{"title":"Sediment signature inside and outside of breakwaters at the planting area with Nymphoides peltata in Lake Kasumigaura","authors":"Y. Kamogawa, M. Yamamuro","doi":"10.3739/RIKUSUI.77.39","DOIUrl":"https://doi.org/10.3739/RIKUSUI.77.39","url":null,"abstract":"Planting Nymphoides peltata may deteriorate sediment quality in terms of organic content through increase the supply of organic materials. Because breakwaters are often constructed at the planting of N. peltata, changing wave action may also alter the sediment quality. To examine the possible effect of N. peltata plantation, we analyzed the quality of sediments on both the landward and offshore sides of the breakwaters. Surface sediments sampled from the landward side of the breakwaters, where plantation of N. peltata had operated and disappeared afterwards, showed higher contents of fine particles, organic carbons and total sulfur compared to the offshore side. Surface sediments sampled from the landward side of the breakwaters, where natural populations of N. peltata had been remaining showed equivalent contents of fine particles, organic carbons and total sulfur with that of the offshore side s. Since the breakwaters constructed at the area where natural populations of N. peltata exist had wide openings, we assumed that these areas experienced less effects brought about by the breakwaters. Keyword:Core sediment, total sulfur, organic carbon, total nitrogen, silt clay content (2015年4月7日受付:2015年5月8日受理)","PeriodicalId":35602,"journal":{"name":"Japanese Journal of Limnology","volume":"77 1","pages":"39-45"},"PeriodicalIF":0.0,"publicationDate":"2015-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69926312","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
H. Kamiya, Shogo Sugahara, Y. Saga, Y. Nojiri, Toshiaki Esumi, T. Godo, H. Ohshiro
{"title":"Release of nitrogen and phosphorus from sediments observed during a high-frequency field study in brackish Lake Shinji","authors":"H. Kamiya, Shogo Sugahara, Y. Saga, Y. Nojiri, Toshiaki Esumi, T. Godo, H. Ohshiro","doi":"10.3739/RIKUSUI.77.305","DOIUrl":"https://doi.org/10.3739/RIKUSUI.77.305","url":null,"abstract":"The release of nitrogen and phosphorus from sediments at high water temperatures was studied by taking weekly measurements at Lake Shinji, a brackish lake in Japan. A severe phosphorus release was observed at high temperatures from August to September. On the other hand, a nitrogen release was observed in July, but not from August to September when the water temperature was higher. Lower nitrite-nitrogen and nitrate-nitrogen concentrations in the water during high water temperature period suggest that the effect of denitrification was minute. The results showed that nitrogen release from sediments in the lake occurs earlier in the year than the phosphorus release.","PeriodicalId":35602,"journal":{"name":"Japanese Journal of Limnology","volume":"77 1","pages":"305-313"},"PeriodicalIF":0.0,"publicationDate":"2015-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69925871","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
H. Kamiya, Shogo Sugahara, Y. Saga, S. Sato, Y. Nojiri, Toshiaki Esumi, M. Kishi, A. Fujihara, T. Godo, H. Ohshiro
{"title":"Nitrogen mass balance and river concentration dependence in the stock in brackish Lake Shinji","authors":"H. Kamiya, Shogo Sugahara, Y. Saga, S. Sato, Y. Nojiri, Toshiaki Esumi, M. Kishi, A. Fujihara, T. Godo, H. Ohshiro","doi":"10.3739/RIKUSUI.77.47","DOIUrl":"https://doi.org/10.3739/RIKUSUI.77.47","url":null,"abstract":"Calculating the change of stock of each month of the nitrogen in Lake Shinji, a brackish lagoon in Japan, it is assumed that TN is released from the sediment. This relationship has not been observed for the mean water temperature and TN release from the sediment. With respect to TN in Lake Shinji, a significant release from the sediment was not seen in the summer, which was observed for TP, but the effect of the TN concentration in River Hii was large as compared to the TN concentration of Lake Shinji. As for TN content in Lake Shinji, a correlation between the TN concentration of River Hii of the same month was observed ( r = 0.57, p < 0.001 ) . Nitrogen mass balance for 19 years was calculated. The percentage of annual deposition of TN to the TN inflow was in the range of -4.2 to 38.4%, and 19.8% on average. We calculated the average annual value balance of TN and TP for 19 years. For TN, 1480 t flowed in, 1170 t flowed out, and 310 t settled in the Lake Shinji, and for TP, 134 t flowed in, 106 t flowed out, and 28 t had settled in Lake Shinji. Settling TN/TP ratio was 10.7, which was 11.4 for an annual average TN/TP ratio of Lake Shinji.","PeriodicalId":35602,"journal":{"name":"Japanese Journal of Limnology","volume":"77 1","pages":"47-54"},"PeriodicalIF":0.0,"publicationDate":"2015-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69926140","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Long-term monitoring of water quality in the monomictic Ishitegawa reservoir indicates carbon limitation","authors":"H. Kagawa, H. Hirotani, Masayoshi