合肥市城郊农业生态系统服务价值评价研究

合肥市是安徽省的省会,生态农业资源十分丰富。对合肥市城郊农业生态系统服务功能价值进行了定量评价,针对合肥市城郊农业生态系统现状,提出了可持续发展对策。     

农业生态环境质量评价研究

根据农业生态系统的组成及其存在的环境问题提出了选择评价农业生态环境质量的评价指标、选择评价指标的原则，评价指标及其权重的确定原则，指出根据评价指标的指数值计算农业生态环境质量指数值，再根据农业生态环境质量分级标准，确定农业生态环境的状态这一研究方法。     

基于层次分析法的陕西省城市生态系统健康动态评价

针对城市快速发展给生态环境带来的压力问题,对陕西省城市生态系统健康评价进行了相关研究。根据城市生态系统健康的内涵及数据的可获得性,从活力、组织力、恢复力、生态系统服务功能和人类健康状况方面构建了健康评价指标体系,确定了健康评价标准。采用层次分析法确定指标权重,进而对该省2013-2017年省域层面城市生态系统健康状况进行动态评价。研究表明,活力与组织结构两要素对生态系统健康有较大贡献,生态系统服务功能随着时间推移在不断提高,自然结构和垃圾处理能力是当前胁迫生态系统健康的主要因素。总体而言陕西省城市生态系统健康水平呈现逐年上升趋势,未来仍有较大的发展潜力和提升空间。     

污水灌溉对我国农业生态系统的影响及其对策

本文运用生态学原理,分析了污灌区农业生态系统的特点,指出了污灌在农业生态系统中既起着水源和肥源,又起着污染源的三重作用。同时,从正反两方面阐述了污灌对我国农业生态系统的影响,提出了污灌条件下建立农业生态系统良性循环的途径,即(1)尽量控制污水中的污染物质进入农业生态系统;(2)减少污染物质在农田生态系统的累积;(3)改变污染物在农业生态系统中的迁移途径。     

生态系统服务价值及其评估方法研究进展

生态系统服务和产生这些服务的自然资本对地球生命支持系统的功能有着极其重要的作用。它们间接或是直接的为人类提供福利,并因而成为地球整体经济价值的一部分。本文在生态系统服务的定义、功能及内涵的基础上,系统归纳了当前国内外生态系统服务价值的实例和主要评价方法研究进展。已有的研究表明对自然资源实行生态系统管理需要对生态系统服务进行多堆的,不同时空尺度上的评价,同时也要建立合理的评价标准体系。由于生态系统服务价值存在时空异质性,当前的研究中还没有提供很好的解决这一问题的方法,本文最后讨论了在生态系统服务价值评估中综合考虑区位等因素的可行性和必要性。     

西北干旱区人口—农业经济—生态耦合协调态势分析——以甘肃省民勤县为例CSSCI

根据2000—2014年甘肃省民勤县人口、农业经济和生态三个方面的相关数据,构建人口—农业经济—生态综合评价指标体系,运用变异系数法和耦合协调度模型对该县人口—农业经济—生态系统的耦合度、耦合协调度和综合评价指数进行了测算与分析。结果表明:近15年来,民勤县的人口—农业经济—生态系统耦合度C为0.372—0.696,经历了颉颃耦合和磨合耦合两个阶段,呈先下降后上升的趋势;耦合协调度D为0.325—0.639,整体实现了由失调衰退到协调发展的良性转化,虽然耦合度和耦合协调度都有所改善,但耦合协调程度较低。根据这一发展态势,结合民勤县特殊的自然条件,提出相应的对策建议。     

西北干旱区人口—农业经济—生态耦合协调态势分析——以甘肃省民勤县为例

根据2000—2014年甘肃省民勤县人口、农业经济和生态三个方面的相关数据,构建人口—农业经济—生态综合评价指标体系,运用变异系数法和耦合协调度模型对该县人口—农业经济—生态系统的耦合度、耦合协调度和综合评价指数进行了测算与分析。结果表明:近15年来,民勤县的人口—农业经济—生态系统耦合度C为0.372—0.696,经历了颉颃耦合和磨合耦合两个阶段,呈先下降后上升的趋势;耦合协调度D为0.325—0.639,整体实现了由失调衰退到协调发展的良性转化,虽然耦合度和耦合协调度都有所改善,但耦合协调程度较低。根据这一发展态势,结合民勤县特殊的自然条件,提出相应的对策建议。     

