[苄基-14C]-毒氟磷在大豆中的残留分布和代谢产物动态变化

为深入了解毒氟磷在植物体内的残留代谢规律,以大豆为研究对象,利用¹⁴C示踪法研究了[苄基-¹⁴C]-毒氟磷在大豆中的残留分布特征及代谢产物动态变化规律。结果表明,施药后毒氟磷主要残留在大豆受施叶上,在豆叶中毒氟磷母体的半衰期为15.32 d,施药后代谢产物的残留浓度均随时间推移而不断增加;至施药20 d时,叶片上毒氟磷母体的残留浓度为6.960 mg·kg^-1, 占总放射性活度的53.443%;代谢产物M4、M3、M1+M2的残留浓度分别为3.838、2.431、1.464 mg·kg^-1; 收获时,可食豆子中残留物含量小于总放射性残留的0.3%,其代谢产物组成与叶中相同;母体及M4的相对含量分别为51.932%和20.301%,且两者残留浓度均大于0.050 mg·kg^-1。本试验为客观评价毒氟磷的安全性提供了重要的代谢数据。     

[噻唑基-2-14C]-毒氟磷在水-沉积物系统中的降解与残留转化研究

毒氟磷是我国自主创制的新型植物抗病毒剂,研究毒氟磷的环境行为和归趋对科学评价其环境风险具有重要意义。本试验采用¹⁴C同位素示踪技术,以[噻唑基-2-¹⁴C]-毒氟磷为示踪剂,研究了毒氟磷在A和B两种水-沉积物系统中的好氧降解动态以及残留转化规律。结果表明,毒氟磷母体在两种水-沉积物系统中的水相消散和降解均符合一级动力学模型,其水相消散半减期分别为7.23 d (A)和13.86 d (B),在水-沉积物整个系统中的母体降解半减期则分别为121.60 d (A)和65.39 d (B)。毒氟磷在供试水-沉积物系统中的残留转化规律存在显著差异,培养结束时(培养时间为100 d),可提态残留在A和B系统中分别占放射性引入量的77.41%和43.71%,矿化量分别占放射性引入量的1.11%和2.83%,结合态残留分别占放射性引入量的24.11%和49.25%;较高的降解率和阳离子交换量是毒氟磷及其代谢产物在B系统中更易形成结合残留的主要原因。本研究结果为科学评价毒氟磷在水-沉积物系统中的安全性提供了基础数据和科学依据。     

[C环-U-14C]丙酯草醚在油菜/水稻中的吸收、运转及分布

丙酯草醚(ZJ0273)是我国创制的一种新型高效油菜田除草剂。本文以[C环-U-14C]丙酯草醚为示踪剂,在实验室条件下,对丙酯草醚在敏感性植物水稻和耐性植物油菜中的吸收、运转及分布规律进行了研究。结果表明：（1）施药后,水稻和油菜对丙酯草醚的吸收量总体呈随时间增加而增加的趋势,且前者大于后者。至384 h,水稻对丙酯草醚的吸收量为24.1%,而油菜仅为4.1%,水稻约为油菜的5.88倍。（2）丙酯草醚被油菜和水稻根系吸收后,均主要分布在根部,不易向上运转。水稻根系与地上部（茎叶）的放射性分布比为7.10︰1,油菜则为4.44︰1;水稻和油菜根系中单位质量放射性活度分别是各自地上部的10.36和9.85倍。（3）水稻根系和茎叶单位质量放射性活度(分别为9.470 Bq/mg和0.910 Bq/mg)显著高于油菜(3.870 Bq/mg和0.390 Bq/mg)。水稻与油菜对丙酯草醚吸收量以及单位质量中积累量的差异可能是丙酯草醚对两者存在选择性的原因之一。     

[C环-U-14C]丙酯草醚在油菜和水稻中的吸收、运转及分布

丙酯草醚(ZJ0273)是我国创制的一种新型高效油菜田除草剂。本文以[C环-U-14C]-ZJ0273为示踪剂,在实验室条件下,对丙酯草醚在敏感性植物水稻和耐性植物油菜中的吸收、运转及分布规律进行了研究。结果表明:(1)施药后,水稻和油菜对丙酯草醚的吸收量总体呈随时间增加而增加的趋势,且前者大于后者。至384h,水稻对丙酯草醚的吸收量为24.1%,而油菜仅为4.1%,水稻约为油菜的5.88倍。(2)丙酯草醚被油菜和水稻根系吸收后,均主要分布在根部,不易向上运转。水稻根系与地上部(茎叶)的放射性分布比为7.10∶1,油菜则为4.44∶1;水稻和油菜根系中单位质量放射性活度分别是各自地上部的10.36和9.85倍。(3)水稻根系和茎叶单位质量放射性活度分别为9.470 Bq/mg和0.910 Bq/mg,显著高于油菜的3.870 Bq/mg和0.390 Bq/mg。水稻与油菜对丙酯草醚吸收量以及单位质量中积累量的差异可能是丙酯草醚对两者存在选择性的原因之一。     

