Three-decade changes in chemical composition of precipitation in Guangzhou city, southern China: has precipitation recovered from acidification following sulphur dioxide emission control?

Abstract

We examined if precipitation had recovered from acidification in Guangzhou, the third biggest city in China, and if sulphur deposition in precipitation had decreased, and to what extent if yes, following abatement strategies in sulphur dioxide (SO2) emission and energy use implemented since 2001. SO2 emissions were decreasing steadily since 2001, but a marked recovery of precipitation acidity occurred only since 2005; precipitation pH values decreased from 4.65 in 2001 to 4.34 in 2005 and then increased to 5.08 in 2010, while in the same period acid rain (pH<5.6) frequency increased from 70% to 81% and then decreased to 48%. During this period, the change in pH value and sulphate concentration more reflected the patterns of SO2 emission at provincial and national scales than at the local scale, suggesting that precipitation chemical composition was largely controlled by the emissions of pollutants from surrounding areas of the study city. Since 2001, sulphate deposition in precipitation decreased significantly (by 40%) but nitrogen deposition remained unaltered. More importantly, the current sulphur (43 kg S ha−1 yr−1 as sulphate) and nitrogen depositions (35 kg N ha−1 yr−1 as ammonium plus nitrate in 2010) were still among the highest in China. These results highlight the fact that ambient sulphur and nitrogen deposition still pose a threat to the health of both terrestrial and aquatic ecosystems. Precipitation may become more acidified in the future because the deposition of alkaline dusts containing calcium is also likely to decrease with stricter SO2 emission control policy and reduced construction activities. Additionally, we recommend that a reduction of emissions of nitrogen and chlorine bearing pollutants is urgently required for complete control on acid deposition

Nitrogen deposition contributes to soil acidification in tropical ecosystems

“…Although SO 2 emissions have declined across Europe and eastern North America since the 1990s (Oulehle et al, 2011) and in China since 2005 (Fang et al, 2013), the contribution…”

A 15-year record (2001–2015) of the ratio of nitrate to non-seasalt sulfate in precipitation over East Asia

“…The results indicated that the fraction of NO 3 -wet deposition gradually increased during the analyzed 15-year period over East Asia, indicating that further attention should 30 be paid attention to the deposition of NO 3 -and related Nr species. This has been coincided with previous reports on several cities in China; Nanjing (Tu et al, 2005), Shenzhen (Huang et al, 2008), Guangzhou (Fang et al, 2013), Pearl River Delta region (Lu et al, 2015), and Beijing . Our study reinforced these implications on a whole scale over East Asia.…”

“…Analyses for long-term precipitation chemistry are still limited. For example, precipitation chemistry over periods of longer than 10 years has been reported for Guangzhou during 1983(Fang et al, 2013, Shenzhen during 1986-2006(Huang et al, 2008), Lijiang during 1989-2006(Zhang et al, 2012, and Nanjing during 1992-2003 (Tu et al, 2005). This study's long-term, 15-year 20 analysis will provide a comprehensive view of the precipitation chemistry over East Asia.…”

Impact of Manufacturing Transfer on SO2 Emissions in Jiangsu Province, China

“…Meanwhile, regional nitrogen emissions and depositions also increased [60][61][62]. This changed the compositions of acid rain [63,64] and brought a new challenge for the regional eco-environment and the regional economies [26,65,66]. (Tables 3-5) and related subsectors transferred from the south to the central and north (Figure 6 and Table 6).…”