Chemical Composition Of Rain Research Articles

Chemical composition of rain at a regional site on the South African Highveld

Relatively limited data have been published on the chemical composition of wet deposition for South Africa, which is considered an important source region for atmospheric pollutants. Concentrations and wet deposition fluxes of ionic species determined in rain samples collected from December 2014 to April 2018 at a regional site, Welgegund, are presented, and contextualised by wet deposition composition in the north-eastern interior of South Africa. 89% of rain samples collected during the sampling period complied with the data quality objectives of the World Meteorological Organisation. The total ionic concentration of rainwater at Welgegund was similar to that at two regional sites located within proximity of industrial activities. The pH of rainwater (4.80) was comparable to that determined at two rural background sites, which indicated increased neutralisation. Similarly to the other sites located in the South African interior, SO42- was the most abundant species in rain, with concentrations thereof in the same order as SO42- levels determined at the two industrially influenced sites. Lower sulphur and nitrogen fluxes at Welgegund were attributed to lower average annual rainfall. The anthropogenic (industrial) source group had the largest contribution to wet deposition chemical composition, which signified the influence of major source regions in the South African interior that impact Welgegund. Relatively large contributions were also calculated from marine and crustal sources. The influence of agricultural activities was also evident, while biomass burning had the lowest contribution due to open biomass burning occurring mainly during the dry season.

Analyzing the status of northern taiga forests amid reduced Severonikel emissions

Based on the analysis of rain- and snowfall, as well as soil waters and conifers (1991–2014), this paper evaluates the status of the forest ecosystems in the Murmansk Region since the copper-nickel plant Severonikel owned by Kola MMC started to cut its emissions. The analysis focused on low-shrub spruce forests with green mosses and low-shrub lichen pine forests going through different stages of degradation caused by human activity. Coniferous forests situated in the impact area have high background concentrations of the main pollutants — i.e. heavy metals and compounds of sulphur, present in different components of the forest ecosystems. The closer it is to the source of emissions, the higher the concentration of pollutants is in rain- and snowfall, as well as in soil waters and conifer tree needles in both pine and spruce forests. The paper demonstrates inter- and intrabiogeocenotical variability in the composition of rain- and snowfall and soil waters in northern taiga forests. The concentration of nickel and copper is typically higher under the trees than in between them, and in spruce forests as compared with pine forests. A significant variability in the chemical composition of rain- and snowfall and soil waters was established. Observations showed a reduced amount of the major pollutants penetrating the soil waters and then falling out with rain in the impact areas with light forest, which is indicative of the airborne industrial pollution levels gradually going down. High concentrations of S, Ni, Cu in the conifer tree needles were noted in 1991, i.e. in the period of major air pollution. The authors looked at the concentrations of heavy metals over the period of over two decades in which emissions were being cut down. Their analysis showed that the concentration of nickel and copper in the pine tree needles of different ages went down in defoliating forests and impact areas with light forest, as well as in the spruce tree needles in the area around the pollution source, in the impact areas with light forest. It is shown that the concentration of sulphur in the pine tree needles went down compared with the 1991 data and reached the level of background variation in defoliating forests and impact areas with light forest. The spruce tree needles saw lowered concentrations of sulphur in the impact areas with light forest in 2007 and 2012.This research study was funded under a governmental assignment (State Registration No. АААА-А18-118021490070-5), as well as under the following grants by the Russian Foundation for Basic Research: 18-05-60142_Arktika and 18-35-00170 mol_a.

17-Year study on the chemical composition of rain, snow and sleet in very dusty air (Krakow, Poland)

The paper presents the results of long-term (1996–2017) studies of the chemical composition of rain, snow and sleet in one of the cities with the highest concentrations of particulate matter in the air in Europe. The study included measurements of 45 chemical constituents of precipitation as well as its pH and EC. Concentrations of PM10, SO2 and meteorological parameters were also analysed. Differences in Cl and Na concentrations were found depending on the type of precipitation (snow or rain). These differences are most probably caused by anthropogenic factors, however, to a small extent (~18–19%), they are associated with the total variability of the concentrations of these chemical constituents. The differences between the concentrations of the remaining constituents of precipitation analysed are of lesser or negligible importance. The main processes affecting the chemical composition of precipitation are the chemical weathering of suspended dust and the formation of mineral acid aerosols. These processes shape the chemical composition of both rain and snow in a similar manner. The differences between the chemical composition of rain and snow are the result of the concentrations of and mutual relations between selected chemical constituents and precipitation pH. An important factor affecting the pH of precipitation is the effectiveness of the chemical weathering of suspended dust, which may make the precipitation more alkaline. It is very likely that pH-buffering will occur, which can prevent the pH of precipitation from decreasing, especially in cold periods. Long-term observations of variability in the concentrations of the chemical constituents indicate a slight, but rather constant decrease in concentrations of most of the chemical constituents analysed, as well as in the concentrations of PM10 and SO2 in the air in Krakow. The directions of these changes reflect, to a certain extent, the complex transformations of industrial, economic and social conditions in Krakow within that period. The typical ranges of variability of the recorded values of concentrations/measurement values of 22 chemical constituents and the physical characteristics of rain, sleet and snow presented in the paper can be used as reference ranges of these parameters, typical for an area with a significant degree of atmospheric dust pollution.

