Analyzing rainwater chemistry at the continental GAW station Nagpur

lkj & bl 'kks/k i= esa 1981 ls 1996 rd dh vof/k esa ukxiqj esa gqbZ o"kkZ ds ikuh esa jklk;fud rRoksa dh miyC/krk dk v/;;u fd;k x;k gSA bl v/;;u ls ;g irk pyk gS fd ukxiqj esa o"kkZ _rq esa ckj&ckj xtZ ds lkFk vkus okys rwQkuksa ds dkj.k o"kkZ ds ikuh esa Na+ vkSj Cl- ds lkanz.kksa esa leqnz dk izHkko de gSA ;gk¡ ij ekulwu _rq ds vkxeu ls igys ds eghuksa esa vkSj iwjh ekulwu _rq ds nkSjku NO3& esa cgqr vf/kd lkanzrk fjdkWMZ dh xbZ gSA ekulwu _rq ds nkSjku K+ dks NksM+dj o"kkZ ds ikuh ds lHkh ?kVdksa dh vxLr rd lkanzrk de gksrh tkrh gSA rFkkfi] flracj esa lHkh ?kVdksa dh lkanzrk esa o`f} ikbZ xbZ gSA Cl- vkSj Na+ ds fu{ksi.k eku rVh; dsanzksa dh rqyuk esa dkQh de ik, x, gSaA SO4&2 ds fu{ksi.k ekuksa dh rqyuk ;w- ,l- ,l- vkj- ds dqN Hkkxksa esa ik, x, ekuksa ls dh tk ldrh gSA o"kkZ ds ikuh ds fofHkUu ?kVdksa ds chp vuqikrksa dk v/;;u djus vkSj leqnz ds ikuh ds vuqikrksa ds lkFk mudh rqyuk djus ls irk pyk gS fd ukxiqj esa o"kkZ ds ikuh esa Na+ dh vf/kdrk dk dkj.k leqnz ds ikuh ds vykok vU; lzksr Hkh gSaA pH ekuksa esa cgqr vf/kd fofHkUurk ikbZ xbZ gSA ekulwu esa] twu ds ]ckn pH de gksrk tkrk gS vkSj flracj rd cgqr de gks tkrk gSA bldk dkj.k o"kkZ ds ikuh }kjk ewy dSVk;uksa dk i`Fkd djuk ekuk tk ldrk gSA vizSy vkSj ebZ ds lcls rst xehZ ds eghuksa esa pH dh vf/kd ek=k dk dkj.k okrkoj.k esa /kwy d.kksa dh ek=k] ftlesa eq[;r% ewy dSVk;u gksrs gSa] dks ekuk tk ldrk gSA ekulwu _rq ds izR;sd ekg ds pH ds v/;;u ls irk pyk gS fd twu vkSj tqykbZ esa o"kkZ dk Lo:i lokZf/kd ekSfyd gS tcfd vxLr vkSj flracj esa ukxiqj esa vEyh; o"kkZ dh dqN ?kVuk,¡ ns[kh xbZ gSaA tc ekpZ vkSj fnlcaj ds nks eghuksa esa pH dk eku 5-0 ls uhps fxj tkrk gS rc vEyh; o"kkZ dh leL;k cgqr vf/kd fodV gksrh gSA ekulwu iwoZ _rq ds nkSjku mPp lapkydrk ekuksa dk dkj.k bl vof/k esa okrkoj.k esa /kwy d.kksa dh vf/kd lkanzrk dks ekuk tk ldrk gSA ?kVdksa vkSj o"kkZ ds chp ds :Ik esa foijhr laca/k ik;k x;k gSA In this paper rainwater chemistry of Nagpur for the period 1981-1996, has been studied. The analysis reveals that at Nagpur rain water there is less marine influence on the concentrations of Na+ and Cl-. Pre-monsoon months, as well as the season as a whole, record higher NO3- concentration which could be attributed to frequent thunderstorm activities in this season. During monsoon months, concentration of all the constituents of rainwater, except K+, goes on decreasing till August. However, in September increase in concentration is observed for all the constituents. Deposition values of Cl- and Na+ are found to be quite low in comparison to that at coastal stations. SO4-2 deposition value is comparable to the values reported in some parts of USSR. Study of ratios between various constituents and a comparison with sea water ratios reveals that rainwater at Nagpur gets enriched in terms of Na+ from other sources besides sea water. pH values exhibited large variation. In monsoon, June onwards pH goes on decreasing and lowest value is obtained in September. This could be attributed to the preferential removal of basic cations by rainwater. In the peak summer of April and May higher values of pH could be attributed to the abundant prevalence of dust particles in the atmosphere chiefly consisting of basic cations. pH of individual months of monsoon season reveals that in June and July rainfall is predominantly basic in nature while in August and September some instances of acid rain has been observed at Nagpur. Acid rain problem seems to be more acute in the month of March and December when pH in these two months falls below 5.0. High conductivity values during pre-monsoon season could be attributed to higher dust concentrations in the atmosphere during this period. An inverse relationship of form Y = AR-B has been found between the constituents and rainfall.

