Linking pesticides and human health: A geographic information system (GIS) and Landsat remote sensing method to estimate agricultural pesticide exposure

Accurate pesticide exposure estimation is integral to epidemiologic studies elucidating the role of pesticides in human health. Humans can be exposed to pesticides via residential proximity to agricultural pesticide applications (drift). We present an improved geographic information system (GIS) and remote sensing method, the Landsat method, to estimate agricultural pesticide exposure through matching pesticide applications to crops classified from temporally concurrent Landsat satellite remote sensing images in California. The image classification method utilizes Normalized Difference Vegetation Index (NDVI) values in a combined maximum likelihood classification and per-field (using segments) approach. Pesticide exposure is estimated according to pesticide-treated crop fields intersecting 500 m buffers around geocoded locations (e.g., residences) in a GIS. Study results demonstrate that the Landsat method can improve GIS-based pesticide exposure estimation by matching more pesticide applications to crops (especially temporary crops) classified using temporally concurrent Landsat images compared to the standard method that relies on infrequently updated land use survey (LUS) crop data. The Landsat method can be used in epidemiologic studies to reconstruct past individual-level exposure to specific pesticides according to where individuals are located.     

Rapid formation of the Small Isles Tertiary centre constrained by precise Ar/Ar and U–Pb ages

The relative chronology of magmatic and tectonic events is key to an understanding of the influence of the Iceland plume on the North Atlantic. In particular, the location and duration of magmatism is of fundamental importance. Initial widespread flood basalt formation occurred in Baffin Island, Greenland, and Britain before complete plate break up at 56 Ma after which time magmatism became concentrated in the active rift zone.

Historically the British Tertiary Igneous Province (BTIP) has been instrumental in advancing many concepts of igneous petrology. However, the absolute age and duration of the province remains unresolved. Here, we present new internally consistent ⁴⁰Ar/³⁹Ar ages that help to constrain the volcanic activity in the Small Isles centre to within 2 my. This short duration has implications for the onset of magmatism in the larger North Atlantic province, the rapid unroofing of the Rum volcano, and more significantly, some of the evidence used to propose pulsing of the Iceland plume.