The induced voltage of the cross-cable is how to generate is expatiated in this paper. At the same time, the operation principle of relay is narrated concisely, taking the first domestic 1×330MW CFB unit expansion project of Jiangxi Fenyi Electric Power Plant as an example. Combing the engineering practice of cable laying, the reasonable control cable and power cable laying are introduced as to avoid induced voltage generation of the cross-cable.
The hazardous effects of environmental lead exposure on children have become a serious problem involving in public health issue.It has been showed by lots of researches that the environmental lead exposure is harmful to the intelligent development of children,especially to infants,and it is one of crucial factors that result in mental malfunction.The effect of lead exposure is accumulative,so is its toxic degree.Furthermore,lead exposure also is one of the factors that result in behavioral anomaly in children.For instance,it has been proved that there is a relationship between hyperactivity and the level of lead exposure.In addition,the development of motor abilities in children was retarded by possible lead exposure.
Comparing their differences between times background, basic theories and technologies, the conclusions can be drawn that Green Revolution has increased the field yield by improving the crop growth environment, and New Green Revolution promotes agricultural productivity by modifying the gene of seeds. Meanwhile, New Green Revolution is also ideological evolution. Furthermore, the view of New Green Revolution meeting the development of Chinese, agriculture is discussed , and the strategies of Chinese agriculture are put forward.
[Objective]The research aimed to study the differences between the tolerance and enrichment characteristics of cadmium of different ecotype Sedum alfredii Hance.[Method]Taken two contrasting ecotypes(non-mined ecotype and mined ecotype) of S.alfredii Hance as materials,and the characteristics of plant growth and uptake of cadmium(Cd) were studied by hydroponic experiments.[Result]The results showed that the critical concentrations of external Cd for non-mined ecotype S.alfredii Hance and mined ecotype S.alfredii Hance were 100 and 400 μmol/L,respectively.The concentrations of Cd in non-mined ecotype S.alfredii Hance and mined ecotype S.alfredii Hance increased with the external Cd supply,and the maximum values were 493 mg/kg(DW) in leaf and 934 mg/kg(DW) in stem respectively for non-mined ecotype S.alfredii Hance,while the maximum Cd concentration in leaf and stem reached at 4 933 and 3 874 mg/kg(DW) for mined ecotype S.alfredii Hance.At the same level of Cd supply,Cd concentrations among various parts within each ecotype plants,the order rootstemleaf was recorded in non-mined ecotype S.alfredii Hance,whereas leaf stemroot was observed in mined ecotype S.alfredii Hance.[Conclusion]It is concluded that mined ecotype S.alfredii Hance has better ability to tolerate,uptake and transport Cd than non-mined ecotype S.alfredii Hance.
In this paper some results of studies on the mechanisms responsible for physiological and biochemical reactions in plants under cadmium stress were reviewed.A number of toxic effects of Cd on plants was discussed,including of inhibition of growth and cell fission,spoiling cellular structure and photosynthesis system as well as enzyme activities.Moreover,Cd tolerance of plants was summarized as limiting Cd absorption,fixation by cell wall,compartmentation in vacuole,activation of antioxidative enzymes and synthesis chelated-peptide.
Characteristics of plant growth and uptake and accumulation of cadmium (Cd) and lead (Pb) by Sedum alfredii Hance in response to Cd and Pb concentration were compared by hydroponic experiments and significant differences were found between the two heavy metals.Results showed that growth of root dry matter weight of the plants was slightly affected by Cd up to 500 μmol/L,whereas growth of shoot dry matter weight increased slightly and peaked at 100 μmol/L Cd.In contrast,growth of shoot dry matter weight was slightly affected by Pb till 1 000 μmol/L,but growth of root dry matter weight enhanced significantly by Pb supply and peaked at 1 000 μmol/L Pb.The thresholds for the plant growth response to external Cd and Pb were 500 and 1 000 μmol/L respectively.Cd contents in different parts were higher than Pb,especially in leaves.At Cd≤500 μmol/L,plant Cd contents among various parts,the order was recorded as leafstemroot,whereas an adverse order of plant Pb contents,i.e.rootstemleaf was observed at Pb≥200 μmol/L.Shoot Cd contents increased with external Cd supply,and reached maximum at 500 μmol/L Cd,being 5.677 and 5.274 g/kg in leaves and stems,respectively.Similarly,shoot Pb contents increased by external Pb,which maximum Pb content in leaves appeared at 200 μmol/L Pb,being (0.169 g/kg);whilst maximum Pb content in stems reached at 1 500 μmol/L Pb,being (1.167 g/kg).Root maximum contents of Cd and Pb both were at 2 500 μmol/L Cd (Pb),being 17.820 g/kg (Cd) and 9.437 g/kg (Pb),respectively.In addition,at 500 μmol/L Cd the plant obtained its maximum shoot Cd accumulation of 3.29 mg/plant,whilst the ratio of shoot/root Cd accumulation reached 16.18.On the contrary,maximum shoot Pb accumulation was 0.32 mg/plant at 1 000 μmol/L Pb and the ratio of shoot/root Pb accumulation was 0.30.It is suggested that Sedum alfredii has higher tolerance to Pb than to Cd,whereas its abilities to uptake and transport Cd were greatly higher than to Pb,and is a Cd hyperaccumulator in terms of its shoot Cd contents.
