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<td colspan="11">Table 3. Summary of Paleo-DO studies in the Chesapeake
Bay.</td>
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<td></td>
<td colspan="2"></td>
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<td><h2 id="study"><strong>Study</strong></h2></td>
<td colspan="2"><p><strong>Primary</strong></p>
<p><strong>Period</strong></p></td>
<td colspan="2"><p><strong>Resolution</strong></p>
<p><strong>Pre- 1700</strong></p></td>
<td><p><strong>Resolution</strong></p>
<p><strong>1700 -1900</strong></p></td>
<td><p><strong>Resolution</strong></p>
<p><strong>20th Century</strong></p></td>
<td><h1 id="area">Area</h1></td>
<td><p><strong>Water</strong></p>
<h1 id="depth">Depth</h1></td>
<td><h1 id="proxy">Proxy</h1></td>
<td><strong>Conclusions</strong></td>
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<td>Zimmerman and Canuel 2000</td>
<td colspan="2">1610 - 1996</td>
<td colspan="2">*/19 years</td>
<td>*/19 years</td>
<td><p>*/3 months –</p>
<p>4 years</p></td>
<td>Channel</td>
<td>15 m</td>
<td>AVS/CRS ratio, TOC, TN, BSi, S, Lipid biomarker</td>
<td>Major shift toward more reducing bottom water conditions occurred
1934-1948</td>
<td colspan="2"></td>
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<td>Adelson et al. 2001</td>
<td colspan="2">~1900 - 2000</td>
<td colspan="2">ND</td>
<td>ND</td>
<td>*/2-4 years</td>
<td>Flank of Chesapeake - Channel</td>
<td>2 – 45 m</td>
<td>Molybdenum concentration</td>
<td>Increased seasonal O<sub>2</sub> depletion since first half of
20<sup>th</sup> century</td>
<td colspan="2"></td>
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<td><p>Cooper and Brush 1991</p>
<p>4 Cores</p>
<p>2 Cores</p></td>
<td colspan="2"><p>1000 – 2000</p>
<p>100-2000</p></td>
<td colspan="2"><p>*/12.5-100 years</p>
<p>“</p></td>
<td><p>*/3.4-100 years</p>
<p>“</p></td>
<td><p>*/5-38 years</p>
<p>“</p></td>
<td><p>Channel</p>
<p>“</p></td>
<td><p>9.1-15.2 m</p>
<p>“</p></td>
<td><p>Pollen, Diatoms, TOC, Degree of pyritization, S, N, acid-soluble
iron</p>
<p>“</p></td>
<td><p>Anoxic conditions have increased since ~1760</p>
<p>Due to land clearance which increased freshwater input</p>
<p>“</p></td>
<td colspan="2"></td>
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<td>Cornwell et al. 1996</td>
<td colspan="2">1880 -2000</td>
<td colspan="2">ND</td>
<td>*/20 years</td>
<td>*/5 years</td>
<td>Channel</td>
<td>15 – 17.5 m</td>
<td>TN, OC, BSi, TP</td>
<td>ND</td>
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<td>Bratton et al. in press</td>
<td colspan="2">-685 - 1997</td>
<td colspan="2">*/ 8-50 years</td>
<td>*/5-40 years</td>
<td>*/2-33 years</td>
<td>Flank of Chesapeake - Channel</td>
<td>7.9 – 26.5 m</td>
<td>δ<sup>15</sup>N, δ<sup>13</sup>C, TN, TOC</td>
<td><p>Significant O<sub>2</sub> summer depletion occurred ~1750</p>
<p>Due to agricultural development</p>
<p>of watershed</p></td>
<td colspan="2"></td>
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<td>Willard et al. in press</td>
<td colspan="2">1700 - 2000</td>
<td colspan="2">ND</td>
<td>*/2.8-20 years</td>
<td>*/2-6.8 years</td>
<td>Flank of Chesapeake - Channel</td>
<td>10 – 26.5 m</td>
<td>Dinocyst Assemblage</td>
<td><p>Before early 17<sup>th</sup> century colonization</p>
<p>Due to climate factors</p></td>
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<td><p>Cooper 1995</p>
<p>4 Cores</p>
<p>2 Cores</p></td>
<td colspan="2"><p>1000 – 2000</p>
<p>“</p></td>
<td colspan="2"><p>*/12.5-100 years</p>
<p>“</p></td>
<td><p>*/3.4-100 years</p>
<p>“</p></td>
<td><p>*/5-38 years</p>
<p>“</p></td>
<td><p>Flank of Chesapeake – Channel</p>
<p>“</p></td>
<td><p>9.1 – 15.2 m</p>
<p>“</p></td>
<td><p>Diatoms, Pollen, BSi, Centric/pennate ratios, diatom assemblages
(cluster analysis)</p>
<p>“</p></td>
<td><p>Anoxia has increased since</p>
<p>~1760. Due to land clearance which increased freshwater</p>
<p>input, turbidity, eutrophication</p>
<p>“</p></td>
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<td>Karlsen et al. 2000</td>
<td colspan="2">1500 - 2000</td>
<td colspan="2">*/4 years</td>
<td>*/4 years</td>
<td>*/2 years</td>
<td>Flank of Chesapeake - Channel</td>
<td>5 – 30 m</td>
<td>Foraminifera Assemblage</td>
<td><p>Parts of 17<sup>th</sup> century experienced limited
O<sub>2</sub> depletion</p>
<p>Due to climatological factors (precipitation) and river
discharge</p></td>
<td colspan="2"></td>
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<td colspan="5"><p>* 1 sample</p>
<p>AVS = iron monoside (FeS)</p>
<p>CRS = pyrite and elemental sulfur (FeS<sub>2</sub> andS°)</p>
<p>TN = total nitrogen</p>
<p>TOC = total organic carbon</p>
<p>BSi = biogenic silica</p>
<p>S = sulfur</p>
<p>N = nitrogen</p>
<p>OC = organic carbon</p>
<p>TP = total phosphorus</p>
<p>ND = no data</p></td>
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