银川市生态系统服务价值评价及驱动力分析

以银川市为例,运用土地利用动态度、生态系统服务价值评价法及线性回归模型对其生态系统服务价值变化及驱动因素进行分析。结果表明:银川市土地利用变化较大;生态系统服务价值由2008年的164.56亿元下降至2018年的158.57亿元;灵武生态系统服务价值最高,兴庆和金凤生态系统服务价值最低;生态系统单项服务价值逐年下降;从驱动力影响因素来看,人口密度越低、工业产值越低、旅游收入越高,生态系统服务价值就越高。     

生态系统评价:问题分析与研究展望

生态系统评价是当前生态学研究中的一个热点和难点，它能够为区域生态系统健康检测、优良生态系统类型筛选、土地利用格局合理配置以及生态服务功能优化提供宝贵的参考和决策依据。论述了生态系统评价的相关内容、研究的尺度问题以及目前相配套的研究方法，分析了其中存在的诸多问题，简明指出了今后的工作重点和努力方向，并展望了生态系统评价的未来走向。认为今后综合性的生态系统评价以及与此相配套的评价方法需要得到大力加强和研发，同时生态系统评价应该和区域水土流失治理、生态安全和可持续发展等重大问题紧密结合。     

农业规划环评中生物多样性影响评价研究

介绍了农业规划环评中生物多样性影响评价的背景、基本内涵和主要内容,概述了生物多样性评价的基本程序和工作内容。针对农业规划环评中生物多样性影响评价几乎是空白的现状,从农区和农业角度,提出农区遗传多样性、农区物种及生境多样性、农区生态系统多样性、农区景观多样性、农业产业结构多样性5个评价尺度,逐一分析了各尺度生物多样性影响评价的主要内容和特点。特别指出在环评实际工作中,应把遗传多样性影响评价的内容与物种多样性、生态多样性影响评价融合在一起描述;对农业产业结构多样性,强调评估当地生物多样性变化可能带来的经济价值变化。最后,提出加强农区生物多样性影响评价的有关建议。     

Two-dimensional modeling of torrefaction of a large biomass particle

A two-dimensional (2-D) model is developed to predict the torrefaction behavior of a large wet biomass particle. Although one-dimensional (1-D) model is found to be adequate for L/D ≥ 6, the necessity of using 2-D model at lower L/D ratios and higher torrefaction temperature is established. Errors up to 18% are observed in predicted mass fractions between 1-D and 2-D models. The center temperatures differed more, up to 96%, between z = 0 and z = L/2 in 2-D model which is not captured by the 1-D model. The model predictions agree well with the experimental results of the present authors and others. The evolution of the temperature profile is found to govern the mass fraction profile. At higher reactor temperature, three distinct zones are visible in the contour plots: peripheral fully torrefied zone, intermediate torrefying zone, and core with unreacted virgin biomass zone. Simulation studies show the formation of two symmetric annular hot spots at the ends, which move inward axially and subsequently merge at the center, the rate being faster for smaller L/D ratio. However, 1-D model does not provide such insight. The effects of reactor temperature, particle size, the residence time, and the initial moisture content on the torrefaction behavior are investigated.     

Optimal nonpoint source pollution control strategies for a reservoir watershed in Taiwan

The purpose of this study is to develop a model for optimal nonpoint source pollution control for the Fei-Tsui Reservoir watershed in Northern Taiwan. Several structural best management practices (BMPs) are selected to treat stormwater runoff. The complete model consists of two interacting components: an optimization model based on discrete differential dynamic programming (DDDP) and a zero-dimensional reservoir water quality model. A predefined procedure is used to locate suitable sites for construction of various selected BMPs in the watershed. In the optimization model, the objective function is to find the best combination of BMP type and placement, which minimizes the total construction and operation, maintenance, and repair (OMR) costs of the BMPs. The constraints are the water quality standards for total phosphorus (TP) and total suspended solids (TSS) concentrations in the reservoir. A zero-dimensional reservoir water quality model of the Vollenweider type is embedded in the optimization framework to simulate pollutant concentrations in Fei-Tsui Reservoir. The resulting optimal cost and benefit of water quality improvement are depicted by the model-derived trade-off curves. The modeling framework developed in the present study could be used as an efficient tool for planning a watershed-wide implementation of BMPs for mitigating stormwater pollution impact on the receiving water bodies.     

