Concentration trends

Chlorine. Nearly all chlorine compounds are readily soluble in water. As a result, the major reservoir for this element in Figure 1 is the ocean (5). Chloride, as noted earHer, is naturally present at low levels in rain and snow, especially over and near the oceans. Widespread increases in chloride concentration in mnoff in much of the United States can be attributed to the extensive use of sodium chloride and calcium chloride for deicing of streets and highways. Ref. 19 points out the importance of the increased use of deicing salt as a cause of increased chloride concentrations in streams of the northeastern United States and the role of this factor in the chloride trends in Lake Ontario. Increases in chloride concentration also can occur as a result of disposal of sewage, oil field brines, and various kinds of industrial waste. Thus, chloride concentration trends also can be considered as an index of the alternation of streamwater chemistry by human development in the industrialized sections of the world. Although chlorine is an essential element for animal nutrition, it is of less importance for other life forms. 

Rasmussen, R. A. and Khalil, M. A. K. (1984). Atmospheric methane in recent and ancient atmospheres Concentrations, trends, and interhemispheric gradient. /. Geophys. Res. 89,11599-11604. 

These considerations require an expanded scope for a monitoring program, involving measurements of ancillary environmental conditions in addition to mercuiy data if the objective is not just to document changes in mercuiy concentrations, but also to gain insight into links between emissions and concentration trends in biota. These issues are addressed in each chapter. 

Borgmann, U. and D.M. Whittle. 1991. Contaminant concentration trends in Lake Ontario lake trout (Salvelinus namaycush) 1977 to 1988. Jour. Great Lakes Res. 17 368-381. 

Fig. 6.2.1. Spatial concentration trend of NPEO in suspended matter from samples taken from the river Rhine (source Ref. [31]).

Long-Term Concentration Trends of Selected Species. 146... 

In addition to these major components, a number of trace elements are also found in bottom ash and fly ash. The trace elemental concentrations can vary considerably within a particular ash or between ashes. Generally, higher trace element concentrations are found in the fly ash than bottom ash however, there are several cases where bottom ash exceeds fly ash concentration. Fly ash demonstrates an increased concentration trend with decreasing particle sizes. 

Husain, L., and V. A. Dutkiewicz, A Long-Term (1975-1988) Study of Atmospheric S04 Regional Contributions and Concentration Trends, Atmos. Environ., 24A, 1175-1187 (1990). 

Smith, D. J. T., and R. M. Harrison, Concentrations, Trends, and Vehicle Source Profile of Polynuclear Aromatic Hydrocarbons in the U.K. Atmosphere, Atmos. Environ., 30, 2513-2525 (1996). 

Fir. 6. Carbon dioxide concentration Trend 1958-2002. (Adapted from Carbon Dioxide InTorniaiion Analysis Center 2000.)... 

Sorci-Thomas MG, Thomas MJ (2002) The effects of altered apolipoprotein A-I structure on plasma HDL concentration. Trends Cardiovasc Med 12 121 128... 

The data for copper indicates that contamination may have come from the platinum crucibles since similar concentration trends were noted for both covered and uncovered crucibles. Under the chosen ashing conditions, vanadium and molybdenum were apparently consistently volatilized. 

These increasing and decreasing concentration trends do not appear to be a function of the spectrometric method. Continuous time vs. relative intensity curves were prepared for the iron internal standard... 

Marzluff, W. F., and N. B. Pandey, Multiple regulatory steps control histone messenger-RNA concentrations. Trends Biochem. Sci. 12 49-51, 1988. 

Concentration —< — Emission -Linear emission trend -Linear concentration trend I... 

The correlation only measures whether the time pattern of indoor concentrations track outdoor concentration trends, it does not provide information on how much a pollutant infiltrates in the indoor environment. In the RUPIOH study, outdoor and indoor nitrate concentrations correlated well in three of the four cities (Fig. 5). However, the infiltration factor was very low, ranging from 0.05 to 0.13. 

Ten patients who had taken lithium for less than 1 year and 13 who had taken it for more than 3 years were assessed for alterations in bone metabolism and parathyroid function (654). There were no differences in bone mineral density, serum calcium concentration, or PTH concentration, but both groups had increased bone turnover and the longterm group had nonsignificantly higher calcium and PTH concentrations (including one hyperparathyroid patient who had an adenoma excised). The authors conclusion that lithium therapy is not a risk factor for osteoporosis needs to be tempered by the small sample size, the case of adenoma, and the blood concentration trends. 

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