Potential phosphorus eutrophication mitigation strategy: Biochar carbon composition, thermal stability and pH influence phosphorus sorption

Abstract

Phosphorus (P) eutrophication is a major pollution problem globally, with unprecedented amount of P emanating from agricultural sources. But little is known about the optimization of soil-biochar P sorption capacity. The study objective was to determine how biochar feedstocks and pyrolysis conditions influences carbon (C) thermal stability, C composition and pH and in turn influence the phosphorus sorption optimization. Biochar was produced from switchgrass, kudzu and Chinese tallow at 200, 300, 400, 500, 550, 650,750 °C. Carbon thermal stability was determined by multi-element scanning thermal analysis (MESTA), C composition was determined using solid state C NMR. Phosphorus sorption was determined using a mixture of 10% biochar and 90% sandy soil after incubation. Results indicate increased P sorption (P< 0.0001) and decreased P availability (P < 0.0001) with increasing biochar pyrolysis temperature. However, optimum P sorption was feedstock specific with switchgrass indicating P desorption between 200 and 550 °C. Phosphorus sorption was in the order of kudzu > switchgrass > Chinese tallow. Total C, C thermal stability, aromatic C and alkalinity increased with elevated pyrolysis temperature. Biochar alkalinity favored P sorption. There was a positive relationship between high thermal stable C and P sorption for Kudzu (r = 0.62; P = 0.0346) and Chinese tallow (r = 0.73; P = 0.0138). In conclusion, biochar has potential for P eutrophication mitigation, however, optimum biochar pyrolysis temperature for P sorption is feedstock specific and in some cases might be out of 300-500 °C temperature range commonly used for agronomic application. High thermal stable C dominated by aromatic C and alkaline pH seem to favor P sorption.

Nutrient uptake and growth of potato: Arbuscular mycorrhiza symbiosis interacts with quality and quantity of amended biochars

“…(), that biochar induced ethylene emission was significantly decreased after 20 days in moist soil. A previous study found positive correlation between pyrolysis temperature and P sorption capacity of biochar ( Ngatia et al., ), indicating the greater P sorption capacity of high temperature biochar. The main mechanism of P sorption to biochar has been proposed to be the precipitation of phosphate with calcium and magnesium ( Karunanithi et al., ), and sorption to the large surface area of biochar ( Trazzi et al., ).…”

Synthesis and adsorption performance of La@ZIF-8 composite metal–organic frameworks

“…3,4 Therefore, methods for reducing the concentration of phosphorus in contaminated water have become a hot topic in environmental science. 5 There are many ways of reducing the concentration of phosphorus in water, such as the membrane separation method, chemical precipitation method, biological degradation method, and so on, but each of these methods is highly targeted due to its specic application scope, 6,7 and so it is extremely important to nd a simple, low-cost method which could have a wide range of applications. Chemical adsorption could become one of the most promising phosphorus-containing waste-water treatment methods in the future because of its unique properties.…”

Nitrogen and Phosphorus Eutrophication in Marine Ecosystems

“…Soil P exists in a range of organic and inorganic compounds that differ remarkably in their biological availability in the soil environment [14]. The inorganic P compounds preferentially couple with crystalline and amorphous forms of Al, Fe, and Ca [15] the coupling is highly influenced by soil pH [16]. Organic P in most soils is dominated by a mixture of phosphate diesters (mainly nucleic acids and phospholipids) and phosphate monoesters (example; mononucleotides, inositol phosphates) with smaller amounts of phosphonates (compounds with a direct carbon-phosphorus bond) and organic polyphosphates (for example; adenosine triphosphate) [17].…”