| Summary: | 碩士 === 國立高雄海洋科技大學 === 海洋環境工程研究所 === 100 === This research focuses on different characteristics of sediment, took 20 samples in Kaohsiung Harbor, including estuaries, waterways and harbors, to determine of heavy metals (copper, zinc, nickel, lead, chromium, cadmium, silver, mercury, arsenic) content with the open system digestion (OSD) and microwave-assisted digestion (MAD). Base on the result, evaluate the difference between the two digestion procedures on the metal content. Furthermore, evaluate to the impact factor between OSD and MAD.
According the result of analysis, detection limits of OSD and MAD range from 0.03 mg/kg (Hg) - 2.08 mg/kg (Pb) and 0.02 mg/kg (Hg) - 2.18 mg/kg (Pb), there are no significant differences between all the metal. Duplicate sample analysis of OSD and MAD range from 2.5±2.6% (Cr) - 12±2.3% (Ag) and 2.9±2.2% (Pb) - 8.8±0.1% (Ag), the metal all in the control, but MAD is lower than OSD about 2.0 - 5.6%. Spiked sample analysis of OSD and MAD range from 81±3.5% (Hg) - 111±1.7% (Pb) and 91±5.5% (Cr) - 102±9.1% (Cu), the metal all in the control, but MAD is better than OSD about 9 - 21%. Certified reference material analysis range from 71 - 90% and 90 - 125%, the recoveries of MAD are higher than OSD about 19 - 35%. It's possible that MAD use a variety of digestive, so that sediment mineral digest more complete.
Determination of metal concentrations based on OSD and MAD, the result of analysis range from 0.5±0.2 mg/kg (Cd) - 352±572 mg/kg (Zn) and 0.4±0.2 mg/kg (Cd) - 399±597 mg/kg (Zn), the recoveries of MAD are higher than OSD. The level of differences between OSD and MAD range from Hg (118±18%) >As (67±32%) >Cr (45±33%) >Cu (36±21%) ≅Cd (28±25%) >Zn (21±21%) ≅Pb (21±25%) ≅Ag (22±16%) >Ni (18±11%). Mercury have a large number of volatile in open acid digestion resulting in difference.The correlate test of the sediments characteristics to the RSD of OSD and MAD shows that, water content and organic matter are significant correlated with Copper, zinc, nickel, lead, chromium and silver. It's possible that one of the main impact factor to the difference between the two methods.
The results of research show that, it is recommended that use the microwave-assisted acid digestion, if investigate the heavy metal of Geological. Because it uses hydrofluoric acid and a variety of inorganic acid with the closed system, it can obtain total metal to the sediment. If it involves assessment of hazard, it is recommended that use the open system digestion. Because it is heavy metal from man-made. In addition, it's possible that the ratio and types of digestive is the key of difference of two digestion procedures. Because different minerals must use different digestive to carries the mineral dissolve. So it must use Sequential extraction, etc. to determine the composition of sediment mineral, by the result of analysis to determine the composition of digestive is the main impact factor to the differences in two digestion procedures.
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