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Suspended sediment and nutrient loadings from agricultural watersheds have lead to habitat degradation in Lake Takkobu. To examine their relationships with land-use activities, we monitored sediment, nutrient and water discharges into the lake for a 1-year sampling period. The Takkobu River contributed the largest portion of the annual water discharge into the lake, compared with the other tributaries. During dry conditions, lake water flowed into the Kushiro River, and conversely during flooding, Kushiro River water flowed into the lake. Inflows from the Kushiro River had a high proportion of inorganic matter, with high concentrations of total nitrogen and total phosphorus, attributed to agricultural land-use development and stream channelization practiced since the 1960s in the Kushiro Mire. Nutrient loadings from these two rivers were significantly higher during flooding than in dry conditions. However, there was no clear correlation between river discharge and nutrient concentrations. Since land-use activities in the Kushiro River and Takkobu River watersheds were concentrated near rivers, nutrients easily entered the drainage system under low flow conditions. In contrast, water discharged from small, forest-dominated watersheds contained a low proportion of inorganic matter, and low nutrient concentrations. The suspended sediment delivered to the lake during the sample period was estimated as approximately 607 tons, while the total nitrogen and total phosphorus inflows were about 10,466 and 1,433 kg, respectively. Suspended sediment input into the lake was 65%, and total nitrogen and total phosphorus were 40% and 48%, respectively, being delivered by the Kushiro River. 相似文献
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Microbial degradation of benzene under anaerobic conditions plays an important role in remediation of contaminated sites but the microorganisms and metabolic pathways involved remain poorly understood. In this study, we evaluated degradation of benzene by a methanogenic enrichment culture obtained from non-contaminated lotus field soil, alone and in the presence of several putative metabolic intermediates, that is, toluene, benzoate and phenol. Using stable isotope (13C) labeled substrate, benzene was shown to be degraded almost completely to equimolar concentrations of methane and carbon dioxide, without detectable accumulation of extracellular metabolites. Concurrently, toluene, benzoate and phenol were also effectively mineralized, but probably by microorganisms other than the benzene degraders. The latter included Hasda-A, which is putative benzene-degrading deltaproteobacterium present in the culture. While toluene and benzoate did not affect benzene degradation, phenol had a moderate inhibitory effect although it was not a major metabolic intermediate of benzene in our culture. Finally, 4-hydroxycoumarin was detected as a compound formed from phenol but further experiments are required to elucidate its relationship to degradation of phenol. 相似文献
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Shinso Yokota Kazuya Iizuka Futoshi Ishiguri Zensaku Abe Nobuo Yoshizawa 《Journal of Material Cycles and Waste Management》2006,8(2):140-144
Delignification from the cell walls with a combination of ozone oxidation and dioxane–water extraction using thin sections
of a softwood, Japanese cypress (Chamaecyparis obtusa Endl.), was studied to determine its suitability for the production of recyclable cellulose-based materials from wood waste.
The visible-light absorption spectra of treated wood sections revealed that delignification from the cell walls with ozone
increased with increasing ozonization time. Ozone delignification proceeded from the lumen side toward the middle lamella
within the secondary wall of a cell, and it proceeded faster in early wood than in late wood within an annual ring. Mild ozonization
for 10–30 min was sufficient for the removal of lignin from the cell walls when sections were extracted with dioxane after
ozonization. The results obtained here demonstrate that microspectrometry coupled with the Wiesner reaction is useful for
the quantitative analysis of lignin in cell walls. 相似文献
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Khatun Dalia Tanaka Tomomi Aranishi Futoshi 《Environmental science and pollution research international》2023,30(2):2649-2664
Environmental Science and Pollution Research - Ayu Plecoglossus altivelis altivelis is a key commercially and culturally important freshwater osmeroid in Japan. Its native population is mostly an... 相似文献
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Nobuo Ishiyama Kazuki Miura Takahiro Inoue Masanao Sueyoshi Futoshi Nakamura 《Conservation biology》2021,35(3):884-896
Forest conversion is one of the greatest global threats to biodiversity, and land-use change and subsequent biodiversity declines sometimes occur over a variety of underlying geologies. However, how forest conversion and underlying geology interact to alter biodiversity is underappreciated, although spatial variability in geology is considered an integral part of sustaining ecosystems. We aimed to examine the effects of forest conversion to farmland, the underlying geology, and their interaction on the stream fishes’ diversity, evenness, and abundance in northeastern Japan. We disentangled complex pathways between abiotic and biotic factors with structural equation modeling. Species diversity of stream fishes was indirectly shaped by the interaction of land use and underlying geology. Diversity declined due to nutrient enrichment associated with farmlands, which was mainly the result of changes in evenness rather than by changes in species richness. This impact was strongest in streams with volcanic geology with coarse substrates probably because of the differential responses of abundant stream fishes to nutrient enrichment (i.e., dominance) and the high dependency of these fishes on large streambed materials during their life cycles. Our findings suggest that remediation of deforested or degraded forest landscapes would be more efficient if the interaction between land use and underlying geology was considered. For example, the negative impacts of farmland on evenness were larger in streams with volcanic geology than in other stream types, suggesting that riparian forest restoration along such streams would efficiently provide restoration benefits to stream fishes. Our results also suggest that land clearing around such streams should be avoided to conserve species evenness of stream fishes. 相似文献
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