Three-Year Variations in Criteria Atmospheric Pollutants and Their Relationship with Rainwater Chemistry in Karst Urban Region, Southwest China

Air pollutants have been investigated in many studies, but the variations of atmospheric pollutants and their relationship with rainwater chemistry are not well studied. In the present study, the criteria atmospheric pollutants in nine monitoring stations and rainwater chemistry were analyzed in karst Guiyang city, since the time when the Chinese Ambient Air Quality Standards (CAAQS, third revision) were published. Based on the three-year daily concentration dataset of SO2, NO2, CO, PM10 and PM2.5, although most of air pollutant concentrations were within the limit of CAAQS III-Grade II standard, the significant spatial variations and relatively heavy pollution were found in downtown Guiyang. Temporally, the average concentrations of almost all air pollutants (except for CO) decreased during three years at all stations. Ratios of PM2.5/PM10 in non- and episode days reflected the different contributions of fine and coarse particles on particulate matter in Guiyang, which was influenced by the potential meteorological factors and source variations. According to the individual air quality index (IAQI), the seasonal variations of air quality level were observed, that is, IAQI values of air pollutants were higher in winter (worst air quality) and lower in summer (best air quality) due to seasonal variations in emission sources. The unique IAQI variations were found during the Chinese Spring Festival. Air pollutant concentrations are also influenced by meteorological parameters, in particular, the rainfall amount. The air pollutants are well scoured by the rainfall process and can significantly affect rainwater chemistry, such as SO42−, NO3−, Mg2+, and Ca2+, which further alters the acidification/alkalization trend of rainwater. The equivalent ratios of rainwater SO42−/NO3− and Mg2+/Ca2+ indicated the significant contribution of fixed emission sources (e.g., coal combustion) and carbonate weathering-influenced particulate matter on rainwater chemistry. These findings provide scientific support for air pollution management and rainwater chemistry-related environmental issues.

Rainwater chemistry observation in a karst city: variations, influence factors, sources and potential environmental effects

The rainwater chemistry and related air contaminants are used to investigate the rainwater ions sources, variations, and influence factors from 2012 to 2014 in Guiyang city (the typical karst urban area of Southwest China). According to temporal rainwater ion concentrations, the obvious variations were presented in the study period, such as Ca2+ (125∼6,652 μeq L−1) and SO42− (11∼4,127 μeq L−1). Consequently, Ca2+, Mg2+, SO42− and Cl− are considered as the leading ions. Three critical influencing factors of rainwater ions concentrations, including sources variations, rainfall amount and long-distance migration (rainfall amount > 100 mm) are identified. Based on the typical ionic ratios, source identification suggested that anthropogenic inputs mainly contributed to F−, NO3− and SO42−, while the dusts (crustal sources) are the primary sources of Mg2+, Ca2+ and K+. Cl− Enrichment in long-distance transport is the main contributor of Cl−. According to the observation of high level of total wet acid deposition, the more detailed spatio-temporal monitoring of rainfall-related acid deposition (particularly sulfur deposition) is required to understand its potential environmental effects in the aquatic ecosystem of the earth surface.

Rainwater Chemistry Reveals Air Pollution in a Karst Forest: Temporal Variations, Source Apportionment, and Implications for the Forest

Temporal rainwater chemistry was used to reveal air pollution in the Maolan National Karst Forest Park (MNKFP), which is representative of the typical karst forest region of southwest China (SW China). The rainwater ions’ sources, variations, trends, and potential environmental effects were investigated from 2007 to 2010 and from 2013 to 2014. Based on the analysis of the temporal ionic concentrations of rainwater in the MNKFP, significant variations of ions were observed, including in NH4+ (9.7~266.6 μeq L−1) and SO42− (14.5~1396.4 μeq L−1), which were mainly controlled by variations in the source and rainfall amount; a decreased trend of rainwater pH was also observed. Accordingly, NH4+, Ca2+, SO42−, and Cl− were regarded as the most dominant ions. Typical ionic ratios and positive matrix factorization (PMF) model-based source apportionment suggested that anthropogenic inputs (coal combustion, industrial, traffic, and agricultural emissions) contributed 51% of F−, 93% of NO3−, 62% of SO42−, and 87% of NH4+, while the natural sources (crustal dust and sea salt) were the main sources of Cl− (74%), Na+ (82%), K+ (79%), Mg2+ (94%), and Ca2+ (93%). In combination with the reducing neutralization trend of temporal rainwater observed in the MNKFP and the potential effect of rainwater ion deposition on karst forests, more detailed monitoring of the rainfall-related deposition process is required for a better understanding of its potential environmental effects on the Earth’s surface.