https://nova.newcastle.edu.au/vital/access/ /manager/Index en-au 5 https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:49607 Tue 23 May 2023 17:32:07 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:39279 max) ranged from 0.29 to 2.18 x 10⁻² mM g⁻¹ soil h⁻¹ and declined by 42.30%–71.01% under PTH stress. The Michaelis constant (K_m) values ranged between 2.90 and 14.17 x 10⁻² mM and exhibited three forms including unchanged, increased (38.16–242.65%) and decreased (13.41–39.23%) when exposed to PTH. Based on the changes in two kinetic parameters, the inhibition of PTH on FDA–H was classified as three types, i.e., noncompetitive, linear mixed and uncompetitive inhibition. The competitive inhibition constant (K_ic) and noncompetitive constant (K_iu) ranged from 0.064 to 0.447 mM and 0.209 to 0.723 mM, respectively, which were larger than the Km in values. The catalytic efficiency (V_max/K_m) of FDA–H is a sensitive integrated parameter to evaluate the PTH toxicity due to the higher inhibition ratio than the V_max. The PTH toxicity to FDA–H decreased with increase of soil organic matter and total nitrogen contents. This implied that the PTH toxicity could be alleviated by an increasing content of soil organic matter due to its buffering capacity to PTH. Besides, soils with a higher content of total nitrogen could provide stable environment for FDA–H to maintain its functionality under PTH pollution. Thus, the results of this study have great implications to the risk assessment of parathion in soils.]]> Thu 02 Jun 2022 15:12:26 AEST ]]>