Progress in developing an ANN model for air pollution index forecast

An air pollution index (API) reporting system is introduced to selected cities of China for public communication on air quality data. Shanghai is the first city in China providing daily average API reports and forecasts. This paper describes the development of an artificial neural network (ANN) model for the API forecasting in Shanghai. It is a multiple layer perceptron (MLP) network, with meteorological forecasting data as the main input, to output the next day average API values. However, the initial version of the MLP model did not work well. To improve the model, a series of tests were conducted with respect to the training method and structure optimization. Based on the test results, the training algorithm was modified and a new model was built. The new model is now being used in Shanghai for API forecasting. Its performance is shown reasonably well in comparison with observation. The application of the old model was only weakly correlated with observation. In 1-year application, the correlation coefficients were 0.2314, 0.1022 and 0.1710 for TSP, SO₂ and NO_x, respectively. But for the new model, for over 8 months application, the correlation coefficients are raised to 0.6056, 0.6993 and 0.6300 for PM₁₀, SO₂, and NO₂. Further, the new algorithm does not rely on manpower intervention so that it is now being applied in several other Chinese cities with quite different meteorological conditions. The structure of the model and the application results are presented in this paper and also the problems to be further studied.     

Environmental forensic investigation of the air pollution from a cement manufacturing unit

Abstract

Cement manufacturing is a process that results in the emission of significant quantities of suspended particulate matter (SPM) to the ambient air. An environmental forensic investigation was carried out in the surroundings of a major cement manufacturing unit at a place called Coimbatore in the southern Indian state of Tamil Nadu. The investigation was carried out to identify the contribution of the cement manufacturing unit to the SPM concentration of the surrounding air environment. The sampling points’ selection and sample collection were done following the principles outlined in the INTERPOL Manual for Pollution Crime Forensic Investigation. On-site monitoring of the air samples was carried out using Mini Laser Aerosol Spectrometer (GRIMM, Mini-LAS Model 11R). The instrument was capable of measuring particles ranging from 0.25 to 32 µm and classifying them into 31 size channels. The test results at majority of the monitoring locations were well above the limits specified in the National Ambient Air Quality Standards of India. Microscopic studies of the dust samples were carried out for surface texture and particle shape. The spatial distribution of particles was analysed using geographic information system (GIS) for the visual identification of the extent of the pollution by keeping the cement factory as the focal point. The results from the GIS and microscopic analysis established the role of the cement factory in the particulate matter pollution of its surroundings, specifically in the areas North-West of the factory. The successfully adopted procedure can serve as a guideline for the environmental forensic investigation of similar pollution incidences.     

Engelbart SST工艺农村生活污水一体化治理设备的应用效果及运行能耗

针对农村生活污水水质水量波动性大的特点,应用基于Engelbart SST工艺的一体化处理设备对农村生活污水进行了处理,并考察了该设备在水质波动情况下的处理效果与运行能耗。结果表明,在DO为0.3~0.5 mg·L⁻¹、回流比为1 000%~2 000%、HRT为12~15 h、MLSS为5 600~8 800 mg·L⁻¹的工艺条件下,配合化学除磷,设备COD、NH₃-N、TN、TP平均去除率分别可达到95.3%、94.9%、78.9%、92.2%。该设备表现出了良好的抗波动能力,在COD、NH₃-N、TN处理负荷较设计值波动幅度分别为−39.7%~171.0%、−34.8%~96.9%、−45.0%~61.1%的条件下,出水COD≤50 mg·L⁻¹、NH₃-N浓度≤5.0 mg·L⁻¹、TN浓度≤15 mg·L⁻¹。该设备利用曝气自动控制系统在经济DO条件下运行,吨水能耗为0.24~0.33 kWh。本研究结果可为农村污水处理的技术选择和运行提供参考。     

Molecular tools for bathing water assessment in Europe: Balancing social science research with a rapidly developing environmental science evidence-base

