Land-use and land-cover changes due to urban expansion is recognized as one of the crucial factors affecting carbon dioxide emissions. In this study, the land conversion effects on soil CO₂ fluxes associated with temperate re-established grasslands within the Forest Botanical Garden found on an anthropogenic landform were investigated. The present work analyses the capabilities and requirements of the CALPUFF Lagrangian puff air quality modelling system to simulate the spatial distribution of ecosystem respired CO₂ in the urban domain. The results are validated against the available observations of CO₂ fluxes in the urban environment using the closed-chamber method with the measurements of the stable carbon isotope ratio (δ¹³C) of daytime soil-respired CO₂. The isotope mass balance partitioning approach was applied to distinguish biogenic portions of CO₂ from the admixture of atmospheric air.

The spatial and temporal amplitude of the simulated CO₂ concentrations from the CALPUFF model showed considerable agreement with the tracer measurements of the biogenic CO₂ component in the near-ground air (0.25 m). In most cases, however, the CALPUFF predictions of ecosystem-derived CO₂ showed a general tendency toward considerable underestimation of real concentration levels. Such discrepancies are related to the difficulties associated with the optimization of biospheric CO₂ flux and uptake from ecosystems by means of local-scale modelling. The modelled results implied that the CALPUFF performance in the dispersion simulation of CO₂ concentrations within the urban ecosystems is very sensitive to the initial meteorological conditions, grid resolution, measurement timescale, and the calculated gas flux rate from soils. A significant negative correlation was found between hourly values of the average modelled CO₂ and observed wind speed during the entire study campaign (r = −0.58 and r = −0.82 for Pearson and Spearman statistics, respectively, p < 0.05). Moreover, analysis of the impact of the deposition parameters on changes in the atmospheric concentration of carbon dioxide indicated significant dependency of the temporal CO₂ distribution patterns on the precipitation-based events. According to the obtained estimates, the wet deposition rate during rain events was approximately two orders higher than the average dry deposition flux.

Overall, the present case study indicates that the CALPUFF model has a rather acceptable predictive ability. A better agreement of model predictions and all field measurements, however, require further studies of CO₂ exchange between the ecosystem and atmosphere and understanding where they need to be improved.

由于城市扩张而引起的土地利用和土地覆盖变化被认为是影响二氧化碳排放的关键因素之一。在这项研究中，调查了在人为地貌上发现的森林植物园内与温带重建草地相关的土壤转化对土壤CO ₂通量的影响。本工作分析了CALPUFF拉格朗日抽吸空气质量建模系统的功能和要求，以模拟城市域中生态系统呼吸的CO ₂的空间分布。结果针对CO的可用观测验证₂通量使用与稳定的碳同位素比率的测量的封闭室方法城市环境（δ ¹³C）白天土壤呼吸的CO ₂。应用同位素质量平衡分配方法从大气混合物中区分出CO _2的生物部分。

CALPUFF模型模拟的CO ₂浓度的时空幅度与近地面空气（0.25 m）中生物CO ₂组分的示踪剂测量结果显示出相当一致。但是，在大多数情况下，CALPUFF对生态系统衍生的CO _2的预测显示出总体趋势，即对实际浓度水平的估计大大偏低。这种差异与通过局部尺度模型优化生物圈CO ₂通量和从生态系统吸收水分有关的困难有关。建模结果表明，CALPUFF在CO ₂扩散模拟中的性能城市生态系统中的浓度对初始气象条件，网格分辨率，测量时间尺度以及从土壤中计算出的气体通量率非常敏感。在整个研究活动中，平均建模的CO _2的小时值与观测到的风速之间存在显着的负相关（对于Pearson和Spearman统计，r = -0.58和r = -0.82，p <0.05）。此外，分析沉积参数对大气中二氧化碳浓度变化的影响表明，时间CO _2的依赖性很大。降水事件的分布模式。根据获得的估计，降雨期间的湿沉降速率比平均干沉降通量高约两个数量级。

总体而言，本案例研究表明CALPUFF模型具有相当可接受的预测能力。然而，要使模型预测与所有现场测量结果更好地吻合，就需要进一步研究生态系统与大气之间的CO ₂交换，并了解需要改进的地方。