Mass conservation above slopes in the Regional Atmospheric Modelling System (RAMS)

This paper examines the mass balance in calculations with the Regional Atmospheric Modelling System (RAMS). An error is pointed out that concerns the calculation of the surface fluxes on slopes. This error affects all the prognostic variables in RAMS when sloping terrain is involved. Here we explain how the error can be corrected. To study the impact of the error, we compared simulations with the uncorrected and corrected model. The model contains CO₂ transport, and online mass balance calculations were performed for this tracer. Without correction, effective surface CO₂-fluxes on mountain slopes were found to be enhanced under certain common conditions to several times the parameterized fluxes. Neglecting this error may cause substantial deviations in both forward and inverse model calculations. After the correction a very good closure of the mass balance is obtained. The correction also modifies the meteorological parameters, although the consequences were limited compared to the CO₂-fluxes.     

Modeling the Cd(II) adsorption onto goethite

The surface complexation of Cd(II) to goethite (α‐FeOOH) at varying concentrations of solid, background electrolyte and Cd(II) has been investigated. The data was quantified according to the generalized version of triple layer (TLM) surface complexation model. In the presence of atmospheric CO₂, it was found that the experimental data of Cd(I) α‐FeOOH system could be explained satisfactorily by incorporating both the > FeOHCd⁺ and > FeOCdHCO₃ in the calculations. However, at excessive concentrations of Cd(II), typically over 13% surface coverages, the TLM predictions significantly underestimated the experimentally observed data obtained for Cd(II)/α‐FeOOH systems.     

太湖流域近地表大气二氧化碳本底体积分数观测研究

基于2003年1月至2005年6月用气相色谱法对太湖流域近地表大气中二氧化碳本底体积分数的监测资料,对太湖流域近地表大气二氧化碳体积分数的变化特征进行了分析研究。结果表明:在观测时段内,太湖流域近地表大气二氧化碳体积分数平均值为(413.7±19.2)×10-6,且呈上升的趋势,主要受人类活动、工农业生产和交通运输业发展的影响;二氧化碳体积分数季节变化明显,冬春季高,夏秋季低,冬季出现峰值,平均体积分数为(417.8±3.7)×10-6,夏季出现谷值,平均体积分数为(400.8±14.7)×10-6,一年中最高值(424.0±1.1)×10-6出现在12月份,最低值(387.7±1.4)×10-6出现在8月份,主要受源汇强度变化影响;二氧化碳体积分数日变化基本呈双峰态,这是源汇强度变化和边界层稳定程度相互作用的结果。     

Chemistry of atmospheric dust and critical load assessment in Delhi region (India)

This is the first study in the Delhi region that assesses the critical load capacity of soil systems with respect to the atmospheric deposition and air quality, from July to October in 2012. Trend analysis of NO₂ and SO₂ in Delhi, using the Central Pollution Control Board (CPCB) data, showed interesting patterns matching with the trends in vehicular load in the city. This was followed by the calculation of the critical load of atmospheric acidity for sulphur and nitrogen in order to check the vulnerability of the soil systems in Delhi. Here, the steady state mass balance approach was majorly applied and the study conducted in the Agra region was taken as reference. The calculated values of critical loads of sulphur (225–275?eq/ha/yr) and nitrogen (298–303?eq/ha/yr), for the soil system in Delhi, were calculated with respect to three plant species, namely Anjan grass, Hibiscus and Black siris. The present loads of sulphur (PL(S)?=?26.40?eq/ha/yr) and nitrogen (PL(N)?=?36.51?eq/ha/yr) were found to be much lower than their respective critical loads. From the results, it can be concluded that the present loads of atmospheric acidic deposition in Delhi region do not pose any danger of acidification of soil system because it is countered by buffering capacity of soil generated dust. However, considering the pace at which the city is growing, it is likely that in coming decades, the present load will increase and thus the values evaluated in this study are likely to serve as an important reference for future assessment of the pollution scenario in the city.     

