Rainfall: chemistry

Many chemical reactions occur in both directions such that the products are able to re-form the reactants. For instance, in rainfall chemistry, we account for the hydrolysis (i.e. reaction with water) of aqueous formaldehyde (HCHO) to methylene glycol (H2C(OH)2) according to the equation ... 

Each exposure site has other materials-damage experiments, in addition to those discussed in this report 3). To supplement all damage studies, an array of meteorological, climatological, air-pollution, and rainfall-chemistry data also will be available for each site. Research-rock-procurement information recently has been published (7-8). 

Location Traffic load Deposition Rainfall Surface water conditions Settlement Rainfall Chemistry Atmosph Chemistry Pressure Airtemp Radiation Ground water conditions Local deposition exhaust emiss. 

SIMMONS, G.L., AND J.M. KELLY. 1989. Influence of Qs, rainfall chemistry, and soil Mg status on growth and ectomycorrhizal colonization of Loblolly pine roots. Water Air Soil Pollut. 44, 159-171. 

The processes through which rainfall is turned into runoff, together with the nature of the material through which water moves, control the chemical characteristics of streamflow. Specific runoff mechanisms operating in a landscape control the flowpaths by which water moves through the landscape. Flowpath-depen-dent differences, such as the total time that water spends in contact with different soil horizons or bedrock (residence time), can strongly influence runoff amounts and timing, the relative contribution of event (new) versus stored (old) water, and runoff chemistry. 

In the CRC Handbook of Chemistry and Physics, the densities are recorded as ranges, rather than single values for the different types of wood. In terms of environmental conditions such as temperature, humidity, amount of rainfall, and disease, explain why samples of the same type of wood might vary slightly in their densities. 

Strachan WMI. 1988. Toxic contaminants in rainfall in Canada 1984. Environmental Toxicology and Chemistry 7 871-877. 

At the opposite end of the fertility scale from ricefields are peat bogs in pluvial landscapes. Nutrient inputs come almost entirely from rainfall, and the nutrient reserves in the organic matter buffering the soil solution are small (Moore and Bellamy, 1974). The chemistry of peat bogs is therefore precarious and changes in the composition of the rainfall can have a large effect on the composition of the soil solution. 

The chemistry of LRL reflects the provenance of its water specific conductance is very low (—12 xS/cm), near that of local rainfall. Total base-... 

The NADP analyzes the constituents important in precipitation chemistry, including those affecting rainfall acidity and those that may have ecological effects. The Netwoik measures sulfate, nitrate, hydrogen ion (measure of acidity), ammonia, chloride, and base cations (calcium, magnesium. potassium). To ensure comparability of results, laboratory analyses for all samples are conducted by the NADP s Central Analytical Lab at the Illinois State Water Survey, A new subnetwork of the NADP, the Mercury Deposition Network (MDN) measures mercury in precipitation. 

Calculation based on global surface area, not an average rainfall. Surface area figure from CRC handbook of Chemistry and Physics. 

Such extensive deforestation may possibly have profound effects on atmospheric chemistry, rainfall, and other climatic factors. Therefore, almost implicit in any consideration of the water cycle in tropical forests is the question what effect does deforestation have That is the theme of this presentation. 

In high-rainfall climates the chemistry of soil water may resemble that of the local precipitation. Such conditions exist where evapotranspiration (ET) losses are minimal because of low temperatures and/or high humidity, or where the soils are quartz-sand-rich and deficient in weatherable minerals. 

Table 8.6 contrasts soil moisture chemistry in a variety of soils and climates. All of the tabulated locations, except for the Sierra Nevada soil, are near the ocean, so that one would expect their precipitation to be dominated by Na and Cl. If ET alone controls infiltrating soil-water chemistry, this same dominance by Na and Cl should persist in the soil water. Such is the case for moisture from the Kauaian soil, which is also in an area of very high rainfall, consistent with its low TDS content of about 30 mg/L. 

Shown in Fig. 9.9 are water-composition ranges for some humid-climate streams (in New Jersey), a dilute, freshwater lake (Lake Huron) and lake-bottom muds from the Great Lakes (Sutherland 1970), and deep-soil moisture from Pennsylvania (Sears 1976 Sears and Langmuir 1982). Lake Huron and the Delaware River are dilute, humid-climate waters. They both plot near the kaolinite-gibbsite boundary. Their composition can be described as water dominated. In other words, their chemistries are controlled chiefly by dilution with fresh rainfall and runoff, not by reactions with geological materials. In a study of acid rain (water-dominated) control of soil moisture and ground-water chemistry of a sandy aquifer in Denmark, Hansen and Postma (1995) found that pore waters were close to equilibrium with gibbsite and supersaturated with kaolinite (Fig. 9.9). Precipitation pH = 4.34 at the site, and log([K+]/lH+]) = -0.95. 

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