Environmental Effects of Solar-Thermal Power Systems. Environmental Effects of Heat Transfer and Storage Fluids: Plant Toxicity and Movement in Soils

摘要

Field experiments on the movement of several heat transfer and storage oils (Therminol 66, Caloria HT43, and Dow 200) in soil and on the plant toxicity of these materials were conducted at Nevada Test Site. These studies were conducted in an area where the soil is nonsaline and calcareous, and the vegetation is mostly Larrea tridentata with Oryzopsis hymenoides, Ambrosia dumosa, and Lycium andersonii. The abiotic factors (air and soil temperatures, rainfall, and soil moisture tension) were monitored during the experimental period and are discussed. The movement of the oils in the soil was determined in two ways - soil columns in plastic boxes and bare-soil plots. In plastic boxes, Therminol 66 moved downward about 6.3 cm in 281 days. Dow 200 moved about 3.8 cm in 281 days and showed virtually no further downward movement to the end of experimental period (555 days). In the bare-soil plots, the limit of downward movement of the oils during the experimental period was 20.6 cm, 18.7, and 14.9 cm for Therminol 66, Caloria HT43, and Dow 200, respectively. The rate of movement was roughly 0.047 cm/day to 16.8-cm depth in 336 days, 0.067 cm/day to 18.7-cm depth in 281 days, and 0.044 cm/day to 14.9-cm depth in 336 days for Therminol 66, Caloria HT43, and Dow 200, respectively. In general, Caloria HT43 showed the greatest movement, while Dow 200 showed the least movement. Of the oils studied, Therminol 66 was the least toxic to native plants, whereas Dow 200 was the most toxic. The toxic effect on plants depended on the growth stage at which the plants were contaminated. Ambrosia dumosa contaminated in its dormant stage was more resistant to the toxic effect of Therminol 66 than when it was contaminated in its green, leafed stage. (ERA citation 07:015701)