Modeling the population dynamics of cotton bollworm Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) over a wide area in northern China

The cotton bollworm Helicoverpa armigera (Lepidoptera: Noctuidae) is one of the most serious crop pests in northern China, calling for accurate prediction of pest outbreaks and strategies for pest control. A computer model is developed to simulate the population dynamics of H. armigera over a wide area in northern China. The area considered covers 12 provinces where serious outbreaks of H. armigera have been observed. In this model, pest development is driven by local ambient temperature, and adults migrate long distances between regions and select preferred hosts for oviposition within a region. Six types of host including cotton, wheat, corn, peanut, soybean and a single category composed of all other minor hosts are considered in this model. Survival rates of eggs and larvae are based on life-table data, and simulated as a function of host type, host phenology and temperature. The incidence of diapause depends on temperature and photoperiod experienced during the larval stage. Survival rate of non-diapause pupae is a nonlinear function of rainfall, and overwinter survival rate is a nonlinear function of temperature. Insecticide is applied when population density exceeds the economic threshold on a host crop within a region. Comparisons of model output with light-trap data indicate that our model reflects the pest population dynamics over a wide area, and could potentially be used for testing novel pest control strategies in northern China.     

攀枝花市大气颗粒物中多环芳烃污染特征分析及来源识别

2007年2月在攀枝花市不同功能区采集了大气PM10样品42个和污染源样品32个,采用超声抽提GC/MS方法测定分析了16种多环芳烃(PAHs)的含量。结果显示攀枝花市PM10颗粒相PAHs单体浓度范围为0.34～416.45ng/m3,总量浓度范围为24.56～2569.66ng/m3;攀枝花市5个采样点中河门口片区PM10多环芳烃单体浓度范围为5.64～416.45ng/m3,污染最严重。源样品测定结果分别为扬尘78.74ug/g,煤烟尘6.12ug/g,钢铁工业尘30.54ug/g,焦化尘3187.42ug/g。应用比值法和化学质量平衡(CMB)模型对污染源进行识别,燃煤和炼焦是攀枝花市PAHs的主要来源,对攀枝花市大气可吸入颗粒物中多环芳烃污染的分担率分别为55.8%、19.9%。     

密云水库上游地区农田土壤有机碳储量及变化模拟

农田土壤有机碳(SOC)库对粮食安全和全球气候变化具有重要影响,因此,开展农田土壤有机碳储量及其动态变化研究在政治经济和生态环境层面具有重要意义.采用农业生物地球化学模型--DNDC对密云水库上游地区农田土壤有机碳储量及其变化进行模拟研究,首先应用当地实测结果进行模型验证,然后根据当地气候条件、土壤性质和现行农业耕作管理特点等建立GIS区域数据库,并在数据库的支持下进行区域模拟和分析.结果表明:2006年密云水库上游地区214 920 hm~2农田土壤(0～25 cm)的总有机碳储量为7 646×10~6 kg,其中位于河北省境内的该地区63.1%的农田储存了全区68.1%的SOC;平均每公顷农田SOC储量为35 576.1 kg,低于全国平均水平;由于化肥和有机肥投入的增加,经过1 a耕种后,2006年该地区农田SOC储量增加142.5×10~6 kg,整个地区及各区县农田土壤碳收支均为正,是大气CO_2的一个汇.情景分析表明,气温升高对该地区农田SOC积累具有显著的负效应;而提高秸秆还田比例、适量施用化肥、增施有机肥、增加灌溉和采取免耕方式等措施均能有效增加土壤有机碳的积累.     

