Global estimates of dry ammonia deposition inferred from space-measurements

Decreased nitrogen deposition in Beijing over the recent decade and its implications

Atmospheric reactive nitrogen (Nr) deposition has been modified significantly by human activities such as agriculture and fossil fuel combustion. Understanding the changes in Nr deposition is essential for maintaining the functionality and sustainability of ecosystems. Taking Beijing as a case study, we report long-term measurements of wet Nr deposition from 1999 to 2022 and dry Nr deposition from 2010 to 2022 and their relationship with China's air pollution control. Total Nr deposition to Beijing decreased by 34 % during 2010-2022, mainly caused by a decrease in dry N deposition by 54.27 %, from 47.86 kg N ha-1 yr-1 in 2010-2014 to 21.89 kg N ha-1 yr-1 in 2018-2022; reduced and oxidized N in dry deposition decreased by 29.93 % and 72.05 %, respectively. This was a result of the "Action Plan for Prevention and Control of Air Pollution (APCP)" and the implementation of the "Zero Growth in Fertilizer Use by 2020" in 2015. Our ground-based measurements provide evidence to support recent achievements in air pollution control and a reference and guidance for other regions of China and other countries for abating Nr pollution.

Determination of Paddy Soil Ammonia Nitrogen Using Rapid Detection Kit Coupled with Microplate Reader

Indophenol blue colorimetry has been widely used for determining soil ammonia nitrogen, but this method has some disadvantages, such as complex reagent preparation, high toxicity, and long colorimetric time. Hence, we aimed to develop a rapid soil ammonia nitrogen determination method using a rapid detection kit. In order to select a suitable extractant, different concentrations of KCl and NaCl solutions were used to extract soil. The ammonia nitrogen content in different types of soils was determined using a rapid detection kit (purchased from Zhejiang Luheng Environmental Technology Limited Company) coupled with a microplate reader. The kit method was compared with the traditional indophenol blue colorimetry method. The results showed no significant difference between the 1 mol·L−1 KCl extraction kit method and indophenol blue colorimetry (p > 0.05). The linearity of the working curve was smooth, the linear detection range was 0.0−2.00 mg·L−1, the average relative standard deviation was 7.00% (n = 5), the standard addition recovery rate was 89.31−118.23%, and the detection limit were was 0.074 mg·L−1. We concluded that the 1 mol·L−1 KCl extraction kit method can be applied to determine the ammonia nitrogen content of paddy soil with different chemical properties. The 1 mol·L−1 KCl extraction kit method has the advantage over indophenol blue colorimetry due to its simple reagent preparation, convenient operation, and shorter detection time (the coloring and colorimetric time for 96 samples was only 30 min using the kit method coupled with a microplate reader). Hence, it has the potential for application due to its rapid determination of soil samples in large quantities.

Improving Estimates of Sulfur, Nitrogen, and Ozone Total Deposition through Multi-Model and Measurement-Model Fusion Approaches

Earth system and environmental impact studies need high quality and up-to-date estimates of atmospheric deposition. This study demonstrates the methodological benefits of multimodel ensemble and measurement-model fusion mapping approaches for atmospheric deposition focusing on 2010, a year for which several studies were conducted. Global model-only deposition assessment can be further improved by integrating new model-measurement techniques, including expanded capabilities of satellite observations of atmospheric composition. We identify research and implementation priorities for timely estimates of deposition globally as implemented by the World Meteorological Organization.

Atmospheric nitrogen deposition: A review of quantification methods and its spatial pattern derived from the global monitoring networks

Atmospheric nitrogen (N) deposition is a vital component of the global N cycle. Excessive N deposition on the Earth's surface has adverse impacts on ecosystems and humans. Quantification of atmospheric N deposition is indispensable for assessing and addressing N deposition-induced environmental issues. In the present review, we firstly summarized the current methods applied to quantify N deposition (wet, dry, and total N deposition), their advantages and major limitations. Secondly, we illustrated the long-term N deposition monitoring networks worldwide and the results attained via such long-term monitoring. Results show that China faces heavier N deposition than the United States, European countries, and other countries in East Asia. Next, we proposed a framework for estimating the atmospheric wet and dry N deposition using a combined method of surface monitoring, modeling, and satellite remote sensing. Finally, we put forth the critical research challenges and future directions of the atmospheric N deposition. CAPSULE: A review of quantification methods and the global data on nitrogen deposition and a systematic framework was proposed for quantifying nitrogen deposition.

Sources and trends of oxidized and reduced nitrogen wet deposition in a typical medium-sized city of eastern China during 2010-2016

Fluxes and composition dynamics of atmospheric nitrogen deposition play key roles in better balancing economic development and ecological environment. However, there are some knowledge gaps and difficulties in urban ecosystems, especially for small and medium-sized cities. In this study, both flux and composition (ratio of NH₄⁺-N to NO₃^--N, R_N) of wet-deposited dissolved inorganic nitrogen (DIN, sum of NO₃^--N and NH₄⁺-N) were estimated and sources were identified at a long-term urban observation station in Tongling, a typical medium-sized city in eastern China during 2010-2016, respectively. Results showed that wet-deposited DIN fluxes were 33.20 and 28.15 kgN ha^-1 yr^-1 in Tongling city during 2010-2011 and 2015-2016, respectively. Compared to these two periods, both DIN and NO₃^--N fluxes decreased by 15.2% and 31.8% for a series of NOx abatement measures applied effectively, respectively. At the same time, the NH₄⁺-N flux remained stable and ranged from 19.53 to 20.62 kgN ha^-1 yr^-1, and the R_N increased from 1.7 to 2.2. Seasonally, winds from the southwest and west-southwest with higher frequencies and speeds in spring and summer brought more NH₄⁺-N and DIN wet deposition from an ammonia plant, which could threaten the safety of regional hydrosphere ecosystems. On the whole, the wet-deposited NH₄⁺-N was threatening regional ecosystems of both the hydrosphere and forest. The wet-deposited DIN including NH₄⁺-N in Tongling city stemmed mainly from a combined source of coal combustion and dust from Cu extraction and smelting, ammonia production, and roads. Therefore, production lines should be updated for Cu extraction and smelting industries, thermal power generations and the ammonia plant, old vehicles should be eliminated, and the use of new energy vehicles should be promoted for regional sustainable development and human health in the medium-sized city.