WQ - Analysis/Equations

pH Hydronium concentration

pH = - log[H3O] OR pH = - log[H] (H3O is hydronium, and both H3O and H must be in molarity.) To find H3O or H from pH : molarity of H3O = 10^-pH molarity of H = 10^-pH E.g., if pH is 8, then your equation will be 10^-8 (pay attention to the negative sign!)

Turbidity

Turbidity=(2.3xA)/L A = absorbance, as measured by a spectrophotometer etc. L = optical path length, in cm (Unit is in cm^-1.) If too turbid (>40NTU), and was diluted : Turbidity = (Td x (Vw+Vo))/Vo Where Td = turbidity of diluted sample in NTU Vw = mL of diluted sample Vo = mL of original sample

DO

After winklter titrating : D.O. in mg/L = (vxNx8x1000)/V Where: V = Volume of sample taken (ml) v = Volume of used titrant (ml) N = Normality of titrant (equal to molarity; for a 200mL sample, it’s=0.025).

BOD

If the sample was unseeded (aka no extra bacteria added) : BOD in mg/L = (DO1 - DO2)xP Where DO1 = mg/L of DO at start of 5-day period DO2 = mg/L of DO at end of 5-day period P = dilution factor = Total volume (sample + water)/volume of sample If the sample was seeded (aka extra bacteria added) : BOD in mg/L = ((DO1 – DO2) – (B1 – B2)x f)/P Where B1 = DO of bacterial seed control at start of 5-day period (in mg/L) B2 = DO of bacterial seed control at end of 5-day period (in mg/L) f = % bacterial seed in the sample /% in the control P = dilution factor = Total volume (sample + water)/volume of sample

Salinity

After EC meter-ing : Salinity (ppt) = EC (in uS/cm per L)x0.00064 Generally : Salinity = Grams of salt/kilograms of total solution

Temp Conversions

Conversion of C to F : F = (Cx9/5) +32 Conversion of F to C: C= (F-32)x5/9

Fecal coliform

FC per 100mL = (# of colonies counted/volume of sample filtered) x100

Nitrates Conversions

Conversion from Nitrate-nitrogen (NO3-N) : Nitrate = Nitrate nitrogenx4.43 Conversion to Nitrate-nitrogen (NO3-N ): Nitrate nitrogen = nitrates x 0.0226

Total solids

((Wfinal - Winitial)x10^6)/Vsample Where Wfinal = Dish w/dried residue Winitial = Clean dish Vsample = sample volume (Liters)

Hardness

Hardness = (2.497x[Ca]) + (4.118 x[Mg]) Ca and Mg must be in molarity.

Phosphates

y = 0.0522x + 0.028 where: Y = absorbance X = phosphate concentration.

Bankfull Discharge

Where: n = Manning's coefficient A = Channel's area (in square feet) R = The hydraulic radius (in feet) S = Energy gradient/slope (legit rise over run)

Manning' s coefficient

Henderson–hasselbalch equation

pH=pKa+log([A-]/[HA]) Where: pKa = The -log of Ka, the acid ionization constant for acid. For pKa, low value=more acidic. For carbonate systems, pKa1 (the one w/ H2CO3)=6.3; pKa2 (the one w/ CO^2-/3) =10.3. A- = The molar concentration of the base HA = The molar concentration of the acid