Department of Environmental Science, Tezpur University, Tezpur, India.
Department of Environmental Studies, Assam Women's University, Jorhat, India.
Environ Sci Pollut Res Int. 2022 Apr;29(17):25276-25295. doi: 10.1007/s11356-021-17385-7. Epub 2021 Nov 28.
This work is a 7-year study of monsoonal rainwater chemistry (n = 302), over mid-Brahmaputra plain during 2012 to 2018. The samples were analyzed for major chemical parameters viz. pH, electrical conductivity (EC), and ions (SO, NO, Br, Cl, F, Mg, Ca, K, NH, Na, and Li) to assess the chemistry. The mean pH of rainwater varied among the years, which was maximum in 2018 (6.18 ± 0.72) and minimum in the year 2014 (5.39 ± 0.54), and the variations were significant at p < 0.0001. Ridgeline plots were drawn to visualize interannual variations, which revealed that Ca was the dominant cation in the early years, whereas NH prevailed in the latter years. Mann-Kendall analysis and Sen's slope statistical tests were employed, and it was found that all the ions showed positive S values indicating increasing trends. Enrichment factors (EF) of K, SO, and NO were found to be high with respect to both soil and seawater suggesting the influence of emissions from fossil fuel and biomass burning in the chemistry of rainwater. Principal component analysis (PCA) was applied to identify the sources of rain constituents, and five factors were obtained explaining crustal dust, biomass burning, fossil fuel combustion, agricultural emissions, and coal burning as possible sources. Airmass back trajectory clusters and Potential Source Contribution Function (PSCF) were computed by application of HYbrid Single-Particle Lagrangian Integrated Trajectory model to appreciate the terrestrial influence on the chemistry. The results indicated inputs from both local and regional dust and anthropogenic constituents that influenced the monsoonal rainwater chemistry over Brahmaputra Valley.
本研究是对 2012 年至 2018 年期间，布拉马普特拉河中游平原的季风降雨雨水化学物质（n=302）进行的为期 7 年的研究。对样品进行了主要化学参数分析，如 pH 值、电导率 (EC) 和离子 (SO、NO、Br、Cl、F、Mg、Ca、K、NH、Na 和 Li)，以评估雨水化学物质。雨水的平均 pH 值在不同年份有所不同，2018 年最高（6.18±0.72），2014 年最低（5.39±0.54），差异在 p<0.0001 水平上显著。绘制了岭线图以可视化年际变化，结果表明 Ca 是早期的主要阳离子，而 NH 在后期占主导地位。采用 Mann-Kendall 分析和 Sen 的斜率统计检验，发现所有离子的 S 值均为正，表明呈上升趋势。K、SO 和 NO 的富集因子（EF）均高于土壤和海水，表明化石燃料和生物质燃烧排放对雨水化学物质的影响。应用主成分分析（PCA）识别雨水成分的来源，得到五个因子，解释了地壳粉尘、生物质燃烧、化石燃料燃烧、农业排放和燃煤等可能的来源。应用混合单粒子拉格朗日综合轨迹模型计算气团后轨迹聚类和潜在源贡献函数（PSCF），以了解陆地对布拉马普特拉河谷季风降雨化学物质的影响。结果表明，当地和区域尘埃以及人为成分的输入影响了季风降雨的化学物质。
