The paper presents the first results of a study of seasonal variations in the grain size distribution and mineral compositions of suspended particulate matter (SPM) of the Northern Dvina River. The SPM samples were collected every month during 2016–2017 at the outlet of the Kuznetchiha arm to Dvina Bay of the White Sea. The grain size fractions were separated by Petelin’s water-mechanical method with retention of fractions for subsequent analyses using an electron microscope, energy-dispersion microanalyzer, and X-ray difractometer. The results demonstrated that the pelitic and subcolloidal fractions predominated in the grain size distribution of river SPM, with subordinate coarser fractions. Seasonal variations in the SPM concentration and the total amount of detrital and clay minerals are influenced by river water discharge and achieved a maximum in high water periods (spring flood and partly at the end of summer–autumn heavy rains). The subcolloidal fraction in the March sample stands out in the fine fraction distribution. Its share in this sample was the highest among these fractions throughout the year. The reason is probably related to the highest content of fine dispersed detrital minerals in the fraction. The question of why this is encountered only in March remains open.

中文翻译：

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德维纳河北部悬浮颗粒物的粒度分布和矿物组成的季节性变化

本文介绍了北德维纳河的粒度分布和悬浮颗粒物（SPM）的矿物成分的季节性变化研究的初步结果。SPM样品于2016–2017年期间每月在库兹涅奇哈支流至白海德维纳湾的出口处采集。通过Petelin的水-机械方法分离出粒度级分，保留级分，以便随后使用电子显微镜，能量分散微分析仪和X射线衍射仪进行分析。结果表明，在SPM河的粒度分布中，主要是黄粉质和胶体级分，次要级分更粗。SPM浓度以及碎屑和黏土矿物总量的季节性变化受河水排放的影响，在高水期（春季洪水和部分在夏末大雨期间）达到最大值。March样品中的胶体下部分在精细部分分布中脱颖而出。在这一样本中，它所占的比例全年最高。原因可能与馏分中细分散碎屑矿物的含量最高有关。为什么仅在三月份才遇到这种问题仍然悬而未决。在这一样本中，它所占的比例全年最高。原因可能与馏分中细分散碎屑矿物的含量最高有关。为什么仅在三月份才遇到这种问题仍然悬而未决。在这一样本中，它所占的比例全年最高。原因可能与馏分中细分散碎屑矿物的含量最高有关。为什么仅在三月份才遇到这种问题仍然悬而未决。