基于DNDC模型评估水位变化对滨海湿地净生态系统CO2交换的影响

水位是影响滨海湿地生态系统蓝碳功能的重要因素。气候变化引起的海平面上升以及极端气候事件的频发,可能加快水位的变化,从而改变生态系统碳交换的过程。然而,滨海湿地碳汇功能响应水位变化的机制尚不清楚。为了评估水位对滨海湿地净生态系统CO₂交换(NEE)特征的影响,以及验证DNDC(denitrification-decomposition)模型对模拟预测滨海湿地生态系统碳交换的适用性,该研究设计了野外水位控制试验(自然水位,地下20 cm水位、地表10 cm水位),并利用DNDC模型模拟和预测水位变化对滨海湿地NEE的影响。结果表明:(1)不同水位处理之间NEE差异显著,地表10 cm水位处理促进CO₂吸收,地下20 cm水位则抑制CO₂吸收;(2)经过校准和验证的DNDC模型可以准确模拟水位变化对黄河三角洲湿地NEE的影响,NEE模拟值的日动态与田间观测结果显著相关(R²>0.6);(3)通过改变气候、土壤和田间管理等输入参数对DNDC模型进行灵敏度检验,生态系统碳交换过程对日均温、降雨和水位改变的响应最为显著,其中,水位对NEE的影响主要作用于土壤呼吸(Rs)。未来气候情境下,不同水位变化下的生态系统碳交换过程随年份增长呈现不同的规律,因此未来的模拟研究应关注DNDC中水文模块和植被演替过程的完善。该研究可为预测水文变化情境下滨海湿地碳汇功能的未来发展以及政策制定提供参考。     

The relative role of age and experience in determining variation in body mass during the early breeding career of the Common Tern (<Emphasis Type="Italic">Sterna hirundo</Emphasis>)

Body mass is a consistent individual trait that characterises the state of adult birds and mammals and is positively related with long-term reproductive success. However, whether and to what extent body mass changes over lifetime in long-lived birds is poorly studied. In this paper, we investigate how individual body mass varies with age. Furthermore, we try to separate possible effects of age and experience on body mass. This study was conducted in a Common Tern colony on the German Wadden Sea coast. Transponders allowed registration of individuals throughout the breeding season and consecutive years with an antenna system combined with electronic balances for recording individual body-mass changes within and between years. Individual body masses of males and females were measured during three stages of the breeding season: at arrival, during incubation and chick rearing when mass was lowest in both sexes. Individual-based longitudinal analyses clearly showed that body mass during arrival, incubation and chick rearing increased up to an age of 5 or 6 years. First-time breeders had lower body mass than experienced breeders. Experience had stronger effects on incubation mass than age. Recruiting age also affected body-mass development of breeders: Three-year-old recruits showed a stronger increase in mass with experience than 4-year-old recruits. We assume that increasing experience enables birds to cope better with the physiological challenge of reproduction. To explain the general phenomenon of higher body mass in older birds, our results support the constraint hypothesis rather than either the selection or restraint hypothesis.     

Nest separation and the dynamics of the Gestalt odor in the polydomous ant Cataglyphis iberica (Hymenoptera, Formicidae)

In the polydomous ant species Cataglyphis iberica, nests belonging to the same colony are completely separated during hibernation. In order to examine whether this separation induces changes both in the hydrocarbon profile and in recognition ability between adult nestmates, we separated groups of workers for several months under two different conditions: at hibernation temperature and at room temperature. At room temperature, recognition remained unchanged but separation led to longer mutual antennations relative to non-separated controls. When half of a colony was placed under hibernation conditions, antennal interactions also increased in duration and a few aggressive interactions emerged between separated ants. This aggressiveness never reached the intercolonial level observed in this species. In both cases, the hydrocarbon profiles showed differences between individuals after separation while remaining homogeneous within each nest. This chemical modification may induce the longer antennations observed. After separated groups were reunited, individuals recovered their previous antennation pattern and a convergence in hydrocarbon profiles was again observed. These concurrent observations suggest that hydrocarbons are transferred between nestmates. In C. iberica, the formation of the colonial odor seems to follow the “Gestalt” model which allows all satellite nests of a colony to have a common colonial odor. In the field, temporary nest isolation during hibernation may induce divergence between satellites. The role of adult transport in connecting nests during the active season to obtain an efficient Gestalt odor is discussed. Received: 16 June 1997 / Accepted after revision: 25 October 1997     

Important organic matter sources and trophic pathways for the nutrition of Hilsa kelee (Cuvier, 1829) and Valamugil buchanani (Bleeker, 1853) in Pangani macro-tidal estuary,Tanzania

