Seasonal changes of redox potential and microbial activity in two agricultural soils of tropical Australia: some implications for soil-to-plant transfer of radionuclides

Occurrence and Distribution of Fusarium Communities in the Root Zone in a Post-Bog Permanent Meadow in Relation to Mineral Fertilization and Growing Seasons

The present study is the first report of a detailed analysis of the frequency of Fusarium and genera related to Fusarium colonizing the root zone of clovers and grasses growing in a permanent meadow established on peat-muck soil in a post-bog habitat. The isolation of fungi was carried out on the Nash and Snyder medium with the plate dilution method. The taxonomic identification of the collection of pure fungal cultures was based on morphological features revealed by macroscopic and microscopic observations. The species dominance coefficients, Marczewski–Steinhaus and Simpson species diversity index were calculated. Eight Fusarium complexes were distinguished. The distribution of the Fusarium population was uneven, which was generally reflected in a higher frequency of the F. oxysporum species complex in the clover root zone and M. nivale, F. avenaceum from the Fusarium tricinctum species complex, and F. culmorum from the F. sambucinum species complex in the grass root zone. The highest similarity of fungi was determined in the rhizoplane and the endorhizosphere. The highest species diversity and the highest population size were determined in the rhizosphere soil. The fertilization treatment reduced the growth rates in the Fusarium sensu lato and in genera related to Fusarium, as evidenced by the decrease in the total abundance and species richness. The root colonization by the Fusarium, especially the F. oxysporum species complex, was not accompanied by plant pathologies, which suggests a saprotrophic and endophytic rather than parasitic character of the relationships with the plant host.

A review of soil to rice transfer of radionuclides in tropical regions of Indian subcontinent

In radioecological studies, soil to plant transfer factors (TF) is commonly used to estimate the food chain transfer of radionuclides, which is an important parameter to assess ingestion doses to humans. Rice is an important (Oryza sativa L.) staple crop in tropical countries and is the major food crop consumed all over the world. Out of the seven countries (India, Pakistan, Bangladesh, Nepal, Bhutan, and the island nations like Sri Lanka and Maldives) of the Indian subcontinent, Bangladesh, Sri Lanka, and Maldives along with a major region of India fall under tropical climate class according to Köppen climate classification. Because, the soil to rice TF under equilibrium conditions are not available for all radionuclides, TF of naturally existing stable elements, which are analogues of radionuclides were compiled. This review paper presents the collection of the TF data of soil to grain and stems & shoots of rice plant for eighteen elements. Data were generated mainly from different sub climatic regions of the tropical environment of India and Bangladesh. An overview of the compilation, analysis, and discussion of the extent and limitations of the data is presented.

A revised IAEA data compilation for estimating the soil to plant transfer of radionuclides in tropical environments

A revision of the International Atomic Energy Agency (IAEA) Technical Report Series No. 472 (TRS 472) transfer parameter data for root uptake of radionuclides by crops in tropical environments was conducted under the IAEA Modelling and Data for Radiological Impact Assessments (MODARIA II) programme (2016-2019). Data on concentration ratios between plant and soil (CR_plant-soil) were collated and summarised following a specific data selection process based on the Köppen-Geiger classification of tropical (class A) climates. An overview of the data collation and analysis methods is presented together with a comparison of CR_plant-soil values between the revised tropical dataset and TRS 472 datasets. The revised dataset of CR_plant-soil values for tropical environments is part of the IAEA MODARIA II programme Technical Document on soil to plant transfer of radionuclides in non-temperate environments.

Will global warming affect soil-to-plant transfer of radionuclides?

Recent assessments of global climate/environmental change are reaching a consensus that global climate change is occurring but there is significant uncertainty over the likely magnitude of this change and its impacts. There is little doubt that all aspects of the natural environment will be impacted to some degree. Soil-to-plant transfer of radionuclides has long been a significant topic in radioecology, both for the protection of humans and the environment from the effects of ionising radiation. Even after five decades of research considerable uncertainty exists as to the interplay of key environmental processes in controlling soil-plant transfer. As many of these processes are, to a lesser or greater extent, climate-dependent, it can be argued that climate/environmental change will impact soil-to-plant transfer of radionuclides and subsequent transfers in specific environments. This discussion attempts to highlight the possible role of climatic and climate-dependent variables in soil-to-plant transfer processes within the overall predictions of climate/environmental change. The work is speculative, and intended to stimulate debate on a theme that radioecology has either ignored or avoided in recent years.