Chemical Composition Of Rainfall Research Articles

The Multiscale TROPIcal CatchmentS critical zone observatory M‐TROPICS dataset III: Hydro‐geochemical monitoring of the Mule Hole catchment, south India

AbstractDespite the importance of tropical ecosystems for climate regulation, biodiversity, water and nutrient cycles, only a few Critical Zone Observatories (CZOs) are located in the tropics. Among these, most are in humid climates, while very few data exist for semi‐arid and sub‐humid climates, due to the difficulty of estimating hydro‐geochemical balances in catchments with ephemeral streams. We contribute to fill this gap by presenting a meteorological and hydro‐geochemical dataset acquired at the Mule Hole catchment (4.1 km2), a pristine dry deciduous forest located in a biosphere reserve in south India. The dataset consists of time series of variables related to (i) meteorology, including rainfall, air temperature, relative humidity, wind speed and direction, and global radiation, (ii) hydrology, including water level and discharge at the catchment outlet, (iii) hydrogeology, including manual (monthly) and/or automated (from 15 min to hourly) groundwater levels in nine piezometers and (iv) geochemistry, including suspended sediment content in the stream and chemical composition of rainfall (event based), groundwater (monthly sampling) and stream water (storm events, 15 min to hourly frequency with an automatic sampler). The time series extend from 2003 to 2019. Measurement errors are minimized by frequent calibration of sensors and quality checks, both in the field and in the laboratory. Despite these precautions, several data gaps exist, due to occasional access restriction to the site and instrument destruction by wildlife. Results show that large seasonal and interannual variations of climatic conditions were reflected in the large variations of stream flow and groundwater recharge, as well as in water chemical composition. Notably, they reveal a long‐term evolution of groundwater storage, suggesting hydrogeological cycles on a decadal scale. This dataset, alone or in combination with other data, has already allowed to better understand water and element cycling in tropical dry forests, and the role of forest diversity on biogeochemical cycles. As tropical ecosystems are underrepresented by Critical Zone Observatories, we expect this data note to be valuable for the global scientific community.

Seasonal variation of atmospheric nutrient deposition in the western part of Rio Grande do Sul, Brazil

The chemical composition of rainfall is influenced by natural or anthropogenic factors; the amount of nutrients deposited is increased by the amount of rainfall. This work sought to estimate the amount of nutrients deposited by precipitation in the Pampa biome, the seasonal variation of the chemical composition of rain water, and the origin of nutrients found in the water. Precipitation collectors were installed in the open area to measure precipitation volumes biweekly over 2 years, and the samples were chemically analyzed. Concentrations of nutrients in the rain water increased over winter; however, since there was less precipitation, the total deposition was similar to the other seasons. Correlation analysis using the Pearson coefficient showed a negative correlation between rain volume and ion contents, indicating a dilution effect. The total amount of nutrients from precipitation during the study was 72.7 kg ha-1, representing an average of 36.3 kg ha-1 year-1. The Ca2+ and K+ ions are predominantly of litholical origin, whereas the SO42- and NO3- ions were of anthropogenic origin. The balance between the sum of cations and the sum of anions was shown to be unitary, indicating excellent data validation. The input of these nutrients occurs gradually, avoiding excessive losses, increasing the stock in the soil.

Chemical Composition of Rainfall, Throughfall, Runoff and Outlet Flow in a Small Watershed of Secondary Forest, Eastern China

Rainfall, throughfall, stemflow, runoff and outlet flow were studied in a secondary forest during a rain season from April to October in 2009. Some of the chemicals in throughfall, stemflow, runoff and outlet flow were increased in contrast with incident rainfall. The pH value of the water sample was in the order rainfall > throughfall > runoff > outlet flow > stemflow. The concentration of chemicals of rainfall was in the order SO42- > NO3- > Na+ > Cl- > K+ > Ca2+ > NH4+> Mg2+ >PO43-. The mean concentrations of nutrients in throughfall, stemflow and runoff were significantly higher than those in incident rainfall except Na+ and NH4+. The concentration of chemicals of outlet flow was in the order SO42- > Cl- > NO3- > Ca2+ > Mg2+ > Na+ > K+ >NH4+ >PO43-.