The use of molecular tools, principally qPCR, versus traditional culture-based methods for quantifying microbial parameters (e.g., Fecal Indicator Organisms) in bathing waters generates considerable ongoing debate at the science–policy interface. Advances in science have allowed the development and application of molecular biological methods for rapid (~2 h) quantification of microbial pollution in bathing and recreational waters. In contrast, culture-based methods can take between 18 and 96 h for sample processing. Thus, molecular tools offer an opportunity to provide a more meaningful statement of microbial risk to water-users by providing near-real-time information enabling potentially more informed decision-making with regard to water-based activities. However, complementary studies concerning the potential costs and benefits of adopting rapid methods as a regulatory tool are in short supply. We report on findings from an international Working Group that examined the breadth of social impacts, challenges, and research opportunities associated with the application of molecular tools to bathing water regulations.     

基于多元统计分析的渭河西咸段水质评价

基于2012年旱季和雨季的水质监测数据,采用主成分分析(PCA)和绝对主成分多元线性回归分析(APCS-MLR)方法对渭河西咸段水体的污染特征进行了综合评价。结果表明,2012年渭河西咸段水体主要以有机污染和富营养化污染为主,同时存在一定的As污染。总体上,研究水体旱季比雨季污染严重,旱季和雨季提取的主成分及大部分断面综合排名不同,说明降雨对水质产生一定的影响。渭河西咸段水体在皂河入渭之前的上游污染相对较轻,污染贡献以干流排污为主;对应的下游水质较差,皂河是其最大的污染源。     

武烈河流域水质污染特征及污染源解析

以武烈河流域2014年1—12月23项指标的监测数据为基础,采用单因子评价法和水质综合指数评价法,对水质污染特征进行综合评价;运用主成分分析法,确定流域主要污染因子及区域水质空间变化特征,并进一步对流域污染来源进行解析。结果表明：武烈河流域上游支流水质为Ⅱ类,干流段监测断面S1与S3水质为Ⅲ类,S2与S4水质为Ⅳ类,主要污染指标为BOD₅与TP;流域水质由2个主成分组成,COD_Cr、COD_Mn为第一主成分,NH₃-N、DO与BOD₅为第二主成分;流域主要污染源包括生活污水、工业废水、农业化肥和农药的投入和畜禽养殖废水等。     

天津市近岸海域水质变化趋势分析及水质目标研究

掌握海域水质变化趋势、制定科学合理的水质目标,有助于精准实施重点海域排污总量控制,制定有效的污染物管控政策。利用广义加性模型（GAM）,基于2007—2018年天津市近岸海域营养盐浓度及降水量数据,建立水质变化趋势分析模型和水质目标确定方法,在评估天津市近岸海域12个监测站位无机氮和活性磷酸盐浓度变化趋势的基础上,提出天津市近岸海域水质控制目标,并分析水质目标的合理性和可达性。结果表明：2013—2018年与2007—2012年相比,天津市近岸海域无机氮浓度总体呈下降趋势,下降比例为13.19%,95%的置信区间为−30.37%～3.96%;活性磷酸盐浓度总体呈上升趋势,上升比例为7.01%,95%的置信区间为−11.43%～25.45%,尚未恢复到2007—2012年的平均水平;提出2025年天津市近岸海域无机氮、活性磷酸盐二者综合优良水质比例达到75%的控制目标;将天津市近岸海域划分成7个区域,建议据此实施海域水质分区管理,进一步加强农业面源污染防治,强化流域上下游协同治理和省际水污染联防联治,持续改善天津市近岸海域水质。

     

