https://ogma.newcastle.edu.au/vital/access/ /manager/Index en-au 5 Ecotoxicity of parathion during its dissipation mirrored by soil enzyme activity, microbial biomass and basal respiration https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:49607 Tue 23 May 2023 17:32:07 AEST ]]> Long-term as contamination alters soil enzyme functional stability in response to additional heat disturbance https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:48327  β-glucosidase > acid phosphatase > FDA hydrolase. Urease activity was generally not affected and showed high stability against heat disturbance. The β-glucosidase activity recovered to the control level by 30 days, while 80% and 90% recovery on average occurred for acid phosphatase and FDA hydrolase, respectively. Long-term As contamination altered soil enzyme functional resistance and resilience to heat disturbance and resulted in three kinds of responses: (i) no apparent alteration (urease); (ii) moderate As contamination increased enzyme heat resistance (β-glucosidase); (iii) the resistance and resilience decreased with increasing As concentration (acid phosphatase and FDA hydrolase). The results demonstrated that different enzyme-catalytic biochemical processes have different functional stabilities under combined As and heat disturbance, and the negative changes in the soil enzyme activity led to losses in soil functions. Our study provides further evidence on the impacts of heavy metal/metalloid on soil enzyme functional stability in response to additional disturbance.]]> Tue 14 Mar 2023 16:47:38 AEDT ]]> Kinetics and catalytic efficiency of soil fluorescein diacetate hydrolase under the pesticide parathion stress https://ogma.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 (Km) 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 (Kic) and noncompetitive constant (Kiu) 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 (Vmax/Km) of FDA–H is a sensitive integrated parameter to evaluate the PTH toxicity due to the higher inhibition ratio than the Vmax. 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 ]]> The effect of arsenic on soil intracellular and potential extracellular β-glucosidase differentiated by chloroform fumigation https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:39536 Mon 08 Aug 2022 11:27:21 AEST ]]> Soil enzyme kinetics indicate ecotoxicity of long-term arsenic pollution in the soil at field scale https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:40598 Fri 15 Jul 2022 11:21:12 AEST ]]> Using soil enzyme Vmax as an indicator to evaluate the ecotoxicity of lower-ring polycyclic aromatic hydrocarbons in soil: Evidence from fluorescein diacetate hydrolase kinetics https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:52970 Fri 03 Nov 2023 15:30:26 AEDT ]]>