primary objective of this study was toassess the potential effects of oil contaminated soils on thewater quality of Devegecidi dam reservoir. For this purpose,limited spill data available were evaluated and soil samplingstudies were conducted in the Beykan oil field to analyze forTPH on oil contaminated soils. Available spill and measured soilTPH data were used in a subsequent modeling study to assess thereservoir water quality impacts due to dissolved mass leachingfrom hydrocarbon contaminated soils. Evaluation of availablespill data between 1989 and 1995 revealed that a total of 252recorded spills resulted in a net spill of 395 tons. The majortypes of oil spills were identified as well heads (WH), returnlines/flow lines (RL/FL), and power oil lines (POL). A total of211 soil samples was collected at selected well heads andanalyzed for TPH in the laboratory. TPH results revealed aconcentration range between 600 and 115 500 mg kg^-1 with a meanconcentration of 20 300 mg kg^-1. Modeling studies focused onbehavior assessment and involved two major components. The firstcomponent is a soil-leaching submodel for estimating theleachate concentration and contaminant mass leaching out of thecontaminated soil body. The second component is a reservoirwater quality submodel assuming complete-mix conditions forestimating the changes of hydrocarbon concentration in thereservoir water as a function of time. These two components arecoupled via a mass inflow term present in the reservoir waterquality model, accounting for contaminant mass loadingcontributed by the leaching of contaminated soil. Simulation runs performed under conservative conditions assuming an annualaverage oil spill volume of 95 tons and the minimum reservoirvolume of 7.3 × 10⁶ m³ revealed that there isno imminent threat to reservoir water quality from the dissolved phase contaminants soils. Limited amount of availablemeasurements of TPH concentrations in soil samples and benzeneconcentrations in reservoir water samples supported model results.     

Modeling of Solute Transport with Bioremediation Processes using Sawdust as a Matrix

Hg and As are widespread contaminants globally and particularly in Asia. We conducted a field study in Baiyangdian Lake, the largest lake in the North China Plain, to investigate bioaccumulation and trophic transfer of potentially toxic metals (total mercury and arsenic) in sites differing in proximity from the major point sources of nutrients and metals. Hg concentrations in fish and As concentrations in water are above critical threshold levels (US Environmental Protection Agency based) considered to pose some risk to humans and wildlife. Hg concentrations in biota are within the range of concentrations in lakes in the Northeast US despite the high levels of Hg emission and deposition in China whereas As concentrations are much higher. Dissolved concentrations of both Hg and As decrease with increasing chlorophyll concentrations suggesting that there is significant uptake of metal from water by algae. These results provide evidence for algal blooms controlling dissolved metal concentrations and potentially mitigating the trophic transfer of Hg to fish. This study also underscores the need for further investigation into this contaminated ecosystem and others like it in China that are an important source of fish and drinking water for consumption by local human populations.     

The Importance of Calcium Deposition in Assessing Impacts of Acid Deposition in China

The extensive use of coal as an energy carrier in China has led to high deposition of sulfur in a large part of the country. In the southern part of China large areas receive acid deposition, while in the northern part of the country the acidity of the emissions is neutralized by alkaline dust from the desert areas. In this paper we demonstrate the importance of knowing the sources and deposition patterns of base cations when assessing the effects of changes in sulfur emissions. Regional-scale data of both sulfur and calcium deposition from modeling and monitoring are combined in order to demonstrate how the acidity of deposition in China has changed historically and may change in the future. The importance of base cation deposition is also demonstrated using the dynamic acidification model MAGIC with input data from an intensive monitoring site outside Guiyang. It is not known what fraction of the deposited base cations is of natural origin and anthropogenic origin, respectively. The relative source strength varies greatly between regions. Future effects of emission changes are highly dependent on the relative reduction in sulfur and base cation emissions.     

Importance of Limestone Specific Surface for Assessing Neutralization Effectiveness in Soilless Root Substrate

The relationship of specific surface to particle diameter and calcium carbonate (CaCO₃) content of limestone was examined. Limestones obtained from 20 North American quarries were wet sieved into eight particle diameter fractions (600 to ?38 µm). Specific surface of particles was measured in each fraction following the Brunauer-Emmett-Teller theory. The range in specific surface across the 20 sources varied from 74-fold in the coarsest particles (600–300 µm) to 20-fold in the finest particles (?38 µm). The pattern of specific surface progressing from the coarsest to the finest particles varied radically between sources. The relationship between specific surface and CaCO₃ content was likewise very weak. While particle diameter and CaCO₃ equivalent remain the traditional measurements for defining limestone for field production, specific surface provides additional information valuable to define the stricter neutralization capacities of limestone for soilless root substrates.     

