Supporting Information: text, 4 tables, 1 figure

Methylmercury bioaccumulation in an urban estuary: Delaware River USA

Kate Buckmana*, Vivien Taylorb, Hannah Broadleya†, Daniel Hockingc, Prentiss Balcomdf, Rob Masond, Keith Nislowe, Celia Chena*

aDepartment of Biological Sciences, Dartmouth College, Hanover NH; bDepartment of Earth Sciences, Dartmouth College, Hanover NH; cDepartment of Biology, Frostburg State University, Frostburg MD; dDepartment of Marine Sciences, University of Connecticut, Groton CT; eNorthern Research Station, USDA Forest Service, Amherst MA; f Harvard John A. Paulson School of Engineering and Applied Sciences, Cambridge MA

†current address: Biology Department, University of Massachusetts, Amherst, MA

*Corresponding Authors:

, phone: 603-646-8768

, phone: 603-646-2376

QA/QC:

Sediment and water:

The average relative percent difference (RPD) for HgT preparation and analytical duplicates was 7% (n=14) for water column samples, and aqueous standard recoveries averaged 101% (n=18, RSD=4%). The average RPD was 8% (n=46) for sediment HgT analytical duplicates, and sediment standard reference material recoveries averaged 99% for both NRCC PACS-3 (n=12, RSD=2%) & MESS-3 (n=52, RSD=9%). HgT method detection limits (MDLs) were 0.26 pM for water analyses, 1.4 pM for particulate analyses, and 0.09 nmol g-1 for sediment analyses.

Water column MeHg sample averages were 93% (n=12, RSD=15%) for distillation spike recoveries, 96% (n=13, RSD=12%) for aqueous standard recoveries, and 16% (RPD, n=11) for distillation duplicates. Sediment sample averages were 101% (n=16, RSD=31%) for distillation spike recoveries, 94 to 109% (n=17 to 53, RSD=13 to 16%) for aqueous standard recoveries, and 12% (RPD, n=21) for distillation duplicates. MDLs were 0.05 pM for water analyses, 0.12 pM for particulate analyses, and 0.02 pmol g-1 for sediment analyses.

Biota:

Method detection limits were 2ng/g for MeHg and 10 ng/g for iHg. Standard reference materials (NRCC TORT-2 lobster hepatopancreas, NIST-2976 mussel, NRCC DORM-4 dogfish muscle, and NIST-1566b oyster), duplicates and fortified blanks were used for quality control. Average recovery for TORT-2 was 115% (n=3, rsd=4.8%) for MeHg and 111% (n=3, rsd=1.3%) of THg, MeHg 87% (n=2, rsd=5.3%) and THg 92% (n=2, rsd=3.3%) for NIST-2976, MeHg 95% (n=4, rsd=1.7%) and THg 101% (n=4, rsd=1%) for DORM-4, and NIST-1566b recovery was 117% (n=4, rsd=7.6%) for MeHg and 84% (n=4, rsd=10.9%) for THg. Analytical duplicate average relative percent difference was 4% for MeHg (n=13) and 8% for iHg (n=3 above detection limit). Average spike recovery was 99% (n=13, rsd=2.5%) for MeHg and 112% (n=13, rsd=5.9%) for iHg.

Table S1: location of sampling sites and percent land cover estimates.

development intensity / forest / wetland
latitude
(degrees) / longitude
(degrees) / low
(%) / medium
(%) / high
(%) / deciduous
(%) / mixed
(%) / woody
(%) / ermergent herbaceous (%)
Penn Treaty / 39.965446 / -75.129447 / 2.0 / 28.4 / 29.0 / 0.2 / 0 / 0 / 0.1
Timber Blvd. / 39.880366 / -75.126942 / 22.6 / 18.4 / 6.0 / 2.0 / 0 / 4.9 / 10.9
Gen Chem / 39.800624 / -75.438841 / 2.9 / 5.4 / 14.2 / 4.4 / 0 / 4.2 / 6.0
Luken’s Marsh / 39.685511 / -75.537554 / 4.0 / 9.8 / 8.8 / 2.2 / 0.2 / 2.2 / 14.7
South of Lukens / 39.673829 / -75.547903 / 7.6 / 8.6 / 10.9 / 3.1 / 0.4 / 1.2 / 8.8
Pennsville Landfill / 39.637828 / -75.547687 / 8.2 / 2.0 / 0 / 10.1 / 0.9 / 6.9 / 5.5
ButtonWood / 39.459469 / -75.508988 / 1.8 / 0.8 / 0.1 / 0 / 0 / 0.2 / 64.0
Sea Breeze / 39.318784 / -75.318121 / 3.6 / 1.7 / 0.2 / 0 / 0 / 0 / 47.0
Fortescue / 39.222818 / -75.165954 / 1.4 / 0.7 / 0.3 / 0 / 0 / 0 / 48.6
North Beach / 39.127372 / -74.888144 / 3.0 / 0.8 / 0 / 0 / 0 / 0.8 / 49.8

Table S2: Range, mean ± st. dev., and (n) of sediment THg, MeHg, and %LOI by site. Top 4cm averages consist of the top two sections of two replicate cores.