The Chemical Composition of Rainfall and Throughfall in Five Forest Communities: A Case Study in Fort Benning, Georgia

In order to investigate the effects of canopy-dependent processes on throughfall chemistry, comparative studies on the chemical composition of throughfall were carried out in five characteristic forest types of the southeastern United States within Fort Benning Military Installation from January 2002 to August 2003. The concentrations and fluxes of and total organic carbon (TOC), total Kjeldahl nitrogen (TKN), and total phosphorus (TP) were determined in rainfall and throughfall. Seasonal variations in chemical fluxes were also evaluated. Throughfall concentrations of TOC, TKN, and TP in matured pine stand were higher than in rainfall and other forest stands. Throughfall nutrient concentrations in wetland were lowest as compared to rainfall as well as hardwood, mixed, plantation, and pine stands. The average TOC, TKN, and TP concentrations in the matured pine stand were 17.2, 0.74, and 0.057 mg/L, respectively. In wetland stands, average concentrations of TOC, TKN, and TP were 4.0, 0.54, and 0.034 mg/L, respectively. Hardwood stand had the lowest TKN concentration of 0.53 mg/L. Nutrient fluxes were generally higher during the dormant season (November–April) as compared to the growing season (May–October). The highest and lowest TOC fluxes during dormant season were contributed from pine stand (801.7 g/ha) and wetland stand (186.2 g/ha), respectively. Rainfall was the major contributor of TKN fluxes in growing season (32.3 g/ha) as well as in dormant season (34.1 g/ha). Similarly, highest TP flux was produced in mixed stand (2.7 g/ha) during the dormant season. Enrichment ratios of nutrients reveal that, in general, forest stands used up nutrients during growing season and washed off during the dormant season.

Major ion chemistry of waters in Lake Qinghai catchments, NE Qinghai-Tibet plateau, China

Major ion concentrations were measured in lake water, river water, ground water, and rainfall water around the Lake Qinghai catchment. The dissolution of carbonate particles in dust has a strong impact on the chemical composition of rainfall as inferred from the Gibbs model and the ternary plots of the major ions. The chemical composition of the ground water can be divided into two groups, one influenced by river water and the other dominated by deeper aquifers. The chemical composition of lake water can be mainly ascribed to evaporation and crystallization. Total dissolved solid (TDS) of river waters during the wet periods is higher than during the dry periods. Calcium and bicarbonate are the dominant cations and anions of the river waters, and they have higher fractions during the wet periods than during the dry periods. Comparisons between (Mg 2+ + Ca 2+)/TZ +, (Mg 2+ + Ca 2+)/(Na + + K +), HCO 3 −/Na +, and Cl −/Na + suggest that the chemical composition of the river waters is mainly controlled by carbonate weathering and that the carbonate weathering is much stronger during the wet periods than during the dry periods. Seasonal melting may be one of the important factors that influence the seasonal variations of water chemistry of the rivers.

Effect of different land use on soil erosion in the pre-alpine fringe (North-East Italy): Ion budget and sediment yield

Data concerning ion budget from rainfall, runoff and soil loss measurements from two experimental plots located in North-East Italy, under different land cover (beech forest and vineyard, respectively), are reported.The chemical composition of rainfall, soil solution and runoff was determined to study the solute cycle within the soil, and the relationships between water, soil and vegetation. The forest ecosystem is more prone to acidification than the agricultural one; the elemental concentration of runoff water is considerably lower than that of soil solution.Comparing the ion input (rainfall) and output (runoff) at the two sites, it was possible to estimate the ion budget in the two soil-vegetation systems. The runoff amount and the ion balance are related to rainfall volumes and composition; the measured runoff under vineyard is 59% in comparison to the one under beech.The soil loss at the two experimental sites (170 kg/ha and 132 kg/ha, respectively) is quite limited. The measured sediment yield of the two catchments (0.24–0.19 t/ha/year, respectively) is consistent with data reported for native forests of western Europe.Comparing rainfall and soil loss at the two sites proved that maintenance of some form of land cover is advisable if runoff and erosion are to be minimized.In the European context, where the most important consequences of erosion are sedimentation downstream and loss of productivity, this type of data will yield valuable information for the understanding of such processes occurring at catchment scale, and will help policy-makers develop appropriate programs for the territory safeguard.

