西太平洋热带海域降水化学特征

1988年在西太平洋热带海域采集雨水样品,分析结果表明,大部分样品偏酸性(pH<5.6).雨水的化学组成结构主要受海盐的影响,这与我国大陆上雨水的情况很不相同.将西太平洋热带海域降水化学特征与南印度海域和西大西洋海域的降水情况作对比分析,结果表明,前两个海域雨水中的SO~(2-)受非海盐源的影响比西大西洋海域的小.

CHEMICAL CHARACTERISTICS OF TROPICAL WESTERN PACIFIC PRECIPITATION

The wet-only marine precipitation samples of 46 from the Tropical Western Pacific Area (TWPA) were collected during a period of September 26 to October 27, 1988. The analyzed results indicated that the rainwater was acidic with an arithmetic mean pH of 5.30, a volume-weighted mean (VWM) pH of 5. 05, and a pH range of 3. 86 to 7. 02. There were two thirds of the samples with pH<5.60. The chemical components of rainwater in TWPA were dominated mainly by sea salt, but they were not simply diluted seawater solutions. The kind of construction of chemical components was different from that from inland area of China. Chemical comparison of the precipitation from TWPA with those in the Southern Indian Ocean Area (SIOA) and with those from Western Atlantic Area (WAA) demonstrated that the mean pH value, the total concentrations of anions and cations in rainwater from TWPA were the highest, followed by those from SIOA. About one thirds of the SO_4~2- Concentrations in the rainwaters from TWPA and SIOA and nearly half of the SO_4~2- in the rainwater from WAA were contributed by non-sea-salt origins, which indicates that the influences of external origins on the SO_4~2- concentrations in rainwaters from TWPA and SIOA are smaller than that in WAA.