A database of modeled gridded dry deposition velocities for 45 gaseous species and three particle size ranges across North America

Atmospheric organic nitrogen deposition around the Danjiangkou Reservoir: Fluxes, characteristics and evidence of agricultural source

Dissolved organic nitrogen (DON) deposition was the substantial component of dissolved total nitrogen (DTN) deposition in the world's nitrogen deposition hot spots areas. However, the information on the importance for DON deposition and its sources was still scarce, which limited the comprehensive assessment of the ecological threat from nitrogen deposition. Six sampling sites around the Danjiangkou Reservoir were set up to collect the dry and wet deposition samples from October 2017 to September 2021. The results showed that dry and wet DTN deposition averaged 34.72 kg ha-1 yr-1 and 22.27 kg ha-1 yr-1, respectively. Dry NH4+-N, NO3--N and DON deposition averaged 14.28 kg ha-1 yr-1, 5.91 kg ha-1 yr-1 and 14.53 kg ha-1 yr-1, respectively. Wet NH4+-N, NO3--N and DON deposition averaged 11.14 kg ha-1 yr-1, 3.89 kg ha-1 yr-1and 7.24 kg ha-1 yr-1, respectively. The contributions of DON to DTN were 41.85% (in dry deposition) and 32.50% (in wet deposition), respectively. Dry DON deposition varied between 26.44 kg ha-1 yr-1 and 9.11 kg ha-1 yr-1, and significantly differed among six sampling sites (P < 0.05). The different intensity of agricultural activities disturbance at the sampling sites was the important reason for the spatial variations of DON deposition. DON deposition was significantly correlated with ammonium nitrogen (NH4+-N) deposition (P < 0.05). According to the results of positive matrix factorization (PMF) model, agriculture source contributed significantly to the DON deposition, the contributions at six sampling sites ranged from 45.8% to 73.7% in dry deposition, and from 56.8% to 81.6% in wet deposition. In summary, our findings found that agricultural activities were the important factors influencing the spatial patterns of DON deposition around Danjiangkou Reservoir and provided new evidence for the anthropogenic source of DON deposition in China.

Atmospheric deposition mapping of particulate elements in the Canadian Athabasca oil sands region

This study used a deposition modeling framework to generate gridded dry, wet, and total (dry + wet) deposition fluxes of 27 particulate elements over the Canadian Athabasca oil sands region and its surrounding areas for the years 2016-2017. The framework employed the element concentrations from the CALPUFF dispersion model outputs that were bias-corrected against measured concentrations, modeled dry deposition velocities, precipitation analysis data, and literature values of element-specific fine mode fractions and scavenging ratios by rain and snow. The annual total deposition (mg/m²/year) of all elements (EM) across the domain ranged from 4.49 to 5450 and the mean and median deposition were 60.9 and 31.0, respectively. Total EM deposition decreased rapidly within a short distance from the oil sands mining area. Annual mean total deposition (mg/m²/year) of EM was 717 in Zone 1 (within 30 km from a reference point, representing the center of the oil sands mining area), 115 in Zone 2 (30-100 km from the reference point), and 35.4 in Zone 3 (beyond 100 km from the reference point). The deposition of individual elements was primarily governed by their respective concentrations and among all elements the annual mean total deposition (μg/m²/year) over the domain varied five orders of magnitude ranging from 0.758 (Ag) to 20,000 (Si). Annual mean dry and wet deposition (mg/m²/year) of EM over the domain were 15.7 and 45.2, respectively. Aside from S, which has relatively lower precipitation scavenging efficiencies, wet deposition was the dominant deposition type in the region contributing from 51% (Pb) to 86% (Ca) of the respective total deposition. Total EM deposition over the domain in the warm season (66.2 mg/m²/year) was slightly higher than that in the cold season (55.6 mg/m²/year). Deposition of individual elements in Zone 1 were generally lower than their deposition at other sites across North America.