Effects on Soil P Content, P Sorption and Risk of Eutrophication of Waterbodies of Outdoor Pig Production Areas

The Mediterranean region offers good weather conditions for outdoor pig production (OPP), which is considered more environmentally friendly than intensive indoor production. However, the continuous input of food and pigs' excreta increases the soil organic matter (SOM) and phosphorus (P), increasing the risk of waterbodies eutrophication. This work aimed at evaluating in OPP areas soil P dynamics and the role of SOM on P sorption and P release. The experiment was done for two years, at an area of 2.8 ha with an animal charge of 9 adults ha-1. Georeferenced soil samples were taken at 0.20 m depth, and a soil P sorption experiment was carried out. At the end of the experiment, for the background value, the levels of SOM increased between 85–376%, and Olsen P values ranged between -82–884%. SOM levels above 2% caused a decrease in the binding energy of P sorption according to the linear model b=-15.541SOM+115.20 (p <0.01) as well as a decrease of the soil P sorption capacity Qmax=-41.272SOM+298.37 (p <0.01). To avoid the accumulation of SOM and P preventing hotspots for waterbodies eutrophication, an adequate animal charge together with soil cultivation for pig grazing can be a cost-effective practice.

Nonlinear and Linear Equation of Gas Diffusion in Coal—Theory and Applications

The authors derived the analytical solution to diffusion equations. The solution requires linearization of diffusion equations, as well as developing the obtained expression into a series. In particular, the result of the first procedure is highly deviated from the exact solution. The authors conducted a sorption experiment and then, in relation to the registered kinetics of the diffusion of CO2 inside hard coal grains, approximated the linear solution and the numerical nonlinear solution by means of the least squares method. As confirmed by the lower value of the sum of deviation squares, it can be clearly demonstrated that the nonlinear equation represents the actual measurement more accurately.

Aspen Soils Retain More Dissolved Organic Carbon Than Conifer Soils in a Sorption Experiment

The effect tree species have on soil organic carbon (SOC) has been hotly debated but, so far, few clear patterns have emerged. One example of a differing tree species effect on SOC are aspen forests in North America, which have been found to have more stable SOC than adjacent conifer forest stands. An important source for the formation of stable organo-mineral complexes in soil is dissolved organic carbon (DOC). DOC concentrations in mineral soil are often higher under the thick O-horizons of conifer forests than under aspen forests, but this does not correspond to more stable mineral SOC. This suggests that, instead of DOC concentration, DOC quality could be driving the observed differences in SOC. Therefore, we quantified the retention of contrasting forest detritus DOC in soils. Using a batch sorption experiment approach, we compared the retention of detritus leachates from four sources – aspen leaves (AL), aspen roots (AR), conifer (subalpine fir) needles (CN), and conifer (subalpine fir) roots (CR) – on soils sampled under aspen and conifer (subalpine fir and Douglas fir) overstories. The calculated sorption isotherms showed a higher retention of AL DOC than AR DOC, as indicated by all four sorption parameters – k and n (curve-fitting parameters), null point concentration (NPC; net sorption = net desorption), and endpoint (EP, retention at the highest initial DOC concentration). Leachates from CN and CR showed very similar retention behavior, and between the two species the retention of root leachates was more similar than the retention of foliage leachates. Soils sampled from aspen forests showed higher affinity for new DOC than conifer soils [higher sorption rate (n), lower NPC, and higher EP] regardless of the DOC source. The findings suggest that the higher DOC sorption on aspen soils might be a major driver for more stable SOC under aspen stands in North America.

Biochar Effect on Nutrients Availability to Barley

Biochar can serve as a soil ameliorant preventing nutrient leaching. Due to its porous structure and chemical composition, it can also adsorb elements on its surface. However, various biochars have different sorption ability, and the mechanistic understanding of nutrient storage in biochar is missing. It is not clear if nutrients adsorbed by biochar will be available for plants. Therefore, it is necessary to investigate biochar efficacy in pure substrates to characterise its specific influence on plants. In this study, the sorption capacity and ability of the wood-based biochar to provide barley plants with nutrients was investigated. The sorption capacity of biochar was investigated by saturating it with Gelrigel nutrient solution. Then nutrient-enriched biochar was tested for its effect on barley growth in comparison with non-enriched biochar. The results of the sorption experiment showed that the wood-based biochar could adsorb high amounts of nutrients such as ammonium (NH4+), potassium, calcium and phosphate (PO43-), but not nitrate (NO3-). Nutrient-enriched biochar showed an ability to support 46% higher dry biomass of barley than non-enriched biochar. These results suggest a potential of nutrient-enriched biochar for recovering essential nutrients for plants.

Sulfamethoxazole sorption in eutrophic Regolithic Neosol

ABSTRACT This study aimed to evaluate sulfamethoxazole sorption kinetics and isotherms using batch method. The experiment was carried out in typic eutrophic Regolithic Neosol (0-20 and 20-60 cm layers) located in the private reserve of the Riacho do Papagaio farm, in São João, PE, Brazil. The tests were carried out under laboratory conditions at 24 ºC and sulfamethoxazole concentration was determined by high-performance liquid chromatography. The sorption experiment through the batch method used sulfamethoxazole solutions with concentrations of 10-3, 5.10-4, 10-4, 5.10-5, 10-5 and 5.10-6 mol L-1 to obtain the analytical curve. For this soil, sulfamethoxazole sorption kinetics was best described by a second-order model and the sorption isotherms were linear. Sulfamethoxazole predominantly interacts with organic matter in this type of soil. The results obtained in this study show that the antibiotic sulfamethoxazole exhibits low adsorption, posing a higher risk of contamination to the groundwaters in this region at pH ≈ 7.

Efficiency of Pb(II) and Mo(VI) Removal by Kaolinite Impregnated with Zero-Valent Iron Particles

In this work, kaolinite modified with zero-valent iron was synthesized and used as a sorbent for Pb(II) and Mo(VI) removal from aqueous solutions. The obtained material was characterized by X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. The methods revealed successful modification by the Fe0particles precipitation on the surface of well-ordered kaolinite. The sorption experiment results showed a significant increase of sorption capacity in relation to the raw kaolinite. The kaolinite with 25% content of Fe0was found to be the best material for Pb(II) and Mo(VI) removal, resulting in approximately 500 mmol·kg-1and 350 mmol·kg-1sorption, respectively. The possible mechanisms responsible for metals’ removal were identified as reduction by Fe0‘core’ and adsorption on the iron hydroxides ‘shell’. The study indicated that the obtained material is capable of efficient Pb(II) and Mo(VI) removal and may be an interesting alternative to other methods used for heavy metals’ removal.

Surface analytical model and sorption artifact designing method

<p class="Abstract">Mass standards with alternative shapes are difficult to design due to the number of complex parameters. An analytical model based on surface sorption experiments is presented to study adsorption. This model is based on an optimization algorithm that is conceptualized to help to design the best sorption artefacts. Experimental artefacts, cylinder-weight and stack-weight, were of the same volume but different surface areas. This algorithm in essence determines the optimum surface of the artefact. After machining the artefact, surface sorption measurements were carried out. A sorption experiment was done by transferring the artefact from air to a vacuum. Then the surface sorption model was set up which represented the relationship between sorption coefficient, time <em>t</em> and relative humidity <em>h. </em>Logarithmic models were used to fit the variation of sorption coefficient per relative humidity <em>h </em>with time <em>t</em>.</p>