Design and Modeling of Post-Denitrification Single-Sludge Activated Sludge Processes

A step-by-step design approach for sizing oxic/anoxic single- sludge activated sludge systems is presented. A computer model utilizing a Lotus 1–2–3 spreadsheet was also developed which simulates the post- denitrification single-sludge activated sludge process. The biokinetic equations developed by Lawrence and McCarty are utilized in the model. The model was calibrated using data from a full-scale, modified pure oxygen activated sludge process operating in the oxic/anoxic mode. Two- tailed, paired comparison student ‘t-tests’ performed on effluent BOD₅, SS, TKN, NH₃-N, NO^- ₃-N, and TN indicated there was no significant difference between the actual effluent values and that predicted by the model at a 99 percent confidence level.     

Probing Particle Processes in Lake Michigan Using Sediment Traps

Sediment trap sampling at an offshore site in southern Lake Michigan has continued for an 18 year period with a sampling frequency ranging from weekly to semi-annually. During the 6 month unstratified period sediment trap mass and tracer profiles are nearly constant and they have been used to describe the extent of sediment resuspension. After stratification, mass flux rapidly declines and particle tracers are removed from the epilimnion at the rate of 0.5–1 m.d¹. Exponential profiles of mass flux clearly show the persistence of a benthic nepheloid layer. High frequency sampling with near-bottom sequencing traps show order of magnitude ranges in mass flux over a few day period.     

基于可变模糊评价法的塔里木河流域水资源承载力研究

结合塔里木河流域2005年自然、社会和经济以及水资源资料,应用可变模糊评价模型对塔里木河流域水资源状况进行了评价研究。研究结果表明:(1)该方法能够科学、合理地确定样本指标对各级指标标准区间的相对隶属度、相对隶属函数,并且能够通过变化模型及其参数,合理地确定出样本的评价等级,提高对样本等级评价的可信度。(2)塔里木河流域水资源承载能力综合评价为2级,水资源开发利用已有相当规模,应由耗水型经济结构向节水型经济结构转变,并加强水资源的综合管理,以便科学、合理地利用流域内有限水资源。     

WAVES模型在黄土区农田尺度水循环模拟中的应用

利用黄土高原长武农业生态试验站冬小麦农田水分循环的长期定位试验资料对澳大利亚科工组水土研究所开发的WAVES模型进行了验证,模拟结果和实测值的比较证实WAVES模型可用于模拟黄土高原农田生态系统水文循环过程,对短时段（1年）和长时段（10年）的模拟都有较高精度,模型对土壤肥力指数反映敏感。文中还讨论了模型为适应黄土高原这一特定水文生态系统需要改进的方面。     

Assessing the Relative Contribution of Wastewater Treatment Plants to Levels of Metals in Receiving Waters for Catchment Management

The selection of control measures for reducing metal contamination in rivers has targeted point sources such as wastewater treatment plants (WWTPs) and industrial discharges without a proper evaluation of their relative contribution to metal loads at the catchment level. The necessity of controlling pollutant inputs in a sound and cost-effective way to prevent the deterioration of chemical and ecological quality of receiving waters has highlighted the need for appropriate source assessment. As metals in rivers emanate from a wide range of sources, it is necessary to understand their relative contribution in order to reduce effectively the concentrations in receiving waters. This study presents a simple method for calculating the relative contribution of WWTPs to levels of metals in receiving waters as applied to the Aire?CCalder catchment in the UK. In this catchment, the apportionments to WWTP effluents of metal levels in rivers were 37, 31, 36 and 60?% of total cadmium (Cd), lead (Pb), mercury (Hg) and nickel (Ni), respectively. Spatial metal distribution in rivers with maximum concentrations of 0.47???g?L^?1 for Cd, 8.54???g?L^?1 for Pb, 0.05???g?L^?1 for Hg and 10.17???g?L^?1 for Ni caused by the discharge of WWTP effluents was estimated. The findings demonstrate that the proposed approach using quantification of metal loads and estimation of concentrations in receiving waters could adequately calculate the relative contribution of WWTP effluents to metal levels in receiving waters. Applications to various river catchments using site-specific data would further validate the effectiveness of the approach proposed.     

