As the largest freshwater wetland in the world, the Pantanal possesses a wealth of floral and faunal biodiversity. It serves its ecosystems through various functions and the wetland\u27s hydrology is vital to the greater region of South America. However, the Pantanal faces numerous threats from the expansion of industrial soybean agriculture into Mato Grosso, Brazil, the largest of which may be pesticide pollution. Yet, few studies have been conducted to assess pesticide contamination of this wetland. In this study, a qualitative and semi-quantitative organochlorine pesticide analysis was conducted. Water samples were collected June - July 2012 from three different rivers in the Northern Pantanal: Rio Cuiabá, Rio Perigara/São Lourenço, and Rio Piquiri. Each sample point was visited three times producing a total of 188 water samples. These samples were then analyzed with Solid-Phase Microextraction (SPME) and Gas Chromatography-Mass Spectrometry (GC-MS). A land cover analysis based on the GlobCover 2009 spatial data set was also conducted to determine forest, agriculture, shrub/grass, urban, and water extents in 2km, 5km, 10km, and 25km buffers. Ten samples were found to contain organochlorine pesticide contamination. The three pesticides identified were endosulfan sulfate, p,p\u27-DDD and m,p\u27-DDD, at concentrations of 3ppb, 0.5 – 2ppb, and 0.7 – 3 ppb, respectively. The land cover analysis exhibited no notable differences in land use among the three rivers. With this study it was determined that organochlorine pesticides are present in the rivers of the Northern Pantanal which can have significant effects on the fauna and flora of the wetland. Organochlorine pesticides are exceptionally potent to organisms and biomagnify in food webs. As soy industrial plantations encroach further on the wetland\u27s borders, these pesticide levels are most likely to increase and, therefore, the health of the wetland and its inhabitants could potentially be severely impacted
