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Abstract  

The after effects of β -decay on time differential perturbed angular correlation (TDPAC) spectra of II–VI semiconductor CdS have been studied using β -emitting111Ag as well as111mCd as probe nuclei. The TDPAC spectrum of111Ag in CdS exhibits a time dependent interaction indicating that the preceding β -decay leaves the daughter nucleus in an excited state. The recovery time (τg) of the probe atom was found to be 16±6 ns while Abragam and Pound's relaxation time (τkr) was found to be 9±2 ns. The results show that β -decay does change the chemical environment around the probe atom.

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Borsó és napraforgó jelzőnövényekkel, 1 kg talajt tartalmazó edényekben végeztünk tenyészedény-kísérletet az 1970-es évek elején, az intenzív műtrágyahasználat kezdetén vett és tárolt talajmintákkal, valamint 30 év elteltével ugyanazokról a helyekről gyűjtött párjukkal. A minták karbonátos talajok (csernozjomok) esetén 6, nem karbonátos talajok (savanyú barna erdőtalajok) esetén pedig 13 mintavételi körzetet reprezentáltak. A virágzásig nevelt növények mintáit elhamvasztottuk és megmértük a P-, K-, Ca-, Mg-, Na- és B-tartalmukat. Korábbi talajvizsgálati adatainkkal egyezően, a savanyú talajokon termesztett növényminták szárazanyagában igen jelentős B-tartalom csökkenés volt mérhető. A mostanra kialakult és vélhetően állandósult helyzetben a savanyú talajokon termesztett növények B-tartalma most már lényegesen kisebb, mint a karbonátos talajokon termesztetteké. Az ebből adódó estleges egészségügyi hatások vizsgálata indokolt lenne. A növények P-tartalma is növekedett, követve a talaj oldható P-tartalmának változását. Ez felveti annak a nagy valószínűségét, hogy jelenleg és még sokáig a növények Zn és más P-antagonista mikroelem-tartalma tartósan alacsony marad. A K-műtrágyázás olyan módon csökkentette a növényi szárazanyag Mg-, Ca- és Na-tartalmát, hogy emellett a növények K-koncentrációja nem minden esetben követte a talajok nagyobb K-ellátottságát. Vizsgálataink szerint tehát a tartós intenzív műtrágyázás hatására lényegesen megváltozott a termesztett növények elemösszetétele, ami a hosszú utóhatás időszakra is állandósult. A változásoknak táplálkozás-egészségügyi hatásai is lehetnek.

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Abstract  

Nuclear quadrupole interaction frequencies at133Cs following the electron-capture decay of133Ba for BaSO4, Ba/BrO3/2 and Ba/NO3/2 were obtained by measuring the perturbation of 356–81 keV cascade of133Ba. Nuclear quadrupole interaction frequencies for BaSO4 and Ba/BrO3/2 are 17.2 Mrad sec–1 and 14.6 Mrad sec–1, respectively, while no perturbation of 356–81 keV cascade was observed in case of Ba/NO3/2. Further the possibility of any after-effects of electron-capture decay is ruled out through the measurement of 276–161 keV gamma-gamma directional correlation.

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The primary (1 st year) and the after-effects (2 nd , 3 rd year) of N fertilizers (KNO 3 , NH 4 Cl) on the soil-plant-atmosphere system were studied in a three-year greenhouse pot experiment with and without maize plants. The two- and three-year balances of the fertilizer N uptake and gaseous N losses were also analyzed. The cumulative values of the gaseous losses showed a similar trend in all years, significant differences were not obtained. On the basis of the three-year balance, the gaseous loss in the planted and unplanted pots was 18-22% and about 37-39%, respectively. Consequently, there was a 50% decrease in denitrificated gaseous losses of fertilizer N due to plant N uptake. The cumulative gaseous loss, calculated by the difference method, was significantly higher in cases of KNO 3 applications than in NH 4 Cl treatments, as an assumed  consequence of the intensive denitrification. It was found that the gaseous loss was not influenced by soil moisture.  In contrast to the gaseous losses, the values of plant N uptake and soil mineral N content showed significant differences in the years studied, as a result of the quick transformation of mineral N to organic N, the non-complete homogenization of the total soil amount, the seasonal climatic differences in the greenhouse during the years studied, and consequently the different microbiological activity. The plant N uptake was found to depend significantly on the fertilizer N form. Results obtained by the difference method and the 15 N-tracer technique were very similar. In the case of KNO 3 treatment and higher soil moisture (WHC = 80%) plant N uptake was more intensive, ranging between 48-57% (calculated by the difference method), and 35-51% (calculated by the 15 N- tracer method) in the first year (1993). It can be concluded that 60-100% of the fertilizer N was used from the soil by plant uptake and gaseous losses, which depends mainly on the treatments and the soil moisture during the first year. These values changed between 7-17% in the 1 st year after-effect and between 1-5% in the 2 nd year after-effect.

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