杀菌剂氟吗啉的14C标记合成

氟吗啉是新型内吸性杀真菌剂。它的14C标记合成经3步完成,其放化收率为35.9%(以14C-碳酸钡计),放化纯度经薄板检测达97.8%。     

好氧土壤中[C环-U-14C] 丙酯草醚的结合残留及其在腐殖质中的分布动态

农药的环境行为与归趋,尤其是结合残留研究,是新农药安全性评价的重要内容之一,这关系到新农药的科学使用。本文利用14C同位素示踪技术,研究了[C环-U-14C]丙酯草醚(ZJ0273)在3种不同类型好氧土壤中的结合残留及其在富啡酸、胡敏酸和胡敏素中的动态分布。结果表明：（1）在整个培养过程中,土壤中的丙酯草醚结合残留量均随时间而递增。培养至75d,红砂土（S1）、黄松土（S2）与淡涂泥田（S3）中的14C-BR最大值分别为引入量的12.55%,20.35%和20.49%,且富含有机质和pH较高的土壤更易与丙酯草醚形成结合残留;（2）丙酯草醚与富啡酸、胡敏酸和胡敏素形成的结合残留,含量大小依次为富啡酸＞胡敏素＞胡敏酸。因此,丙酯草醚与土壤基质形成结合残留的过程中,富啡酸起主要作用,而胡敏酸的作用最小。     

[A环-U-14C]丙酯草醚在土壤中的迁移和淋溶

在实验室模拟条件下,采用同位素成像及液体闪烁测量技术对[A环-U-14C]丙酯草醚在7种土壤中的迁移和淋溶特性进行了研究。结果显示:[A环-U1-4C]丙酯草醚在7种土壤(S1~S7)薄板层析中的Rf值分别为0.36、0.27、0.21、0.31、0.30、0.15和0.24,这表明丙酯草醚在S1中属于中等移动农药,而在其余6种土壤中均属于不易移动农药。结果还表明,[A环-U1-4C]丙酯草醚在7种土壤中随水(最大降雨量200mm/24h)的淋溶性较弱,在S1和S4中其主要分布在0~6cm土层,其余5种土壤中则主要分布在0~4cm土层。丙酯草醚在7种供试土壤中的最大淋溶量峰值均出现在0~2cm表层。因此,从迁移和淋溶特性看,田间使用丙酯草醚不易对地下水造成污染。     

铝毒胁迫下磷对荞麦根系铝形态和分布的影响

以2个荞麦（Fagopyrum esculentum Moench）品种＂江西荞麦＂（铝耐性）和＂内蒙荞麦＂（铝敏感）为材料,采用水培法,研究铝毒胁迫下磷对荞麦根系总铝和单核2种形态以及Al在根尖和细胞壁中的分布情况的影响。结果表明,与200μmol/L Al处理相比,1.0mmol/L磷预处理分别使江西荞麦和内蒙荞麦的相对根长增加了24.4%和35.9%,根系总Al含量分别降低了18.2%和22.5%,根系单核Al含量分别降低了95%和63.2%。根尖细胞壁荧光检测结果为在单Al胁迫下细胞壁的荧光强度最大,1.0mmol/L磷预处理大幅度减弱细胞壁的荧光强度。表明外源磷供应可降低根系总Al和单核Al含量,使毒性形态的铝转化为无毒形态,以及减少Al在根尖以及细胞壁的积累,以缓解Al对根伸长的抑制,提高荞麦根系的抗铝毒害能力。     

小麦根-土界面磷的分布规律

在人工气候室采用32P标记土壤和土-根平面系统研究小麦根际磷的分布。结果表明，小麦根-土界面磷呈亏缺分布，但在报表0.5mm以内，大约培养15天左右磷常出现相对累积。磷的亏缺强度在高含水量和低空气湿度时较大。随培养时间的延长，磷亏缺量和亏缺范围随之增大。此外，磷亏缺量以中下部根系较大。根-土界面磷分布以方程C／Co＝a＋blnX或C／Co＝aXb拟合为优;时（t）空（X）作用下的磷分布可用t和X三次非线性多项式拟合。     

