辽宁省主要河流冰封期及开河后浮游硅藻变化规律

目的观察分析辽宁3条河流中浮游硅藻数量及种群构成在冰封期及开河后的变化规律，探讨其在法医学应用中的意义。方法于2012年1～4月中旬分别在辽河、浑河沈阳段及太子河本溪段布点取水，逐月观测硅藻数量及种群构成的变化规律，计算3条河段各月水样中硅藻数量平均值（个／10mL）以及主要硅藻属种及其构成比。结果3条河流冰封期及开河后硅藻种属数量和构成比均有明显变化。在冰封期（1～3月）硅藻种属数量趋于稳定，中心纲硅藻为优势种群，仅见少量羽纹纲硅藻，各月之间硅藻数量变化缺乏统计学差异；初春开河后（4月）硅藻种属数量显著增加，与冰封期差异明显（P〈0．01），中心纲及羽纹纲硅藻混杂存在。结论辽宁主要河流在冰封期及开河后水中硅藻种群构成及数量变化大，春季水中浮尸的死因鉴定及落水点判断应合理分析现场水样与脏器中硅藻种群及数量差异。

The variation of planktonic diatom in frozen and thawing periods in Hun river,Liao river and Taiziriver

Objection For investigating the diatom in forensic application, we chose 3 rivers in Liaoning Province, and observed variation of quantity and species composition of planktonic diatom in frozen and thawing periods. Methods We sampled at differently spot in Hun river, Liao river, Taizi river from January to April in 2012, and observed monthly variation of quantity and species composition of diatom, and counted the mean value and species composition ratio of diatom in the sample. Results Hun river, Liao river, Taizi river were frozen from January to March each year and thawed every April. Comparison of frozen and thawing periods, the species composition, dominant species and quantity of diatom in three rivers have varied obviously. The quantity of diatom were stable from January to March, and increased sharply in April. The quantity of diatom were significantly different in the two periods （P 〈 0.01 ）. From January to March, Centricae diatoms became the dominant species and Pennate diatoms were rare, then Centricae diatoms and Pennate diatoms became the dominant species alternately in April. Conclusion The species composition, dominant species and quantity of diatom have varied obviously in frozen and thawing periods of Liaoning rivers, we should analyze the results carefully in forensic drowning cases.