Amelioration of Hexachlorocyclohexane-Induced Oxidative Stress by Amaranth Leaves in Rats

The effect of prefeeding dehydrated amaranth leaves (AL), at 10 and 20% levels on hexachlorocyclohexane (HCH)-induced free radical stress in rat liver was evaluated. The HCH-induced raise in malonadialdehyde (MDA), conjugated dienes and hydroperoxides was diminished by AL. The effect of AL was highly effective with respect to reduction in these cytotoxic products, especially at 20% level. AL intake resulted in a significant increase in hepatic vitamin A and glutathione (GSH). However, the AL consumption reduced hepatic tocopherols. Feeding of AL at 10%level increased the hepatic glucose-6-phosphate dehydrogenase (G-6-PDH) activity while that at 20% level increased the hepatic glutathione reductase (GSSGR) as well, in addition to G-6-PDH. Amaranth leaves at 10 and 20% levels of feeding reduced the hepatic superoxide dismutase and glutathione peroxidase (GSH-Px) activities. The pre-feeding of AL resulted in the reversal of HCH-induced alteration in GSH-Px and G-6-PDH activities. The significant reduction in the level of glutathione S-transferase brought about by HCH was restored to control level by feeding 20% AL. It is concluded that the consumption of AL at 20% level produces reduction in the HCH-induced impairment of antioxidant status in rat liver.     

Accelerated aerobic degradation of γ-hexachlorocyclohexane in suspensions of flooded and non-flooded soils pretreated with hexachlorocyclohexane

Summary A commercial wettable-powder formulation (50% a. i.) of hexachlorocyclohexane (HCH) was applied to unplanted and planted (to rice) soils under flooded and non-flooded conditions at 1 kg a. i. ha^–1 at 15-day intervals. A mineral salts medium supplemented with -HCH as a sole source of C was inoculated with suspensions from HCH-treated and untreated soils (unplanted or planted to rice) and incubated under aerobic conditions. -HCH disappeared completely within 10 days from the aerobically incubated medium inoculated with the suspension from the treated soil compared to less than 30% loss from the uninoculated medium or from the medium inoculated with the suspension from the untreated soil, during the corresponding period. Soil samples from HCH-treated flooded pots lost their capacity for accelerated degradation of -HCH after autoclaving. The addition of HCH clearly stimulated aerobic degradation of -HCH, even in predominantly anaerobic flooded soil. The factor responsible for the accelerated degradation of -HCH in pretreated soil was not detected in the deeper layers (>10 cm) of flooded soil and in fields that had dried following the rice harvest.     

Biodegradation of hexachlorocyclohexane-isomers in contaminated soils

Several sites that are contaminated with isomers of the chlorinated insecticide hexachlorocyclohexane (HCH) are present across the globe and cause toxicity. For their bioremediation, we studied the degradation of HCH-isomers in contaminated soils by an isolate Pseudomonas aeruginosa ITRC-5. The degradation is optimal at 2 mg technical-HCH (t-HCH)/g soil, 15% water content, pH 8.0, temperature 28 °C and inoculum density 10⁶ colony forming unit/g soil. Under these conditions, from 5 kg soil, >98% α- and γ-HCH, 17% β-HCH and 76% δ-HCH are degraded after 15 days of incubation, which is accompanied with the release of 600 μg chloride/mg t-HCH. Concomitant to the degradation, a four-fold reduction in the toxicity of HCH-isomers to earthworm, Eisenia foetida, is also observed. Addition of ITRC-5 enhanced the degradation of soil-applied HCH-isomers in ‘open field’ conditions as well, and 97%, 43%, 94% and 77% of α-, β-, γ- and δ-HCH, respectively, are degraded after 12 weeks of incubation. Thus, the bacterium causes microbial degradation and detoxification of HCH-isomers, and can be used for the bioremediation of contaminated soils.     

小麦中六六六、滴滴涕残留量标准分析方法可行性验证研究

小麦中BHC、DDT残留检测标准分析方法的可行性试验得出,回收率达到90.94±6.42%,损失率在允许范围之内,农药残留量实测值的变异系数在1.5—11.8%,重现性也在允许偏差范围之内,证实我国沿用的“磺化法”可提供为国家标准分析方法。     

Persistence of hexachlorocyclohexane isomers in soil planted with rice and in rice rhizosphere soil suspensions

Summary The relative persistence of -, and -isomers of hexachlorocyclohexane (HCH) was studied in a flooded soil with and without rice seedlings under greenhouse conditions. -HCH was more stable than - and -HCH in both planted and unplanted systems. - and -HCH decreased to negligible levels (5.5% for the -isomer and 2.4% for the -isomer) after 30 days in planted and unplanted soils. During the same period, 30.9% of the added -HCH was recovered from planted soil and 50.6% from unplanted soil. Likewise, in anaerobically (H₂ + CO₂ atmosphere) incubated mineral salts solution inoculated with suspensions from rice rhizosphere and non-rhizosphere soils, -HCH decreased to low levels (< 15%) within 5 days. Most of the added -HCH was recovered from mineral solution inoculated with nonrhizosphere soil suspension even after 30 days while -HCH decreased to 53.6% of the original level in mineral solution inoculated with rice rhizosphere soil suspension. The data reveal that the degradation of anaerobically unstable HCH isomers is not retarded by the possible aeration of a flooded soil by rice roots.     

六六六对红壤和紫色土中细菌群落多样性及结构的影响

尽管六六六已被禁用多年,但由于难降解、易持留的特性,其在土壤中检出率仍较高。残存的六六六对土壤细菌群落多样性和组成结构的影响一直备受关注,相关认识仍待深化。采用小麦盆栽试验,借助高通量测序技术,模拟研究了不同施药浓度(0、600、1 500 g·hm^–2)下六六六对旱地红壤和紫色土中细菌群落多样性和结构的影响。α指数分析结果表明,在培养初期,施用六六六显著提高红壤细菌群落多样性,而对紫色土无显著影响;但随培养时间延长,在第42天时细菌群落多样性均恢复至对照组(CK)水平。细菌群落组成分析显示,红壤中优势菌门为变形菌门(Proteobacteria)和放线菌门(Actinobacteria)。分析OTUs(可执行分类操作单元)丰度发现,六六六提高了红壤放线菌门和酸杆菌门(Acidobacteria)的多样性和丰度,从而导致红壤细菌群落多样性指数上升;紫色土中优势菌门为变形菌门和酸杆菌门。六六六增加了红壤中固氮菌Bradyrhizbium(慢生根瘤菌)丰度,600和1 500 g·hm^–2六六六处理组较对照分别增长了150%和180%;紫色土中,...     

水稻及其根际土壤中六六六、滴滴涕残留量探析

对四川省水稻及其根际土壤中主要有机氯农药六六六(BCH)和滴滴涕(DDT)残留现状研究结果表明,在抽检的10套样品水稻籽实中均未检出有机氯污染物六六六和滴滴涕,符合国家颁布的食品卫生标准。而根际土壤中普遍检出滴滴涕农药残留,且德阳孝泉镇还检出六六六农药残留,但根据土壤环境质量标准(GB15618—95)其土壤中六六六和滴滴涕的残留尚未超标,符合自然土壤背景值标准。建议继续禁用六六六和滴滴涕农药,并应间断性对食用农产品进行抽样调查,同时尽快禁止食用性植物生产中使用三氯杀螨醇。