Rainwater composition in northeast Uruguay

The chemical composition of rainfall in northeast Uruguay in 1999 and 2000 and the sources that contribute to the rainwater chemistry are assessed in this study, contributing to a limited knowledge base of rainwater quality in South America. Principal factor analysis and cluster analysis indicate that four main source groups influence the rainfall chemistry over a range of spatial scales. Terrigenous sources (e.g. rock, soil and dust) and agricultural sources (e.g. livestock and crop fertilization) contribute to rainwater chemistry on a local and sub-regional scale. Influx of marine air from the Atlantic Ocean has a regional-scale influence while biomass burning contributes at both a local and sub-regional scale (e.g. fuel wood, and agroindustries) and through long-range transport (forest fires and land clearing). As may be expected in this area dominated by agriculture, the concentrations of ions that are indicative of industrial emissions, NO 3 − and SO 4 2−, are typical of background measurements. The current data are limited, but provide an indication of rain quality and the sources that influence its chemistry in Uruguay. It may be inferred that large-scale biomass burning in the central parts of the continent influence rainwater chemistry on a scale far larger than indicated by the Uruguayan network. Similarly, but to lesser extent, the influx of marine air off the Atlantic Ocean has a greater regional-scale influence than suggested by these data.

Nutrient cycling in a clonal stand of Eucalyptus and an adjacent savanna ecosystem in Congo : 1. Chemical composition of rainfall, throughfall and stemflow solutions

The dynamics of nutrients was compared in a clonal Eucalyptus plantation and in a native savanna in Congo. This paper focuses on changes in the precipitation chemistry during the transfer of solutions aboveground in both ecosystems. Average rainfall during the rainy and the dry seasons was 151 and 7 mm per month, respectively. Chemical analyses performed monthly over a 3-year period showed that the concentration of all the elements in rainfall increased sharply during the dry season. Wet depositions were dominated by the cations Na +, N-NH 4 +, H + and the anions Cl −, S-SO 4 2−, N-NO 3 − and amounts of dry depositions of Ca 2+, Cl − and H + were highly variable depending on the characteristics of the collector. Throughfall and stemflow were enriched in most of the elements, but N foliar uptake was observed in both stands. Clear differences in behaviour between the savanna and the Eucalyptus stand were evidenced. Whereas the enrichment of solutions through the foliage mainly made up of dry depositions in the plantation, foliar leaching processes were much greater in the savanna, particularly for K +, Mg 2+ and P-H 2PO 4 −. Stemflow solutions followed the same pattern as throughfall solutions. They were greatly enriched for most elements but N uptake also occurred. The low availability of K + in the soil might account for the particularly low levels of foliar leaching of this element in the Eucalyptus stand compared to values reported for most forest ecosystems. The time course of concentrations of elements in rainfall, throughfall and stemflow provided relevant data to distinguish external inputs from foliar leaching in the enrichment of solutions through both stands. This qualitative information will be helpful to establish input–output budgets of nutrients in these ecosystems.

Chemical, mineralogical and morphological characterization of wet and dry deposition in campania region (Southwest Italy)

Samples of wet and dry depositions were collected during the period December 1996‐September 1998 at 16 stations located at different latitudes in the Campania Region (southwest Italy). Most of the rainwater samples showed neutral to alkaline reaction, with pH values below 5.50 only in the southern part of the study area. Chemical composition of rainfall was somehow characterized by high level of acid precursors, especially sulphates of possible marine and transboundary origin, mainly Saharan dust, with higher depositions in the south‐eastern sectors. No correlation was found between H+ and strong acidic anions (non marine sulphate and nitrate), as well as between SO4 2− and Ca2+ and acidic species and H+. Concentrations of trace metals (zinc, copper, lead) and Ca2+ showed distinct east‐west gradient in dry deposition as a possible consequence of long distance transport of Saharan dust. The mineralogy of the dry contributions revealed the prevalence of quartz, feldspars, illite, chlorite and smectite. In some samples palygorskite, kaolinite and dolomite were also recognized.

