A study based on soil samples taken from 200 sites in 30 states should help resolve that question.
At the first three levels, the study was based on soil samples collected throughout a 2000 km2 area, with a different sampling scheme for each level.
Two new species of Trichoderma are described based on soil samples from the Hubei and Tibet regions of China, and named as Trichoderma shennongjianum and Trichoderma tibetense.
This study used a sampling design based on soil samples taken on farm plots, which had been submitted to a wide range of spatial and temporal sequential land-uses, including soils that were only recently denuded.
The preliminary results released by the state last week were based on soil samples from 146 additional homes spread over a two-square mile area stretching out from the plant and into Boyle Heights, Maywood, Huntington Park and East Los Angeles.
The preliminary results are based on soil samples taken from 146 properties spread across a two-square mile area, including Boyle Heights, Maywood, Huntington Park and East Los Angeles, which were used to model what concentrations are likely to exist at thousand of other homes.
Modeling could have included hydrogeologic assessments of contaminant delivery through tapwater, assessments of airborne contaminant spread based on air sampling and wind pattern data, estimations of soil contamination based on soil sample data from representative sites within the affected area.
The diplomats said the report might not lay explicit blame, but that its factual reporting - based on soil, blood and urine samples, and interviews with doctors and witnesses - could suggest who was responsible.
The exposure assessment for the present study was based on soil vapor and indoor air sampling, which were used to determine the exposure areas.
Soil samples were collected from four depth increments (0 30, 30 60, 60 120 and 120 180 cm) from 147 sampling locations identified using a stratified random and nested sampling design based on soil, land use and elevation strata.