grab THg (ng/g DW) / grab %LOI / top 4cm avg THg (ng/g ) / top 4cm avg MeHg (ng/g) / top 4cm avg %LOI / top 4cm avg %MeHg
PT / 195-372
272±50
(18) / 6.8-12.1
9.6±1.2
(18) / 228±27 / 1.57±0.34 / 7.7±0.6 / 0.69±1.3
TB / 17.4-183
75.9±52.1
(20) / 0.51-13.5
2.6±3.0
(20) / 125±45 / 0.37±0.28 / 4.0±2.5 / 0.30±0.61
GC / 66.7-338
259±72.0
(20) / 5.56-11.7
8.7±1.4
(20) / 275±17 / 1.51±0.19 / 7.6±0.6 / 0.55±1.1
LM / 255-1966
628±415
(20) / 4.9-16
8.5±2.5
(20) / 246±48 / 0.83±0.32 / 6.3±0.9 / 0.34±0.67
SL / 37-830
322±224
(20) / 0.96-11
4.6±3.1
(20) / 183±35 / 0.80±0.67 / 7.2±0.2 / 0.44±1.9
PL / 7.1-1452
281±428
(20) / 0.33-12.1
3.6±4.3
(20) / 133±139 / 0.24±0.27 / 4.1±4.1 / 0.18±0.20
BW / 4.5-419
110± 129
(20) / 0.48-71
23±27
(20) / 132±145 / 4.90±4.88 / 11.0±8.0 / 3.7±3.4
SB / 1.4-402
70±103
(18) / 0.31-15
6.8±5.6
(18) / 61±28 / 2.81±1.96 / 6.7±3.0 / 4.6±7.0
FS / 1.4-166
69±59
(20) / 0.2-16
7.0±5.9
(20) / 20±6.2 / 0.23±0.21 / 10.1±4.2 / 1.1±3.4
NB / 10.7-321
53±70
(19) / 0.7-21
8.7±5.3
(19) / 26±0.82 / 0.08±0.10 / 14.9±3 / 0.32±12.2

PT=Penn Treaty, TB= Timber Blvd., GC= Gen Chem, LM=Luken’s Marsh, SL=South of Lukens, PL=Pennsville Landfill, BW=Buttonwood, SB=Sea Breeze, FS=Fortescue, and NB=North Beach.

Table S3: Significant sediment correlations within grab samples as assessed by Spearman’s rank.

variable 1 / variable 2 / site / spearman’s rho / p
THg / %LOI / all combined / 0.51 / <0.0001
THg / %LOI / Timber Blvd / 0.91 / <0.0001
THg / %LOI / Gen Chem / 0.80 / <0.0001
THg / %LOI / Luken’s Marsh / 0.46 / 0.04
THg / %LOI / Pennsville Landfill / 0.92 / <0.0001
THg / %LOI / Buttonwood / 0.86 / <0.0001
THg / %LOI / Fortescue / 0.94 / <0.0001
THg / %LOI / SeaBreeze / 0.71 / 0.001

Table S4:Mean ± st. dev. ofbiota MeHg tissue concentration (ng/g DW) and length (mm) data for all species. MeHg,length, (n).

mummichog / banded killifish / blue crab / grass shrimp / striped bass - muscle / white perch- whole / white perch - muscle / croaker / clam1 / eel / fiddler crab / silverside / mussel2
PT / 208
82 (1) / 99±39
66±6 (4) / 64±7
38±2 (3) / 29±5
22±1 (3) / 111±16
65±9 (3)
TB / 49±27
69±8 (4) / 67±14
65±3 (5) / 25±1
21±3 (3) / 95±29
60±3 (3)
GC / 50±8
43±4 (3) / 16±14
49±5 (3) / 19±7
40±4 (3) / 485
148 (1) / 81±11
79±6 (3) / 375±87
153±21 (3) / 17±4
20± 5(3)
LM / 123±57
67±5 (7) / 93
58 (1) / 35±29
40±5 (3) / 461±55
156±35 (4) / 122±21
90±5 (3) / 973±508
196±27 (3) / 32±2
97±15
(3)
SL / 94±33
65±8 (7) / 166±54
64±4 (7) / 21±4
48±5 (3) / 24±7
41±6 (3) / 457±174
153±8 (3) / 46±48
7±16 (3) / 395±215
147±4 (3) / 105±20
98±7 (3) / 32±14
12±2 (3)
PL / 91±23
68±4 (6) / 28±10
50±13 (3) / 16±4
43±6 (3) / 35±20
88±12 (3) / 11±1
11±2
(3) / 65±11
60±3
(3)
BW / 61±16
74±7 (4) / 22±26
37±1 (3) / 277±57
125±18(2) / 45±10
93±8 (2) / 25±6
95±3
(3) / 97
109
(1)
SB / 39
78 (1) / 49±30
54±8 (6) / 24±18
46±3 (3) / 46±23
35±2 (3) / 131±84
134±8 (4) / 24±8
128±9
(3) / 10±4
12±1
(3) / 59±12
59±2
(3) / 23±1
24±3 (3)
FS / 48±7
64±7 (6) / 38±17
59±11 (6) / 14±7
46±10 (3) / 32±8
38±4 (3) / 13±0.3
12±2 (3) / 70±40
63±2
(3) / 42±3
32±2 (3)
NB / 39±19
61±4 (6) / 55±11*
57±12 (3) / 43±14
51±6 (3) / 63±18
35±2 (3) / 78±7
89±11 (3) / 46±8
100±15
(3) / 21±15
12±1 (3) / 61±10
60±1
(3) / 33±7
32±2 (3)

1Corbicula fluminea 2Geukensia demissa

*one outlier at 489 ng/g DW MeHg concentration was excluded from analyses

PT=Penn Treaty, TB= Timber Blvd., GC= Gen Chem, LM=Luken’s Marsh, SL=South of Lukens, PL=Pennsville Landfill, BW=Buttonwood, SB=Sea Breeze, FS=Fortescue, and NB=North Beach.

Figure S1: Mean ± st, dev of %MeHg in grass shrimp.