The study investigated the spatial variation in the main sources of organic matter (OM) and trophic pathways for zooplanktivorous Hilsa kelee and phytodetritivorous Valamugil buchanani in fresh-water-influenced zone versus sea-water-dominated zone of Pangani estuary. The findings indicated significant inter-specific variations in δ¹³C and δ¹⁵N values (ANOVA, F?≥?84.3, p?F?≥?9.4, p?=?0.001) in both estuarine zones. Results also showed significant zonal-intraspecific variations in stable isotopes (δ¹³C and δ¹⁵N), FA profile and marginal differences in diet for the V. buchanani while no considerable differences were observed for H. kelee from two estuarine zones. The isotope mixing models and FA biomarkers revealed that the most important carbon sources to the nutrition of H. kelee were derived from microphytobenthos, macro-algae and sea grasses transferred through phytoplankton and detrital trophic pathways. In contrast, C₃ terrestrial plants and microphytobenthos were the main carbon source to the diet of V. buchanani; and were transferred via the benthic and detrital trophic pathways. Therefore, both terrestrial and in-situ OM sources were the main trophic resources base fuelling the planktonic and benthic food webs in Pangani estuary.     

持续提高黄土高原植被水土保持功能的配套技术(I)森林保持水土的条件

阐述了森林保持水土的条件 ,即良好的林分结构、必要的面积比例和一定的林龄 ,揭示了成林过程中水土保持功能的动态变化 ,为研究防护林体系水土保持功能持续提高技术提供了理论基础     

A system dynamics model for the management of the Manila clam, Ruditapes philippinarum (Adams and Reeve, 1850) in the Bay of Arcachon (France)

The Manila clam Ruditapes philippinarum (Adams and Reeve, 1850) is one of the mollusc species that, driven mainly by the shellfish market industry, has extended throughout the world, far beyond the limits of its original habitat. The Manila clam was introduced into France for aquaculture purposes, between 1972 and 1975. In France, this venerid culture became increasingly widespread and, since 1988, this species has colonised most of the embayments along the French Atlantic coast. In 2004, this development resulted in a fishery of ca. 520 t in Arcachon Bay.     

An integrated modeling framework for performing environmental assessments: Application to ecosystem services in the Albemarle-Pamlico basins (NC and VA, USA)

The U.S. Environmental Protection Agency uses environmental models to inform rulemaking and policy decisions at multiple spatial and temporal scales. As decision-making has moved towards integrated thinking and assessment (e.g. media, site, region, services), the increasing complexity and interdisciplinary nature of modern environmental problems has necessitated a new generation of integrated modeling technologies. Environmental modelers are now faced with the challenge of determining how data from manifold sources, types of process-based and empirical models, and hardware/software computing infrastructure can be reliably integrated and applied to protect human health and the environment.In this study, we demonstrate an Integrated Modeling Framework that allows us to predict the state of freshwater ecosystem services within and across the Albemarle-Pamlico Watershed, North Carolina and Virginia (USA). The Framework consists of three facilitating technologies: Data for Environmental Modeling automates the collection and standardization of input data; the Framework for Risk Assessment of Multimedia Environmental Systems manages the flow of information between linked models; and the Supercomputer for Model Uncertainty and Sensitivity Evaluation is a hardware and software parallel-computing interface with pre/post-processing analysis tools, including parameter estimation, uncertainty and sensitivity analysis. In this application, five environmental models are linked within the Framework to provide multimedia simulation capabilities: the Soil Water Assessment Tool predicts watershed runoff; the Watershed Mercury Model simulates mercury runoff and loading to streams; the Water quality Analysis and Simulation Program predicts water quality within the stream channel; the Habitat Suitability Index model predicts physicochemical habitat quality for individual fish species; and the Bioaccumulation and Aquatic System Simulator predicts fish growth and production, as well as exposure and bioaccumulation of toxic substances (e.g., mercury).Using this Framework, we present a baseline assessment of two freshwater ecosystem services-water quality and fisheries resources-in headwater streams throughout the Albemarle-Pamlico. A stratified random sample of 50 headwater streams is used to draw inferences about the target population of headwater streams across the region. Input data is developed for a twenty-year baseline simulation in each sampled stream using current land use and climate conditions. Monte Carlo sampling (n = 100 iterations per stream) is also used to demonstrate some of the Framework's experimental design and data analysis features. To evaluate model performance and accuracy, we compare initial (i.e., uncalibrated) model predictions (water temperature, dissolved oxygen, fish density, and methylmercury concentration within fish tissue) against empirical field data. Finally, we ‘roll-up’ the results from individual streams, to assess freshwater ecosystem services at the regional scale.     

