Compound contamination and secondary ecological effects of Cd and As in soil－alfalfa ecosystems

d and As both have harmful effects on the growth,development and seed germination of alfalfa, especially in such a condition as the coexistence of Cd and As in soil environment The research using the pot-culture imitative method first found that if soil was simultaneously polluted by Cd and As,function of alfalfa absorbing Cd from soil may be promoted because of the existence of As,in conversely,Cd may inhibit alfalfa plant from absorbing As It was also found that secon- dary ecological effects were most likely to be brought out due to the coexistence of Cd and As. For example,alfalfa is passive to excessively absorb Cu and Pb .The harmful effects undoubtedly intensi- fy the contamination of alfalfa, The results showed that the mechanism of the interaction among Cd,As,Pb and Cu in soil-alfalfa ecosystems is very complicated.

Effects of 4 Types of Remediation Agents on Reducing Cd Contents in Soil and Rice on Cd-contaminated Farmland

A field experiment was carried out in Cd-contaminated rice fields in a county of Hengyang to explore the effects of different types of remediation agents on the contents of soil available Cd and rice Cd,and rice yield by using one rice variety Longliangyouhuazhan,and 4 kinds of remediation agents:DG foliar control agent,SMA microbial inoculant,XFJ organic fertilizer and LXM calcium-and silicon-based passivator as test materials.The results showed that compared with CK,after applying DG foliar control agent,soil available Cd content increased rather than decreased,whereas rice Cd content decreased,not reaching a significant level.When applied with SMA microbial inoculant,soil pH value,soil available Cd and rice Cd contents showed a downward then upward trend with the increase of its application rates.Between 3 levels of SMA treatments,the content of soil available Cd in SMA2 was the lowest,decreased by 8.59%in comparison with CK,contrarily,two other SMA treatments were increasing instead of decreasing in the content of soil available Cd.The application of XFJ organic fertilizer and LXM calcium-and silicon-based passivator increased soil pH value,and reduced soil available Cd and rice Cd contents;the contents of soil available Cd and rice Cd decreased with their application rates increasing.Compared with CK,XFJ3 reduced soil available Cd content by 9.40%,and significantly reduced rice Cd content by 57.28%.In LXM3 treatment,soil available Cd content reduced by 14.57%,rice Cd content was 71.57%lower than CK,reaching the lowest level.In general,LXM calcium-and silicon-based passivator had the best Cd reduction effect,with the optimal application amount of 6000 kg/hm^(2).

Inhibition and Control Effects of Different Amendments on Cd Activation in Soil and Cd Absorption in Rice

Through pot tests of early rice and late rice in Cd polluted environment(soil Cd content,1.0 mg/kg),the inhibition and control effects of single application of organic fertilizers involving pig manure and biochar,and their combined application with alkaline amendments involving lime and oyster shell powder on soil Cd activation and rice Cd absorption were compared.And the correlation between soil available Cd and rice grain Cd was discussed.The results showed that compared with CK which did not involve amendments,the grain yields of early rice and late rice increased by 15.52%~36.01%and 12.02%~27.28%,respectively,the grain Cd content decreased by 24.76%~64.53%and 4.93%~58.32%,respectively,and the grain Cd accumulation decreased by 22.27%~51.76%and 33.84%~46.95%,respectively,except for single pig manure treatment.In particular,the Cd reduction effect of biochar was significantly better than that of pig manure,and the combined application with oyster shell powder was better than that with lime;after the harvest of early and late rice,the available Cd content in soil applied with amendments decreased by 35.00%~65.88%and 30.93%~68.57%,respectively,compared with CK.Further analysis showed that the soil available Cd content and rice grain Cd content could fit the linear equation well(R2>0.70,P<0.05),which demonstrated that the combined application of organic fertilizers and alkaline amendments can quickly reduce the Cd content of rice grain by passivating soil available Cd,and the combined application between biochar and oyster shell powder had a better effect.

Suppressive effect of dexamethasone on the neutrophil expression of CD18 in rats with radiation induced brain edema

