黄河口沉积物中无机磷酸盐的存在形态

本文对1989年5月和8月采集的黄河口附近浅海表层沉积物及柱状沉积物进行了磷酸盐形态(吸附态磷、铝磷、铁磷、闭蓄态磷和钙磷)的分析,并对几个样品的不同粒级也分别作了形态分析。结果表明,钙磷占无机磷的大部分;闭蓄态磷次之;铝磷和吸附态磷再次之;铁磷含量极微。除钙磷(由于有矿物磷的存在)在粉砂粒级中含量最高外,其它各形态磷的含量均随粒度变细而增高。     

Reproductive biology of the mackerel scad Decapterus macarellus from Cabo Verde and the implications for its fishery management

The mackerel scad Decapterus macarellus is of great social and economic importance to Cabo Verde citizens; however, in recent years catches have shown an unexplained decline. The harvest is regulated by way of a minimum legal size and a seasonal closure, with both measures based on the results of reproductive studies that did not consider the microscopic characteristics of the gonads. This study aimed to analyse the gonads microscopically in order to classify the sexual development stage of individuals and to estimate the size at first maturity and the reproductive season. This information was then used to analyse the match between the reproductive parameters and the management measures. The samples comprised 284 females (20–36 cm fork length [FL]) and 85 males (21–35 cm FL). The annual variation in gonadosomatic index and the monthly frequencies of mature phases suggest that the reproductive season occurs from March to October, with two spawning peaks, one in March and another from July to October. The current seasonal closure (from July to September) covers the main reproductive period. However, the species has a long spawning period and the timing of peaks can vary between years; hence, a reassessment of this management measure is recommended. The sizes at first maturity were estimated at 24.1 cm FL for females, and 26.6 cm FL for males. These values are higher than the minimum legal size (20 cm FL) currently established for management of the species at Cabo Verde; thus, we strongly recommend an increase in the minimum legal size in an attempt to reduce catches of immature individuals.     

厦门湾水体中铀、钍同位素及悬浮颗粒物的粒径谱--颗粒物采集方法的影响

运用增强型混合纤雏素(CN-CA)膜、聚碳酸酯膜和聚丙烯滤芯过滤3种不同的方法采集、研究厦门湾水体中悬浮颗粒物(SPM)及其U、Th同位素的粒径谱．发现3种方法所得SPM总浓度和U、Th各同位素的总比活度具有很好的一致性,但粒级分布存在差异．SPM的浓度随粒径的增大而增加,并且SPM的粒径谱控制着颗粒活性很强的4种钍同位素的拉径谱．对于所研究的3种方法,采用聚碳酸脂膜过滤是研究沿岸海域SPM及颗粒活性核素粒级分布比较理想的方法。     

长江中下游地区7500—5000aB.P.气候变化序列的初步研究

孢粉分析方法可以比较客观地反映古植被类型,而各植被类型只能在一定的气候指标范围内生长。本文根据这一基本原理,利用现代植被生长的基本气候指标和有关气象资料,对长江中下游地区7500—5000aB.P.的孢粉资料进行处理、转化,从而得出这一阶段每500年一个时间段的气候变化序列。研究结果表明,研究区在7500—5000aB.P.时间内,年平均温度偏暖于今日-0.1—1.5℃,最高温出现在6500—6000aB.P.,气温高于现在1.5℃。     

石油烃污染物存在下旋链角毛藻生长的粒度效应初步研究

研究了在石油烃存在下旋链角毛藻的最大生长速率 ,探讨了石油烃对细胞粒度的影响 ,并在此基础上讨论了细胞生长的粒径效应。结果表明 ,石油烃的存在促进旋链角毛藻的生长 ,促进作用随石油烃浓度的增加先增加后降低 ,添加0 .5mg·dm-3 石油烃的实验组促进作用最大 ;石油烃不改变细胞生长过程中的粒径分布形态 ,粒径分布呈现Gauss分布 ,中值等效球径为 3 .5 4～ 4.42 μm ;μmax与MESDμ 之间存在“U”形曲线的关系 ,即当MESDμ<4.0 9μm时 ,μmax随MESDμ 的增加而降低 ,符合“表面积规则” ,而当MESDμ>4.0 9μm时 ,μmax随MESDμ 的增加 ,偏离了“表面积规则”。