Kinetics and Mechanisms of Atrazine Adsorption and Desorption in Soils Under No-Till and Conventional Management

Both soils (Maury silt loam and Sadler) exhibited three apparent mechanisms of atrazine adsorption. The first two mechanisms were very rapid (10 minutes) and were assigned to soil-clay surface adsorption reactions via hydrogen bonding. The quantity of atrazine involved in these two reactions for the 0.5 mg/1 solution atrazine varied, depending on the soil, from 67 μg/100 g clay to 219 μg/100 g clay. The reason there were two possible atrazine sinks in this range of atrazine adsorption was believed to be the presence of two types of reactive surfaces, the clay inorganic phase and the organic carbon phase. The latter phase exhibited more influence on the Maury silt loam soil than on the Sadler soil, where the Maury silt loam soil contained more organic carbon than the Sadler soil. The third mechanism involved an atrazine condensation mechanism. It was a relatively slow reaction and it appeared to persist for at least 2 hours. This mechanism accounted for about three fourths of the total atrazine adsorbed. After 75 minutes of solution flow the total atrazine adsorbed by the soil clay samples varied from 333 μg/100 g to 710 μg/100 g. Reversibility of the adsorption process was shown to be limited. Approximately one-third of the adsorbed atrazine was desorbed after a 2 hour leaching with l mmol L-1 CaCl2 solution. The desorption process was shown to be controlled by two types of reactions. A short rapid one and a long extremely slow one (diffusion controlled). The above findings suggest that the amount of atrazine leaching into surface water or groundwater would depend on the amount of time atrazine had to react with the soil. If it rained immediately following atrazine application then most of the atrazine would be carried in the runoff, making water the main mechanism of atrazine movement. If, on the other hand, a significant amount of time passed after atrazine was applied then a much smaller proportion of the applied atrazine would be leached, making soil erosion the main mechanism of atrazine movement. Equations for all these processes have been developed to aid in modeling the movement of atrazine during rain fall events

Inhibition of Progenitor Dendritic Cell Maturation by Plasma from Patients with Peripartum Cardiomyopathy: Role in Pregnancy-associated Heart Disease

Dendritic cells (DCs) play dual roles in innate and adaptive immunity based on their functional maturity, and both innate and adaptive immune responses have been implicated in myocardial tissue remodeling associated with cardiomyopathies. Peripartum cardiomyopathy (PPCM) is a rare disorder which affects women within one month antepartum to five months postpartum. A high occurrence of PPCM in central Haiti (1 in 300 live births) provided the unique opportunity to study the relationship of immune activation and DC maturation to the etiology of this disorder. Plasma samples from two groups (n = 12) of age- and parity-matched Haitian women with or without evidence of PPCM were tested for levels of biomarkers of cardiac tissue remodeling and immune activation. Significantly elevated levels of GM-CSF, endothelin-1, proBNP and CRP and decreased levels of TGF- were measured in PPCM subjects relative to controls. Yet despite these findings, in vitro maturation of normal human cord blood derived progenitor dendritic cells (CBDCs) was significantly reduced (p < 0.001) in the presence of plasma from PPCM patients relative to plasma from post-partum control subjects as determined by expression of CD80, CD86, CD83, CCR7, MHC class II and the ability of these matured CBDCs to induce allo-responses in PBMCs. These results represent the first findings linking inhibition of DC maturation to the dysregulation of normal physiologic cardiac tissue remodeling during pregnancy and the pathogenesis of PPCM