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1.
为降低蔬菜采后体内多环芳烃(PAHs)对人体的危害风险,以豇豆为材料,利用不同浓度洗洁精、食盐、米酒、米醋、植物油及清水分别对豇豆豆荚进行浸洗,通过高效液相色谱-质谱联用法检测豇豆采后体内PAHs的含量,并筛选出豇豆体内PAHs的最佳净化方法。结果表明,米酒和米醋处理对豇豆体内PAHs的去除效果基本一致,其中米酒处理组的∑PAHs(美国环保局公布的优先监测的16种多环芳烃的含量总和)降低68.92%,米醋处理组的∑PAHs降低73.88%,且对萘、二苯并(a,h)蒽和茚并(1,2,3-c,d)芘等均有明显的去除效果;清水浸洗可有效降低豇豆体内的茚并(1,2,3-c,d)芘含量,但会使菲的含量增加;食盐处理使∑PAHs增加了77.15%,主要表现在增加了2、3环PAHs在豇豆体内的积累;植物油处理可降低个别PAHs单体含量,但会引入其他PAHs单体,同时增加∑PAHs含量。毒性当量计算结果表明,米酒能有效降低豇豆体内的PAHs毒性,同时食盐处理也使豇豆体内的PAHs毒性当量降低。米酒和米醋能有效降低豇豆体内∑PAHs和二苯并(a,h)蒽的含量及其毒性当量。 相似文献
2.
Abstract. In Australia, stubble burning and tillage are two of the major processes responsible for the decline of soil organic carbon concentration in cropped soils, and the resulting soil degradation. However, the relative importance of these two practices in influencing the soil organic carbon concentration and the long-term impact on soil quality and productivity are not clear. The effects of stubble burning as practised by farmers in southeastern Australia were evaluated in two field trials, one of 19 years duration, the other of 5 years. Conventional tillage (three tillage passes) led to greater loss of soil organic carbon than stubble burning. Loss of total soil organic carbon attributed to stubble burning in the 0–10 cm layer was estimated to be 1.75 t C ha−1 over the period of the 19-year trial, equivalent to 29% of that lost due to tillage. In the 5-year trial, no change in soil organic carbon due to stubble burning was detectable. Changes in soil quality associated with stubble burning detected in the longer trial included a reduction in macro-aggregate stability, and increases in pH and exchangeable K+ . Only the latter two were detected in the shorter trial. A higher mean wheat yield (average 0.15 t ha−1 ) following stubble burning was observed in the 19-year trial but not in the 5-year trial. Research to monitor the longer term effects of stubble burning is needed, and to identify conditions where loss of soil organic carbon is minimized. 相似文献
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Dense planting and less basal nitrogen (N) fertilization have been recommended to further increase rice (Oryza sativa L.) grain yield and N use efficiency (NUE), respectively. The objective of this study was to evaluate the integrative impacts of dense planting with reduced basal N application (DR) on rice yield, NUE and greenhouse gas (GHG) emissions. Field experiments with one conventional sparse planting (CK) and four treatments of dense planting (increased seedlings per hill) with less basal N application were conducted in northeast China from 2012 to 2013. In addition, a two-factor experiment was conducted to isolate the effect of planting density and basal N rate on CH4 emission in 2013. Our results show that an increase in planting density by about 50% with a correspondingly reduction in basal N rate by about 30% (DR1 and DR2) enhanced NUE by 14.3–50.6% and rice grain yield by 0.5–7.4% over CK. Meanwhile, DR1 and DR2 reduced GWP by 6.4–12.6% and yield-scaled GWP by 7.0–17.0% over CK. According to the two-factor experiment, soil CH4 production and oxidation and CH4 emission were not affected by planting density. However, reduced basal N rate decreased CH4 emission due to it significantly reduced soil CH4 production with a smaller reduction in soil CH4 oxidation. The above results indicate that moderate dense planting with less basal N application might be an environment friendly mode for rice cropping for high yield and NUE with less GHG emissions. 相似文献
6.
The ecological environment in Central Asia is vulnerable to pressure from human activity due to the physical geography and climatic fragility of this region. A set of indicators suitable for the future assessment of this pressure needs to be proposed. Thirty‐six topsoil samples (0–5 cm) were collected from roadsides in a suburban region of Bishkek, the capital of the Kyrgyz Republic in Central Asia, and a risk assessment of anthropogenically disturbed potentially toxic elements (PTEs) was systematically conducted with classic statistical methods. The results of detrended correspondence analysis and principal component analysis clearly showed that topsoil samples with high contents of PTEs (Pb, Zn and Cu) were strongly affected by traffic within a distance threshold of 200 m and that anthropogenic effects decreased significantly with increasing distance from the highway. The enrichment factor and anthropogenic contribution for Pb were the highest among the three PTEs, with average values of 2.0% and 47.4%, respectively, suggesting enrichment. However, the results of the human health risk assessment also indicated that noncarcinogenic risks did not occur for any of the anthropogenic PTEs. The reported method provides a new systematic pathway to reveal anthropogenic influences on the geochemical composition of soil. The conclusions of this work will be highly valuable as important guidelines for agriculture, and the results of the PTE contents will provide a scientific basis for soil collection in future studies. 相似文献
7.
