Modeling PM 2.5 transport from mazut-fired plants to cities 90 km away, analyzing exponential decay and wind-driven urban air impact
Abstract
The pace of industrialization in the economic systems of the above-mentioned regions makes it imperative that the mazut fuel be used in a massive production of electricity observed in peak load hours [1]. In presenting the objective of the current study, the authors have set the scene in introducing a comprehensive mathematical model intended to assess the transboundary environmental effect of PM 2.5 pollutants emitted from the mazut fuel being used in a 1,000-ton thermal power station per day [2]. The aim of the study is to simulate, in a mathematical model, the long-range transport of the mentioned pollutants to the urban air mass situated 90 km away from the site of emission [3]. The mathematical model presented in the study relies fundamentally on the applicability of the exponential decay algorithm. The algorithm provides the conceptual framework that the mass of PM 2.5 particulate matter reduces by 50% for each successive 10kilometer distance away from the point of emission of the pollutants in the Earth's terrain [4]. The proposed algorithm reflects the natural mechanisms of the Earth's atmosphere, including the phenomena of dry deposition and gravity settling in the lower atmosphere of the troposphere [5]. In addition, the model involves a critical urban penetration coefficient of 0.3, representing the fact that only 30% of the total incoming particulate mass can actually penetrate into the city's residential and industrial areas due to local aerodynamic obstacles and building morphology [6]. For realistic modeling, meteorological variables, amongst which horizontal wind speed represents the most important factor, are included as secondary dilution parameters [7]. The interference of wind speed with the buoyancy of the plume is examined in determining the drop off of concentration beyond the base exponential velocity-dependent drain [8]. Numerical results obtained under this regime show that, although the immediate source emission caused by burning 1,000 tons of mazut gives rise to an enormous primary plume, its 512-fold dilution along a 90 km radius appreciably alleviates the immediate direct toxicological impact [9]. Together with the 30% penetration factor, however, the residual PM 2.5 concentration may still contribute a readily measurable η/m3 value to the city's general background air quality and be in excess of WHO daily guidelines during conditions of low wind dispersion [10]. The outcome verifies that the distance of 80-90 km is insufficient to provide 'complete immunity' against the emissions of industries, thereby prompting the use of 'clean coal' technology/WESP in the power stations [11]. In conclusion, it can be asserted that the simplified exponential wind model is an essential 'tool' in the hands of regional planners to estimate the 'risks to the environment' in the absence of complex 'dispersement software tools' in the initial stage [12]. Lastly, the outcome strongly supports the formulation of a tough 'legislative policy regarding the use of mazut in thermal power stations to protect the health of distant urban areas' [13].