Mori","doi":"10.3739/RIKUSUI.76.111","DOIUrl":"https://doi.org/10.3739/RIKUSUI.76.111","url":null,"abstract":"The monomictic Ishitegawa Reservoir (surface area: 0.50 km; total capacity: 1.28 × 10 m; mean retention time: 0.33 y) is located on the Ishite River (N 33 53 , E 132 50 ) in Ehime Prefecture, Japan. In this reservoir, summer chlorophyll a concentrations (Chl-a) have been observed to decrease gradually from year to year, but the cause remains unclear. To determine the cause, we first examined a monthly data set from January 1983 to January 2003 that contained measures of water temperature (WT), pH, Chl-a, total phosphorus and total nitrogen taken at 0.5 m water depth at the main station in the reservoir (Sta. R). We found two significant long-term linear regressions of pH against date: a positive relationship when pH≤ 8.10 (R = 0.099, p < 0.001, n = 123) and a negative relationship when pH > 8.10 (R = 0.164, p < 0.001, n = 118). This pattern was also found at a station near the head of the reservoir where river inflow occurs (Sta. H). Low pH ( ≤ 8.10) was observed mainly in the circulation period (October – March) and high pH (> 8.10) was found during times of stratification (April – September). Next, we examined the relationship of pH = 8.1 with other limnological parameters by using a monthly data set of dissolved inorganic carbon (DIC), dissolved oxygen, and main cation and anion concentrations from February 1993 to January 2003. Concentration of free CO2 (dissolved CO2 + H2CO3) was calculated from DIC, pH, WT and ionic strength by using the dissociation equations of carbonic acid. pH was negatively related to the log partial pressure of gaseous CO2 in equilibrium with free CO2 (R 2 = 0.968, p < 0.001, n = 120). At pH 8.1, free CO2 was in equilibrium with atmospheric CO2 (360 μatm partial pressure). Chl-a concentrations during the stratification period (pH > 8.10) decreased from year to year following the gradual decrease in the free CO2 concentration and the gradual increase in pH in the preceding circulation period. This data suggests that partial carbon limitation of phytoplankton growth may have occurred under high pH (> 8.10). In addition, plastic-coated sheet fences that were installed across the upper 5 m of the water column near Sta. H during several intervals in the study period formed a strong interflow of river water below the fences, and may have strengthened carbon limitation at Sta. R.","PeriodicalId":35602,"journal":{"name":"Japanese Journal of Limnology","volume":"76 1","pages":"111-127"},"PeriodicalIF":0.0,"publicationDate":"2014-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69924632","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Amount of organic carbon and its fractionation dissolved from Nymphoides peltata and Phragmites australis","authors":"T. Uehara, M. Yamamuro","doi":"10.3739/RIKUSUI.76.1","DOIUrl":"https://doi.org/10.3739/RIKUSUI.76.1","url":null,"abstract":"This study aims to clarify the possible effects of organic matter originating from asaza (Nymphoides peltata) and reed (Phragmites australis) on water quality. Leaves and petioles of asaza and leaves and stems of reed are used. The experiment was carried out for a period of 100 days, and controlled at a temperature of 20°C in dark. The amount of dissolved organic carbon (DOC) and dissolved oxygen was measured periodically during the course of the experiment. Two main sources of water were used for the experiment, Milli-Q water and water taken from Lake Teganuma. The results of fractionation is used to evaluate the composition of DOC. DOC supplied per plant carbon after 100 days in Milli-Q and lake water was 43.4±1.54 mg C g C and 43.7±1.51 mg C g C for leaf and stem of reed. Those of the petiole of asaza was 17.7±2.76 mg C g C・73.0±1.89 mg C g C, the latter was more than four times larger than former. The leaf of asaza supplied DOC with 163±5.4 mg C g C in Milli-Q water and 267 ± 7.5 mg C g C in lake water. Considering the lake water exposed condition, it was observed that asaza leaves displayed 6 times more DOC than the reeds; for a period of 100 days, and asaza petiole displayed nearly double of the reeds. Comparing the samples in terms of their DOC fractions revealed distinct differences between the samples. For reeds, it was determined that both the hydrophilic and hydrophobic acid fractions together make up 96.4% of total DOC. For the case of asaza, in terms of the DOC fraction, the petiole consisted mainly of hydrophobic acid, about 48.4% of total DOC, while the leaves consisted mainly of the hydrophilic fraction having a value of 46.2% total DOC. Keyword: purification of water quality, COD, refractory organic matter, trihalomethanes formation potential 摘 要 湖岸もしくは湖岸近傍で前年に成長・枯死したヨシやアサザから供給される溶存有機物と酸素消費が 湖沼水質に与える影響を見積もるため,20°C・100 日間・暗条件での分解・溶出実験を Milli-Q 水と手賀 沼湖水を用いて行った。また溶存有機物の分画も行った。100 日後に得られた濃度から計算した植物体","PeriodicalId":35602,"journal":{"name":"Japanese Journal of Limnology","volume":"76 1","pages":"1-10"},"PeriodicalIF":0.0,"publicationDate":"2014-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69924577","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}