苹果汁加工和储藏中稳定性的研究

对苹果汁加工和储藏中稳定性的研究进行了综述.混浊苹果汁在加工和储藏过程中发生的非酶促褐变主要是由酚类的氧化聚合而引起,可通过低温储藏和添加0.006%Vc(W/V)加以控制.加胶或破碎时通蒸汽可改善苹果汁混浊稳定性.同时,对今后的研究重点进行了讨论.     

多元醇对油菜衰老的生理调控及增产作用探讨

 研究了不同时期喷施多元醇对甘蓝型油菜的生理效应及增产效果。结果表明：初花期喷施多元醇能显著提高油菜叶片叶绿素含量和光合速率，减少脂质过氧化产物丙二醛积累和乙烯释放量，使叶片超氧物歧化酶与过氧化氢酶活性下降变慢；多元醇能增强油菜根系活力，使植株稳健生长；多元醇还能改善油菜的经济性状，增加有效分枝数和每株角果数，初花期和盛花期喷施多元醇分别增产10.4%和7.2%，对油菜籽的品质无不良影响，对油菜生育期影响不大。     

黑曲霉、荧光假单胞菌去除污水中重金属试验研究

将黑曲霉和荧光假单胞菌引入到传统的卡鲁塞尔氧化沟工艺模型中,参照规范中氧化沟的水力停留时间,分别选取12、16、20、24、28、32和36 h水力停留时间进行试验,研究了不同水力停留时间2种菌种对重金属Cd、Cr、Pb和Cu的吸附降解规律.对水力停留时间为36 h进行了接种对比试验研究.研究发现接种2种菌种后,当水力...     

氧化塘深度对猪场厌氧消化液后处理的影响

采用小试装置对3个不同深度氧化塘处理猪场厌氧消化液的效果进行了研究,结果表明:当平均气温为21.9℃,停留时间在80 ～110天,进水负荷为0.05 m3·m-2d-1的条件下,氧化塘对NH4-N的去除率达到了90％以上,CODcr,TP的去除率分别为50％,40％.硝化作用和藻类的吸收是氧化塘去除NH4-N的主要方式,沉淀作用则是CODcr和TP的主要去除方式,在较长停留时间下,微生物对于溶解性CODcr的分解和同化也能提供一定的去除效果.当平均气温为21.9℃,在表面负荷为0.05 m3·m-2d-1的条件下,有效深度为0.3m和0.7m的氧化塘面积去除负荷分别为1.41 g·m-2d-1,1.49 g·m-2d-1,容积去除负荷分别为4.7g·m -3d-1,2.8g·m-3d-1.虽然较深氧化塘具有较高的面积去除负荷,但较浅的氧化塘却有更高的容积去除负荷.     

Biochemical and histopathological studies to assess chronic toxicity of triazophos in blood, liver and brain tissue of rats

Triazophos, O,O-diethyl-1-H-1,2,4-triazol-3-yl phosphorothioate, (TZ) is an organophosphorus pesticide which is extensively used in agriculture for controlling insect pests. Except a FAO/WHO report no study has investigated its short-term toxicity with respect to its potential to cause biochemical and histopathological alterations. The present study was designed to identify the effect of TZ at different doses (1.64, 3.2 and 8.2 mg/kg) on the oxidative stress parameters in blood as well as organs involved in xenobiotic metabolism (liver and brain) following chronic exposure for 90 days. Moreover, the study also delineates the effect of TZ on the histo-architecture of these organs. The results indicated a dose dependent induction (p < 0.001) of oxidative stress, as evident by increased malondialdehyde (MDA) level and compromised antioxidant defense including glutathione S transferase (GST) activity, glutathione (GSH) content and ferric reducing ability of plasma (FRAP) in blood, and increased MDA level with concomitantly decreased GSH content in tissues, following chronic exposure to TZ. The ratio of MDA: FRAP in blood was found to be increased following chronic exposure to TZ and may serve as a suitable indicator of severity of oxidative damage. Onset of such biochemical alterations is one of the early adaptive responses to TZ exposure which leads to histopathological alterations in terms of diffuse fatty changes expanding from mid-zonal area to whole lobule in liver. However, increased oxidative stress did not bring any morphological alteration in brain. The present study concludes that induction of oxidative stress, leading to subsequent histopathological alterations in liver, is an important mechanism underlying the TZ induced chronic toxicity.     

Exogenously applied hexaconazole ameliorates salinity stress by inducing an antioxidant defense system in Brassica napus L. plants

The ability of hexaconazole (HEX) to ameliorate salinity stress was studied in canola plants (Brassica napus L.). Canola seedlings were subjected to sodium chloride (NaCl) treatment. A treatment with 200 mM NaCl reduced growth parameters, chlorophyll content and protein content as well as increased the proline (Pro) content in canola plants. In addition, NaCl stress increased the endogenous, nonenzymatic antioxidants and the activity of antioxidant enzymes, such as peroxidase (POX; EC 1.11.1.7), superoxide dismutase (SOD; EC 1.15.1.1) and catalase (CAT; EC 1.11.1.6). When these plants were treated with a combination of NaCl and 50 mg L⁻¹ HEX, the inhibitory effects of NaCl stress were decreased by increasing the root growth, shoot growth, dry weight (DW), chlorophyll content, protein content and antioxidant enzyme activity by ameliorating the salinity injury. These results suggested that HEX has an important role in the enhancement of plant antioxidant systems and resistance to salinity in canola plants.     