Evaluating the impact of uncertainty and variability on the value chain optimization of a forest biomass power plant using Monte Carlo Simulation

Mathematical programming models have been used to optimize the design and management of forest bioenergy supply chains. A deterministic mathematical model is beneficial for making optimum decisions; however, its applicability to real-world problems may be limited because it does not capture all the complexities, including uncertainties in the parameters, in the supply chain. In this paper, a combination of Monte Carlo Simulation and optimization model is used to evaluate the impact of uncertainty in biomass quality, availability and cost, and electricity prices on the supply chain of a forest biomass power plant. The optimization model is a deterministic mixed integer non-linear model with monthly time steps over a 1-year planning horizon. Variability in biomass quality, i.e. moisture content (MC) and higher heating value (HHV), based on the historical data of a real case study is studied in detail and fitted probability distributions are used in the model, while for electricity prices different scenarios are considered. The results show that the impact of variability in the MC on profit is higher than that of uncertainty in HHV. It is observed that the annual profit ranges between $13.3 million and $17.9 million in the presence of all possible uncertainties while its average is $15.5 million. Uncertainty in biomass availability and cost and electricity price results in the risks of having annual profit of less than $14 million and low monthly storage levels.     

Does intensity of change matter? Factors affecting adoption of agri-environmental schemes in Spain

Agri-environmental schemes (AES) are the main policy instrument currently available in the EU to promote environmentally-friendly farming practices. However, the rate of adoption of these measures is still relatively low in southern Europe, and understanding how these rates can be increased is still an open issue. The goal of this paper is to increase that understanding by testing whether the factors which determine AES sign-up decisions are influenced by the intensity of change in farming practices that are brought about by adopting the scheme. A micro-economic model reflecting farmer AES sign-up decisions is proposed and applied to two schemes in Spain respectively requiring major or minor intensity of change in practices by surveying farmers eligible for both schemes. The results show that farm structural factors play a role when major practice change is required by the scheme, yet when dealing with minor change, individual farmer characteristics play a more determining role. Social capital and farmer attitude are important factors in both the AES surveyed. Therefore, it may be concluded that improving agronomic design would be an important tool to improve farmer participation in AES where major change is involved, whereas improved targeting and extension would help uptake for AES involving a lesser degree of change.     

LAKEMAP: A 2-D AND 3-D MAPPING SYSTEM FOR VISUALIZING WATER QUALITY DATA IN LAKES1

ABSTRACT: The visualization of water quality data in lakes was achieved by integrating the U.S. Environmental Protection Agency's (EPA) STORET water quality database, lake shoreline polygons from EPA's Reach File (version 3), and the UNIMAP 2-D and 3-D interactive mapping and modeling software. Based on lake name (and state abbreviation), a lake shoreline polygon can be accessed from the Reach File. The coordinates of the polygon are portrayed by the U.S. Geological Survey (USGS) 1:100,000 scale Digital Line Graph (DLG) hydrography layer. This polygon is passed, in turn, to the STORET water quality file. Monitoring stations located within the polygon boundary are extracted along with the complete sampling survey. Specific parameters, such as total phosphorus, pH, ammonia, and optional time and depth restrictions can be selected to build a file of x, y, z₁, z₁…, zn data which is imported to UNIMAP. Up to four parameters, including depth, can be selected at a time. Within UNIMAP, the data is gridded and then displayed as a 2-D color contour map, 3-D perspective contour map, or 2-D projected time or depth slices. This system operates on the EPA ES9000 mainframe computer located in Research Triangle Park (RIP), North Carolina. LAKEMAP is the culmination of an effort to bridge the gap between the vast array of environmental data collected by the EPA and the complex analytical and display software resident on the mainframe.     

Coupling hydrologic and economic modeling for wetland management multi-optimization in Tram Chim National Park,Vietnam

We developed a comprehensive coupling framework with a multi-objective optimization that bridges a water balance model (WBM) and a wetland service model (WSM) to supporting wetland management. The framework was tested for management in Tram Chim National Park (with four wetland zones) where hydro-economic optimization was needed. The framework used (1) a model coupling process bridging WBM and WSM to create a modular hydro-economic model (MHEM), (2) a multi-objective optimization, and (3) an anneal scheduling for scenario optimization. The framework demonstrated its competency in identifying cause–effect/interaction flows (bridges) between WBM and WSM to design MHEM to simulate optimized scenarios; for the case study, the multi-objective optimization was met for all wetland zones. Results suggested a flexible consideration of management scales for optimization, i.e. hydrologic optimization at a zone level and net benefit optimization at a Park level. Our framework is applicable to supporting complex wetland decisions considering multiple objectives.     