三峡库区农业面源污染风险评估及治理清单

针对三峡库区农业面源污染风险评估指标体系不完善、个别指标计算时基础数据获取难度大的问题,该研究充分考虑农业面源污染产生、形成及调控全过程因素,构建了基于层次分析法的三峡库区面源污染风险评价指标体系,以更易获取的数据为基础参数、应用韦伯-费希纳定律克服个别风险指标过大的问题,给定了三峡库区面源污染风险评估指标计算方法,评估了三峡库区农业面源污染风险,并提出了三峡库区县域单元的纵向和横向污染治理清单。研究结果表明,三峡库区各县域农业面源污染总体处于中风险,库区内湖北省夷陵区、重庆市南岸区风险值最高,其次是重庆市大渡口区、沙坪坝区等市辖区、巫溪县以及湖北省兴山县和秭归区,之后是开州区、万州区、丰都县、云阳县等区域;化肥强度指数、畜禽养殖强度指数、降雨侵蚀指数、环保投资指数是三峡库区农业面源污染风险的主要影响指标;三峡库区各县域化肥强度指数以及畜禽养殖强度指数风险值之和占总压力指数风险值的比例平均为79%,巫溪县、巴东县、巫山县甚至达到90%;重庆市南岸区、大渡口区以及湖北省各县域化肥施用强度较高,建议开展茶果树施肥技术提升,畜禽养殖强度相对较大的区域主要集中在重庆市云阳县、开州区、巫溪县、巫山县以及湖北省各县区,建议更多开展猪和羊畜禽废污处理能力提升,此外还应加大环保投入以及合理调整种植结构;从纵向管控来看,三峡库区农业面源污染治理应以南岸区和夷陵区为优先管控区域,河流水质优先治理区域为大渡口区、九龙坡区以及湖北省的各县区,从横向管控来看,大部分县域的主要污染防控因素为化肥减量和畜禽养殖治理,其中三峡库区上游和下游地区应当更多关注化肥减量,中游则更多关注畜禽养殖的污染防控,该研究成果可为三峡库区农业面源污染政策制定提供有力参考。     

Modeling Contaminant Transport Through Capped Dredged Sediment Using a Centrifuge

The presence of contaminated sediment poses a barrier to essential waterway maintenance and construction in many ports and harbors, which support 95% of U.S. foreign trade. Cost effective solutions to remediate contaminated sediments in waterways need to be applied. Capping is the least expensive remediation alternative available for marine sediments that is unsuitable for open water disposal. Dredged material capping and in situ capping alternatives, however, are not widely used because regulatory agencies are concerned about the potential for contaminant migration through the caps. Numerous studies have been conducted on the effects of diffusion through caps, however, there is a lack of experimental data documenting the effects of consolidation induced transport of contaminants through caps. This study examines consolidation induced advective contaminant transport in capped sediment utilizing a research centrifuge. Centrifuge modeling simulates the increase in the gravitational acceleration (g) of a prototype, which is N times larger than the model, where N is gravitational acceleration factor. For contaminant migration, the time of transport in the model is inversely proportional to the square of the acceleration factor in the prototype. In this study, consolidation induced advective transport was modeled for 22.5 hours at 100-g, which modeled a contaminant migration time of 25 years for a prototype that was 100 times larger than the centrifuge model. Thus, advection and dispersion dominated the migration of contaminants. The centrifuge modeling results were compared to an analytical solution for advection and dispersion.     

