Prairie pothole lakes (PPLs) are located within the extensively farmed Great Plains region of North America, and many are negatively impacted by nonpoint source pesticide pollution. To date, the environmental fate of pesticides in these lakes remains largely unknown. In this study, two PPLs in the Cottonwood Lake area of North Dakota were sampled, and transformations of four chloroacetanilide pesticides in sediment porewaters were examined. The reduced sulfur species in the porewaters, such as bisulfide (HS(-)) and polysulfides (S(n)(2-)), readily transformed the target pesticides into sulfur-substituted products. Although HS(-) and S(n)(2-) played a dominant role, other reactive constituents in PPL porewaters also contributed to the transformation. Results from this study revealed that abiotic reactions with reduced sulfur species could represent an important removal pathway for pesticides entering PPLs.

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Sediment pore-water dissolved organic matter (DOM) in two North Dakota prairie pothole lakes was quantified by dissolved organic carbon analysis (DOC) and its composition was characterized as a function of sediment depth for molecular weight distribution (MWD), molar absorptivity at 280 nm (e280), and fluorescence properties. Fluorescence excitation emission matrices were further analyzed by creating a Parallel Factor Analysis (PARAFAC) model specific to sedimentary pore-water DOM. The range of absolute pore-water DOC concentrations (, 26-183 mg C L 21 ) greatly exceeded abundances reported for other wetlands and generally increased with depth. Significant changes occurred in e280 and fluorescence seasonally. Prairie pothole pore-water DOM is primarily allochthonous in nature and three 'humic-like' components explained , 90% of total sample fluorescence, while a single 'non-humic' component was responsible for the remaining 10%. The contribution of the non-humic component, however, was more significant in the top 7 cm of sediment in samples collected in early autumn and is presumably derived from algal precursor material produced by primary production in the water column over the summer. The PARAFAC results corroborate e280 and MWD changes in pore-water DOM composition over the growing season. This dynamic process could affect the type of DOM available for biogeochemical processes seasonally.The majority of the upper Midwest and Northern Great Plains regions of the north-central United States and southcentral Canada are a glaciated prairie containing an abundance of freshwater, saline, and hypersaline depressional wetlands, known as prairie pothole lakes (PPLs), in relatively flat outwash plains and hummocky moraines (Winter and Rosenberry 1998). PPLs were formed glacially during the late Pleistocene Epoch and cover an area of , 700,000 km 2 of the United States and Canada, known as the prairie pothole region (PPR; van der Valk 2005). They are an important lacustrine and hydrologic feature in this part of North America.Dissolved organic matter (DOM) plays an integral role in a variety of biogeochemical processes in wetland and lacustrine ecosystems and influences ecosystem function in a variety of ways. DOM also plays a vital role in the overall global carbon cycle (Lam et al. 2007), in oxidationreduction reactions (Hakala et al. 2009), and has been shown to serve as an electron acceptor for microbial respiration (Lovely et al. 1996). Further, organic contaminants can be transformed in the presence of natural DOM in anoxic environments (Hakala et al. 2009;Zeng et al. 2011Zeng et al. , 2012.One well-studied wetland complex in the PPR is the Cottonwood Lakes Study Area (CWLA) in Stutsman County, North Dakota. Eighteen small pothole lake basins comprise the wetland complex. The CWLA has been investigated extensively since the 1960s (Winter and Rosenberry 1998;Euliss et al. 2004;Holloway et al. 2011) with respect to its hydrologic, chemical, and biologic attributes. To date, however, little is known about th...

Herein, we report the synthesis and structural characterization of K[(CO)Pu](μ-η-η-O)·12HO. This is the second Pu-containing addition to the previously studied alkali-metal peroxocarbonate series M[(CO)A](μ-η-η-O)·xHO (M = alkali metal; A = Ce or Pu; x = 8, 10, 12, or 18), for which only the M = Na analogue has been previously reported when A = Pu. The previously reported crystal structure for Na[(CO)Pu](μ-η-η-O)·12HO is not isomorphous with its known Ce analogue. However, a new synthetic route to these M[(CO)A](μ-η-η-O)·12HO complexes, described below, has produced crystals of Na[(CO)Ce](μ-η-η-O)·12HO that are isomorphous with the previously reported Pu analogue. Via this synthetic method, the M = Na, K, Rb, and Cs salts of M[(CO)Ce](μ-η-η-O)·xHO have also been synthesized for a systematic structural comparison with each other and the available Pu analogues using single-crystal X-ray diffraction, Raman spectroscopy, and density functional theory calculations. The Ce salts, in particular, demonstrate subtle differences in the peroxide bond lengths, which correlate with Raman shifts for the peroxide O-O stretch (O = O atoms of the peroxide bridges) with each of the cations studied: Na [1.492(3) Å/847 cm], Rb [1.471(1) Å/854 cm], Cs [1.474(1) Å/859 cm], and K [1.468(6) Å/870 cm]. The trends observed in the O-O bond distances appear to relate to supermolecular interactions between the neighboring cations.