| 2016年夏季南海海盆水体颗粒物粒径分布特征* |
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| 引用本文： | 郑文迪,周雯,曹文熙,王桂芬,邓霖,徐文龙,许占堂,李彩,蔡建南.2016年夏季南海海盆水体颗粒物粒径分布特征*[J].热带海洋学报,2018,37(5):74-85. |
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| 作者姓名： | 郑文迪 周雯 曹文熙 王桂芬 邓霖 徐文龙 许占堂 李彩 蔡建南 |
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| 作者单位： | 1. 热带海洋环境国家重点实验室(中国科学院南海海洋研究所), 广东 广州 5103012. 中国科学院大学, 北京 1000493. 河海大学海洋学院, 江苏 南京 2100984. 近海海洋环境科学国家重点实验室(厦门大学), 福建 厦门 361005; |
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| 基金项目： | 国家自然科学基金(41576030, 41431176, 4176045, 4176044, 41376042);热带海洋环境国家重点实验室自主研究项目(LTOZZ1602);广州市科技计划重点项目(201504010034, 201707020023, 201607020041);广东省科技计划重点项目(2016A020222008);中科院A类先导专项(XDA11040302) |
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| 摘 要： | 颗粒物粒径分布(Particle Size Distribution, PSD)代表了颗粒物浓度与颗粒物粒径之间的关系, 影响着海洋生态环境和水体光学特性等。文章基于2016年夏季航次调查的生物光学剖面数据, 研究了南海海盆海域PSD的分布特征。研究发现, 幂律函数可以较好地拟合南海海盆区域的PSD, 对数空间中的实测的PSD与模拟的PSD平均决定系数高达0.95。PSD斜率(ξ)的分布范围为1.27, 7.65], 均值为3.93±0.56。南海海盆区域表层水体的ξ均值与全球大洋表层水体的ξ均值相近, 但高于海湾等表层水体的ξ均值。ξ能较好地表征颗粒物平均粒径DA的大小, 两者存在明显负相关关系, 即ξ值越高, DA越小; 反之, DA越大。通过分析T1断面的生物光学剖面数据及总体平均的PSD剖面数据, 发现PSD剖面分布特征如下: 1)表层水体的ξ值相对较高, 且DA值相对较低, 推测可能是由于微微型藻类为主导颗粒物所致; 2) ξ值极小值层出现在次表层叶绿素浓度极大值层(Subsurface Chlorophyll Maximum Layer, SCML)中, 并伴随DA极大值层的出现, 其原因可能是SCML中的大粒径浮游植物占比显著增加; 3)弱光层中的ξ值较SCML中的高, 但略低于表层的ξ值, 而DA则位于表层与SCML的DA之间, 这可能与浮游植物及其碎屑的絮凝、分解、沉降等过程相关。PSD特征影响着海水的固有光学特性, 分析发现: 由于SCML中的叶绿素浓度增加, 颗粒物散射系数(bp(532))和颗粒物后向散射系数(bbp(532))也相应呈现显著增加的趋势。弱光层中的平均bp(532)与平均bbp(532)最小。ξ与颗粒物衰减光谱斜率之间呈高分散性, Boss 等(2001b)的模型适合用于粗略估算区域性的ξ分布范围及均值。
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| 关 键 词： | 南海海盆 颗粒物粒径分布 PSD斜率 平均粒径 光学特性 |
| 收稿时间： | 2018-02-08 |
| 修稿时间： | 2018-04-09 |
Characterization of particle size distribution in the South China Sea basin during summer 2016 |
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| Wendi ZHENG,Wen ZHOU,Wenxi CAO,Guifen WANG,Lin DENG,Wenlong XU,Zhantang XU,Cai LI,Jiannan CAI.Characterization of particle size distribution in the South China Sea basin during summer 2016[J].Journal of Tropical Oceanography,2018,37(5):74-85. |
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| Authors: | Wendi ZHENG Wen ZHOU Wenxi CAO Guifen WANG Lin DENG Wenlong XU Zhantang XU Cai LI Jiannan CAI |
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| Institution: | 1. State Key Laboratory of Tropical Oceanography (South China Sea Institute of Oceanology, Chinese Academy of Sciences), Guangzhou 510301, China2. University of Chinese Academy of Sciences, Beijing 100049, China3. College of Oceanography, Hohai University, Nanjing 210098, China4. State Key Laboratory of Marine Environmental Science (Xiamen University), Xiamen 361005, China; |
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| Abstract: | Particle size distribution (PSD) describes the relationship between particle concentration and particle size, influencing marine ecosystem environment, the optical properties of sea water, and so on. Based on the in-situ profiles of biological and optical properties during summer 2016 in the South China Sea basin, characterization of PSD was studied. The power-law model was fit to describe the PSD, and the results indicated that the mean coefficient of determination between in-situ PSD and simulated PSD could reach 0.95 in the logarithmic space. The PSD slope (ξ) ranged in 1.27, 7.65] with a mean of 3.93±0.56. The mean of ξ in the surface water of the South China Sea basin was similar to the mean of ξ in global ocean surface water, but higher than that in the surface water of other areas such as the bay. There was a strong negative relationship between ξ and the mean diameter (DA). Taking section T1 as an example, we analyzed the mean PSD profile of these stations. The features of PSD profiles are as follows. 1) At the surface, there were high values of ξ with low values of DA because the dominate particle was pico-phytoplankton. 2) The minimum value of ξ appeared in the subsurface chlorophyll maximum layer (SCML) with higher DA, which may result from the higher proportion of big phytoplankton. 3) In the twilight layer, the values of ξ as well as the values of DA were between those at the surface and in the SCML. This phenomenon may be related to the process of flocculation, decomposition, and settlement of phytoplankton. The traits of PSD would influence the inherent optical properties (IOP) of seawater. We found that both particulate beam scattering coefficient at 532 nm (bp(532)) and particulate beam backscattering coefficient at 532 nm (bbp(532)) would be higher in the SCML because of the increasing chlorophyll-a concentration. However, the lowest mean bp(532) and the lowest mean bbp(532) were found in the twilight layer. Furthermore, although the relationship between ξ and the particulate beam attenuation sepctral slope was weak, the model of Boss et al. (2001b) is suitable for estimating the regional range and mean value of ξ roughly. |
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| Keywords: | South China Sea basin particle size distribution (PSD) PSD slope mean diameter optical properties |
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