1.1 MB pdf - Bolsa Chica Lowlands Restoration Project
1.1 MB pdf - Bolsa Chica Lowlands Restoration Project 1.1 MB pdf - Bolsa Chica Lowlands Restoration Project
SECTION 3: ANALYSIS Summaries of total (i.e., sum over all pathways) and partial (pathway-specific) exposure estimates are presented and compared to toxicity values in Section 4.1. Life History Parameters The specific life history parameters required to estimate exposure of each receptor to COPECs include body weight, ingestion rates of food and water, dietary components and percentage of the overall diet represented by each major food type, and approximate amount of soil and/or sediment that may be incidentally ingested based on feeding habits. These parameters were obtained primarily from the literature and are presented in Table 3-11. Bioaccumulation Factors A critical component for the estimation of external exposure of birds and mammals is measurements of concentrations of COPECs in wildlife foods. The most preferred data are direct measurements of concentrations in samples collected from the field. Available data for concentrations of COPECs in wildlife foods collected from the Lowlands were summarized in Tables 3-4 through 3-9. Not all food types consumed by the selected avian and mammalian receptors, nor are all areas within the Lowlands represented. To allow estimation of exposure to COPECs for all receptors and locations within Bolsa Chica, estimation of concentrations of COPECs in wildlife foods was necessary. Bioaccumulation factors for each wildlife food type were developed based on site-specific data. Bioaccumulation factors were calculated where both abiotic (sediment/soil or water) and biotic (tissue concentrations) were available for each Cell. The median concentrations of each abiotic and biotic medium (presented in Tables 3-2 through 3-9) were combined within a given Cell and a Cell-specific bioaccumulation factor (BAF) was calculated using the following equation: BAF = tissue concentration abiotic medium concentration ( mg / kg) ( mg / kg) Where: BAF = chemical-specific bioaccumulation factor for a given receptor group Tissue concentration = chemical concentrations (mg/Kg) measured in terrestrial plants, terrestrial invertebrates, aquatic invertebrates, bird eggs, or small mammals collected from the Bolsa Chica Lowlands Abiotic medium concentration = chemical concentrations (mg/Kg) measured in sediment/soil or surface water collected from the Bolsa Chica Lowlands The BAFs for each receptor and chemical were then combined across all Cells and summarized as shown in Table 3-12 for sediment/soil and in Table 3-13 for surface water. The 90th percentile BAF for each chemical was then used in the food chain uptake model when direct measured tissue concentrations were not available for a given food item within a given evaluation area. SAC/143368(003.DOC) 3-23 ERA REPORT 7/31/02
SECTION 3: ANALYSIS 3.1.5 Exposure Profile The exposure profile establishes the linkage between stressors and receptors based on potential exposure under current and future conditions at the site. This linkage was established through identification of ecological receptors, identification of potential sources and spatial distribution of COPECs, calculation of exposure point concentrations for various exposure media and receptors based on the most likely exposure scenario for each species, and calculation of reasonable maximum daily dosages for chemical intake from abiotic and biotic sources by terrestrial and semi-aquatic birds and terrestrial mammals. For the Bolsa Chica Lowlands, the potential future exposure conditions may be more important than the current exposure conditions because the site will be restored to various upland, wetland, and estuarine/marine habitats that will attract a wide variety of wildlife. As such, the representative species selected for evaluation were those that currently use the site and are expected to occur there in the future. These species are summarized below: • Aquatic and semi-aquatic representative species − Plants — aquatic grasses and forbs − Invertebrates — benthic macroinvertebrates − Fish — mosquitofish, topsmelt, killifish, tilapia − Birds (semi-aquatic) — black-crowned night-heron, black-necked stilt, and least tern • Terrestrial/upland representative species − Plants — terrestrial grasses and forbs − Invertebrates (terrestrial) — insects and spiders − Birds (upland) — American kestrel and Belding’s savannah sparrow − Mammals — western harvest mouse and coyote The potential exposure pathways for current and future receptors were evaluated as part of the ecological conceptual site model (see Section 