Effect of biochar on fate and transport of manure-borne estrogens in sandy soil.

The feasibility of using two types of biochars to reduce steroid hormone pollution from poultry and swine manure application on agricultural land was evaluated. The sorption affinity and desorption resistance of softwood and hardwood biochars were also determined for two estrogen hormones, 17ß-estradiol (E2) and its primary metabolite estrone (E1). The softwood and hardwood biochars demonstrated high retention capacity for both estrogens. The effective distribution coefficient (Kdeff) of soil-softwood-derived biochar (SBS450) was significantly higher than soil-hardwood-derived biochar (SBH750), indicating the stronger sorption affinity of SBS450 for estrogens. To validate the laboratory results, a field lysimeter experiment was conducted to study the fate and transport of E2 and E1 in soil and leachate in the presence of 1% softwood-biochar (BS450) in topsoil and to compare it with soil without any amendments. The spatio-temporal distribution of both estrogens was monitored at four depths over a 46-day period. The lysimeters, in which the surface layer of soil was amended with biochar, retained significantly higher concentrations of both estrogen hormones. Although they leached through the soil and were detected in leachates, collected at 1.0m depth, the concentrations were significantly lower in the leachate collected from biochar-amended lysimeters. The result confirmed the efficacy of biochar amendment as a remediation technique to alleviate the manure-borne hormonal pollution of groundwater.

Effect of nonionic surfactant Brij 35 on the fate and transport of oxytetracycline antibiotic in soil.

In many parts of the world, river water is used for irrigation. Treated, partially treated, and even untreated water from wastewater treatment plants is discharged directly into rivers, thereby degrading the quality of the water. Consequently, irrigation water may contain surfactants which may affect the fate and transport of chemicals such as pesticides and antibiotics in agricultural soils. A field lysimeter study was undertaken to investigate the effect of the nonionic surfactant, Brij 35, on the fate and transport of an antibiotic, Oxytetracycline, commonly used in cattle farms. Nine PVC lysimeters, 1.0 m long × 0.45 m diameter, were packed with a sandy soil to a bulk density of 1.35 Mg m(-3). Cattle manure, containing Oxytetracycline, was applied at the surface of the lysimeters at the recommended rate of 10 t/ha. Each of three aqueous Brij 35 solutions, 0, 0.5 and 5 g L(-1) (i.e., 'good,' 'poor' and 'very poor' quality irrigation water) were each applied to the lysimeters in triplicate. Over a 90 day period, soil and leachate samples were collected and analyzed. Batch experiment results showed that the presence of the nonionic surfactant Brij 35 significantly reduced the sorption coefficient of OTC from 23.55 mL g(-1) in the aqueous medium to 19.49, 12.49 and 14.53 in the presence of Brij 35 at concentrations of 0.25, 2.5 and 5 g L(-1), respectively. Lysimeter results indicted the significant downward movement of OTC at depths of 60 cm into soil profile and leachate in the presence of surfactant. Thus, the reuse of wastewater containing surfactants might enhance the mobility of contaminants and increase ground water pollution.

Sorption and desorption of salinomycin sodium in clay, loamy sand, and sandy soils.

Salinomycin sodium (BIO-COX) is polyether ionophore, commonly used in the poultry industries for the prevention of coccidial infections and promotion of growth. Salinomycin sodium (SAL-Na) is very toxic, and may be fatal, if swallowed, inhaled, or absorbed through the skin than many other antibiotics, thus evaluating their fate in the soil environment is of importance. Sorption of SAL-Na was measured in clay, loamy sand, and sandy soil at different pH 4, 7, and 9, and desorption with phosphate buffer (pH 7) using batch equilibration technique. SAL-Na was sorbed by all the soils studied, the sorption of SAL-Na by the sandy soil increased as the pH decreased, while the sorption of salinomycin in clay and loamy sand soil increased as the pH increased. Desorption of salinomycin from the soil with phosphate buffer (pH 7) over the 24 h period was 80-95% of the amount added. The similar trend was observed in desorption with pH 4, 7 and at different concentrations and slight less desorption was observed in pH 9. When compared to clay and loamy sand soil, sandy soil was recorded maximum (95%) desorption.

The effect of composting on the degradation of a veterinary pharmaceutical.

Composting has been identified as a viable means of reducing the environmental impact of antibiotics in manure. The focus of the present study is the potential use of composting on the degradation of salinomycin in manure prior to its field application. Manure contaminated with salinomycin was collected from a poultry farm and adjusted to a C:N ratio of 25:1 with hay material. The manure was composted in three identical 120 L plastic containers, 0.95 m height x 0.40 m in diameter. The degradation potential for salinomycin was also ascertained under open heap conditions for comparison (control). Salinomycin was quantified on HPLC with a Charged Aerosol Detector, at an interval of every 3 days. The salinomycin level in the compost treatment decreased from 22 mg kg(-1) to 2 x 10(-5) microg kg(-1) over 38 days. The corresponding decrease in the control was from 27.5 mg kg(-1) to 24 microg kg(-1). The changes in pH, EC (dS m(-1)), temperature, total kjeldahl nitrogen (TKN), total potassium (TK), total phosphorus (TP) and carbon content in both the composting and the control samples were monitored and found to be different in compost as compared to the control. During the composting process, the loss of TKN was 36%, which was substantially lower than corresponding loss of 60% in the control. The loss of carbon was 10% during composting, whereas the loss in the control was 2%. In composting, the temperature modulated from 27 degrees C (initially) to a high of 62.8 degrees C (after 4 days), and then declined to 27.8 degrees C at the end of 38 days. On the basis of the results obtained in this study, it appears that the composting technique is effective in reducing salinomycin in manure.