Chemical weathering rates of clastic sedimentary rocks from the Paraná Basin in the Paulista Peripheral Depression, Brazil

The chemical weathering plays an important role in the processes of surface geochemistry, which is fundamental to understand the landscape evolution. The Paraná Basin is an intracratonic sedimentary basin developed on the South American platform from Paleozoic to Cenozoic, with area of 1.5 × 106 km2 and 5000 km3 of clastic sediments and igneous rocks. The main clastic sedimentary rocks in the Paraná Basin are sandstones and mudstones. Surprisingly, there are no studies assessing the chemical weathering rates of clastic sedimentary rocks from the Paraná Basin under tropical climate conditions in Brazil or in South America. Thus, two small watersheds were chosen to assess the chemical weathering rates of clastic sedimentary rocks from the Paraná Basin in the Paulista Peripheral Depression (São Paulo State, Brazil), i.e. the Monjolo Grande and Jacutinga stream basins. The chemical composition of rain and surface waters, as well as the chemical and mineralogical composition of the fresh rocks (sandstones and mudstones) and soil (horizon C) were characterized. The instantaneous daily flux indicates that ca. 60% of the dissolved solids loads are carried from October to March in both watersheds. The natural fluxes due to chemical weathering (Fw) were ca. 4.5 t km−2 yr−1, with a mixed of local rainwater and chemical weathering of sandstones and mudstones controlling the surface waters composition. The possible chemical weathering processes of sandstones and mudstones occur by quartz dissolution and partial hydrolysis (monossialitization) of albite, microcline and illite, respectively. The chemical weathering rates were of 0.3 and 0.8 m Myr−1 for the Monjolo Grande and Jacutinga Streams basin, respectively, confirming the lower chemical weathering rates for clastic sedimentary rocks in relation to basalts (Paraná CFB) of the Paraná Basin and for the igneous and metamorphic rocks of the Ribeira Belt, other important geological units in the São Paulo State. In addition, these chemical weathering rates are also lower than the suggested for other rock types elsewhere, i.e., carbonates, basalts, granites, schist, gneisses or alkaline rocks. Finally, the effect of climate on [SiO2] was demonstrated, also described in basaltic and granitic watersheds, suggesting that the chemical weathering of sandstones and mudstones are more effective in the wet season.

Potential effect of environmental pollution on the degree of dissolution of iron and aluminium oxides in lateritic soils

Problems associated with surface and groundwater pollution by aluminium and iron is becoming a serious environmental challenge facing the limited sources of quality drinking water. Al and Fe sesquioxides predominates in most of the lateritic soils within the tropical region. Their degree of dissolution and mobility into the surface and groundwater system is determined by the chemistry of the prevailing aqueous environment. This work assessed the potential effect of environmental pollution on the chemical composition of rain and its resultant runoff, hence its contribution to the degree of dissolution of Al and Fe oxides. This was achieved by first determining the sources of pollutants which could possibly affect the physicochemical composition of runoff using remotely sensed information and field observations. Thereafter rain and runoff water samples were collected from theses pre-determined sources, and were analysed for their physicochemical compositions. Similarly, soil samples were also collected from the field and analysed for their mineral and chemical compositions. An empirical method was then employed to determine the degree of dissolution of Fe and Al oxides in aqueous solutions of varying hydrogen ion concentration which was prepared using the combinations of sulphuric acid, nitric acid, ammonium hydroxide, and deionised water. The results revealed that the degree of dissolution of Fe and Al oxides in lateritic soils increases with increasing acidity and/or alkalinity of the aqueous solutions. Increase in the acidity and/or alkalinity of the prevailing rain and runoff was attributed to their high level of ammonium, sulphate, and nitrate content which was introduced into the environment through anthropogenic activities.