2.5). The representative species and exposure pathways evaluated in the ERA are based on the use of site-specific (fieldcollected) abiotic and biotic exposure media. These pathways are listed below: • Terrestrial plants – direct contact via root uptake from sediment/soil • Terrestrial invertebrates – direct contact and ingestion of sediment/soil • Terrestrial and semi-aquatic birds – ingestion of biota, sediment/soil, and surface water • Terrestrial mammals – ingestion of biota, sediment/soil, and surface water • Aquatic plants – direct contact and root uptake from sediment/soil and surface water • Aquatic macroinvertebrates – direct contact and ingestion of sediment/soil • Fish – direct contact and ingestion of surface water The primary sources of COPECs include oil and gas production, nonpoint source pollution, and historic farming and hunting activities on or near the site. Exposure point concentrations for abiotic (sediment/soil and surface water) and biotic (field-collected plants, invertebrates, bird eggs, small mammals, and fish) exposure media were calculated based on the most likely exposure area and pathways for selected representative species. Reasonable maximum daily dosages (presented in Section 4.1) were calculated for intake of the exposure media mentioned above by terrestrial and semi-aquatic birds and terrestrial mammals. ERA REPORT 3-24 SAC/143368(003.DOC) 7/31/02
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SECTION 3: ANALYSIS<br />
Summaries of total (i.e., sum over all pathways) and partial (pathway-specific) exposure<br />
estimates are presented and compared to toxicity values in Section 4.1.<br />
Life History Parameters<br />
The specific life history parameters required to estimate exposure of each receptor to<br />
COPECs include body weight, ingestion rates of food and water, dietary components and<br />
percentage of the overall diet represented by each major food type, and approximate amount<br />
of soil and/or sediment that may be incidentally ingested based on feeding habits. These<br />
parameters were obtained primarily from the literature and are presented in Table 3-11.<br />
Bioaccumulation Factors<br />
A critical component for the estimation of external exposure of birds and mammals is<br />
measurements of concentrations of COPECs in wildlife foods. The most preferred data are<br />
direct measurements of concentrations in samples collected from the field. Available data for<br />
concentrations of COPECs in wildlife foods collected from the <strong>Lowlands</strong> were summarized<br />
in Tables 3-4 through 3-9. Not all food types consumed by the selected avian and mammalian<br />
receptors, nor are all areas within the <strong>Lowlands</strong> represented. To allow estimation of exposure<br />
to COPECs for all receptors and locations within <strong>Bolsa</strong> <strong>Chica</strong>, estimation of concentrations of<br />
COPECs in wildlife foods was necessary. Bioaccumulation factors for each wildlife food type<br />
were developed based on site-specific data. Bioaccumulation factors were calculated where<br />
both abiotic (sediment/soil or water) and biotic (tissue concentrations) were available for<br />
each Cell. The median concentrations of each abiotic and biotic medium (presented in Tables<br />
3-2 through 3-9) were combined within a given Cell and a Cell-specific bioaccumulation<br />
factor (BAF) was calculated using the following equation:<br />
BAF<br />
=<br />
tissue concentration<br />
abiotic medium concentration<br />
( mg / kg)<br />
( mg / kg)<br />
Where:<br />
BAF = chemical-specific bioaccumulation factor for a given receptor group<br />
Tissue concentration = chemical concentrations (mg/Kg) measured in<br />
terrestrial plants, terrestrial invertebrates, aquatic invertebrates, bird eggs, or<br />
small mammals collected from the <strong>Bolsa</strong> <strong>Chica</strong> <strong>Lowlands</strong><br />
Abiotic medium concentration = chemical concentrations (mg/Kg) measured<br />
in sediment/soil or surface water collected from the <strong>Bolsa</strong> <strong>Chica</strong> <strong>Lowlands</strong><br />
The BAFs for each receptor and chemical were then combined across all Cells and<br />
summarized as shown in Table 3-12 for sediment/soil and in Table 3-13 for surface water.<br />
The 90th percentile BAF for each chemical was then used in the food chain uptake model<br />
when direct measured tissue concentrations were not available for a given food item within<br />
a given evaluation area.<br />
SAC/143368(003.DOC) 3-23 ERA REPORT<br />
7/31/02
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