Fine root dynamics and root architecture were studied in the organic and mineral soil layers of a Cryptomeria japonica plantation. Fine root biomass (<1 mm) showed seasonal changes whereas fine root ...biomass (1–2 mm) was unchanged over the study period. Root tips were grouped into size classes based on root tip diameter, including <0.5, 0.5–1, and 1–2 mm. Root tip density (<1 mm) was significantly correlated with fine root biomass (<1 mm). Root tip density and fine root biomass (<1 mm) increased in summer and decreased in winter, and both showed a similar seasonal pattern. Root tip dynamics influenced fine root dynamics. Root architecture as expressed by branching intensity changed with root tip production and mortality. Branching intensity also showed a similar seasonal pattern of root tip density dynamics. Root tips of both <0.5 and 0.5–1 mm were mainly produced in the organic soil layer, while root tips of 0.5–1 mm were mainly produced in the mineral soil layer. Because of the high RT1 root tip production in the organic soil layer, branching intensity was higher in the organic soil than in the mineral soil layer during summer. Root tip dynamics influenced fine root dynamics and the architecture of root systems in both organic and mineral soil layers.
Fine roots of Cryptomeria japonica were separated into two functional groups: primary roots that serve as the principal agent for water and nutrient absorption and secondary roots that have transport ...capacity and protect the plant from environmental stress. Individual roots can also be categorized by three characteristics: diameter, branching order, and number of protoxylem groups. We investigated the relationships of these two functional groups with the three categories and evaluated which category was a better index for distinguishing primary from secondary roots by using the Pianka overlap index. Primary and secondary roots showed no exact correspondence to any of the three categories and had overlap in each category. Therefore neither was a useful indicator to distinguish primary from secondary roots. However, in the case of Cryptomeria japonica, we can roughly distinguish primary from secondary roots on the basis of whether root diameter is less than or greater than 0.6 mm.
We conducted a 13CO2 pulse-labeling experiment to trace the transfer of recently assimilated carbon (C) from woody plants to soil microarthropods. We investigated the utilization of root-derived C ...for six species of Collembola that differ in terms of their morphological traits and vertical distributions. Although species living in deeper soil layers, such as humus and mineral soil, have traditionally been considered to have close relationships with plant roots, we showed that even species that inhabit the litter layer utilized root-derived C. Additionally, we found interspecific differences in root-derived C utilization among species living in the same soil layer. This result suggests that collembolan species exhibiting the same vertical distribution have species-specific functional roles in soil processes, which contrasts with the previously accepted view that they are relatively redundant in terms of their belowground functions related to their dietary traits.
This study validated the chemicals monitoring ability of a polar organic chemical integrative sampler (POCIS) under non-steady-state conditions resulting from natural disasters and environmental ...accidents in aquatic environments via laboratory experiments. The goal of this work was to contribute toward monitoring the actual state of chemical contamination resulting from emergencies and natural disasters. A chamber replicating the chemical contamination of an aquatic environment established by a chemical exposure assessment model was set up in a clean booth. The concentrations of seven neonicotinoid pesticides were increased to a maximum of 1,000, 100, or 10 µg/L for one day and decreased by 50% per day thereafter. A POCIS was set up with polyethersulfone as the permeation membrane and a resin (Oasis hydrophilic-lipophilic balance) as the receiving phase. Calibration tests of the POCIS were also conducted. The results of this study led to the addition of six neonicotinoid pesticides to the list of POCIS-measurable targets. The results of the chamber experiments showed that a POCIS is a good tool for chemicals monitoring under non-steady-state conditions in an aquatic environment.
In preparation for the leakage of chemical substances from factories and business establishments caused by disasters and accidents, it is desirable for each local government to grasp the daily stock ...amount of chemical substances in advance. This time, the technique to estimate the stock amount of chemical substances in factories and business establishments from PRTR notification data was examined.Using existing survey data by the Ministry of the Environment, the relationship between the annual handling amount of chemical substances in factories and business establishments and the stock amount on the first day of the fiscal year and the end of the fiscal year was analyzed, and it was found that the stock amount was about 3.9 to 5.4% of the handling amount (about 2 weeks to 20 days). We have developed a method to estimate the handling amount from the release and transfer amount of PRTR notification data, and it seems that the estimation of the stock amount becomes possible by combining with this technique.
We compared the management of chemical substances and leak prevention measures in small-scale business establishments during disasters with those of large-scale establishments. Businesses were ...categorized into four groups based on their number of employees（with a threshold of 20 people）and the amount of chemical substances they handle（with a threshold of 1 ton）. We distributed questionnaires to 1,571 businesses across 21 cities and towns in Osaka Prefecture, all of which potentially handle chemical substances. The primary questions revolved around: 1）annual expenses related to chemical substance management, 2）leak prevention measures, 3）reasons if no measures were implemented, and 4）awareness of seminars and informational pamphlets on chemical substance management. The valid response rate was 20.2％. For establishments handling over a ton of chemical substances, both awareness of seminars/pamphlets and the execution rate of leak prevention measures were noticeably low in smaller businesses. It was also found that the presence of a dedicated department for chemical substance management tends to increase awareness regarding such substances.
As the result of promoting notification of the plan for environmental risk reduction measures for the large-scale disasters to a given size or larger factories and business establishments, the plans ...have been submitted from all of the 482 target entities during fiscal years of 2014-2016. In order of handling amount of designated chemical substances in Osaka prefecture, chemical industry, petroleum and coal products industry, and warehousing business were ranked in classifying by industry, and Toluene, Xylene, and Benzene by substance. Handling amount of chemical substances were about 5,000-30,000 times as large as those of release amount, and they were the largest at the area of Senshu and Sakai-City where industrial complex of oil and chemical factories has been located in the coastal area.
In the Japanese Pollutant Release and Transfer Register（PRTR）framework, which is a chemical substance management system, small-scale business operators who employ less than 21 employees are not ...required to report the amount of any released chemicals. This paper proposes a method to estimate the distribution of the number of small-scale business operators by industry and another method to estimate the amount of chemicals released from their corresponding operations. By combining the relevant data, the distribution of emissions from small-scale businesses was estimated in an area with a cluster of small-scale business establishments in the Osaka Prefecture and visualized through geographic information system mapping. Depending on the chemical substance and industry, the estimated distribution of the released chemicals was different from that in the PRTR. This finding suggested that the reported release in PRTR is not sufficient in assessing the risk of chemical leakage during a natural disaster.
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