Characteristics of Atmospheric Inorganic Nitrogen Wet Deposition in Coastal Urban Areas of Xiamen, China

Miming Zhang,Suqing Xu,Yang Luo,Jun Shi,Hang Yang,Qi Lin,Shanshan Wang,Jinpei Yan,Yao Feng,Liping Jiao,Shuhui Zhao

doi:10.3390/atmos12111447

Miming Zhang, Suqing Xu + Show 9 more

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https://doi.org/10.3390/atmos12111447

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Abstract

To evaluate the impact of increasing atmospheric nitrogen deposition input to the coastal ecosystem, measurements were conducted to analyze the inorganic nitrogen wet deposition to Xiamen Island during April to August in 2014. Using ion chromatography and shown to contain main nine water-soluble ions—including Na+, NH4+, K+, Mg2+, Ca2+, Cl−, NO−, NO3−, and SO42−—we analyzed the composition of the wet deposition sample and verified the contribution of different ions to the different sources. The results showed that the mean NO3−-N and NH4+-N concentration in rainfall for five months was 4.55 ± 5.15 mg·L−1 (n = 31) and 1.20 ± 1.16 mg·L−1 (n = 33), respectively. Highest NO3−-N (74.65 mg·N·L−1) and NH4+-N (16.06 mg N·L−1) values were both observed in May. Maximum NO3−-N deposition (507.5 mg·N·m−2) was also in May, while the highest NH4+-N deposition (99.8 mg·N·m−2) was in June. The total inorganic wet nitrogen flux during sampling period was 11.1 kg·N·ha−1. The HYSPLIT backward air masses trajectory and USEPA PMF model was used, as the composition of the air masses passing over the sample area were impacted from three sources: fertilizers and biomass combustion, formation of secondary aerosol, and Marine aerosols. The concentration ratio of SO42− and NO3− in ranged between 0.5 and 3 in rainfall samples with an average of 1.34, suggesting that the contribution from vehicle exhaust to air pollution in the sample area is increasing. Long-term continuous monitoring of wet deposition in this region needs to be expanded to fully understand the impacts of human activity on air quality and to quantify N deposition to local marine ecosystems.

Highlights

Nitrogen is an essential biogenic element and is one of the most complex elements with many valence states
Using the MFA method to create a detailed model of nitrogen flow, the results showed that increasing the removal rate of NOx emissions at the point of fossil fuel consumption and adopting management practices within the surrounding watersheds to limit the loss of N-containing compounds would greatly help reduce the presence of Ncontaining pollutants in the Xiamen region [16]
SO42−, NO3−, Cl−, and NH4+ were the main water-soluble ions, they accounted for 36.04%, 29.91%, 10.80%, and 8.67% of the total ion mass of the samples, respectively

Summary

Introduction

Nitrogen is an essential biogenic element and is one of the most complex elements with many valence states. Nitrogen is a limiting factor for biological productivity, which gives it a central role in oceanic biogeochemical cycles. The wet deposition of atmospheric nitrogen is the process by which nitrogen is deposited in terrestrial or aquatic ecosystems by raindrops or snowfall. Precipitation chemistry and sedimentation rates are important factors for understanding and predicting the impacts of anthropogenic atmospheric discharge on ecosystems [2]. The rapid expansion of the global population has been accompanied by an increase in N emissions and a subsequent increase in N deposition. There has been a non-negligible increase in atmospheric nitrogen deposition year by yeardue to increases in certain human activities (such as fossil fuel emissions, artificial fertilizers, etc.), and this deposition into the natural environment has put a heavy pressure on ecosystems. The growth in number of motor vehicles has led to increased oxynitride emissions since 2000 [3]

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