Maternal characteristics and the production and recruitment of sons in the eastern kingbird (<Emphasis Type="BoldItalic">Tyrannus tyrannus</Emphasis>)

Sex allocation theory predicts that if variance in reproductive success differs between the sexes, females who are able to produce high-quality young should bias offspring sex ratio towards the sex with the higher potential reproductive success. We tested the hypothesis that high-quality (i.e., heavy) female eastern kingbirds (Tyrannus tyrannus) that bred early in the breeding season would produce male-biased clutches. A significant opportunity for sexual selection also exists in this socially monogamous but cryptically polygamous species, and we predicted that successful extra-pair (EP) sires would be associated with an excess of male offspring. Although population brood sex ratio did not differ from parity, it increased significantly with female body mass and declined with female breeding date, but was independent of the morphology and display (song) behavior (correlates of reproductive success) of social males and EP sires. Male offspring were significantly heavier than female offspring at fledging. Moreover, the probability that male offspring were resighted in subsequent years declined with breeding date, and was greater in replacement clutches, but lower when clutch size was large. Probability of resighting female offspring varied annually, but was independent of all other variables. Given that variance in reproductive success of male kingbirds is much greater than that of females, and that male offspring are more expensive to produce and have a higher probability of recruitment if fledged early in the season, our results support predictions of sex allocation theory: high-quality (heavy) females breeding when conditions were optimal for male recruitment produced an excess of sons.     

Modelling above- and below-ground mass loss and N dynamics in wooden dowels (LIDET) placed across North and Central America biomes at the decadal time scale

This article focuses on modelling above and below-ground mass loss and nitrogen (N) dynamics based on the wooden dowels (Gonystylus bancanus [Miq.] Kurz) of the decadal Long-term Intersite Decomposition Experiment (LIDET) data. These dowels were placed at 27 locations across North and Central America, involving tropical, temperate and boreal forests, grasslands, wetlands and the tundra. The dowel, inserted vertically into the soil with one half remaining exposed to the air, revealed fast mass and N losses under warm to humid conditions, and slow losses under wet as well as cold to dry conditions. The model formulation, referred to as the Wood Decomposition Model, or WDM, related these losses to (i) mean annual precipitation, mean monthly January and July air temperatures, and (ii) mean annual actual evapotranspiration (AET) at each location. The resulting calibrations conformed well to the time-in-field averages for mass remaining by location: R² = 0.83 and 0.90 for the lower and upper parts, respectively. These values dropped, respectively, to 0.41 and 0.55 for the N concentrations, and to 0.28 and 0.43 for N remaining. These reductions likely refer to error propagation and to as yet unresolved variations in N transference into and out of the wood specific to each individual dowel location. Recalibrating the model parameters by ecosystem type reduced the R² values for actual versus best-fitted mass loss by about 0.15. Doing the same without location- or ecosystem-specific adjustments reduced the R² values further, by about 0.3.     