三峡库区山地不同森林地段烘干土入渗过程研究

利用室内定水头入渗法,观测三峡不同森林地段烘干土的入渗性能,比较大孔隙域与基质域烘干土入渗的差异,探究影响烘干土入渗性能的原因,评价常用入渗模型对不同属性烘干土壤入渗过程的适宜性。结果表明:三峡库区各森林地段基质域A层土壤的入渗能力强于B(或C)层土壤,B(或C)层土的40 min累积入渗量只占到A层土的29.79%~45.07%;不同林型覆盖下基质域烘干土壤入渗能力相比较,温性落叶阔叶林山地棕壤>常绿落叶阔叶混交林山地黄棕壤>暖性针叶林山地黄壤>常绿阔叶林山地棕红壤,温性落叶阔叶林山地棕壤40 min的累积入渗量是常绿阔叶林山地棕红壤的32.08~48.53倍。大孔隙域烘干土的入渗速率亦符合先下降后趋于稳定的一般入渗规律,大孔隙域比基质域烘干土的入渗性能更好,其40 min累积入渗量可以达到基质域的0.99~2.95倍。三峡库区森林烘干土的入渗能力与土壤容重和土粒密度呈极显著负相关关系(P<0.01),与土壤通气孔隙度(>0.02 mm)和有机质含量呈极显著正相关关系(P<0.01)。方正三通用公式对于基质域A层土和大孔隙域烘干土的入渗过程拟合效果较好,Horton方程对于基质域B(或C)层烘干土的入渗过程有较高的拟合度。     

Elemental Speciation and Distribution in Sediments of a Eutrophied Subtropical Freshwater Reservoir Using Postextraction Normalisation

The speciation and distribution of trace and major elements (Al, As, Cd, Cr, Cu, Fe, Mn, Ni, P, Pb and Zn) in the sediments of Emigrant Creek Dam (ECD), New South Wales Australia were investigated using sequential extraction, postextraction normalisation and spatial mapping to indicate source and dispersion patterns. Subsurface coring provided an estimate of elemental enrichment and showed that As 1.9?>?P 1.7?>?N 1.5????Cd 1.5?>?Mn 1.3 were enriched. Moreover, a high proportion of the enriched elements (mean 57, 34, 47 and 87?% for As, P, Cd and Mn, respectively) were assessed as being bioavailable. Comparisons with ISQGs found that sediments from sites in proximity to Emigrant Creek inflows had the highest accumulations of metals and the greatest potential for causing biological harm. Spatially, contaminants accumulate in ECD sediments adjacent to anthropogenic sources including a cattle dip site, dredged sediment and macrophyte dump areas, and agricultural/residential runoff. Moreover, the integrated technique and postextraction normalisation allow assessment of texturally diverse and difficult sediments.     

水库消涨带铺地黍植被护坡技术研究

在深圳市松子坑水库及其附近的月亮、獭湖水库等具有不同水位消涨节律和消涨带高差的库岸以铺地黍作植被护坡试验,结果表明,铺地黍长期在旱生陆地上生长良好,在浅淹、半淹甚至接近全淹时生长正常,在全淹8~9个月退水后仍能存活,耐淹、耐旱、耐瘠,且水土保持效果明显,是迄今为止发现的对水库消涨带生境最为适应的草本植物。     

An ARPS-CMAQ Modeling Approach for Assessing the Atmospheric Assimilative Capacity of the Beijing Metropolitan Region

A coupled ARPS–CMAQ modeling system was applied to investigate the atmospheric assimilative capacity (AAC) of PM₁₀ in the Beijing metropolitan region of China. The AAC was defined as the maximum allowable pollutant emission that can be discharged to the atmosphere without violating the desired air quality objective in the planning region. The coupled modeling system was firstly evaluated through comparing the simulation results of PM₁₀ concentration with the corresponding observations during four representative months in 2002, which showed an acceptable modeling performance. By using a trial-and-error approach, the validated modeling system was run through gradually reducing the emission strength within the modeling domain from a GIS-based pollutant emission database until a desired air quality objective was achieved. The air quality objective was characterized by the air quality guideline-satisfaction ratio (AQGSR) which was defined as the ratio of days when the daily PM₁₀ concentrations are below the air quality standard during a certain time period. The PM₁₀ emission within the modeling domain after such trial-and-error reduction under the condition of satisfying a certain AQGSR was considered its corresponding assimilative capacity. Accordingly, the atmospheric assimilative capacities of PM₁₀ in the study region were identified corresponding to the AQGSR of 60, 65, 70, 75 and 80%, respectively. The relation between such capacity and guideline-satisfaction ratio was then established through regression analysis. The results could provide sound basis for decision makers in terms of effective air quality management by understanding the allowable pollutant discharge under different desired air quality objectives.     