土壤中~(14)C-甲磺隆的结合残留及其在腐殖质中的分布规律

实验室培养条件下 ,研究了14 C 甲磺隆在 7种不同类型土壤中形成结合残留( 14 C BR)的规律、主要影响因子及14 C BR在腐殖质中的动态分布规律等。结果表明 :( 1 ) 14 C 甲磺隆在 7种土壤中形成的14 C BR含量在培养初期的 2 0d内与土壤pH呈显著负相关且与土壤粘粒含量呈显著正相关 ;而 2 0d后 ,14 C BR含量只与土壤pH呈显著负相关。土壤pH是14 C 甲磺隆在土壤中形成BR的主要影响因子。14 C -甲磺隆在各类土壤中的14 C BR的最大值分别占引入量的 48 5%、46 5%、52 6%、1 9 3 %、49 7%、42 0 %和 46 5% ;( 2 )在整个培养试验过程中 ,14 C 甲磺隆在 7种不同类型土壤中的14 C BR ,主要分布在富啡酸和胡敏素中 ,前者中的相对百分比大于后者 ,而在胡敏酸中的相对百分比较小。土壤中14 C 甲磺隆BR的形成过程中 ,富啡酸的作用 >胡敏素 胡敏酸     

Distribution of 14C in Pulse-Labelled Spring Barley. Effect of Light Intensity and Length of Photoperiod Before Labelling

Abstract

The distribution of photoassimilated C in spring barley plants was determined at different times after the onset of light and at different light intensities during assimilation. The plants were grown in pots in a greenhouse, and at late tillering and late elongation, ¹⁴CO₂ pulse-labellings of 2 h duration were carried out 1.5, 4 or 8.5 h after the onset of light. At the labelling started after a 4 h photoperiod, two light intensities was included (80 and 170 W m^?2).

To analyse samples low in ¹⁴C, a ¹⁴CO₂-trapping system interfaced with a Leco high-temperature induction furnace was developed. The ¹⁴CO₂ was trapped directly in the scintillation vial in 5 mL of liquid Carbosorb, enabling subsequent liquid ¹⁴C-scintillation counting to take place without subsampling.

The proportion of photosynthate translocated below ground tended to be higher early in the morning than later in the day. Labelling 1.5 h after the onset of light, 19.8 and 7.6% was translocated below ground at late tillering and late elongation, respectively. Corresponding values found at later labellings were 15.4–16.0 and 6.0–6.4%.

Higher proportions tended to be translocated below ground when plants were exposed to low light intensity. Exposing plants to low light intensity caused below ground translocation to be 15.4 and 6.0% of the ¹⁴C recovered at late tillering and late elongation, respectively, compared with 12.1 and 5.2% after exposure to a higher light intensity. Further experiments are needed to substantiate the observations of this study. The results suggest that the distribution of photoassimilates varies during the daytime and light intensity during the labelling.     

[A环-U-~(14)C]丙酯草醚在土壤中的吸附与解吸特性研究

丙酯草醚(ZJ0273)是我国拥有自主知识产权的新型高效油菜田除草剂。本文以[A环-U-14C]丙酯草醚为示踪剂,在实验室模拟条件下,采用液体闪烁测量技术对其在7种土壤中的吸附和解吸特性进行了研究。结果表明:(1)丙酯草醚在7种土壤中的吸附等温线均能极显著符合Freundlich、Langmuir和线性模型,相对而言,前两种模型的相关系数R2(0.9883~0.9998)明显高于线性模型(R2=0.9173~0.9593);(2)丙酯草醚在7种土壤中的解吸等温线能被Freundlich模型和线性模型很好地描述;(3)丙酯草醚极易被土壤吸附,不同类型的土壤对其吸附的差异较大,吸附常数KF与土壤有机质含量呈显著正相关,与之对应的解吸率极低。丙酯草醚吸附解吸过程存在明显的滞后现象,应科学合理地在有机质丰富的土壤中使用。     

Degradation of [14C]phosphinothricin (glufosinate) in soil under laboratory conditions: Effects of concentration and soil amendments on 14CO2 production

Summary Degradation of the herbicide phosphinothricin (L-homoalanine-4-yl-(methyl)-phosphinic acid) in a phaeozem was investigated by monitoring the ¹⁴CO₂ release from [1-¹⁴C] and [3,4-¹⁴C]phosphinothricin. The degradation was largely due to microbial activity, since the rate decreased by more than 95% when the soil was sterilized by -radiation. Data obtained with both labels suggested that decarboxylation of phosphinothricin preceded oxidation of its C-atoms 3 and 4, since a metabolite, probably 3-methylphosphinico-propanoic acid, was only labelled when [3,4-¹⁴C]phosphinothricin was used as the substrate. Maximum rates of ¹⁴CO₂ production from both the 1- and 3,4-label positions occurred without a lag phase during the breakdown of phosphinothricin as monitored for a total of 30 days at 5-day intervals. This result indicated that a phosphinothricin-degrading microbial community was already present in the soil. With low concentrations of [1-¹⁴C]phosphinothricin (10.7 mg kg^-1 soil), complete decarboxylation at 25°C was observed within 30 days of incubation, compared to 15.9% ¹⁴CO₂ release from [3,4-¹⁴C]phosphinothricin. Increasing the quantity of the herbicide in the soil (10.7–1372 mg kg^-1) resulted in increased degradation rates, irrespective of whether the herbicide was labelled in the positions 1 or 3 and 4. Addition of glucose and other carbohydrates stimulated ¹⁴CO₂ release while addition of a yeast extract had a negative effect. Glucose stimulation was reversed by ammonium nitrate, suggesting that the microorganisms were using the herbicide as a source of N.     

