Sediment Quality in the Sediment Quality in the Corpus Christi BayCorpus Christi Bay

Natalie BartoshNatalie BartoshGIS in Water Resources, Fall 2003GIS in Water Resources, Fall 2003

Dr. Maidment, The University of Texas AustinDr. Maidment, The University of Texas Austin

Corpus Christi Bay is the gateway to the Corpus Christi Bay is the gateway to the nation’s sixth largest port and the third nation’s sixth largest port and the third largest refinery and petrochemical largest refinery and petrochemical complex.complex.

Coastal Bend refineries have the combined Coastal Bend refineries have the combined capacity to process more than 700,000 capacity to process more than 700,000 barrels per day of crude oil, accounting for barrels per day of crude oil, accounting for approximately 13 percent of Texas approximately 13 percent of Texas production and 5 percent of the U.S. total.production and 5 percent of the U.S. total.

The number of oil and chemical spills has The number of oil and chemical spills has decreased since about 1990, primarily due decreased since about 1990, primarily due to the enactment of the Oil Pollution Act of to the enactment of the Oil Pollution Act of 1990 which imposed new requirements for 1990 which imposed new requirements for vessel construction, crew licensing, and vessel construction, crew licensing, and financial responsibility for damages.financial responsibility for damages.

Oil and petrochemicals make up more than Oil and petrochemicals make up more than 90 percent of the cargo tonnage moved by 90 percent of the cargo tonnage moved by ship and barge on the waters of the Coastal ship and barge on the waters of the Coastal Bend Bays. Bend Bays.

In addition to petroleum refining, the bay is In addition to petroleum refining, the bay is heavily used for commercial and heavily used for commercial and recreational shrimping and fishing.recreational shrimping and fishing.

Importance of Good Sediment QualityImportance of Good Sediment Quality Sediment quality is important because Sediment quality is important because

sediments are a ‘sink’ or repository for sediments are a ‘sink’ or repository for pollutants such as metals and pesticides. pollutants such as metals and pesticides.

Sediments accumulate and concentrate Sediments accumulate and concentrate pollutants over a long period of time. When pollutants over a long period of time. When activities such as dredging disturb activities such as dredging disturb contaminated sediments the result can be a contaminated sediments the result can be a reintroduction of pollutants into the water reintroduction of pollutants into the water column.column.

Many factors contribute to water and Many factors contribute to water and sediment quality. In addition tosediment quality. In addition to

discharges from municipal and industrial discharges from municipal and industrial wastewater treatment plants (point wastewater treatment plants (point sources), we must also consider the diffuse sources), we must also consider the diffuse runoff from urban and rural areas (nonpoint runoff from urban and rural areas (nonpoint sources).sources).

The question then becomes, “How do I The question then becomes, “How do I effectively model the quality of the effectively model the quality of the sediments in the Corpus Christi Bay?”sediments in the Corpus Christi Bay?”

Answer: Via the use of the Environmental Answer: Via the use of the Environmental Protection Agency’s (EPA) Regional Protection Agency’s (EPA) Regional Environmental Monitoring and Assessment Environmental Monitoring and Assessment Program (REMAP).Program (REMAP).

REMAPREMAP REMAP is an EPA program REMAP is an EPA program

designed to use environmental designed to use environmental monitoring data from multiple monitoring data from multiple spatial and temporal scales to spatial and temporal scales to assess ecological conditions and assess ecological conditions and forecast potential risk to our natural forecast potential risk to our natural resources. resources.

The Texas Coastal Region REMAP The Texas Coastal Region REMAP Project consisted of 109 random Project consisted of 109 random testing locations over the length of testing locations over the length of the Texas Coast.the Texas Coast.

The Corpus Christi Bay included 52 The Corpus Christi Bay included 52 locations in which data was taken locations in which data was taken from 1993-1994.from 1993-1994.

The recorded data included top and The recorded data included top and bottom water quality, sediment bottom water quality, sediment grain composition and chemistry, grain composition and chemistry, and fish species.and fish species.

Sediment ChemistrySediment Chemistry

826 chemical species were 826 chemical species were measured at each locationmeasured at each location

The task then became a need The task then became a need to narrow down the list to a few to narrow down the list to a few select species that would tell select species that would tell the most about the quality of the most about the quality of the sediment.the sediment.

The following metals were The following metals were chosen for analysis:chosen for analysis:

Arsenic, Chromium, Copper, Arsenic, Chromium, Copper, Lead, Mercury and Zinc.Lead, Mercury and Zinc.

