Large Contribution of Nitrous Acid to Soil-Emitted Reactive Oxidized Nitrogen and Its Effect on Air Quality

Abstract

Soil emissions have long been recognized as an important source of nitric oxide (NO), which regulates atmospheric oxidative capacity and the production of air pollutants. Recent research has also indicated that nitrous acid (HONO) can be emitted in significant quantities from soil microbial activities. However, only a few studies have quantified emissions of HONO along with NO from a wide range of soil types. In this study, we measured emissions of HONO and NO from soil samples collected from 48 sites across China and found much higher emissions of HONO than of NO, especially for samples from northern China. We performed a meta-analysis of 52 field studies in China, which revealed that long-term fertilization increased the abundance of nitrite-producing genes much more than the abundance of NO-producing genes. This promotion effect was greater in northern China than in southern China. In simulations using a chemistry transport model with laboratory-derived parametrization, we found that HONO emissions had a greater effect than NO emissions on air quality. Moreover, we determined that with projected continuous reductions in anthropogenic emissions, the contribution from soils to maximum 1 h concentrations of hydroxyl radicals and ozone and daily average concentrations of particulate nitrate in the Northeast Plain will increase to 17%, 4.6%, and 14%, respectively. Our findings highlight the need to consider HONO in the assessment of the loss of reactive oxidized nitrogen from soils to the atmosphere and its effect on air quality.

Quantifying the Nitrogen Sources and Secondary Formation of Ambient HONO with a Stable Isotopic Method

“…For example, Wang et al evaluated the impact of soil emissions on air quality in North China, finding that soil emissions contributed ∼17% of HONO, with this contribution reaching ∼50% during fertilization. 40,41 Although our sampling site is located in an urban area, it is surrounded by extensive cultivated land (Figure S9). The findings of this study and others highlight soil emission as an important source of HONO.…”

Soil Emissions of Reactive Nitrogen Accelerate Summertime Surface Ozone Increases in the North China Plain

“…We find that assuming an uncertainty of 20% in GWETTOP and its representation of SWC in units of % leads to −12–19% and 4–22% differences in the estimated HONO soil emissions in 2017 over China and NCP compared to our base estimate, respectively. More measurement studies are required to provide better observational constraints on soil HONO emission parametrization in CTMs. , …”

“…More measurement studies are required to provide better observational constraints on soil HONO emission parametrization in CTMs. 21,31 Figure 2 presents the N r emissions from anthropogenic fuel combustion and soil emissions in June−July. We note that we do not include traffic HONO emissions due to the lack of available emission inventory, and also because the traffic HONO emissions are much smaller than those from soil and contribute negligibly to the daytime HONO except for central urban areas.…”

“…Soil has been identified as an important source of N r . − N r emissions from soil are controlled by available soil nitrogen content and edaphic conditions such as soil water content (SWC) and temperature. ,,,, The NCP region occupies a large area of cultivated land (∼0.3 × 10 6 km 2 ) that is regularly treated with intensive chemical nitrogen fertilizers and also receives extensive nitrogen deposition. , The high soil nitrogen content from both agricultural fertilizer input and deposition have led to large soil N r emissions in the summertime. − These soil emissions are conventionally considered as biogenic sources, even though a large proportion of them are originally from anthropogenic agriculture activities. A number of studies estimated significant episodic surface ozone enhancement from soil NO x and/or HONO emissions by up to 8 ppbv. ,,− Lu et al pointed out a competing effect between NO x emissions from fuel combustion and soil on ozone formation in the NCP region, suggesting that soil ozone contribution may vary with changes in NO x emissions from fuel combustion.…”

Nanoplastic Stimulates the Amyloidogenesis of Parkinson's Alpha‐Synuclein NACore

“…[5][6][7][8][9][10][11][12][13][14][15][16] Microplastics, specifically, have been implicated as detrimental to the bladder epithelial cells of mice [17] and the gut health of zooplankton Daphnia magna. [18] Regarding the adverse effects of nanoplastics, in 2010 we first reported algal photosynthesis impaired by the surface adsorption of cationic and anionic polystyrene (PS) nanoparticles. [19] Later studies have revealed that nanoplastic accumulation in the gonad of Caenorhabditis elegans hampered their reproductivity and energy metabolism, [20] while gestational exposure to high-dose nanoplastics incited hepatic steatosis in the dam and dysregulation of de novo lipogenesis in mice.…”