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Human Excreta as a Stable and Important Source of Atmospheric Ammonia in the Megacity of Shanghai.

ABSTRACT: Although human excreta as a NH3 source has been recognized globally, this source has never been quantitatively determined in cities, hampering efforts to fully assess the causes of urban air pollution. In the present study, the exhausts of 15 ceiling ducts from collecting septic tanks in 13 buildings with 6 function types were selected to quantify NH3 emission rates in the megacity of Shanghai. As a comparison, the ambient NH3 concentrations across Shanghai were also measured at 13 atmospheric monitoring sites. The concentrations of NH3 in the ceiling ducts (2809(-2661)(+5803) ?g m(-3)) outweigh those of the open air (~10 ?g m(-3)) by 2-3 orders of magnitude, and there is no significant difference between different seasons. ?15N values of NH3 emitted from two ceiling ducts are also seasonally consistent, suggesting that human excreta may be a stable source of NH3 in urban areas. The NH3 concentration levels were variable and dependent on the different building types and the level of human activity. NH3 emission rates of the six residential buildings (RBNH3) were in agreement with each other. Taking occupation time into account, we confined the range of the average NH3 emission factor for human excreta to be 2-4 times (with the best estimate of 3 times) of the averaged RBNH3 of 66.0±58.9 g NH3 capita(-1) yr(-1). With this emission factor, the population of ~21 million people living in the urban areas of Shanghai annually emitted approximately 1386 Mg NH3, which corresponds to over 11.4% of the total NH3 emissions in the Shanghai urban areas. The spatial distribution of NH3 emissions from human excreta based on population data was calculated for the city of Shanghai at a high-resolution (100×100 m). Our results demonstrate that human excreta should be included in official ammonia emission inventories.

SUBMITTER: Chang Y

PROVIDER: S-EPMC4681533 | biostudies-literature | 2015

REPOSITORIES: biostudies-literature

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Human Excreta as a Stable and Important Source of Atmospheric Ammonia in the Megacity of Shanghai.

Chang Yunhua Y Deng Congrui C Dore Anthony J AJ Zhuang Guoshun G

PloS one 20151214 12

Although human excreta as a NH3 source has been recognized globally, this source has never been quantitatively determined in cities, hampering efforts to fully assess the causes of urban air pollution. In the present study, the exhausts of 15 ceiling ducts from collecting septic tanks in 13 buildings with 6 function types were selected to quantify NH3 emission rates in the megacity of Shanghai. As a comparison, the ambient NH3 concentrations across Shanghai were also measured at 13 atmospheric m ...[more]

PMID: 26656636

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Project description:The wide spread of the coronavirus disease (COVID-19) has significantly influenced human activities around the world, providing a unique opportunity to investigate the response of air pollution to anthropogenic emission reduction. Compared with numerous studies on conventional air pollutants, atmospheric ammonia (NH3) that has matched sources from both anthropogenic and natural emissions has been rarely investigated. Here we assess impacts of the COVID-19 lockdown on ambient NH3 variation across India, one of the most severe NH3 pollution region in the world. The role of meteorology in shaping emission contribution to NH3 pollution and respective contribution of each emission source to ambient NH3 before and after the COVID-19 outbreak were investigated using the XGBoost algorithm coupled with WRF-Chem model. Results showed that ambient NH3 concentrations in the seven major cities (Hyderabad, Bengaluru, Chennai, Delhi, Lucknow, Kolkata and Mumbai) decreased by 2.1-53.8 % whereas in Ahmedabad increased by 20.3 % during the COVID-19 lockdown period. Obvious decrease in NH3 in Indo-Gangetic Plain (-17.1 %) was mainly driven by favorable meteorology, whereas the slight decline in NH3 in South India was mainly driven by epidemic-related emission control (-8.56 %). Source appointment results showed that the contribution of industrial emission (Ind) to ambient NH3 in most megacities showed a decreasing trend (between 11 % and 26 %) during the lockdown period. However, the reduction effect was mostly compensated by increasing contributions (15-25 %) of residential emission (Res) or agricultural soil emission (Ags). Particularly, in Ahmedabad and Lucknow ambient NH3 increased by 20.3 % and 12 % during the lockdown period, the reduction effect of Ind on ambient NH3 (-23 % and -11 %, respectively) was absolutely compensated by enhanced contribution of Res (24 %) and Ags (12 %), respectively. Our results highlight the importance of eliminating residential and agricultural NH3 emissions especially in North India.

Dataset Information

Human Excreta as a Stable and Important Source of Atmospheric Ammonia in the Megacity of Shanghai.

Publications

Human Excreta as a Stable and Important Source of Atmospheric Ammonia in the Megacity of Shanghai.

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