Soil sorption of acidic pesticides: modeling pH effects

A model of acidic pesticide sorption in soils was developed from theoretical modeling and experimental data, which initially considered a combination of a strongly acidic pesticide and a variable-charge soil with high clay content. Contribution of 2,4-D [(2,4-dichlorophenoxy) acetic acid] anionic-form sorption was small when compared with molecular sorption. Dissociation of 2,4-D was not sufficient to explain the variation in Kd as a function of pH. Accessibility of soil organic functional groups able to interact with the pesticide (conformational changes) as a function of organic matter dissociation was proposed to explain the observed differences in sorption. Experimental 2,4-D sorption data and K(oc) values from literature for flumetsulam [N-(2,6-difluorophenyl)-5-methyl [1,2,4] triazolo [1,5-a] pyrimidine-2-sulfonamide] and sulfentrazone [N-[2,4-dichloro-5-[4-(difluromethyl)-4,5-dihydro-3-methyl-5-oxo-1H-1,2,4-triazol-1-yl] phenyl] methanesulfonamide] in several soils fit the model.     

Environmental effects of agri-environmental schemes in Western Europe

Agri-environmental schemes (AES) have been introduced as part of European Union's (EU) Common Agricultural Policy and are now an important part of this. A methodological approach to analyse the policy effects of AES is outlined, in which we distinguish between performance effects (on agricultural practices) and outcome effects (environmental impact). The performance effects are further approached including measurement of improvement and protection effects based on 12 indicators on changes/maintenance of land use and agricultural management.Data from personal interviews of participating and non-participating farmers in AES measures in nine EU Member States and Switzerland were used to analyse policy effects, including single indicator effects on agricultural practices as well as combined effects at the agreement level. Significant effects were found for mineral N-fertiliser use, stocking density reduction, maintenance of a minimum livestock density and pesticides. For AES agreements regulating grassland management, fertiliser use and pesticides, clear indications of combined improvement and protection effects were found. In addition clear improvement effects of agreements regulating fertiliser and pesticides use on mainly arable lands were revealed. It is concluded that the approach presented including the 12 selected indicators has proven to be operational.     

Does the Temporal Resolution of Precipitation Input Influence the Simulated Hydrological Components Employing the SWAT Model?

This study aimed to evaluate the influence of sub‐daily precipitation time steps on model performance and hydrological components by applying the Green and Ampt infiltration method using the Soil and Water Assessment Tool (SWAT). Precipitation was measured at a resolution of 0.1 mm and aggregated to 5‐, 15‐, 30‐, and 60‐min time steps. Daily discharge data over a 10‐year period were used to calibrate and validate the model. Following a global sensitivity analysis, relevant parameters were optimized through an automatic calibration procedure using SWAT‐CUP for each time step. Daily performance statistics were almost equal among all four time steps (NSE ≈ 0.47). Discharge mainly consisted of groundwater flow (55%) and tile flow (42%), in reasonable proportions for the investigated catchment. In conclusion, model outputs were almost identical, showing simulations responded nearly independently of the chosen precipitation time step. This held true for (1) the selection of sensitive parameters, (2) performance statistics, (3) the shape of the hydrographs, and (4) flow components. However, a scenario analysis revealed that the precipitation time step becomes important when saturated hydraulic conductivities are low and curve numbers are high. The study suggests that there is no need in using precipitation time steps <1 h for lowland catchments dominated by soils with a low surface runoff potential if daily flow values are being considered. Editor's note : This paper is part of the featured series on SWAT Applications for Emerging Hydrologic and Water Quality Challenges. See the February 2017 issue for the introduction and background to the series.     

COMPARISON OF 1-D AND 2-D MODELING OF OVERLAND RUNOFF AND SEDIMENT TRANSPORT1

ABSTRACT: One-dimensional and two-dimensional modeling approaches were compared for their abilities in predicting overland runoff and sediment transport. Both 1-D and 2-D models were developed to test the hypothesis that the 2-D modeling approach could improve the model predictions over the 1-P approach, based on the same mathematical representations of physical processes for runoff and sediment transport. The models developed in this study were applied to overland areas with cross slopes. A hypothetical case and an experimental study reported by Storm (1991) were used. Based on the simulation results from the selected hypothetical case and experimental study, the 2-D model provided better representation of spatial distribution of flow depths and sediment concentrations than the 1-D model. However, no significant differences in predictions of total runoff volume and sediment yield at the outlet area were found between the 1-D and 2-D models.