The influence of meteorology and atmospheric transport patterns on the chemical composition of rainfall in south-east England

Rainwater composition was examined at event temporal resolution, over a 6 month period, at a site in southeast England. The data were used to assess the overall levels of acidic deposition at the site, and to identify functional relationships between wet deposition and causal meteorological processes. Rainfall-weighted average concentrations were close to those estimated from the U.K. national acid deposition network, but deposition levels were below those suggested by network data because of the unusually dry summer in 1989. The rainfall chemistry data were related to locally recorded wind direction, and to back trajectories calculated with analysed wind field data from U.K. Meteorological Office numerical weather prediction models. The influence of local wind direction during rainfall was significant in terms of observed concentrations and deposition. However back trajectory analysis was a better indicator of the Lagrangian history and pollutant loading of the air masses reaching the site, with clear differences in rainfall composition noted between different transport patterns. A power-law relationship existed between wet deposition and rainfall amount, although the data exhibited considerable scatter around the functional relationship because of the influence of transport pattern. Proportional ionic composition was also influenced by transport pattern with enhanced chloride levels for maritime events. The nitrate : sulphate ratio was inversely related to the time of travel from major anthropogenic source regions.

Influence of Tree Canopies on the Quantity of Water and Amount of Chemical Elements Reaching the Peat Surface of a Basin Mire in the Midlands of England

(1) The influence of three different tree canopies on the quantity and chemical composition of rainfall was studied at a small forested basin mire for two years. (2) Percentage throughfall of incident precipitattion under pine, fen and mixed broadleaved woodlands was 68%, 79%, and 80%, respectively. Marked variation was also observed over time. (3) Substantial quantities of plant nutrient elements reach the mire surface in rainfall which is supplemented in passing through the tree layer. The order of increase in total chemical complement of throughfall is: pine woodland > fen woodland > mixed woodland. (4) Comparison is made with rainfall and throughfall data collected at other forest sites in Britain and elsewhere. The ways in which vegetation canopies may change the chemical content of rainfall are discussed and the external sources of nutrient enrichment to rainfall are considered. (5) Of the ions studied, those which show greatest increase in passing through the tree canopies are sodium, potassium, calcium, magnesium, ammonium, sulphate and chloride. The highest input occurs during the winter months when rainfall is maximal.

The chemical composition of rainfall in a city of Northern Spain

A study was carried out over a period of 4 yr on precipitation in Santander, a coastal city with heavy rainfall in the north of Spain. An increase in acidity was found for the latter period studied, from April 1984 to April 1985, possibly due to a change in the meteorology of the area in this period. The correlations between the ions themselves, and with pollution from SO2 and suspended particulate matter, as well as possible correlations with meteorological variables were analyzed using a multiple linear regression method. The influence of mid- and long-range transport of pollutants was also analyzed and found to be important when air masses come from highly industrialized zones both in Central Europe and in neighboring Spanish regions, although the contribution of the latter to total acid deposition is less owing to low frequency and the usually low volume of precipitation.

Chemical composition of rainfall and groundwater in recharge areas of the Bet Shean-Harod multiple aquifer system, Israel

The Bet Shean and Harod valleys are regional recipients and mixing zones for groundwaters draining from a regional multiple-aquifer system comprising two different carbonate and two basalt aquifers as well as deep-seated reservoirs of confined brines. This paper, the first of two, describes the hydrochemistry of the groundwater bodies related to this multiple aquifer system. The paper deals with the chemical composition of rain falling on natural recharge areas, the chemical contribution of the aquifer rocks and the chemical evolution of groundwaters in the upper flow courses of all aquifers of this regional system. The methodology applied is based on the determination of major dissolved ions and on the examination of their ratios and changes along the upper flow paths. Rain water falling on natural recharge areas has an average chlorinity of 12mgl −1Cl − and a calcium bicarbonate composition caused by dust-borne terrigenous material. This rain-water salinity decreases with distance from the sea-shore. Fresh groundwaters flowing through the different aquifers may be identified and differentiated by their characteristic salinity levels and ionic ratios. Groundwaters flowing through carbonate aquifers are identified by different salinity levels and by distinct rMg/rCa ratios reflecting dolomite-calcite ratios in aquiferr rocks. The groundwaters of the two basalt aquifers have typical cation assemblages and high Na + and Mg 2+ concentrations, far in excess of those typical of the recharging rainfall. Groundwater in the upper flow courses of all aquifers investigated is deficient in SO 2− 4 and K + relative to recharging rain water.

