1. Chemical Analysis of Fat Particles Mike Delaney, MWRA Outfall Monitoring Science Advisory Panel April 1, 2013
Update on Outfall monitoring for 2005, focus on findings

3. Chemical Analysis of Fat Particles
Chemical Analytes and Methods
Results – focusing on detects
Loadings – what fraction of total is from fat particles

4. Chemical Analytes and Methods
Total and Volatile Solids
Mercury
21 Chlorinated Pesticides
20 Polychlorinated Biphenyl (PCB) congeners
48 Polycyclic Aromatic Hydrocarbons (PAH) including alkyl homologues
Chemical analysis methods were similar to the routine methods used by MWRA on effluent samples and fertilizer pellets, adapted for the fat particle matrix.
Cold Vapor Atomic Absorption Spectrometry for Mercury
Selected Ion Monitoring Gas Chromatography – Mass Spectrometry for Organics (SIM GC-MS)

5. Solids and Mercury Results
Total Solids: 39.4 – 51.8 %
Volatile Solids: 89.4 – 94.0 % of TS
Mercury: < mg/kg dry weight (ppm)

6. Chlorinated Pesticide Results
Detected Pesticides (Maximum, ug/kg dry weight): (ppb)
2,4’-DDD: 22.0
4,4’-DDD: 38.2
4,4’-DDT: 41.0
alpha-Chlordane: 23.2
cis-Nonachlor: 1.74
gamma-Chlordane: 59.1
Hexachlorobenzene: 1.46
trans-Nonachlor: 12.8

7. PCB Results Detected PCBs (Maximum, ug/kg dry weight): (ppb)
BZ 44 Tetrachlorobiphenyl: 13.1
BZ 52 Tetrachlorobiphenyl: 26.5
BZ 66 Tetrachlorobiphenyl: 9.35
BZ 101 Pentachlorobiphenyl: 35.6
BZ 105 Pentachlorobiphenyl: 9.91
BZ 118 Pentachlorobiphenyl: 25.3
BZ 138 Hexachlorobiphenyl: 16.1
BZ 153 Hexachlorobiphenyl: 12.6
BZ 180 Heptachlorobiphenyl: 13.2
BZ 187 Heptachlorobiphenyl: 6.55
Total AMP PCBs: 155

8. PAH Results Most PAH were detected.
Highest unsubstituted PAH (Maximum, ug/kg dry weight): (ppb)
Phenanthrene: 2070
Naphthalene: 1100
Biphenyl: 681
Acenaphthene: 645
Fluoranthene: 644
Pyrene: 638

9. Toxic Load from Fat Particles
DITP effluent on average 32 ppb by weight (mg/kg) floatables.
14% non-degradable floatables (e.g. plastic fruit labels).
86% degradable floatables (e.g. fat particles and plant matter).
Based on a mean daily flow of 380 million gallons from the plant it is estimated that 39 kg of degradable floatables would enter Massachusetts Bay each day from the DITP effluent.
To be conservative, the following calculations assume that all the degradable material is in the form of fat particles.

10. Mercury
Mercury: highest result for these fat particles (0.196 mg/kg dry) would correspond to about 7.8 milligrams of mercury per day.
DITP discharges about 10.2 grams of mercury per day.
So the fraction of mercury loading to Massachusetts Bay from these fat particles is only at most about 0.08% of the total loading.

11. Alpha-Chlordane
Alpha-Chlordane: highest result for these fat particles would correspond to about 0.89 milligrams of mercury per day.
DITP discharges about 1.3 grams of alpha-Chlordane per day.
So the fraction of alpha-Chlordane loading to Massachusetts Bay from these fat particles is only at most about 0.07% of the total loading.

12. PCBs
Total AMP PCBs: highest result for these fat particles corresponds to about 6.0 milligrams of Total AMP PCB per day.
DITP discharges about 1.4 grams of Total AMP PCB per day.
So the fraction of Total AMP PCB loading to Massachusetts Bay from these fat particles is only at most about 0.4% of the total loading.

13. PAH
The PAH compounds were observed at higher concentrations than for the pesticides and PCBs.
The highest result for a single PAH was 1-Methylnaphthalene at 2,830 mg/kg, which corresponds to a fat particle loading of 0.11 g/day compared to the total effluent loading of 3.9 g/day. So, fat particles are conservatively estimated to comprise 2.8% of the total loading of PAH.

14. Summary
Mercury, certain chlorinated Pesticides, PCBs, and PAHs were detected at low concentrations in wet-weather tow fat particles.
Overall even worst case after blending during wet weather, the fat particles appear to constitute only a small fraction of already-low total DITP effluent contaminant loadings to Massachusetts Bay.