用低水平放射性测量技术研究海洋新生产力

初级生产力是自养生物通过光合用制造有机物的速率，新生产力是输入到真光层的营养元素支持的那部分初级生产力，在稳态条件下等于真光层颗粒有机碳的净输出。所以，新生产力表现为真光层对外部输入碳的同化能力和供次级或更高营养级生产所需营养的能力。在真光层，几乎均匀分布的＾２３８Ｕ和＾２２６Ｒａ衰变产生的＾２３４Ｔｈ和＾２１０Ｐｂ极易吸附在悬浮颗粒物上并随其沉降，形成与生源颗粒物吸收碳沉一致的运移图象。人们用低

Study of Marine New Productivity Using Low level Radioactivity Measuring Technique

Primary productivity is the rate of autotroph producing organism through photosynthesis and new productivity is that supportedby nutrient element imported into euphotic zone and that is equal with net export of particulate organic carbon under steady state condition.So new productivity in euphotic zone is assimilating capacity with carbon imported from outside and supporting capacity to product of high trophic level.In euphotic zone,the distributions of 238 U and 226 Ra are rather homogeneous,but their daughters 234 Th and 210 Pb can be easily absorbed by suspension particulate and sink down.That shows an image that is very similar with biogenic particulate absorbing carbon and sink down.People measure contents and distributions of 238 U, 226 Ra and 234 Th and 210 Pb in seawater using measurement technique of low level radioactivity and study particulate dynamics and new productivity of euphotic zone through disquilibrium relations.This paper introduces contents mentioned above,significance of new productivity and the study progress of new productivity in China.