Mercury contamination was found to be widespread in soils at a property in Upstate New York. Historical site use suggested that the mercury did not result from prior industrial use of the property. Soil contamination ...Mercury contamination was found to be widespread in soils at a property in Upstate New York. Historical site use suggested that the mercury did not result from prior industrial use of the property. Soil contamination may have resulted from atmospheric deposition of mercury released from properties in close proximity to the contaminated property. The purpose of this forensics investigation was to examine to what extent atmospheric deposition of elemental mercury may have influenced mercury levels found in surficial soils on the contaminated property and further to identify the source(s) of the mercury. Work efforts included an examination of historical records available for a chlor-alkali plant (CAP) upwind of the contaminated property to establish historical use and disposal practices for elemental mercury. Mercury emissions test data from the Upstate New York chlor-alkali facility were modeled (USEPA ISC3) as a means of estimating impacts on ambient air and soils vicinal to the facility. Mercury emissions from the facility were modeled as both a point source and volume source. For example, at a location 305 meters to the east and 30 meters to the north of the modeled source centerline elemental mercury concentrations in ambient air were estimated at 270 ng/m<sup>3</sup> (average results based upon 5 years of meteorological data). This value is contrasted to a background concentration of 1.6 ng/m<sup>3</sup> (USEPA Report to Congress 1997). As a result of the modeling data in combination with findings related to mercury use and disposal practices at the NY CAP documented from the records review, it was concluded that emissions from the CAP facility during the period of operation (1897-1991) most likely accounted for the concentrations of elemental mercury found in surficial soils at properties situated downwind of the CAP. These findings were further corroborated by information available in the open literature for CAPs world-wide.展开更多
Five samples of perfluoroheptyl end capped polyacrylic acid ( F P A A) having ahigh surface activity were prepared by free radicalpolymerization ofacrylicacid . Theinitiatorwas perfluorooctanoyl peroxide which produce...Five samples of perfluoroheptyl end capped polyacrylic acid ( F P A A) having ahigh surface activity were prepared by free radicalpolymerization ofacrylicacid . Theinitiatorwas perfluorooctanoyl peroxide which produced the free radicalof heptyl at 45 ℃. The yieldsof F P A A were in the range of 10 % to 25 % . The weight average molecular weights were2 62 ×104 to 7 99 ×104 and the polydispersity indexes were 1 97 to 5 64 ,depending on theconcentration of the initiator in the monomer. The surface tension was about 15m N/m at30 ℃forthe aqueous solution of F P A Awith the weight average molecular weight2 62 ×104in the concentration of about 0 01g/ m L. The molecular areas of F P A A at the air waterinterface under the condition ofcritical micelle concentration were 3 2 to 4 6n m2 ,which areobviously larger than the area per molecule of perfluorooctanoic acid (2 14nm 2) and muchsmaller than that of ordinary polyacrylic acid (83 4nm 2) . It means that the polymermoleculesin the surface adsorbed layer form the brush structure because of the special effectof the perfluoroalkyl groups at the chain ends .展开更多
文摘Mercury contamination was found to be widespread in soils at a property in Upstate New York. Historical site use suggested that the mercury did not result from prior industrial use of the property. Soil contamination may have resulted from atmospheric deposition of mercury released from properties in close proximity to the contaminated property. The purpose of this forensics investigation was to examine to what extent atmospheric deposition of elemental mercury may have influenced mercury levels found in surficial soils on the contaminated property and further to identify the source(s) of the mercury. Work efforts included an examination of historical records available for a chlor-alkali plant (CAP) upwind of the contaminated property to establish historical use and disposal practices for elemental mercury. Mercury emissions test data from the Upstate New York chlor-alkali facility were modeled (USEPA ISC3) as a means of estimating impacts on ambient air and soils vicinal to the facility. Mercury emissions from the facility were modeled as both a point source and volume source. For example, at a location 305 meters to the east and 30 meters to the north of the modeled source centerline elemental mercury concentrations in ambient air were estimated at 270 ng/m<sup>3</sup> (average results based upon 5 years of meteorological data). This value is contrasted to a background concentration of 1.6 ng/m<sup>3</sup> (USEPA Report to Congress 1997). As a result of the modeling data in combination with findings related to mercury use and disposal practices at the NY CAP documented from the records review, it was concluded that emissions from the CAP facility during the period of operation (1897-1991) most likely accounted for the concentrations of elemental mercury found in surficial soils at properties situated downwind of the CAP. These findings were further corroborated by information available in the open literature for CAPs world-wide.
文摘Five samples of perfluoroheptyl end capped polyacrylic acid ( F P A A) having ahigh surface activity were prepared by free radicalpolymerization ofacrylicacid . Theinitiatorwas perfluorooctanoyl peroxide which produced the free radicalof heptyl at 45 ℃. The yieldsof F P A A were in the range of 10 % to 25 % . The weight average molecular weights were2 62 ×104 to 7 99 ×104 and the polydispersity indexes were 1 97 to 5 64 ,depending on theconcentration of the initiator in the monomer. The surface tension was about 15m N/m at30 ℃forthe aqueous solution of F P A Awith the weight average molecular weight2 62 ×104in the concentration of about 0 01g/ m L. The molecular areas of F P A A at the air waterinterface under the condition ofcritical micelle concentration were 3 2 to 4 6n m2 ,which areobviously larger than the area per molecule of perfluorooctanoic acid (2 14nm 2) and muchsmaller than that of ordinary polyacrylic acid (83 4nm 2) . It means that the polymermoleculesin the surface adsorbed layer form the brush structure because of the special effectof the perfluoroalkyl groups at the chain ends .
