Fog Water Chemical Composition on Ailaoshan Mountain, Yunnan Province, SW China

Abstract

Between December 2015 and March 2016, fog water was collected at the subtropical mountain cloud forest site Ailaoshan in SW China at 2476 m above mean sea level. An active fog collector was employed to collect 117 samples during more than 140 hours of fog, covering 6 major fog events. The chemical analysis included acidity and inorganic ion concentrations. The median pH values of the fog events varied between 3.7 and 4.2, characterizing the fog water as acidic (pH < 5.0) to very acidic (pH < 4.0). The ion composition was dominated by H + , NH 4 + , SO 4 2-and NO 3 -, which made up more than 86% of the total ionic concentration (TIC). The generally rather high ion concentration levels cannot be explained by nearby emission sources but rather by long-range transport of air pollutants from various sources in East Asia. During one event on February 8, 2016, it is evident that it was the emissions from a large coal-fired power plant in Myanmar that led to high concentrations of sulphuric acid. This pilot study of fog chemistry in rural, mountainous SW China should be complemented by studies spanning the moist summer monsoon season and covering more chemical species.

Global modeling of cloud water acidity, precipitation acidity, and acid inputs to ecosystems

“…We find that precipitation pH increases by 0.4-1 unit in the Amazon, tropical Africa, and southeast Asia, which is consistent with observations (Andreae et al, 1990;Sanhueza et al, 1992;Sigha-Nkamdjou et al, 2003;Yoboué et al, 2005). Over the US, Europe, and eastern China the increase in pH is 0.1-0.4 units, which is similar to the observed contribution of carboxylic acids to precipitation H + (10 %-60 %) in these areas (Keene and Galloway, 1984;Kawamura et al, 1996;Peña et al, 2002;Xu et al, 2010;Niu et al, 2018). Over the oceans, the change in pH from HCOOH and CH 3 COOH is small (∼ 0.15 units) and is in agreement with marine observations (Keene et al, 2015).…”

Classification of Clouds Sampled at the Puy de Dôme Station (France) Based on Chemical Measurements and Air Mass History Matrices

“…The samples do not come from the same population. We observe, in particular, high sea salts concentrations (Cl − , Mg 2+ , and Na + ) for both "marine" and "highly marine" categories, and high concentrations of potentially anthropogenic ions (NH4 + , NO3 − , and SO4 2− ) [68][69][70][71][72] for both "polluted" and "continental" categories (Table S2). In red, the smallest category (nine objects), referred to as "polluted" in Figure 1 displays peak concentrations for SO 4 2− , NH 4 + , and NO 3 − , suggesting the air mass passed over an urbanized area.…”

“…The samples do not come from the same population. We observe, in particular, high sea salts concentrations (Cl − , Mg 2+ , and Na + ) for both "marine" and "highly marine" categories, and high concentrations of potentially anthropogenic ions (NH 4 + , NO 3 − , and SO 4 2− )[68][69][70][71][72] for both "polluted" and "continental" categories (TableS2).Distribution of inorganic ions (Cl − , Mg 2+ , Na + , NH4 + , NO3, and SO4 2− ) of the cloud waters sampled at PUY for each air mass category (marine, highly marine, continental, and polluted). Distribution of inorganic ions (Cl − , Mg 2+ , Na + , NH 4 + , NO 3 , and SO 4 2− ) of the cloud waters sampled at PUY for each air mass category (marine, highly marine, continental, and polluted).…”

Effects of altitude on soil properties in coastal fog ecosystems in Morro Moreno National Park, Antofagasta, Chile

“…Similar results were reported for fog water samples by Beiderwieden et al (2005), with median pH and EC values of 4.58 and 23 μS cm −1 , respectively. Nieberding et al (2018) reported that the pH values of fog events in a subtropical mountain cloud forest varied from acidic (pH < 5.0) to very acidic (pH < 4.0). Both Beiderwieden et al (2005) and Nieberding et al (2018) reported varying concentrations of ions such as Ca 2+ , Mg 2+ , Na + , SO 4 2− , and NO 3 − .…”