著者

臼井 恵次 進藤 晴夫 丸本 卓哉 岸野 拓男

出版者

公益社団法人 日本水環境学会

雑誌

水環境学会誌 (ISSN:09168958)

巻号頁・発行日

vol.17, no.9, pp.596-599, 1994-09-10 (Released:2008-01-22)

参考文献数

13

被引用文献数

2 1

---

A release of phosphorus from calcium phosphate, iron(III) phosphate, and aluminum phosphate owing to the complex formation of their metals with fulvic acid was examined. Fulvic acid was extracted from lake sediments and treated with Amberlite XAD-8 resin. The non-adsorbed fraction of fulvic acid on the resin, which has highly Cu2+-complexing capacity, was used in this study, because the adsorbed fraction has only little Cu2+-complexing capacity as reported in our previous paper.The non-adsorbed fraction was able to release phosphorus from calcium phosphate, but not from iron(III) phosphate, and aluminum phosphate. The application of X-ray analysis to the calcium phosphate indicated that the major component is hydroxyapatite. The stability constant of the Cu2+-fractionated fulvic acid was determined to be 2×105 (log K=5.3) and the average molecular weight of the fulvic acid was 1,026.

著者

臼井 恵次 岸野 拓男 東 俊雄 進藤 晴夫 丸本 卓哉

出版者

公益社団法人 日本水環境学会

雑誌

水環境学会誌 (ISSN:09168958)

巻号頁・発行日

vol.16, no.10, pp.690-695, 1993-10-10 (Released:2008-04-21)

参考文献数

19

被引用文献数

5 3

---

Fulvic acid extracted from lake sediments was treated with Amberlite XAD-2 and XAD-8 resins. The metal complexing ability of the fulvic acid was measured at pH 6.0 with a Cu2+ titration method, in which free Cu2+ was determined with an ion selective electrode. A two binding site model, in which there are two kinds of the molecules having strong and weak complexing ability and they complex with metal ion at the ratio of 1 : 1, was employed for the determination of the stability constant and complexing capacity of the fulvic acid, because the hyperbolic approxmation could apply to the Scatchard plot of the found values.The stability constants of the fulvic acids having strong complexing ability and weak complexing ability were in the range of 6.33-7.12 and 4.35-4.66, respectively. Both colorless fractions of the fulvic acid which were not adsorbed on XAD-2 and XAD-8 resins had such a high complexing ability as 44 and 32 μmol·g-1, respectively.On the other hand, both colored fractions of the fulvic acid which were adsobed on the resins had only little complexing capacity.

著者

沼辺 明博 井上 隆信 海老瀬 潜一

出版者

Japan Society on Water Environment

雑誌

水環境学会誌 (ISSN:09168958)

巻号頁・発行日

vol.15, no.10, pp.662-671, 1992

被引用文献数

25 30

---

The runoff loadings and characteristics of pesticides applied to paddy fields after transplanting of rice plant were estimated by means of analysis of pesticides in drainage river water in weekly and at the rainfall events.<br>The largest loadings of herbicides were found between one and two weeks after transplanting of rice plant. On the other hand, the largest loadings of insecticides were found at about ten days later than that of herbicides.<br>The runoff loadings of herbicides during one rainfall event ranged 20 to 25% of total runoff amounts. Therefore, the runoff investigation of pesticides in river water at and after the rainfall are very important for estimation of pesticides runoff from agricultural fields to drainage river.<br>The runoff characteristics of insecticides and herbicides were differed, and it was recognized that the runoff loadings of insecticides were decreased more rapidly than herbicides at the rainfall event.<br>The runoff rates of pesticides were ranged from 25% for fenobucarb to 0.02% for fenitrothion.<br>From this results concerned in rainfall event, the runoff rates of pesticides from agricultural fields to river were more higher than that of the previous literature.

著者

中曽根 英雄 山下 泉 黒田 久雄 加藤 亮

出版者

公益社団法人 日本水環境学会

雑誌

水環境学会誌 (ISSN:09168958)

巻号頁・発行日

vol.23, no.6, pp.374-377, 2000 (Released:2006-12-01)

参考文献数

10

被引用文献数

15 16

---

We found a special irrigation reservoir in which there are no algae, insects, or fish. Therefore, we have surveyed the water quality of an irrigation reservoir to find the reason for no living creatures. As the results of the survey, we found three factors such as high nitrate concentration, high aluminum concentration, and low pH value which will affect the lives of creatures in this irrigation reservoir. Among these three factors, the most important one is low pH in this irrigation reservoir. This low pH of the irrigation reservoir is derived from the overuse of nitrogen fertilizer at tea yards. About 1,000kg · ha-1 · y-1 of nitrogen fertilizer has been used to the tea yards for a long time. The remained nitrogen fertilizer which was not taken up by tea crop infiltrates through soils and enters into the ground water. This causes an over the Cation Exchange Capacity of soil and high aluminum concentration of this irrigation reservoir. To prevent this phenomenon from occurring, dozing lime under the root zone and reducing use of nitrogen fertilizer might be effective.