N. Fitton C. P. Ejerenwa A. Bhogal P. Edgington H. Black A. Lilly D. Barraclough F. Worrall J. Hillier P. Smith 《Soil Use and Management》2011,27(4):491-501
The aim of this paper is to assess the greenhouse gas (GHG) mitigation potential of croplands and grasslands in Great Britain under different management practices. We consider the feasible land management options for grass and cropland using county level land‐use data with estimates of per‐area mitigation potential for individual and total GHGs, to identify the land management options with the greatest cost‐effective mitigation potential. We show that for grasslands, uncertainties still remain on the mitigation potential because of their climatic sensitivity and also their less intensive management. For croplands in Great Britain, the technical mean GHG mitigation potentials for all cropland management practices range from 17 Mt CO2‐eq. per 20 yr to 39 Mt CO2‐eq. per 20 yr. There are significant regional variation in all cases, with the greatest potentials in England, negligible potential in Wales and intermediate potential in Scotland, with country differences largely driven by the areas of cropland and grassland in each country. Practices such as agronomic improvement and nutrient management are the most promising options because of their impact on N2O emissions and also their larger potential at low cost. In terms of annual emissions from agriculture, calculated mitigation potentials are small, where the technical mitigation potential of agronomy and nutrient management strategies are ca. 4.5 and 3.8%, respectively (agricultural emissions account for ca. 9% or 47.7 Mt CO2‐eq., of total Great Britain GHG emissions, Department of Energy and Climate Change, UK). However when compared with the land use, land‐use change and forestry sector (LULUCF) emissions, nutrient management would reduce further emission reductions by approximately half of the 2005 LULUCF sink (i.e. ?1.6 Mt CO2‐eq. per year). 相似文献
8.
Comparison of emission estimates for non‐CO2 greenhouse gases from livestock and poultry in Korea from 1990 to 2010 下载免费PDF全文
It has often been claimed that non‐carbon dioxide greenhouse gases (NCGGs), such as methane, nitrous oxide and fluorinated greenhouse gases, are significant contributors to climate change. Here we nvestigate emission estimates of methane and nitrous oxide from livestock and poultry production, which is recognized as a major source of those NCGGs, in Korea over the period of 1990 through 2010. Based on the data on livestock and poultry populations, emission estimates of methane and nitrous oxide are first derived based on the Tier 1 approach. Then, the Tier 2 approach is adopted to obtain emission estimates of methane and nitrous oxide from cattle, which are known to be the largest sources of these NCGGs and account for about 70% of emissions from livestock and poultry in Korea. The result indicates that the Tier 2 estimates of methane and nitrous oxide emissions from enteric fermentation and manure management are significantly different from the Tier 1 estimates over the analysis period. 相似文献
9.
对Bt毒蛋白不同抗性水平棉铃虫品系的生物学研究 总被引:1,自引:0,他引:1
用对Bt毒蛋白(Cry1Ac)具有一定抗性水平的安阳品系和相对敏感的新疆品系棉铃虫进行Bt毒蛋白(Cry1Ac)的室内毒力测定结果表明,两品系的LC50值分别为8.7645g·L 1和0.2547g·L 1,前者是后者的34.4倍。用转Bt基因抗虫棉中棉所29和常规棉花品种中棉所35蕾期的倒3叶饲养安阳品系和新疆品系棉铃虫的初孵幼虫(孵化后24h),结果表明:两个棉铃虫品系在取食抗虫棉后的累计校正死亡率在1~2d内差异不明显;新疆品系棉铃虫在转Bt基因抗虫棉上发育的最高龄期为4龄,其比率为6.7%;而安阳品系部分棉铃虫能够在转Bt基因抗虫棉上完成生长发育,其4龄幼虫的比率为45.5%,5、6龄幼虫的比率分别为12.6%和3.8%,有1.6%的幼虫能够正常化蛹;用常规棉棉叶饲养的安阳品系和新疆品系棉铃虫各龄幼虫的发育历期差异不显著,而用转Bt基因抗虫棉棉叶饲养的安阳品系棉铃虫幼虫的发育历期与新疆品系虽然差异不显著,但前者的发育历期均短于后者。 相似文献
10.
Hui Mao Zhaohui Wang 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2013,63(2):141-149
Large areas of China have soils low in both available selenium (Se) and zinc (Zn). In order to investigate whether Se supplied as either selenate or selenite can increase germination and growth compared with low-Se controls we used broccoli, an important vegetable with anticancer effects, especially when biofortified with Se. Broccoli was grown under both Zn adequacy and Zn deficiency to determine whether interactions between these minerals affect plant growth. Selenite and selenate at a wide range of doses increased the speed and extent of germination. Both inorganic Se forms increased early root and shoot growth at low concentrations, with selenite having a stronger effect than selenate. A sand culture trial showed a similar growth increase due to low-dose Se under Zn deficiency but not under Zn adequacy. Conversely, at high Se levels, the results provided evidence from biomass, water use, photosynthesis and gas exchange that broccoli growth was inhibited at high Se levels, with selenite being more toxic than selenate. In this broccoli trial, the two Se forms were equally effective in increasing leaf Se concentration, whereas in most plants selenite is largely converted to organic Se forms and stored in the roots. This study suggests that Se, supplied either as selenate or selenite, may improve germination and growth in broccoli, especially on Zn-deficient soils. Field trials conducted on soils which are very low in both plant-available Se and Zn are needed. 相似文献