预测沉积物-水微宇宙系统中化学品浓度变化的多介质模型

沉积物-水微宇宙系统是经济合作发展组织(Organisation for Economic Co-Operation and Development,OECD)颁布的化学品测试准则中推荐的试验系统之一,可用来测试化学品对底栖生物的慢性毒性。为了在试验前对化学品的浓度变化进行预测,进而确定试验方法,以摇蚊慢性毒性试验系统为例,采用环境多介质模型的建模方法,构建了一种可通过化学品理化性质和试验系统参数,对化学品在沉积物-水试验系统中浓度变化进行预测的模型。结合试验数据和文献资料,给出了模型中试验系统参数的推荐取值,并使用Matlab软件中的Simulink工具对模型进行编程和求解。以此模型为基础,给出了模型在3个方面的应用,即预测蓄积时间、预测平衡时间以及拟合试验数据。对80种已有或假想化学品的蓄积时间和平衡时间进行了计算,得出的范围分别为1~204 d和1~73 d。此外,适当修改模型结构和模型参数,也可将其应用于其他暴露场景中。但使用模型对化学品浓度进行预测时发现,模型仅对沉积物中化学品浓度的预测结果较为准确,而对水中化学品浓度的预测结果与实测值相差1~2个数量级。模型对浓度的预测精度未来仍需进一步提高。上述研究结果完善了沉积物-水微宇宙系统试验方法。

A Multimedia Model for Prediction of Chemicals Concentration Changes in Sediment-Water Microcosm Systems

Sediment-water microcosm system, which is one of the recommended test systems in the OECD guidelines for the testing of chemicals, can be used to test chronic toxicity of chemicals to sediment-dwelling organisms. Before test performance, it is necessary to predict chemicals concentration changes and then confirm test method. This study aimed to build a mathematical model for this prediction. The model, parameterized for chironomid chronic toxicity test system as an example, could predict chemicals concentration changes in the sediment-water test system by chemical properties and test system parameters using multimedia environmental modeling approach. Combined with test data and documentation, recommended values were put forward for test system parameters in the model. The model was programmed and solved by Simulink tools in Matlab software. Based on the model, its three application fields were given, e.g. predicting accumulation period, equilibration period and matching test data. And then accumulation and equilibration periods of 80 existing or hypothetical chemicals were calculated, and scopes were <1-204 d and <1-73 d respectively. In addition, via modifying model structures and parameters properly, the model could also be applied in other exposure scenarios. However, when predicting chemicals concentrations, the model could only give relatively accurate results for chemicals concentration in sediment and the results for that in water deviated from the measured values by 1-2 order of magnitudes, which still needs to be improved further. The results presented in this study perfect the sediment-water microcosm system test method.