GIS-based modeling of the geographic distribution of Quercus emoryi Torr. (Fagaceae) in México and identification of significant environmental factors influencing the species’ distribution

The greatest concentration of oak species in the world is believed to be found in Mexico. These species are potentially useful for reforestation because of their capacity to adapt to diverse environments. Knowledge of their geographic distribution and of species–environment relations is essential for decision-making in the management and conservation of natural resources. The objectives of this study were to develop a model of the distribution of Quercus emoryi Torr. in Mexico, using geographic information systems and data layers of climatic and other variables, and to determine the variables that significantly influence the distribution of the species. The study consisted of the following steps: (A) selection of the target species from a botanical scientific collection, (B) characterization of the collecting sites using images with values or categories of the variables, (C) model building with the overlay of images that meet the habitat conditions determined from the characterization of sites, (D) model validation with independent data in order to determine the precision of the model, (E) model calibration through adjustment of the intervals of some variables, and (F) sensitivity analysis using precision and concordance non-parametric statistics applied to pairs of images. Results show that the intervals of the variables that best describe the species’ habitat are the following: altitude from 1650 to 2750 amsl, slope from 0 to 66°; average minimum temperature of January from −12 to −3 °C; mean temperature of June from 11 to 25 °C; mean annual precipitation from 218 to 1225 mm; soil units: lithosol, eutric cambisol, haplic phaeozem, chromic luvisol, rendzina, luvic xerosol, mollic planosol, pellic vertisol, eutric regosol; type of vegetation: oak forest, oak–pine forest, pine forest, pine–oak forest, juniperus forest, low open forest, natural grassland and chaparral. The resulting model of the geographic distribution of Quercus emoryi in Mexico had the following values for non-parametric statistics of precision and agreement: Kappa index of 0.613 and 0.788, overall accuracy of 0.806 and 0.894, sensitivity of 0.650 and 0.825, specificity of 0.963, positive predictive value of 0.945 and 0.957 and negative predictive value of 0.733 and 0.846. Results indicate that the variable average minimum temperature of January, with a maximum value of −3 °C, is an important factor in limiting the species’ distribution.     

Identifying key life-traits for the dynamics and gene flow in a weedy crop relative: Sensitivity analysis of the GeneSys simulation model for weed beet (Beta vulgaris ssp. vulgaris)

The benefits of genetically modified herbicide-tolerant (GMHT) sugar beet (Beta vulgaris) varieties stem from their presumed ability to improve weed control and reduce its cost, particularly targeting weed beet, a harmful annual weedy form of the genus Beta (i.e. B. vulgaris ssp. vulgaris) frequent in sugar beet fields. As weed beet is totally interfertile with sugar beet, it is thus likely to inherit the herbicide-tolerance transgene through pollen-mediated gene flow. Hence, the foreseeable advent of HT weed beet populations is a serious threat to the sustainability of GM sugar beet cropping systems. For studying and quantifying the long-term effects of cropping system components (crop succession and cultivation techniques) on weed beet population dynamics and gene flow, we developed a biophysical process-based model called GeneSys-Beet in a previous study. In the present paper, the model was employed to identify and rank the weed life-traits as function of their effect on weed beet densities and genotypes, using a global sensitivity analysis to model parameters. Monte Carlo simulations with simultaneous randomization of all life-trait parameters were carried out in three cropping systems contrasting for their risk for infestation by HT weed beets. Simulated weed plants and bolters (i.e. beet plants with flowering and seed-producing stems) were then analysed with regression models as a function of model parameters to rank processes and life-traits and quantify their effects. Key parameters were those determining the timing and success of growth, development, seed maturation and the physiological end of seed production. Timing parameters were usually more important than success parameters, showing for instance that optimal timing of weed management operations is more important than its exact efficacy. The ranking of life-traits though depended on the cropping system and, to a lesser extent, on the target variable (i.e. GM weeds vs. total weed population). For instance, post-emergence parameters were crucial in rotations with frequent sugar beet crops whereas pre-emergence parameters were most important when sugar beet was rare. In the rotations with frequent sugar beet and insufficient weed control, interactions between traits were small, indicating diverse populations with contrasted traits could prosper. Conversely, when sugar beet was rare and weed control optimal, traits had little impact individually, indicating that a small number of optimal combinations of traits would be successful. Based on the analysis of sugar beet parameters and genetic traits, advice for the future selection of sugar beet varieties was also given. In climatic conditions similar to those used here, the priority should be given to limiting the presence of hybrid seeds in seed lots rather than decreasing varietal sensitivity to vernalization.