Reactions of nitrite with goethite and surface Fe(II)-goethite complexes.

Chemodenitrification-the abiotic (chemical) reduction of nitrite (NO) by iron (II)-plays an important role in nitrogen cycling due in part to this process serving as a source of nitrous oxide (NO). Questions remain about the fate of NO in the presence of mineral surfaces formed during chemodenitrification, such as iron(III) (hydr) oxides, particularly relative to dissolved iron(II). In this study, stirred-batch kinetic experiments were conducted under anoxic conditions (to mimic iron(III)-reducing conditions) from pH 5.

Nitrite reactivity with magnetite.

Under Fe(3+)-reducing conditions, soil Fe(2+) oxidation has been shown to be coupled with nitrate (NO3(-)) reduction. One possible secondary reaction is the involvement of NO3(-) and nitrite (NO2(-)) with magnetite, a mixed valence Fe(2+)/Fe(3+) mineral found in many natural environments. Currently, little information exists on NO3(-) and NO2(-) reactivity with magnetite.

Estimating soil phosphorus requirements and limits from oxalate extract data.

Excessive fertilizer and manure phosphorus (P) inputs to soils elevates P in soil solution and surface runoff, which can lead to freshwater eutrophication. Runoff P can be related to soil test P and P sorption saturation, but these approaches are restricted to a limited range of soil types or are difficult to determine on a routine basis. The purpose of this study was to determine whether easily measurable soil characteristics were related to the soil phosphorus requirements (P(req), the amount of P sorbed at a particular solution P level).

Rapid, sensitive, microscale determination of phosphate in water and soil.

A rapid and sensitive analysis of inorganic and organic phosphorus (P) is needed to analyze water and soil extracts at submicromolar concentrations. The proposed method, based on the complexation of malachite green with phosphomolybdate under acidic conditions, was adapted to a 96-well microtiter plate format, and was tested for matrix interferences using 15 soils and some common extractants, including water, KCI, CaCl2, NaOH, and HCl. The accuracy of P determination was affected when CaCl2 and HCl concentrations were greater than 0.