Spatial and temporal variation of acid rain in the Mexico City Metropolitan Zone

At the end of the 1980´s particulates and sulfur dioxide (SO 2 ) were the main atmospheric pollutants in the Mexico City Metropolitan Zone (MCMZ). To reduce emissions, fuel oil was replaced by natural gas at power plants located inside Mexico City. Currently, SO 2 levels do not exceed its air quality standard; however, acid rain is present with a high contribution of sulfate (SO 4 2– ). In this study, spatial and temporal variations in the chemical composition of rain in Mexico City between 2003 and 2014 were analyzed. Major ions (Na + , NH 4 +, K + , Mg 2+ , Ca 2+ , SO 4 2– , NO 3 – and Cl – ), pH, and electrical conductivity (EC) were analyzed weekly at 16 sampling stations located in the MCMZ. The pH decreased from north to south, with the lowest annual volume weighted mean (VWM) of 4.16 in 2006. Annual ion concentrations were, in decreasing order: NH 4 + , SO 4 2 – , NO 3 – and Ca 2+ for the entire study period at most of the sampling sites. The highest values for wet atmospheric deposition (kg/ha) were found in the Western area and were the maximum in 2007. Wet deposition had major levels for SO 4 2– and NO 3 – of 24 and 20 kg/ha, respectively, and were similar to the levels registered in the USA in 2013 and 2014. Considering that external emission sources play a decisive role in acid rain within the City, it is necessary to establish strategies for the emission reductions of acid rain precursors from upwind sources.

Acid deposition during two contrasting frontal rainfall events

Analysis of the chemical composition of rain at high temporal resolution provides additional information on wet deposition processes. High resolution data was obtained using a microprocessor-based acid rain monitor at two sites in SW Scotland and SE England. Meteorological details of the transport and wet deposition processes during two frontal rain events were examined and related to rainfall composition. Rapid depletions of ion concentrations during heavy rainfall in the first event were interpreted using a rainfall scavenging model. The sub-event data for the second event showed the influence of frontal discontinuities. Increasing ionic concentrations during this second event were attributed both to the change in air mass, and to diminished upwind precipitation scavenging.

CHEMICAL COMPOSITION OF RAIN WATER OVER BHUBANESWAR, ORISSA

Mon soon ram water over Bhubaneswar were collected and analysed during 198&. 1989 and 1991for CO}. HeO, . a . 50,.<NO}. Na. K Ca. Me. SiD: . EC and pH. The data shows that the chemical composition ofrain water is sready affected by meteorological cond itions. «r. intens ity, quantity and interva l between successiveshowers and al.so on wind velocity. II was round that with some exceprlon the ini tial showers are eenerally moresa lin e th an the subsequent o nes. the rati os between variou s co nstituents varyquite irregularly,Thesourcesofvariousconstituents have bee n discussed and th e amount of various ptant nutrients though sm all in relation 10 overallrequirem ent s of pla nu brought down by r-ain have been ca lcu lated in kg/hec.

Chemical composition of rain in Thessaloniki, Greece, in relation to meteorological conditions

Wet precipitation was collected in Thessaloniki, Greece, during the period March 1989–December 1990 by using an automatic wet-only precipitation sampler. Rainwater samples were analysed for major cations (H +, NH 4 +, Na +, K +, Ca 2+, Mg 2+) and anions (Cl −, NO 3 −, SO 4 2−), in addition to acidity and conductivity measurements. The majority of rain had a neutral or alkaline character as a result of neutralization, primarily caused by calcareous soil dust and secondarily by atmospheric ammonia. In all rain, SO 4 2− concentration exceeded NO 3 − concentration. The contribution of maritime sources to the total SO 4 2− concentration was very low (<2%). The chemical composition of precipitation was analysed in conjunction with meteorological variables (season of the year, precipitation type, airflow patterns) to evaluate temporal variations and chemical source influence. Rain caused by weak, localized flows showed the highest acidity and the minimum influence of neutralization processes.