Comparison of the MetalsComparison of the Metals

Zinc Lead

Comparison of the Metals, Cont’d.Comparison of the Metals, Cont’d.

Copper Chromium

Comparison of the Metals, Cont’d.Comparison of the Metals, Cont’d.

ArsenicMercury

Analysis of Sediment DataAnalysis of Sediment Data Effects Range – Low (ER-L): Effects Range – Low (ER-L):

Concentration of a chemical in Concentration of a chemical in sediment below which toxic effects sediment below which toxic effects are rarely observed among are rarely observed among sensitive species. sensitive species.

As the table indicates, the only As the table indicates, the only metals to be concerned about (at metals to be concerned about (at least for now) are Mercury and least for now) are Mercury and Zinc.Zinc.

Metals ER-L ER-MValue -

LowValue - High

Arsenic 8.2 70.0 1.2 13

Chromium 81.0 370.0 4.1 58.8

Copper 34.0 270.0 2.8 55.2

Lead 46.7 218.0 3.6 39

Mercury 0.2 0.7 0.001 0.505

Zinc 150.0 410.0 12.9 802.2

Frequency of DetectionFrequency of Detection The frequency at which a given The frequency at which a given

chemical or chemical group is chemical or chemical group is responsible for sites in the NSI being responsible for sites in the NSI being categorized as Tier 1 or Tier 2 is often categorized as Tier 1 or Tier 2 is often a reflection of the number of times that a reflection of the number of times that chemical is measured and detected in chemical is measured and detected in sediment samples. sediment samples.

Thus, chemicals that are measured Thus, chemicals that are measured and detected less frequently might not and detected less frequently might not often be identified as posing a often be identified as posing a potential risk to aquatic life or human potential risk to aquatic life or human health, even though the chemical is health, even though the chemical is highly toxic.highly toxic.

Metal

Number of Times

Measured in

Sediment

Number of Positive

Sediment Results

Number of Times

Measured in Tissue

Number of Positive Tissue

Results

Tier 1 Level

Results

Tier 2 Level

Results

Arsenic 22281 18791 5528 2113 189 8613Chromium 27504 25216 5508 3283 426 4126Copper 27956 25452 6284 5533 - 11213Lead 29979 24971 6654 3008 - 8883Mercury 26142 16632 9752 8424 1951 5049Zinc 27065 26473 4580 4553 - 5176

Future WorkFuture Work

Reading through an analysis of the Corpus Christi Bay entitled: Reading through an analysis of the Corpus Christi Bay entitled:

Current Status and Historical Trends of Ambient Water, Sediment, Fish and Current Status and Historical Trends of Ambient Water, Sediment, Fish and Shellfish Tissue Quality in the Corpus Christi Bay National Estuary Program Shellfish Tissue Quality in the Corpus Christi Bay National Estuary Program Study Area (summary report). Ward, G.H. and N.E. Armstrong. 1997. Study Area (summary report). Ward, G.H. and N.E. Armstrong. 1997.

This paper will hopefully give me insight as to the numbers I have seen in This paper will hopefully give me insight as to the numbers I have seen in my comparisons of the metals and help me to make an educated my comparisons of the metals and help me to make an educated assessment of the bay.assessment of the bay.

My next step is to use the GIS kriging tools to better evaluate the My next step is to use the GIS kriging tools to better evaluate the concentrations of the metals in the bay.concentrations of the metals in the bay.

References and ThanksReferences and Thanks Ken Dunton of the UT Marine Science Institute in Port Aransas, TxKen Dunton of the UT Marine Science Institute in Port Aransas, Tx

The Coastal Bend Bays Plan, August 1998.The Coastal Bend Bays Plan, August 1998.

http://www.sci.tamucc.edu/ccbnep/Home/Plan/cbbin.pdfhttp://www.sci.tamucc.edu/ccbnep/Home/Plan/cbbin.pdf

EPA REMAP EPA REMAP http://www.epa.gov/nerleerd/emapremap.htmhttp://www.epa.gov/nerleerd/emapremap.htm

EPA National Sediment Quality Survey EPA National Sediment Quality Survey http://www.epa.gov/waterscience/cs/vol1/appdx_d.pdfhttp://www.epa.gov/waterscience/cs/vol1/appdx_d.pdf

Dr. MaidmentDr. Maidment

Questions?Questions?