RAINFALL AND WATER QUALITY IN THE SOUTHERN PLAINS

ABSTRACT The chemical composition of rainfall, agricultural runoff, groundwater, and pond water at several rural Oklahoma and north Texas locations was determined over a number of years (1972–1985). The inputs of acid, P, Cl, and cations in rainfall are not of major agronomic importance, although inputs of N (as NO3-N and NH4-N) and S (as SO4) in rainfall can contribute a significant proportion of the uptake of these elements by grasses or crops. The mean annual pH of rainfall was consistently greater than that of pure rainfall (5.6) averaging 6.5, while the average pH of two farm ponds (7.8) was even greater than that of rainfall. If a decrease in the pH of rainfall in the Southern Plains should occur in the future, the impact of the acidity on surface water will be reduced to a certain degree by the buffering capacity of the area soils. Appreciably more acid was added annually to the agricultural soils of the area via fertilizer P and N than in rainfall. Under present conditions it would take up to 1,500 years rainfall to add as much acid as added by fertilizer in one year. Even with a dramatic decrease in rainfall pH to 4.0, this period would be 10 years. Thus, rainfall acidity presents no immediate threat to agricultural soils, groundwater, or lakes in Oklahoma and north Texas under continuing management practices, although periodic monitoring is recommended due to an increasing number of coal-fired power stations located in this area.

Chemical composition of rainfall and wet deposition over northern Britain

Results are presented for the chemical composition of precipitation sampled monthly at 16 sites in northern Britain for 1981. Distribution maps of concentration of H +, NO 3 − and non-marine SO 4 2− show gradients increasing from the north-west to the south and east (H + from 10 to 40 μeq ℓ −1, NO 3 − from 10 to 30 μeq ol −1, non-marine SO 4 2− from 15 to 60 μeq ℓ −1) but the distribution of NH 4 + was not simple. Deposition of all ions was greatest in the mountainous areas of the south and west, where rainfall amounts were largest. Concentrations of NH 4 + and NO 3 − were approximately the same in 1980and 1981, but H + and non-marine SO 4 2− concentrations were significantly smaller in 1981 than in 1980. Longer term trends (1978–1982) were site-dependent, with large variability between years. Acidity decreased at all sites over this period, but no conclusions can be drawn on the causes of the observed decrease. Seasonal variations in 1981 were also strongly site-dependent; pronounced annual cycles in concentration were observed at southeastern sites for H +, NH 4 +, NO 3 − and non-marine SO 4 2−, with maxima in late spring. Sea-derived material (Na + and Cl −) showed pronounced cycles in concentration at all sites, with maxima in autumn/winter, annual cycles in deposition depending upon the annual cycle in precipitation amount. Deposition of H +, NH 4 +, NO 3 − and non-marine SO 4 2− was greatest in the autumn at northwest sites and in the spring at southeast sites.

Variation of rain chemistry during storms at two sites in northern California

The chemical composition of rainfall at Menlo Park, on San Francisco Bay, is compared with rainfall at Petrolia, which is near the coast about 500 km north of San Francisco. Sequential samples representing 1.35 to 5.4 mm of rain were collected from November 1971 to January 1972. At rural Petrolia the Cl:Na ratio was that of seawater for Cl concentrations ranging from 0.02 to 38 mg/l. In metropolitan Menlo Park the Cl:Na ratio in rain closely approximated that in seawater above about 0.5 mg/l Cl, but at lower Cl concentrations the ratio exceeded that in seawater, a fact attributed to the presence of anthropogenic Cl. Other constituents dissolved in Menlo Park rain (along with their concentration ranges in milligrams per liter), and believed to be derived in part from anthropogenic sources, were Ca (0.01–1.07), Mg (<0.01–1.08), Pb (0.003–0.035), Zn (0.002–0.013), Mn (0.0001–0.0057), Cu (0.0008–0.0024), NO3‐N (0.02–0.54), and Br (<0.01–0.12). The range of pH values was smaller in the rural than in the metropolitan areas; average H+ activity corresponded to a pH of 5.1 to 5.2 in both areas. At Petrolia, pH decreased with increased dissolved salts in rainfall, but no relation between pH and dissolved salts was evident at Menlo Park.