Experimental assessment of influence of soil moisture on the <sup>137</sup>Cs accumulation in shoots of spring wheat

The aim of this research was to analyze the effect of soil moisture regime on the intensity of 137Cs transfer into cereals using spring wheat as a model species. Accumulation of 137Cs in shoots of spring wheat grown on soil substrates differ by water and nutrients content was analyzed. The investigated water regimes were 40 % (insufficient moisture supply), 70 % (optimal moisture supply) and 85 % (excessive moisture supply) of full moisture capacity of the soils; substrates with optimal and low content of essential mineral nutrients were used in the experiment. The plants were grown in a chamber with controlled climate conditions. Increasing water content in the soil from 40 to 85 % of the total moisture capacity significantly reduces the 137Cs content in plants. The shape of the relationship between soil moisture and the soil-to-plant transfer of 137Cs depends on the agrochemical characteristics of the soil. The difference in the radioisotope accumulation in the shoots of wheat grown on extreme water regimes is about four times when substrate with optimum content of nutrients was used. The difference is less than two times when substrate with a low content of essential nutrients was used; moreover, there are no differences between the 70 and 85 % variants on a substrate with low content of nutrients. The revealed dependencies cannot be explained by the change in the share of bioavailable forms of 137Cs in the soil since it does not significantly change in soils with different moisture regimes.

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Factors controlling alterations in the performance of a runoff model in changing climate conditions

Journal of Hydrology and Hydromechanics ◽

10.2478/johh-2018-0031 ◽

2018 ◽

Vol 66 (4) ◽

pp. 381-392 ◽

Cited By ~ 8

Author(s):

Patrik Sleziak ◽

Ján Szolgay ◽

Kamila Hlavčová ◽

Doris Duethmann ◽

Juraj Parajka ◽

...

Keyword(s):

Soil Moisture ◽

Air Temperature ◽

Mean Annual Precipitation ◽

Moisture Regime ◽

Validation Period ◽

Average Volume ◽

Climate Conditions ◽

Soil Moisture Regime ◽

The Mean ◽

Runoff Model

Abstract In many Austrian catchments in recent decades an increase in the mean annual air temperature and precipitation has been observed, but only a small change in the mean annual runoff. The main objective of this paper is (1) to analyze alterations in the performance of a conceptual hydrological model when applied in changing climate conditions and (2) to assess the factors and model parameters that control these changes. A conceptual rainfall-runoff model (the TUW model) was calibrated and validated in 213 Austrian basins from 1981–2010. The changes in the runoff model’s efficiency have been compared with changes in the mean annual precipitation and air temperature and stratified for basins with dominant snowmelt and soil moisture processes. The results indicate that while the model’s efficiency in the calibration period has not changed over the decades, the values of the model’s parameters and hence the model’s performance (i.e., the volume error and the runoff model’s efficiency) in the validation period have changed. The changes in the model’s performance are greater in basins with a dominant soil moisture regime. For these basins, the average volume error which was not used in calibration has increased from 0% (in the calibration periods 1981–1990 or 2001–2010) to 9% (validation period 2001–2010) or –8% (validation period 1981–1990), respectively. In the snow-dominated basins, the model tends to slightly underestimate runoff volumes during its calibration (average volume error = –4%), but the changes in the validation periods are very small (i.e., the changes in the volume error are typically less than 1–2%). The model calibrated in a colder decade (e.g., 1981–1990) tends to overestimate the runoff in a warmer and wetter decade (e.g., 2001–2010), particularly in flatland basins. The opposite case (i.e., the use of parameters calibrated in a warmer decade for a colder, drier decade) indicates a tendency to underestimate runoff. A multidimensional analysis by regression trees showed that the change in the simulated runoff volume is clearly related to the change in precipitation, but the relationship is not linear in flatland basins. The main controlling factor of changes in simulated runoff volumes is the magnitude of the change in precipitation for both groups of basins. For basins with a dominant snowmelt runoff regime, the controlling factors are also the wetness of the basins and the mean annual precipitation. For basins with a soil moisture regime, landcover (forest) plays an important role.

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