Institute of Environmental Processes and Pollution Control, and School of Environmental and Civil Engineering, Jiangnan University, Wuxi 214122, China.
School of Environmental Science, University of Liverpool, Brownlow Hill, Liverpool L69 7ZX, United Kingdom; Department of Biological Sciences, Xi'an Jiaotong-Liverpool University, Suzhou, Jiangsu 215123, PR China.
Sci Total Environ. 2022 Mar 10;811:152178. doi: 10.1016/j.scitotenv.2021.152178. Epub 2021 Dec 6.
The bioavailability of pollutants is a key factor affecting environmental risk. Whole-cell bioreporters are a demonstratedly effective tool for the investigation of pollutant bioavailability in water and soil/sediment. Unlike aqueous samples, transmittance of bioreporter optical signal is reduced in direct-contact assays with soil/sediment, which affects the accuracy of bioreporter-detected pollutant bioavailability. No studies have measured the magnitude and variability of soil/sediment effects on signal in direct-contact assays or how associated uncertainties influence results. In this study, we investigate the optical effects of soil/sediment particles in suspensions on bioreporter signal transmittance and quantify how variable these optical effects are from sample-to-sample. We find that neglecting bioreporter signal diminution by soil/sediment, as many studies do, can lead to order-of-magnitude errors in results, underestimating risk. Correction based on methods in ad hoc use (e.g. comparison to signal from non-inducible reporter or use of reference soil/sediment) are also problematic for some types of experiment, and could lead to errors in excess of 30%. Our findings have a sound basis in theory, and we provide recommendations concerning the most suitable type of approach to use for different experimental settings. Generally, if best accuracy is not needed to quantify bioavailability, for samples that have been ground, sieved, and are of reasonably uniform color, it may be possible to use a single or average correction factor, particularly for experiments performed at a single slurry concentration. For investigations studying bioavailability under varying solid-phase:water ratios (e.g., sorption/desorption), detailed compensation measurements are needed for independent variables, including each specific soil/sediment sample, slurry concentration, and in some cases bioreporter signal intensity. Our measurements and calculations indicate that best results are obtained when working in the region of ballistic photon transmittance. Findings herein will be useful in areas that require information on bioavailability, such as ecotoxicology and environmental risk assessment.
污染物的生物利用度是影响环境风险的关键因素。全细胞生物报告器被证明是一种有效的工具，可用于调查水和土壤/沉积物中污染物的生物利用度。与水样品不同，生物报告器光学信号的透过率在与土壤/沉积物的直接接触测定中会降低，这会影响生物报告器检测到的污染物生物利用度的准确性。目前还没有研究测量土壤/沉积物对直接接触测定中信号的影响的大小和可变性，以及相关的不确定性如何影响结果。在这项研究中，我们研究了悬浮液中土壤/沉积物颗粒对生物报告器信号透过率的光学影响，并量化了这些光学影响从一个样品到另一个样品的可变性。我们发现，像许多研究一样，忽略土壤/沉积物对生物报告器信号的衰减，可能会导致结果出现数量级的误差，从而低估风险。基于特定用途的方法（例如，与非诱导报告器的信号进行比较或使用参考土壤/沉积物）进行的校正对于某些类型的实验也是有问题的，并且可能导致超过 30%的误差。我们的发现有坚实的理论基础，并且我们就不同实验设置最适合使用的方法类型提出了建议。一般来说，如果不需要定量生物利用度来获得最佳准确性，对于已经研磨、过筛且颜色均匀的样品，可能可以使用单个或平均校正因子，特别是对于在单一泥浆浓度下进行的实验。对于研究在不同固-水比下的生物利用度（例如，吸附/解吸）的实验，需要对包括每个特定的土壤/沉积物样品、泥浆浓度在内的独立变量进行详细的补偿测量，在某些情况下还需要生物报告器信号强度。我们的测量和计算表明，在弹道光子透过率区域工作可以获得最佳结果。本文的研究结果将在需要生物利用度信息的领域（如生态毒理学和环境风险评估）中很有用。
