Data Report 2021

The Data Report 2021 of the Acid Deposition Monitoring Network in East Asia (EANET) provides a comprehensive analysis of acid deposition and air concentration data collected across 13 participating countries. The report presents findings from five key environmental monitoring activities: wet deposition, dry deposition (air concentration), soil and vegetation, inland aquatic environments, and catchment-scale monitoring. It details methodologies, site classifications, and data management processes, ensuring the consistency and reliability of monitoring efforts. The results offer insights into regional air pollution trends, deposition rates, and ecosystem impacts, contributing to scientific understanding and policy-making on acid deposition. The report also includes statistical summaries, quality assurance measures, and historical data comparisons to track long-term environmental changes. This information serves as a valuable resource for researchers, policymakers, and stakeholders working towards mitigating acid deposition effects in East Asia.

The EANET Data Report 2021 compiles the year’s observations from the Acid Deposition Monitoring Network in East Asia (EANET), a cooperative program spanning 13 participating countries: Cambodia, China, Indonesia, Japan, Lao PDR, Malaysia, Mongolia, Myanmar, Philippines, Republic of Korea, Russian Federation, Thailand, and Viet Nam. The network tracks five environmental items—wet deposition, dry deposition (air concentration), soil and vegetation, inland aquatic environment, and catchment-scale monitoring—to evaluate the state of acid deposition and its ecosystem impacts, and to inform policy across the region. Participating countries submit their data annually to the Network Center, which quality-checks and consolidates them for review by EANET’s technical bodies.

The report explains the monitoring network layout and site typologies. EANET classifies sites as urban, rural, or remote (for air/acid deposition monitoring) and as basic survey or ecosystem analysis sites (for ecological effects). In 2021, 65 sites were nominated: 26 urban, 18 rural, 21 remote. This structure supports spatial assessments from built environments to background locations and enables cross-country comparability.

For wet deposition, laboratories follow the Technical Manual for Wet Deposition Monitoring in East Asia (2010), with ion chromatography recommended for major anions and cations. Data quality objectives (DQOs) include detection limits for ions (e.g., SO₄²⁻ 0.3 μmol L⁻¹; NO₃⁻ 0.5 μmol L⁻¹; NH₄⁺ 0.8 μmol L⁻¹), and datasets undergo ion balance (R1) and conductivity agreement (R2) checks before submission. Sites are encouraged to couple precipitation chemistry with meteorological measurements (wind, temperature, humidity, precipitation, solar radiation) or obtain these from nearby stations to interpret unusual events.

For dry deposition / air concentration, EANET uses both automatic monitors and manual methods. Automatic monitoring targets SO₂, O₃, NO, NO₂, PM₁₀, and PM₂.₅, following QA/QC criteria in the 2013 air concentration manual. Manual methods include the four-stage filter pack (for SO₂, HNO₃, HCl, NH₃ and particulate ions: SO₄²⁻, NO₃⁻, Cl⁻, NH₄⁺, Na⁺, K⁺, Mg²⁺, Ca²⁺) and passive samplers for SO₂, NH₃, NO₂, and O₃. In 2021, automatic monitors operated in eleven countries, while the filter pack was used widely and passive samplers were applied in Indonesia and Russia.

The report also covers ecological effects through soil & vegetation and inland aquatic environment modules (site selection, field and laboratory protocols, and 2021 results are provided in later chapters and appendices).

A notable integrative component is catchment-scale monitoring, which evaluates input–output budgets (linking atmospheric deposition, stream chemistry, and water balance) to quantify material/elemental cycles (e.g., nitrogen and sulfur). Data management includes standardized units—mm for water fluxes, molc L⁻¹ for concentrations, molc ha⁻¹ or molc m⁻² for ion fluxes, and kg ha⁻¹ y⁻¹ for elemental N and S—compiled on a water-year basis before submission to the Network Center. 2021 submissions included Japan’s Lake Ijira catchment and the Philippines’ La Mesa Watershed, reflecting expanding regional capacity for integrated assessments.

Overall, the 2021 report documents a multi-country, QA/QC-driven monitoring system that produces harmonized regional datasets on atmospheric chemistry, deposition, and ecosystem responses. It emphasizes standard methods, site classifications that capture urban–rural–remote gradients, and an expanding focus on catchment-scale mass balances—creating an evidence base for assessment and policy support throughout East and Southeast Asia and parts of North/Central Asia.

Keywords (from the report)

EANET, acid deposition, air concentration, wet deposition, dry deposition, ion chromatography, DQO, ion balance (R1), conductivity agreement (R2), automatic monitoring, filter pack, passive sampler, SO₂, O₃, NO₂, PM₂.₅, site classification (urban/rural/remote), ecosystem analysis, inland aquatic environment, soil and vegetation, catchment-scale monitoring, input–output budget, water balance, Network Center, SAC/STM review.