Characterization of the Salinisation Processes in Aquifers Using Boron Isotopes; Application to South-Eastern Spain

Use of δ¹¹B provides a solid tool for discriminating hydrogeochemical processes in complex coastal aquifers. Its efficiency increases markedly when it is applied along with other major or minor constituents. Nevertheless, various factors may affect its interpretation: the presence of clays, which favour adsorption and desorption, the influence of wastewaters, and even the presence of geothermalism. The δ¹¹B has been applied to the study of a series of aquifers in south-eastern Spain: Castell de Ferro (Granada), Campo de Dalías, Lower Andarax and Sorbas (Almería), all of which are complex and heterogeneous. The results obtained demonstrate that the concentration of Br, the SO₄/Cl and Cl/Br ratios are good indicators of marine intrusion. Inland some negative values of δ¹¹B (?16.7 and ?8.1‰) are related to a geothermal influence (34.8 and 51.5°C). The boron solubility is directly related to temperature favours boron mobilization, even from the associated metapelitic deposits. The difference in the boron isotope content in two carbonate units must be caused by the different composition of the carbonate rocks, as well as a long residence time.     

不同土壤水分与温度条件下土根系统中水分传导的变化及其相对重要性

依据试验资料，分析了土壤水势和温度对根系收缩程度、土根间隙水分传导和土根系统中各部分水分传导相对重要性的影响。结果表明：植物根系收缩程度银合欢＜台湾相思＜向日葵＜玉米，植物在水分胁迫下的根系收缩能反映植物的抗旱性；在相同土水势条件下，土根间隙水分传导表现出银合欢＞台湾相思＞向日葵＞玉米；在土根间隙传导（Ｌ_ｇ）、根系传导（Ｌ_r）与土壤有效传导（Ｌ_s）三者之间，Ｌ_s的变幅最大，Ｌ_r的变幅最小，对于不同植物种类Ｌ_r、Ｌ_ｇ与Ｌ_s成为系统中的水分传输限制因子所对应的土水势范围不同；当土水势（ψ）高于－１．０ＭＰａ时，温度升降对玉米与向日葵的根系收缩无显著影响，当ψ＜－１．０ＭＰａ时，高温环境中的根系收缩加剧，当ψ＞－１．１０ＭＰａ时，玉米、向日葵的Ｌ_ｇ随温度增加而略有增加，而当ψ＜－１．１０ＭＰａ时，其Ｌ_ｇ则随温度增高而下降。     

基于三维激光扫描的坡沟系统侵蚀产沙过程研究

为了探究野外自然坡沟系统土壤侵蚀过程,研究于黄土丘陵沟壑区典型流域辛店沟内自然坡面开展5场放水冲刷试验,利用地面三维激光扫描技术(Terrestrial laser scanning, TLS)获取高精度地形信息,并采用DEM of difference(DoD)地形变化监测方法计算产沙量,利用实测产沙量评估TLS的监测精度,并探讨了坡沟系统侵蚀/沉积的变化特征。结果表明：(1)累积场次中,DoD不确定性(即level of detection, LoD)平均值(范围)为16.5 mm(16.2～16.8 mm)。单场次中,LoD值平均值为16.4 mm(16.2～16.6 mm);(2)累积场次中,梁峁坡、沟谷坡、坡沟系统TLS扫描所得产沙量相对误差的平均值(范围)为52.63%(26.06%～106.98%),56.68%(30.26%～75.49%)和56.28%(33.37%～73.28%),与实测数据显著相关(R²>0.9,p<0.05)。单场次TLS扫描相对误差波动范围更大且平均值高于累积场次,其值分别为83.70%(4.08%～190.4...     

用AFLP技术进行水稻光合作用光保护有关基因候选分子标记的研究初探

本项目用扩增片段长度多型性(AFLP)技术,研究了水稻光合作用和光保护机制有关的8个性状F2代极端样本,在32对引物的研究中,全部引物可以在亲本中检出多型性,有28对引物可以在F2群体,8组极端样本之间找到差异条带标记,每个性状可以找到7～22个差异条带.在叶绿素ab含量、玉米黄素+花黄素总量、超氧化物歧化酶活性上,Lemont具有明显的增效片段优势.玉米黄素+花黄素+紫黄质数总量和活性蛋白总量可能是提高光合作用的最大限制因子.同时研究表明,对预选PCR 产物进行纯化处理,可大大提高AFLP分析技术的有效性.