Pyrolysis of [14C]-chlorantraniliprole in tobacco

The pyrolysis of [(14)C]-chlorantraniliprole {3-bromo-1-(3-chloro-2-pyridinal)-N-[4-chloro-2-methyl-6-[(methylamino)carbonyl]phenyl]-1H-pyrazole-5-carboxamide} in tobacco was examined. Typically five commercially available cigarettes were treated separately with either [pyrazole carbonyl-(14)C] or [benzamide carbonyl-(14)C]-chlorantraniliprole at a concentration of 20 ppm (μg chlorantraniliprole equivalent/g cigarette weight; main study) to 40 ppm (for degradate identification only). All treated cigarettes were smoked using an apparatus designed to collect mainstream (MS) and sidestream (SS) smoke through a glass fiber filter and a series of liquid traps. The material balance for recovery of applied radiolabel ranged from 92.4 to 94.9%. Unchanged chlorantraniliprole was the major component found in butt and filter extracts, averaging a total of 17.4-17.9% of the applied radioactivity. A nonpolar degradation product, 2-[3-bromo-1-(3-chloro-2-pyridinyl)-1H-pyrazol-5-yl]-6-chloro-3,8-dimethyl-4(3H)-quinazolinone, designated 1, represented an average of 10.1-15.9% of the applied radioactivity in the [pyrazole carbonyl-(14)C] or [benzamide carbonyl-(14)C]-chlorantraniliprole cigarettes, respectively. (14)CO(2) was the major degradate, representing an average of 32.9 and 25.1% of the applied radioactivity in pyrazole and benzamide experiments, respectively. In the pyrazole carbonyl label a polar degradate, 5-bromo-N-methyl-1H-pyrazole-3-carboxamide (2) was present in the filter extracts at an average of 9.5% of the applied radioactivity. The most nonpolar degradate, 2,6-dichloro-4-methyl-11H-pyrido[2,1b]quinazolin-11-one (3), was present in [benzamide carbonyl-(14)C]-treated cigarettes only and represented an average of 14.7% of the applied radioactivity.     

Uptake and metabolic fate of [14C]-2,4-dichlorophenol and [14C]-2,4-dichloroaniline in wheat (Triticum aestivum) and soybean (Glycine max)

The uptake and metabolism of [14C]-2,4-dichlorophenol (DCP) and [14C]-2,4-dichloroaniline (DCA) were investigated in wheat and soybean. Seeds were exposed to a nutrient solution containing 50 microM of one of two radiolabeled compounds, and plant organs were harvested separately after 18 days of growth. In wheat, uptake of [14C]-2,4-DCP was 16.67 +/- 2.65 and 15.50 +/- 2.60% of [14C]-2,4-DCA. In soybean, uptake of [14C]-2,4-DCP was significantly higher than [14C]-2,4-DCA uptake, 38.39 +/- 2.56 and 18.98 +/- 1.64%, respectively. In the case of [14C]-2,4-DCP, the radioactivity absorbed by both species was found mainly associated with roots, whereas [14C]-2,4-DCA and related metabolites were associated with aerial parts, especially in soybean. In wheat, nonextractable residues represented 7.8 and 8.7% of the applied radioactivity in the case of [14C]-2,4-DCP and [14C]-2,4-DCA, respectively. In soybean, nonextractable residues amounted to 11.8 and 5.8% of the total radioactivity for [14C]-2,4-DCP and [14C]-2,4-DCA, respectively. In wheat, nonextractable residues were nearly equivalent to extractable residues for [14C]-2,4-DCP, whereas they were greater for [14C]-2,4-DCA. In soybean, the amount of extractable residues was significantly greater for both chemicals. However, in both species, nonextractable residues were mainly associated with roots. Isolation of soluble residues was next undertaken using excised shoots (wheat) or excised fully expanded leaves including petioles (soybean). Identification of metabolite structures was made by comparison with authentic standards, by enzymatic hydrolyses, and by electrospray ionization-mass spectrometric analyses. Both plant species shared a common metabolism for [14C]-2,4-DCP and [14C]-2,4-DCA since the malonylated glucoside conjugates were found as the final major metabolites.