一类新型植物生长延缓剂的作用机理及其应用

含有降冰片烯二氮杂环丁烯、三唑、嘧啶、吡啶和咪唑类结构的一类新型植物生长延缓剂,其共同的特征是在分子内杂环中的 sp~2杂化 N 上具有一对孤对电子。这对孤对电子作为第六配体结合到细胞色素 P-450内血红素铁上,代替了催化反应中所需的氧,导致某些依赖细胞色素P-450的单氧酶失活,并因此影响与 GA,ABA 和甾醇等有关的代谢途径,进而调节植物的生长和发育过程。因此,这类植物生长延缓剂在农林和园艺等方面具有广泛的应用前景。     

Soil organic matter in urban soils: Estimation of elemental carbon by thermal oxidation and characterization of organic matter by solid-state C nuclear magnetic resonance (NMR) spectroscopy

To reduce soil destruction by urban sprawl, land use planning has to promote the use of soils within cities. As soil functions are now protected by law in Germany, urban soil quality has to be evaluated before soil management. We studied contributions from elemental carbon (EC) and soil organic matter (SOM) quality in topsoil horizons at seven sites in Stuttgart, Germany, differing in impurities by technogenic substrates. The most disturbed site was found at a disused railway area while high-density areas, public parks and garden areas showed varying degrees of disturbance by anthropogenic activities. For most soils, compounds derived from plant litter dominated organic matter (OM) quality characterized by nuclear magnetic resonance (NMR) spectroscopy. Although high contents of EC (up to 70% of soil organic carbon) were indicated by thermal oxidation, this was not confirmed by aromatic C intensities in NMR spectra. Only for the highly aromatic railway soil were results for elemental carbon by thermal oxidation and NMR similar. As other technogenic substrates beside EC like plastics may also contribute in the long-term to OM in urban soils, new analytical techniques are therefore required. This knowledge will promote the evaluation of urban soil properties and their sustainable use.     

Labile carbon and methane uptake as affected by tillage intensity in a Mollisol

Methane (CH₄) oxidation potential of soils decreases with cultivation, but limited information is available regarding the restoration of that capacity with implementation of reduced tillage practices. A study was conducted to assess the impact of tillage intensity on CH₄ oxidation and several C-cycling indices including total and active microbial biomass C (t-MBC, a-MBC), mineralizable C (C_min) and N (N_min), and aggregate-protected C. Intact cores and disturbed soil samples (0–5 and 5–15 cm) were collected from a corn (Zea mays L.)–soybean (Glycine max L. Merr.) rotation under moldboard-plow (MP), chisel-plow (CP) and no-till (NT) for 8 years. An adjacent pasture (<25 years) and secondary growth forest (>60 years) soils were also sampled as references. At all sites, soil was a Kokomo silty clay loam (mesic Typic Argiaquolls). Significant tillage effects on t-MBC and protected C were found in the 0–5 cm depth. Protected C, a measure of C retained within macro-aggregates and defined as the difference in C_min (CO₂ evolved in a 56 days incubation) between intact and sieved (<2 mm) soil samples, amounted to 516, 162 and 121 mg C kg⁻¹ soil in the 0–5 cm layer of the forest, pasture and NT soils, respectively. Protected C was negligible in the CP and MP soils. Methane uptake rate (μg CH₄-C kg⁻¹ soil per day, under ambient CH₄) was higher in forest (2.70) than in pasture (1.22) and cropland (0.61) soils. No significant tillage effect on CH₄ oxidation rate was detected (MP: 0.82; CP: 0.41; NT: 0.61). These results underscore the slow recovery of the CH₄ uptake capacity of soils and suggest that, to have an impact, tillage reduction may need to be implemented for several decades.     

Effect of potassium phosphate fertilization on production and emission of methane and its C-stable isotope composition in rice microcosms

Rice fields are an important source for atmospheric CH₄, but the effects of fertilization are not well known. We studied the turnover of CH₄ in rice soil microcosms without and with addition of potassium phosphate. Height and tiller number of rice plants were higher in the fertilized than in the unfertilized microcosms. Emission rates of CH₄ were also higher, but porewater concentrations of CH₄ were lower. The δ¹³C values of the emitted CH₄ and of the CH₄ in the porewater were both 2-6% higher in the fertilized microcosms than in the control. Potassium phosphate did not affect rate and isotopic signature of CH₄ production in anoxic soil slurries. On the other hand, roots retrieved from fertilized microcosms at the end of incubation exhibited slightly higher CH₄ production rates and slightly higher CH₄-δ¹³C values compared to roots from unfertilized plants. Addition of potassium phosphate to excised rice roots generally inhibited CH₄ production and resulted in increasingly lower δ¹³C values of the produced CH₄. Fractionation of ¹³C during plant ventilation (i.e. δ¹³C in pore water CH₄ versus CH₄ emitted) was larger in the fertilized microcosms than in the control. Besides plant ventilation, this difference may also have been caused by CH₄ oxidation in the rhizosphere. However, calculation from the isotopic data showed that less than 27% of the produced CH₄ was oxidized. Collectively, our results indicate that potassium phosphate fertilization stimulated CH₄ emission by enhancing root methanogenesis, plant ventilation and/or CH₄ oxidation, resulting in residence times of CH₄ in the porewater in the order of hours.