东莞溺死案多发河段硅藻种群分布及其法医学意义

A study on community distribution of diatoms in tributaries of Dongjiang River within Dongguan administrative area where drowning occurs frequently and its applicability in forensic practice

目的调查东莞溺死案多发河段硅藻种群分布,探讨其在溺死地点推断中的意义。方法于2009年6月至9月收集东莞市东江沙田、道滘、麻涌、石碣、石龙、茶山和企石共7个河段采样点江水样本126份,并收集2例已知落水地点溺死尸体;制作各样本硅藻涂片,计算样本间Sprensen相似系数及弦平方距离(SCD),并进行聚类分析。结果 126份水样中共鉴定出70种硅藻,其中优势度>0.02的优势种群有4种;2个案例样本分别与道滘和石碣河段样本的相似度最高,与实际落水地点基本一致。结论建立区域性溺死多发河段硅藻数据库,利用Sprensen相似系数及SCD值及聚类分析进行落水地点推断具有一定可行性。

Objective To investigate the species distribution of diatoms in Dongguan section of Dongjiang River,where drowning occurs frequently and its applicability to prediction of possible drowning site.Methods 126 water samples were collected from Shatian,Daojiao,Mayong,Shijie,Shilong,Chashan and Qishi tributaries of Dongjiang River located in Dongguan administrative area from June to September,2009.The lung tissues were taken from two corpses died from drowning at known location.The diatoms were harvested with microwave digestion method.Sprensen＇s similarity coefficient and squared-chord distance（SCD） were calculated among the samples.Cluster analysis were performed after the diatoms were analyzed qualitatively and quantitatively.Results 70 types of diatoms were detected from 126 samples,among which four dominant species（dominance 0.02） were found.The morphological characteristics of the diatoms from Daojiao and Shijie branches showed the greatest similarity to the diatoms detected in the two drowning cases respectively,where the bodies were found.Conclusion The present study indicates that it is feasible to determine the drowning site by the analog and cluster analysis with the database of diatoms in the rivers.