首页   按字顺浏览 期刊浏览 卷期浏览 Kinetics and effect of moisture content and preincubation on the decomposition of14C‐la...
Kinetics and effect of moisture content and preincubation on the decomposition of14C‐labeled herbicides in soil

 

作者: John Stenström,  

 

期刊: Toxicity Assessment  (WILEY Available online 1990)
卷期: Volume 5, issue 1  

页码: 15-27

 

ISSN:0884-8181

 

年代: 1990

 

DOI:10.1002/tox.2540050103

 

出版商: Wiley Subscription Services, Inc., A Wiley Company

 

数据来源: WILEY

 

摘要:

AbstractThe kinetics and the influence of soil moisture content (MC) on the mineralization of14C‐labeled linuron were investigated at 15 different MCs in the range from air‐dried soil to 100% of the water‐holding capacity (WHC). For all MCs used, the data on the liberated amount of14C (x) were initially described by Eq. (1)x=k1t+a—after which the data were described by Eq. (2)x=k2t1/2+b—wheretis time,k1andk2are rate constants, andaandbare constants. The rate constantsk1andk2for MCs<100% of WHC were mathematically described by the equationk=l+m. MC12, wherekis either of the rate constants,lis a constant that can account for a threshold value of MC below which no decomposition occurs, andmis a constant. The validity of this equation for first‐order rate constants was tested by using data from the literature. The kinetics of mineralization of14C‐labeled glyphosate were investigated by adding glyphosate after different times of preincubation (tp) of a previously frozen soil. An initial phase of 11 days linear witht[Eq. (1)] was obtained when the herbicide was added immediately after the thawing, after which a phase linear witht1/2[Eq. (2)] ensued. The length of the initial phase decreased andk1increased with increasingtp, and fortp≥ 8 days the initial phase could not be confirmed. The following phase was almost unaffected by the preincubation. Thus, the phases represented by Eqs. (1) and (2) are separate, since they can be affected independently of each other. It is suggested that the initial phase is an induction phase, or lag phase, which reflects the disturbances introduced by handling the soil, and that the second phase is t

 

点击下载:  PDF (609KB)



返 回