Effects of ambient rain chemistry on field-grown radish ? An exploratory approach by multiple linear regression

In a modeling approach multiple regression was used to describe plant growth of radish (Raphanus sativus L. cv. ‘Cherry Belle’) by a range of environmental variables including chemical characteristics of ambient rain. In a 2-yr field study, staggered radish crops were harvested in 2-d intervals. During the entire vegetative growth, the weights of the major organs (shoot, hypocotyl, root) were determined and mean relative growth rates (RGR) were calculated. Different climatic variables, which were modified by a range of time lag periods, were combined to describe total plant RGR and hypocotyl RGR for each of 2 or 3 developmental phases of the crop. In a second step, variables characterizing the ion concentration and deposition of ambient rain (mean pH 4.35 and 4.15 in 1989 and 1990, respectively) were introduced and tested for their significance of contribution to the models. Generally, the earlier development stages of radish were more responsive to changes in environmental variables and the growth models were improved significantly by introducing variables of rain chemistry during these early growth phases only. Hypocotyl growth was not more sensitive to the chemical composition of rain than was total plant growth. Disparities in frequency and amount of rain between the 2 yr may have caused differences in the relative contribution of rain chemistry variables towards the models. The limitations and advantages of this modeling approach are discussed in respect to the importance of different growth stages on the sensitivity to acid rain stress.

Water chemistry and isotope study of streams and springs in northern Chile

The relationship between the stable isotopic and chemical composition of rain, spring, and stream water was studied in the high Andes of northern Chile. The isotopic pattern of the springs is mainly a reflection of the altitude of their recharge areas; however, processes that occur during snow melting seem to play a major role in the high-altitude springs. The streams show patterns similar to the springs in the higher part of the basins, but their isotopic composition is modified along the river course, due mainly to evaporation. The difference in chemical composition between the springs at high and intermediate elevations reflects the duration of water-rock interaction. The best parameter to trace this length of travelling time is the Na + K + ratio, which increases as a result of removal of K + into alteration minerals (K-silicates). The Na + Cl − ratio increases with salinity in springs and decreases in stream water. This reflects the different sources of salt, whereas the main source of salts in spring water is the dissolution of silicate and sulfide minerals. Halite accumulations close to the surface is the main salt source in the streams. During floods the stream water chemical characteristics change, Na + Cl − increases with decreased salinity and Na + K + decreases.

Observations on the chemical composition of rain using short sampling times during a single event

Sequential samples of rain, each corresponding to 0.23 mm of rainfall, were collected during single precipitation events at a site in western Michigan and analysed for specific conductance, pH, SO 2− 4, NO − 3, Na +, K +, Ca 2+ and Mg 2+. A rapid decrease in the concentration of all the measured components except H + was observed during the initial portion of the event. The H + concentration of the rainwater generally increased during the initial portion of the event. This converse relationship between the H + concentration and the SO 2− 4 and NO − 3 concentrations is attributed to the rapid washout of atmospheric particulates containing basic salts. Depending upon the type and duration of the event, this washout can cause 50% of the total SO 2− 4 and NO − 3 deposition to occur during the first 15–20% of the total rainfall.

The free radical chemistry of cloud droplets and its impact upon the composition of rain

Calculations are presented that simulate the free radical chemistries of the gas phase and aqueous phase within a warm cloud during midday. It is demonstrated that in the presence of midday solar fluxes the heterogeneous scavenging of OH and HO2 from the gas phase by cloud droplets can represent a major source of free radicals to cloud water, provided the accommodation or sticking coefficient for these species impinging upon water droplets is ≥10−4. The aqueous‐phase HO2 radicals are found to be converted to H2O2 by aqueous‐phase chemical reactions at a rate that suggests that this mechanism could produce a significant fraction of the H2O2 found in cloud droplets. The rapid oxidation of sulfur species dissolved in cloudwater by this free‐radical‐produced H2O2 as well as by aqueous‐phase OH radicals could conceivably have a significant impact upon the chemical composition of rain.

Chemical composition of rain, dry fallout, and bulk precipitation at Menlo Park, California, 1957-1959

Winter precipitation is defined as rain, dry fallout, and bulk precipitation - the last being a mixture of the other two. The division of winter precipitation into phases is based on collection procedures. Each phase shows distinctive characteristics of chemical composition. Rain displays the strong influence of the nearby Pacific Ocean and San Francisco Bay. Dry fallout, collected between rains, shows strong effects from locally derived materials in the atmosphere. Bulk precipitation shows, in chemical composition, the expected blending of the two environmental influences and is about 4 to nearly 10 times higher in mineral concentration than rainwater is. Bulk precipitation is considered the geochemically significant phase that should be used in studies relating contributions of atmospheric salts to surface- and groundwater supplies, to weathering, and to the nourishment to growing plants. Comparison with published data indicates that, wherever sampled, bulk precipitation contains more dissolved mineral content than rainwater does. Detailed comparisons, however, are not feasible because of widely differing procedures in sampling and analysis used in various studies. Increasing attention should be given to minor constituents in precipitation, as well as recognition of the several phases of precipitation.