Precipitation chemistry

The drawback is that the precipitation chemistry results in suspended solids that must be fluidized and removed from the boiler by BD, so a polymeric sludge conditioner (dispersant, deposit control agent) product and additional BD is required. The higher the FW hardness, the more BD is required because of the buildup of suspended solids, so there is a trade-off in terms of operating with lower quality FW and the resulting reduced efficiency. 

Stensland, Gary . Whelpdale, D.M. Oehlert,G. Precipitation Chemistry, In ACID DEPOSITION LONG TERM TRENDS, National Academy of Sciences Press, Washington, DC, 1986, pp 128-199. 

Stallard, R. F. and Edmond, J. M. (1981). Geochemistry of the Amazon 1. Precipitation chemistry and the marine contribution to the dissolved load at the time of peak discharge. /. Geophys. Res. 86, 9844-9858. 

Avilla A, Alarcon M (1999) Relationship between precipitation chemistry and meteorological situations at a rural site in NE Spain. Atmos Environ 33 1663-1677... 

Ro, C-U., Sirois, A., Vet, R. J. (1997). Time trends in Canadian air and precipitation chemistry data. Paper 97-TA 28.05,90th AWMA Annual Meeting, Air Waste Management Association, Pittsburgh. 

Bogen, D. C., et al, Baseline Precipitation Chemistry Measurements by Ion Chromatography, paper 361, Pittsburgh Conference on Analytical Chemistry and Applied Spectroscopy, Cleveland, Ohio (1978). 

Lake and Mountain Lake evaporative losses exceed precipitation in the west (Cedar and Mountain), but represent only about 60% of the precipitation falling in northern Wisconsin (Little Rock). Precipitation chemistry varies along the same gradient, with pH increasing from 4.6 in northern Wisconsin to 4.8 in northeastern Minnesota and 5.2 in western Minnesota. The corresponding values for wet sulfate deposition decrease from 15 kg/ha per... 

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. 

Arsenic in precipitation from unpolluted ocean air averages about 0.019 pg L 1 (Hering and Kneebone, 2002), 157 and terrestrial rainwater concentrations (at least over the USA) also have similar averages of around 0.013-0.032 pgL-1 ((Smedley and Kinniburgh, 2002), 522 Table 3.17). As the precipitation infiltrates into the subsurface, its chemistry changes as it reacts with sediments, soils, and rocks. Therefore, the arsenic chemistry of the groundwater of an area may be very different than its precipitation chemistry. 

Andreae, M. O., R. W. Talbot, H. Berresheim, and K. M. Beecher. 1990. Precipitation chemistry in central Amazonia. Journal of Geophysical Research 95 16987-16999. 

Edmonds, R. L., T. B. Thomas, and J. J. Rhodes. 1991. Canopy and soil modification of precipitation chemistry in a temperate rain forest. Soil Science Society of America Journal 55 1685-1693. 

Eklund, T. J., W. H. McDowell, and C. M. Pringle. 1997. Seasonal variation of tropical precipitation chemistry La Selva, Costa Rica. Atmospheric Environment 31 3903—3910... 

Lewis, W. M., Jr. 1981. Precipitation chemistry and nutrient loading by precipitation in a tropical watershed. Water Resources Research 17 169-181. 

McDowell, W. H., C. Gines-Sanchez, C. E. Asbury, and C. R. Ramos-Perez. 1990. Influence of sea salt aerosols and long-range transport on precipitation chemistry at El Verde, Puerto Rico. Atmospheric Environment 24A 2813-2821. 

Eisenreich, S. J. Hollad, G. J. Langevin, S. Precipitation chemistry and atmospheric deposition of trace elements in northeastern Minnesota prepared for the Minnesota Environmental Quality Council and Minnesota State Planning Agency, 1978. 