BACKGROUND： Stereo-tactic radiation therapy （SRT） is widely used to treat intracranial diseases, but some patients suffered from radiation induced brain edema after SRT. Once radiation induced brain edema occurs, the treatment is quite difficult, and it always leads to a poor outcome. Dexamethasone has certain therapeutic effect on traumatic brain edema, but the biological mechanism is still unclear. OBJECTIVE ： To observe the effect of dexamethasone on the neutrophil expression of CD18.DESIGN ： A randomized control observation.SETTING： Changhai Hospital of the Second Military Medical University of Chinese PLA. MATERIALS ： The experiment was carried out in Changhai Hospital of the Second Military Medical University of Chinese PLA from January 1999 to December 1999. Twenty SD rats （male and female each in half） weighing （250±50） g were used. METHODS： Twenty SD rats were divided into four groups at random. ① Blank control group （n=5）： The rats were not treated without dexamethasone or irradiation;② Irradiation group （n=5）： The rats were given irradiation but no dexamethasone treatment; ③ Irradiation＋1 mg/kg dexamethasone group （n=5）; The rats were treated with irradiation and dexamethasone of 1 mg/kg; ④Irradiation＋5 mg/kg dexamethasone group （n=5）： The rats were treated with irradiation and dexamethasone of 5 mg/kg. The heads of the rats were irradiated with 10 MeV X-ray （30 Gy）, and brain tissue was removed after 2 weeks to observe the pathological changes. Blood samples were taken from the carotid artery, gradient centrifugation was used, and neutrophile layer was obtained, the level of neutrophile expression of CD18 mRNA and quantity of membrane proteins in blood were detected with Northern blot and flow cytometry respectively. MAIN OUTCOME MEASURES： ① Blood cell count; ② Pathological results; ③ level of neutrophile expression of CD18 mRNA and quantity of membrane proteins. RESULTS ： All the 20 SD rats were involved in the analysis of results without deletion. At 2 weeks after irradiation, obvious cell injury could be observed under light microscope. The level of neutrophile expression of CD18 mRNA and quantity of membrane proteins in blood were obviously increased, but the severity of cell injury was relieved in the irradiation＋1 and 5 mg/kg dexamethasone groups, and the CD18 expression was markedly suppressed （P 〈 0.05）, and the suppression was more obvious in the irradiation＋5 mg/kg dexamethasone group than in the irradiation＋1 mg/kg dexamethasone group （P 〈 0.01 ）. CONCLUSION： Dexamethasone can reduce the radiation induced brain edema by inhibiting the expression of CD18.

Effect of Ligustrazine on CD_(34) Antigen Expression of Bone MarrowCells in Immune-Induced Aplastic Anemia Mice

Objective:To explore the effect of ligustrazine on CD34 antigen expression of bone marrow cells in immune-induced aplastic anemia（AA）mice.Methods:The model of immune aplastic anemia mice was in duced by means of 6.0GY60γ-rayirr adi at ion and lym phocyte infusion through tail vein.Immuneinduce dAA micewere divided into 3 groups:thenormal group,the AA control group and the ligustrazine group.Miceof the ligustrazine group were fed by 4 mg of ligustrazine in jecti on twicea day bygastro gavage.On the 10 thday,CD34 an tigen expression intensity of bone marrow cell membrane was measured by flowcy tometer an alysis system.Results:CD34 antigen expressionin tensity of ligustrazine group was 77.6±6.5,with no statistic difference from that in normal group（80.0±2.6),while that of the control group was muchhigher（68.6±4.5,P＜0.05).Conclusion:Ligustrazine could promote proliferation of stem and progenitor cell of AA mice through in fluencing on bone marrowmicro-environment so as to increase the CD34antigen expression of bone marrow cells.

The oscillations in ESR spectra of Hg_(0.76)Cd_(0.24)Te implanted by Ag^+ at the X and Q-bands

The objects of the investigation were uniformly Ag~＋ doped Hg_（0.76）Cd_（0.24） Te mercury chalcogenide monocrystals obtained by ion implantation with subsequent thermal annealing over 20 days. After implantation and annealing the conductivity was inverted from n-type with carrier concentration of 10^（16） cm^（-3） to p-type with carrier concentration of ≈ 3.9 × 10^（15） cm^（-3）. The investigations of microwave absorption derivative（d P/d H） showed the existence of strong oscillations in the magnetic field for Ag：Hg_（0.76）Cd_（0.24） Te in the temperature range 4.2–12 K. The concentration and effective mass of charge carrier were determined from oscillation period and temperature dependency of oscillation amplitude. We suppose that this phenomenon is similar to the de Haas–van Alphen effect in weakly correlated electron system with imperfect nesting vector.

Using DGT to Assess Cadmium Bioavailability to Ryegrass as Influenced by Soil Properties

A generally accepted method for predicting the bioavailability and transfer of cadmium(Cd) from soil to plants has not yet been established. In this study, the diffusive gradients in thin films(DGT) and conventional extraction methods for metal fractions were used to investigate how effective these methods were at predicting Cd bioavailability to ryegrass(Lolium perenne) and to assess whether these holistic variables were independent of the soil property variables. The influences of soil properties on the predictive capabilities of the different methods were evaluated using multivariate statistics. The Cd concentrations in the shoots and roots of ryegrass correlated more closely with the effective Cd concentration measured by DGT(CE), compared with those with soil total Cd, pore water Cd, and ethylenediaminetetraacetic acid disodium salt(Na2EDTA)- and acetic acid(HOAc)-extractable Cd. When soil properties were included in a stepwise multiple linear regression, Cd transfer to L. perenne was negatively influenced by p H and positively influenced by organic matter(OM). The multivariate statistics showed that the adjusted correlation coefficients for the plots involving soil total Cd, pore water Cd, and Na2EDTA- and HOAc-extractable Cd had been significantly improved after considering the influences of soil properties, which suggested that these methods were p H and OM dependent. For CE, the relationship was p H independent or only dependent in strongly acidic soils. These results suggested that the main soil factors affecting bioavailability had the lowest impact on the DGT technique. Therefore, the DGT technique provided significant advantages over conventional methods when assessing Cd bioavailability.