Interactions of Carbamazepine in Soil: Effects of Dissolved Organic Matter

Abstract

Pharmaceutical compounds (PCs) and dissolved organic matter (DOM) are co-introduced into soils by irrigation with reclaimed wastewater. We targeted carbamazepine (CBZ) as a model compound to study the tertiary interactions between relatively polar PCs, DOM, and soil. Sorption-desorption behavior of CBZ was studied with bulk clay soil and the corresponding clay size fraction in the following systems: (i) without DOM, (ii) co-introduced with DOM, and (iii) pre-adsorption of DOM before CBZ introduction. Sorption of the DOM to both sorbents was irreversible and exhibited pronounced sorption-desorption hysteresis. Carbamazepine exhibited higher sorption affinity and nonlinearity, and a higher degree of desorption hysteresis with the bulk soil than the corresponding clay size fraction. This was probably due to specific interactions with polar soil organic matter fractions that are more common in the bulk soil. Co-introduction of CBZ and DOM to the soil did not significantly affect the sorption behavior of CBZ; however, following pre-adsorption of DOM by the bulk soil, an increase in sorption affinity and decrease in sorption linearity were observed. In this latter treatment, desorption hysteresis of CBZ was significantly increased for both sorbents. We hypothesize that this was due to either strong chemical interactions of CBZ with the adsorbed DOM or physical encapsulation of CBZ in DOM-clay complexes. Based on this study, we suggest that DOM facilitates stronger interactions of polar PCs with the solid surface. This mechanism can reduce PC desorption ability in soils.

Impacts of Long-Term Irrigation of Domestic Treated Wastewater on Soil Biogeochemistry and Bacterial Community Structure

“…apid population growth across the globe, an increase in per capita water consumption, and, in part, global climate change have resulted in increased demands on available freshwater resources (1)(2)(3). Many countries are turning to wastewater recycling in order to meet these increased freshwater demands (3)(4)(5).…”

“…Many countries are turning to wastewater recycling in order to meet these increased freshwater demands (3)(4)(5). Therefore, planned and managed reuse of wastewater is increasingly practiced not only in arid or semiarid regions but also in temperate and subtropical regions that do not routinely face water shortages (6)(7)(8)(9).…”

“…Among the nutrients originating from land application of wastewater, nitrate (NO 3 Ϫ ) is considered to be a ubiquitous contaminant worldwide (20,21), threatening aquatic ecosystems and subsurface aquifers, which are often the major source of potable water. Thus, it comes as no surprise that over 20% of rural wells in some parts of the United States contain NO 3 Ϫ concentrations above the drinking water limit of 10 mg/liter (22); inputs of even a few milligrams/liter of NO 3 Ϫ can have significant and long-lasting environmental impacts (23).…”

“…Recent reports from Florida (Tallahassee) and Colorado (Denver and Fort Collins) have shown that groundwater sampled downgradient from farmlands receiving spray-irrigated TWW contained elevated levels of sodium (Na), boron (B), phosphorus (P), NO 3 Ϫ -N, chloride, and even pharmaceutical and personal care products (PPCPs) (6,(24)(25)(26)(27). Studies conducted by the U.S. Geological Survey (USGS) on the same location used to conduct this study showed that land application of TWW is a major contributor to eutrophication in Wakulla Springs, FL (28), the world's largest freshwater spring, located downgradient from the wastewater-receiving agroecosystem (Fig.…”

“…This is in line with previous reports of the conversion of ammonium and organic nitrogen to nitrate in the upper part of the unsaturated zone beneath the root zone (28). Because TWW-associated NO 3 Ϫ -N has been identified as a major pollutant to the receiving agroecosystem soils and groundwater (23) and is known to persist in the environment for decades (29), our main objective in this study was to investigate the fate of applied TWW-associated nitrate, which is known to recycle in the soils and groundwater primarily via denitrification.…”