Related research result of the form and transport of cadmium in soilplant system were summarized.And their relationships between its form and bioavailability and transport characteristics were analyzed.In addition,the absorption and translocation mechanism of soil cadmium in plant were elucidated.
Characteristics of plant growth and uptake and distribution of zinc (Zn) in Zn hyperaccumulating and non-hyperaccumulating ecotypes of Sedum alfredii Hance in response to Zn concentration were compared by solution culture experiments and significant differences were found between the two ecotypes. The optimum Zn concentration for growth of Zn hyperaccumulating ecotype is 1.0 mmol/L Zn, at which dry weight of the plant increased linearly with time in initial 16 days; thereafter, the plant growth rate decreased gradually. In contrast, the optimum Zn concentration for growth of non-hyperaccumulating ecotype is 0.001 mmol/L. At this external Zn level growth of the plant dry weight increased linearly in whole period. The maximum Zn concentration in the shoots of Zn hyperaccumulator was much greater than in that of non-hyperaccumulator, but an inverse relationship between the two ecotypes was found when their Zn concentrations in roots were compared. In Zn hyperaccumulating plant, Zn concentrations in different plant cell fractions were in the following order: cell wallcytosolcell organelle/membrane system, while in non-hyperaccumulating plant, cell wall and cytosol contained Zn at similar level, which was higher than that in cell organelle/membrane system. It is suggested that the Zn hyperaccumulating ecotype was formed as a result of long time adaptation and evolution in Zn-enriched environment.
Research advance in cadmium polluted soil and phytoremediation was summarized in recent years.The cadmium background values and contaminative source as well as current situation of cadmium pollution of farming soil in China were analyzed.Furthermore,the mechanism,plant resources and regulative measures for phytoremediation of cadmium polluted soil were elucidated.
[Objective] To reveal the differences of tolerance and uptake characteristics of cadmium in soil between mined ecotype and non-mined plants of S.alfredii.[Method] Using pot culture,different amount of Cd were put into soil as treatment,to study the growth responses of two ecotypes plants of S.alfredii in soil with different Cd content and the change of Cd content and accumulation.[Result] The growth responses were different obviously between the two plants.The tolerance threshold of mined ecotype S.alfredii to Cd was 300 mg/kg,and the non-mined ecotype was 50 mg/kg.Maximum Cd concentrations reached 893 mg/kg in shoots and 344 mg/kg in roots of the mined ecotype plant respectively;while the maximum Cd concentration in shoots was 124 mg/kg,the root was 212 mg/kg for the non-mined ecotype plant.Cd concentration in shoots was higher than roots for the mined ecotype,whereas Cd concentration was always lower in shoots than in roots for the non-mined ecotype.The Cd accumulation in shoots of the mined ecotype reached the maximum of 151.67 μg/plant,while the non-mined ecotype reached 11.99 μg/plant.Compare the two ecotypes of S.alfredii,concentration and accumulation of Cd in shoots of the mined ecotype was obviously higher than the non-mined ecotype in same content treatment of Cd in soil.[Conclusion] Cd tolerance and accumulation of the mined ecotype of S.alfredii is remarkably more than the non-mining ecotype.The mined ecotype of S.alfredii is a Cd hyperaccumulator.
'/%3e%3cuse xlink:href='%23a' transform='rotate(23.036 .093 25.536)'/%3e%3cuse xlink:href='%23a' transform='rotate(45.87 1.273 16.18)'/%3e%3cuse xlink:href='%23a' transform='rotate(69.945 .996 12.078)'/%3e%3cuse xlink:href='%23a' transform='rotate(20.66 -19.689 31.932)'/%3e%3c/svg%3e)