The EMEP monitoring network of precipitation chemistry consists of about a hundred stations distributed in almost 30 countries across Europe.1 All of these measure inorganic ions as well as pH and conductivity. Figure 17.1 illustrates the concentration levels of sulfate (corrected for sea salt), nitrate, and ammonium in 2006. The monitoring sites of heavy metals and persistent organic pollutants (POPs) are less densely distributed 2 in 2006, there were around 50 for heavy metals such as lead... 

Collecting a representative sample of snow for precipitation chemistry measurements poses special problems. Most electronic sensors on precipitation chemistry samplers do not detect snow, particularly light, dry snow, as efficiently as rain. Light, dry snow may also fall into and then be blown out of an open container or funnel. Snow may stick to sampler parts and later be blown into the sample container. Ice may coat sampler parts and prevent proper operation. Heavy snow may... 

Water chemistry Fate of inorganic and organic pollutants in natural waters Analytical chemistry of natural waters and trace contaminants Trace metal-particulate matter interactions Structure-activity relationships for organic compounds Aquatic colloid chemistry Precipitation chemistry/acid rain... 

To illustrate western precipitation chemistry as compared with... 

Table III. Summary of Apparent Trends in Annual Median Precipitation Chemistry Data from the USGS Sites and Hubbard Brook (1965-1980) Sites (Reproduced with permission from Ref. 4, Copyright 1984 APCA)...

The measurement program has two components, long-term and intensive. For the long-term component, data collection to determine the composition of wet deposition at Lewes, Delaware, and on Bermuda began in 1980. In 1984, another site was added at Adrigole, Ireland. From 1981 to 1985 during May-October, precipitation samples were also collected on two ships cruising weekly between New York City, Bermuda, and Nassau. Precipitation-chemistry data from the three land-based sites and from the ships were used to calculate... 

Impact of North American Emissions on Wet Deposition to the Western Atlantic Ocean. Wet deposition has been collected by event during WATOX at two sites on Bermuda, one site near Lewes, Delaware, and on board ships. These wet-deposition samples have been analyzed for acidic species, metals, and organic compounds. This section discusses our interpretation of the marine precipitation-chemistry data and the results of our analyses as well as the influence of North American emissions on precipitation composition. 

In interpreting marine precipitation-chemistry data, the differentiation of sea-salt and non-sea-salt (or excess sea-salt) components is essential. Uncertainties in such calculations arise from the uncertainties regarding (1) the composition of seawater, (2) the analyses, (3) the amount of dry-deposited sea salt in the samples,... 

Figures 3, 4, and 5 illustrate month by month comparisons between wet and dry deposition of sulfur, as derived from the dry deposition operation described here and from the published records of the MAP3S precipitation chemistry network. For the dry deposition, inferred values of the deposition of sulfur as sulfur dioxide have been added...

Figure 3. A comparison between dry and wet deposition rates of sulfur, as computed from the trial dry deposition data reported here and from records of MAP3S precipitation chemistry network, for Oak Ridge, Tennessee. Data are reported as average weekly values, computed for each month.

To better assess potential inorganic-organic ion relationships and the plausibility of various pathways that could lead to the presence of low molecular weight organic ions in precipitation, statistical analyses and equilibrium scavenging calculations were performed on organic and inorganic precipitation chemistry data obtained at three sites in the eastern United States. The results of these analyses were compared to theoretical expectations based on the various pathways. 

Previously published data from two sites on the Wisconsin Acid Deposition Monitoring Network (2) and the University of Virginia site of the MAP3S Precipitation Chemistry Network (PCN) (3, 8) were used in the current study. The Wisconsin data were obtained for samples collected during the spring of 1984, and the Virginia data were related to selected samples analyzed during the summer of 1983. 

Statistical analysis of precipitation chemistry data collected at three sites in the United States indicates that the inorganic and organic analytes show little or no correlation. In contrast, formate and acetate concentrations are highly correlated (r> 0.89) and consistently produce a formate/acetate ratio of approximately 2. 

Rothert, J. E. Dana. M. T. The MAP3S Precipitation Chemistry Network Seventh Periodic Summary Report (1983), PNL-5298, Pacific Northwest Laboratory Richland, WA, 1984. 

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