大气中微量元素的沉降对海洋生态系统的影响

大气中的微量元素通过大气的干、湿沉降过程最终进入海洋，对海洋生态系统产生重要的影响。重金属对生物具有毒性，对生物的生长起抑制作用，而由降水事件带入的营养元素使海洋初级生产力的短期内迅速增加。本文根据近年来国内外对大气中微量元素的研究成果，介绍了气溶胶中营养盐和重金属的浓度、来源及其时空变化，较为系统地评述了营养盐和重金属的输入对海洋环境、海洋生态系统的影响，并探讨了今后该领域的研究重点。     

Behavior of different phosphorus species in suspended particulate matter in the Changjiang estuary

Suspended particulate matter (SPM) collected in the Changjiang (Yangtze River) estuary in June 2006 was separated into five fractions via water elutriation: clay-very fine silt (<8 μm), fine silt (8–16 μm), medium silt (16–32 μm), coarse silt (32-63 μm) and sand (>63 μm). The SPM and fractionated particles were sequentially analyzed by a modified SEDEX sequential extraction method to obtain six species of phosphorus: exchangeable or loosely-sorbed P, organic P, Fe-bound P, authigenic P, detrital P and refractory P. The results indicated that all particulate phosphorus species except for detrital P were negatively correlated to particle size; a high detrital P content was found in coarse silt and very coarse silt. From the inside of the river mouth to the gate of the river mouth, organic P, Fe-bound P and refractory P in the suspended particles decreased and a higher amount of exchangeable P appeared around the gate of the river mouth. From the gate of the river mouth to the sea, exchangeable P and organic P in suspended particles increased distinctly. The total particulate P flux into the estuary from the Changjiang River was about 45.45×10⁸ μmol/s during sampling. Of this, about 8.27×10⁸ μmol/s was associated with the “truly suspended” fraction. The bio-available particulate P flux was about 13.58×10⁸ μmol/s. Of this, about 4.24×10⁸ μmol/s was transported by “truly suspended” particles.