多重水质评价方法在地下水水质评价中的对比研究—以北京市朝阳区为例

目前地下水水质评价方法众多,选择合适的评价方法对地下水的管理与利用具有重要意义。以北京市朝阳区2020年枯水期采集的地下水水样检测结果为基础,利用改进的层次分析法、单因子指数法和综合污染指数法对地下水水质进行评价,并对比3种方法评价结果的准确性以及存在的不合理之处。结果表明：1）3种方法的水质评价结果差异较大,改进的层次分析法的水质评价结果最优,单因子指数法的评价结果最差,综合污染指数法的评价结果与其他方法的一致性最高;2）在进行水质评价时可优先选择综合污染指数法,单因子指数法适用于水质要求较高或超标污染物少的水体,改进的层次分析法适用于有多种污染物超标的水体;3）为进一步确定3种方法对地下水水质评价结果的准确性,将3种方法的评价结果与可靠性分析结果进行对比,发现改进的层次分析法、单因子指数法和综合污染指数法与可靠性分析的水质评价结果相同的占比分别为90.48%、42.86%、47.62%。因此,在对地下水水质进行综合评价时,可使用改进的层次分析法。

     

Estimation of Cumulative Frequency Distribution for Carbon Monoxide Concentration from Wind-Speed Data, in Buenos Aires (Argentina)

In this article we apply and test a methodology to estimate cumulative frequency distribution for air pollutant concentration from wind-speed data. We use the inverse relationship after Simpson et al. (Atmospheric Environment, 19, 75–82, 1985) between the opposing percentile values in the statistical distributions for air pollutant concentrations and wind-speed data. This relationship is valid, irrespective of the statistical distributions of both variables, if an inverse relationship between them is also applicable. The available data are five years of 8-h average carbon monoxide concentration and 8-h mean wind-speed, observed in Buenos Aires (Argentina). The performance of the obtained empirical expressions in estimating cumulative frequency distributions for 8-h CO is statistically evaluated. The results show that it is possible to obtain an acceptable cumulative frequency distribution for 8-h CO concentration at the site if the cumulative frequency distribution for wind-speed is known. Q–Q plots show a good agreement between estimated and observed values. From our data, the mean relative error of the estimations was found to be as much as 8.0%.     

Modeling Parent and Metabolite Fate and Transport in Subsurface Drained Fields With Directly Connected Macropores1

Abstract: Few studies exist that evaluate or apply pesticide transport models based on measured parent and metabolite concentrations in fields with subsurface drainage. Furthermore, recent research suggests pesticide transport through exceedingly efficient direct connections, which occur when macropores are hydrologically connected to subsurface drains, but this connectivity has been simulated at only one field site in Allen County, Indiana. This research evaluates the Root Zone Water Quality Model (RZWQM) in simulating the transport of a parent compound and its metabolite at two subsurface drained field sites. Previous research used one of the field sites to test the original modification of the RZWQM to simulate directly connected macropores for bromide and the parent compound, but not for the metabolite. This research will evaluate RZWQM for parent/metabolite transformation and transport at this first field site, along with evaluating the model at an additional field site to evaluate whether the parameters for direct connectivity are transferable and whether model performance is consistent for the two field sites with unique soil, hydrologic, and environmental conditions. Isoxaflutole, the active ingredient in BALANCE^® herbicide, was applied to both fields. Isoxaflutole rapidly degrades into a metabolite (RPA 202248). This research used calibrated RZWQM models for each field based on observed subsurface drain flow and/or edge of field conservative tracer concentrations in subsurface flow. The calibrated models for both field sites required a portion (approximately 2% but this fraction may require calibration) of the available water and chemical in macropore flow to be routed directly into the subsurface drains to simulate peak concentrations in edge of field subsurface drain flow shortly after chemical applications. Confirming the results from the first field site, the existing modification for directly connected macropores continually failed to predict pesticide concentrations on the recession limbs of drainage hydrographs, suggesting that the current strategy only partially accounts for direct connectivity. Thirty‐year distributions of annual mass (drainage) loss of parent and metabolite in terms of percent of isoxaflutole applied suggested annual simulated percent losses of parent and metabolite (3.04 and 1.31%) no greater in drainage than losses in runoff on nondrained fields as reported in the literature.