A Interrelationships Among Water Testing Parameters in Environmental Monitoring
Relationship Between Hexavalent Chromium and Total Chromium
Chromium in water typically exists as trivalent and hexavalent forms, which can convert under certain conditions. Total chromium is the sum of trivalent and hexavalent chromium. Therefore, for the same water sample, the following logical relationship holds:
Total Chromium > Hexavalent Chromium
Relationship Between Sulfides and Heavy Metals
In the same water sample, high sulfide concentrations correlate with lower concentrations of heavy metals (Cu, Pb, Zn, Cd, etc.). However, this relationship may not hold if heavy metals exist in complexed forms.
Relationship Between Total Bacteria Count, Coliform Bacteria, and Fecal Coliform Bacteria
Coliform bacteria represent only one population among bacterial species and have limited contamination pathways. Long-term testing indicates that samples detecting coliform bacteria also detect total bacteria count. Conversely, samples with high total bacteria counts do not necessarily detect total coliform bacteria. Fecal coliform bacteria belong to the total coliform group and are detected at 44.5°C, which is higher than the 37°C detection temperature for total coliform bacteria. Therefore, fecal coliform values are typically lower than total coliform values, i.e., fecal coliform value < total coliform value.