An Assessment of Sediment Metals Data from the Delaware Estuary ...
An Assessment of Sediment Metals Data from the Delaware Estuary Benthic Inventory (DEBI)
Rick Greene Delaware DNREC February 1, 2011
Presentation Outline
Background on DEBI Questions i addressed dd d using i the h metals l data d Data assessment methods Findings Recommendations
Delaware Estuary Benthic Inventory
Circa. 2005, scientists and resource managers identified need to better characterize & understand the benthic environment of the Delaware Estuary.
Benthic: “of, relating to, or occurring at the bottom of a body of water ..” (i.e., aquatic sediments and their physical, chemical, & biological attributes).
To meet the need, need a major field survey s r e was as undertaken ndertaken in 2008 - one component involved collection & analysis of metals & PCBs in sediments. No tox tests.
Delaware requested the draft data from PDE to better inform a pressing i managementt decision d i i (main ( i channel h l deepening). d i )
DEBI Sampling & Analysis Field e d Work: Wo :
Led by PDE & EPA 3, with assistance from many others Sampling from EPA’s R/V Lear 7/9/2008 – 9/12/2008 227 sub-tidal estuarine stations, South Philadelphia to Capes based on a random stratified design Ponar grabs collected surface sediment
Laboratory:
Conducted by EPA 3 Fort Meade, MD lab 15 metals plus grain size Methods: 200.7 (ICP-AES); 200.8 (ICP-MS); and 245.5 (CV-AA). Total, hot acid digestion not performed. Results reflect labile, readily extractable metal, not total.
DEBI Sediment Sampling Sites DRBC Zones Zone 3 to upper 5 urban/industrial Main Navigation Channel
Zone 6 agriculture/ Z i lt / rural/marsh
Questions
Do metals in the sediments of the Delaware Estuary pose a significant risk to benthic aquatic life? This is a baseline, predredging question.
Does deepening/dredging the main navigation channel mobilize metals to the water column & create acutely toxic, potential lethal conditions in the turbidity plume near the dredge?
What is the fate of metals excavated during channel deepening & does d the th release l near the th dredge d d + return t flows fl from f the th CDF cause broader scale violations of chronic aquatic life criteria & human health criteria?
Data Assessment: InIn-place Sediments
Plot the data, look for spatial patterns & correlations.
Use equilibrium partitioning (EqP) to predict dissolved metal concentrations t ti in i sediment di t pore water t (dissolved (di l d metal t l is i better b tt measure of bioavailability & therefore toxicity).
Calculate toxic units (TUs) as ratio of predicted dissolved metal conc. to dissolved aquatic life criterion. When ∑ T.U.s > 1 for divalent metals, there’s potential toxicity to benthic aquatic life.
DID NOT compare sediment conc. conc to SQGs (e.g., (e g ERLs ERLs, ERMs, ERMs AETs, TELs, PELs, etc). Also, DID NOT compare to other datasets (e.g., NOAA, EMAP, USGS) since analytical method were different.
Copper in Sediment & Surface Water
Concentration highest in upper zone 5 Higher towards shore Significant relationship with silt clay fraction (p
Rick Greene Delaware DNREC February 1, 2011
Presentation Outline
Background on DEBI Questions i addressed dd d using i the h metals l data d Data assessment methods Findings Recommendations
Delaware Estuary Benthic Inventory
Circa. 2005, scientists and resource managers identified need to better characterize & understand the benthic environment of the Delaware Estuary.
Benthic: “of, relating to, or occurring at the bottom of a body of water ..” (i.e., aquatic sediments and their physical, chemical, & biological attributes).
To meet the need, need a major field survey s r e was as undertaken ndertaken in 2008 - one component involved collection & analysis of metals & PCBs in sediments. No tox tests.
Delaware requested the draft data from PDE to better inform a pressing i managementt decision d i i (main ( i channel h l deepening). d i )
DEBI Sampling & Analysis Field e d Work: Wo :
Led by PDE & EPA 3, with assistance from many others Sampling from EPA’s R/V Lear 7/9/2008 – 9/12/2008 227 sub-tidal estuarine stations, South Philadelphia to Capes based on a random stratified design Ponar grabs collected surface sediment
Laboratory:
Conducted by EPA 3 Fort Meade, MD lab 15 metals plus grain size Methods: 200.7 (ICP-AES); 200.8 (ICP-MS); and 245.5 (CV-AA). Total, hot acid digestion not performed. Results reflect labile, readily extractable metal, not total.
DEBI Sediment Sampling Sites DRBC Zones Zone 3 to upper 5 urban/industrial Main Navigation Channel
Zone 6 agriculture/ Z i lt / rural/marsh
Questions
Do metals in the sediments of the Delaware Estuary pose a significant risk to benthic aquatic life? This is a baseline, predredging question.
Does deepening/dredging the main navigation channel mobilize metals to the water column & create acutely toxic, potential lethal conditions in the turbidity plume near the dredge?
What is the fate of metals excavated during channel deepening & does d the th release l near the th dredge d d + return t flows fl from f the th CDF cause broader scale violations of chronic aquatic life criteria & human health criteria?
Data Assessment: InIn-place Sediments
Plot the data, look for spatial patterns & correlations.
Use equilibrium partitioning (EqP) to predict dissolved metal concentrations t ti in i sediment di t pore water t (dissolved (di l d metal t l is i better b tt measure of bioavailability & therefore toxicity).
Calculate toxic units (TUs) as ratio of predicted dissolved metal conc. to dissolved aquatic life criterion. When ∑ T.U.s > 1 for divalent metals, there’s potential toxicity to benthic aquatic life.
DID NOT compare sediment conc. conc to SQGs (e.g., (e g ERLs ERLs, ERMs, ERMs AETs, TELs, PELs, etc). Also, DID NOT compare to other datasets (e.g., NOAA, EMAP, USGS) since analytical method were different.
Copper in Sediment & Surface Water
Concentration highest in upper zone 5 Higher towards shore Significant relationship with silt clay fraction (p
