Impact of brackish groundwater and treated wastewater on soil chemical and mineralogical properties.

The long-term effect of using treated wastewater is not clearly defined: some researchers argue that it is better than freshwater for the soil health; others disapprove, claiming that irrigation with unconventional water resources causes soil degradation. This study assesses the impact of irrigation with non-traditional water on the chemical and mineralogical properties of a calcareous clayey soil from West Texas. The exponential rise in population and the realities of climate change contribute to the global increase in freshwater scarcity: non-conventional water sources, such as treated wastewater (TWW) and brackish groundwater (BGW), offer potentially attractive alternative water resources for irrigated agriculture. For this research, the differences between TWW and BGW were addressed by collecting and analyzing water samples for salt and nutrient content. Soil samples from three horizons (Ap, A, and B) were obtained from three different fields: Rainfed (RF), BGW irrigated, and TWW irrigated. Soil was analyzed for texture, salinity, sodicity, and carbon content. Clay mineralogy of the three different fields was analyzed using the B-horizons. The outcomes from the analysis showed that the BGW from the Lipan aquifer has higher salinity and is harder compared to TWW. Although the exchangeable sodium percentage (ESP), sodium adsorption ratio (SAR), and electroconductivity (EC) increased marginally compared to the control soil (RF), the soils were in good health, all the values of interest (SAR < 13, ESP < 15, pH < 8.5, and EC < 4) were low, indicating no sodicity or salinity problems. Smectite, illite, and kaolinite were identified in the three B-horizon samples using bulk X-ray diffraction (XRD). Overall, no major changes were observed in the soil. Thus, TWW and BGW are viable replacements for freshwater irrigation in arid and semi-arid regions.

Development of High Capacity Enterosorbents for Aflatoxin B1 and Other Hazardous Chemicals.

Previously, a calcium montmorillonite clay (NovaSil) included in the diet of animals has been shown to bind aflatoxin B1 (AfB1) and reduce the symptoms of aflatoxicosis. To investigate and improve the capacity and efficacy of clay-based materials as aflatoxin sorbents, we developed and tested calcium and sodium montmorillonite clays amended with nutrients including l-carnitine and choline. Also, we determined the sorption of AfB1 by isothermal analysis and tested the ability of these amended sorbents to protect adult hydra from AfB1 toxicity. The results showed that exchanging montmorillonite clays with l-carnitine and choline inhibited swelling of the clays and increased the sorption capacity and efficacy of clay surfaces for AfB1. Results from dehydroxylated and heat-collapsed clays suggested that AfB1 was primarily adsorbed in the clay interlayer, as predicted from thermodynamic calculations and computational modeling. The hydra bioassay further indicated that the modified clays can significantly protect adult hydra from AfB1 with as low as 0.005% clay inclusion. This enterosorbent therapy may also be applied to screen hazardous chemicals such as pesticides and PAHs based on similar sorption mechanisms. Taken together, enterosorbent therapy could be delivered in nutritional supplements, foods that are vulnerable to aflatoxin contamination, flavored liquids and animal feeds during emergencies and outbreaks of acute aflatoxicosis, and as a screening model for hazardous environmental chemicals.