Interaction of pig manure-derived dissolved organic matter with soil affects sorption of sulfadiazine, caffeine and atenolol pharmaceuticals

Pharmaceutically active compounds (PhACs) released into the environment have an adverse impact on the soil and water ecosystem as well as human health. Sorption of PhACs by soils and its potential modification through introduced DOM in the applied animal manure or treated wastewater (TWW) determines the mobility and environmental relevance of PhACs. Sulfadiazine, caffeine and atenolol were selected as target PhACs to investigate their sorption behaviors by five selected arable soils in the absence and presence of pig manure DOM. Sulfadiazine was least sorbed, followed by caffeine and atenolol according to the Freundlich sorption isotherm fit (soil average Kf [μg(1−n) mLn g−1] 4.07, 9.06, 18.92, respectively). The addition of manure DOM (31.34 mg C L−1) decreased the sorption of sulfadiazine and especially of caffeine and atenolol (average Kf 3.04, 6.17, 5.79, respectively). Freundlich sorption isotherms of the PhACs became more nonlinear in the presence of manure DOM (Freundlich exponent n changed from 0.74–1.40 to 0.62–1.12), implying more heterogeneous sorption of PhACs in soil–DOM binary systems. Sorption competition of DOM molecules with sulfadiazine and caffeine mostly contributed to their decreased soil sorption when DOM was present. In contrast, the formation of DOM–atenolol associates in the solution phase caused the largely decreased soil sorption of atenolol in the presence of DOM. It is suggested that DOM concentration (e.g., ≥ 60 mg C L−1) and its interaction with PhACs should be taken into consideration when assessing the environmental impact of land application of animal manure or irrigation with TWW.

Soil sorption characteristics of benzobicyclon hydrolysate and estimated leaching risk in soils used for rice production

Environmental contextThe behaviour of herbicides in the environment is largely determined by the partitioning of the compounds between soil solids and soil solution. We determined that the rice herbicide-metabolite benzobicyclon hydrolysate partitions more into soil solution, and does so increasingly as pH increases. These results indicate that benzobicyclon hydrolysate is a risk for leaching in much of the rice-producing area in the US mid-South. AbstractBenzobicyclon hydrolysate (BH) is the major metabolite and active molecule in the pro-herbicide benzobicyclon (BZB), which is pending registration for use in US mid-Southern rice (Oryza sativa L.) production. The current study objectives were to (i) determine BH soil sorption coefficients; (ii) quantify relationships among BH sorption and soil properties; and (iii) estimate leaching potential using calculated retardation factors (RFs). Sorption coefficients for 10 representative Arkansas rice-production soils were determined by batch-equilibration experiments. Soil sorption (KD=0.25–44.3mLg−1), soil organic carbon partitioning (KOC=28.2–7480mLg−1), and soil organic matter partitioning (KOM=17.9–2580mLg−1) coefficients were negatively correlated with soil pH (r=−0.93 – −0.94). Clay and silt were significant secondary regression parameters, accounting for up to 93% of the variation in KD in combination with pH. Clay and silt effects on sorption coefficients increased when regression analyses excluded the lowest pH soil. Soil sorption coefficients were greater in soils with clay ≥27%, which may be a useful parameter for informing herbicide-use rates. Using the calculated RF’s, the estimated depth of leaching over the growing season exceeded the assumed 15-cm plough layer depth in eight of the 10 soils, and only two of the 10 soils had an estimated time to plough layer breakthrough less than the typical six-month growing season (April–September) under average water flux conditions. The results suggest that BH leaching below the plough layer is a potential risk for much of the rice-producing area in the US mid-South.

Sorption Capacity of Sandy Soil Under Long-Term Fertilisation

In this paper, the results of an investigation of the effects of particle-size distribution, soil organic matter content and its parameters on soil sorption capacity are presented and their mutual relationships in sandy soils under long-term fertilisation experiments are determined. Soil samples were taken at the experimental station of Warsaw University of Life Sciences located in Skierniewice, (Poland) in spring 2017. The study included 94- and 41-year-old experiments with mineral fertilisation (no fertilisation, NPK, CaNPK) and 25-year-old experiment with mineral fertilisation + farmyard manure (FYM) in 4-year cycle: FYM, FYM+NPK and FYM+CaNPK. The results show that in the 94-year-old experiment in NPK and CaNPK treatments, hydrolytic acidity (Ha) decreased in comparison with the control by 30% and 88%, respectively, while in 25- and 41-year-old experiments only the application of NPK significantly increased Ha values. The sum of basic cations increased by a factor of 10 at the most in the CaNPK treatment in the 94-year-old experiment. The same effect was also observed in the 25-year-old experiment. On the one hand, the sorption complex gradually became fully saturated as a result of fertilisation in the 94-year-old experiment. On the other hand, in the 25- and 41-year-old experiments, base saturation was substantially reduced. A higher humus stability was an important agent for improving soil sorption capacity in 41- and 94-year old experiments.

Fire-Induced Changes in Soil and Implications on Soil Sorption Capacity and Remediation Methods

Vegetation changes caused by fire events are visible instantly but changes in soils are less apparent, and could be short-term, long-term or permanent in nature. Research has shown that soils undergo changes in their mineralogical, geochemical, physico-chemical and biological properties after a fire event that may vary depending on the intensity and duration of the fire, and the properties of the soil. Some of these properties make significant contributions towards soil’s ability to sorb contaminants. Changes in these properties could affect soil sorption complex and the effectiveness of remediation methods used to clean these soils when contaminated. This review synthesizes available information on fire-induced changes in soil properties affecting soil sorption and the factors which dictate these changes. The implications of changes in these properties on the soil’s natural attenuation capacity and choice of remediation method to clean up fire-affected contaminated soils are also discussed.