Yes, there are indices that can be used to compare sediment analysis data, specifically pH, conductivity, and heavy metals. You can try Sediment Quality Guidelines (SQGs) or Ecological Risk Index (ERI). I attached a link with my answer, which can be helpful to understand more about these indices.

Chapter Water Quality Ecological Risk Assessment with Sedimentologic...

For sediment analysis, the commonly used reference for comparison is the Sediment Quality Guidelines (SQGs) or Sediment Quality Standards (SQS). These guidelines provide threshold values for various parameters, indicating acceptable levels of contamination. For example, the SQGs may specify that the concentration of a certain heavy metal in sediment should not exceed a certain limit to maintain ecological health. By comparing the measured values of sediment properties and contaminant concentrations to the SQGs, scientists can assess the quality of the sediment and potential risks to aquatic life and ecosystems. The SQGs vary between regions and are specific to different sediment types and ecological conditions.

Check the following articles; they might be helpful:

https://doi.org/10.3389/feart.2021.658737

http://docsdrive.com/pdfs/sciencepublications/ajessp/2009/678-687.pdf

https://doi.org/10.1016/j.sciaf.2021.e01074

https://doi.org/10.1177/ASWR.S10081

Research Comparison Study of Produced Water Treatment Using Electroco...

Sediment quality guidelines are very useful to screen sediment contamination by comparing sediment contaminant concentration with sediment Quality Guidelines (SQGs) and sediments indices such as contamination factor, I geo and Ecological risk

most of the country has their own water quality standards but in our country we also follow united states health services.