水環境学会誌
Online ISSN : 1881-3690
Print ISSN : 0916-8958
ISSN-L : 0916-8958
24 巻, 5 号
選択された号の論文の5件中1~5を表示しています
原著論文
  • 金 範洙, 迫田 章義, 藤井 隆夫, 酒井 康行, 鈴木 基之
    2001 年 24 巻 5 号 p. 293-299
    発行日: 2001/05/10
    公開日: 2007/02/22
    ジャーナル フリー
    We proposed a method for describing and predicting the changes in the total toxicity based on the concentrations of toxic-controlling chemicals during the ozonation of landfill leachates. In a model experiment, DOC of the sample landfill leachate decreased but its cytotoxicity increased with the increase of ozonation time. Molecular weight fractionation of the most toxic water samle (ozonated for 300 min) showed almost all the toxicity was attributable to the low-molecular-weight (less than 100) fraction. Further chemical analysis revealed that this strong toxicity was mostly explained by the presence of formaldehyde in that fraction. The toxicity reduction by removing this fraction from the whole water sample was predicted using multi-chemical toxicity analysis, and the result was well correlated with the observed toxicity. We attempted to describe these phenomena using a simple numerical model assuming three groups of toxic chemicals; that is, a group consisting of originally-contained chiemicals, a group consisting of moderately-toxic chemicals emerging at a relatively early stage of the ozonation, and a group whose toxicity is explained by formaldehyde. This simple assumption was largely successful in describing the changes in the total toxicity during the ozonation. On the basis of this simple model, toxicity reduction was predicted for pre-aggregation treatment before ozonation and for ozone concentration during the ozonation. The method proposed in this study would be useful in optimizing water treatment processes and their running conditions in terms of the toxicity reduction efficacy.
  • 梅本 諭, 駒井 幸雄, 井上 隆信
    2001 年 24 巻 5 号 p. 300-307
    発行日: 2001/02/10
    公開日: 2007/02/22
    ジャーナル フリー
    The T-N and T-P concentrations of the wet depositions from every event and total depositions were measured in an urban area (at Kobe) and a forest area (at Ikuno) since 1995. The loads of these parameters were estimated and compared to each other.
    The T-N and T-P concentrations of the wet depositions from every event and the total depositions widely fluctuated, especially for the lower rainfall. The average T-N concentration of the wet depositions from every event and the total depositions at Kobe was nearly twice those at Ikuno, but the average concentrations of T-P in both depositions were the same. Also, the T-N loads for the total depositions at Kobe were about 1.6 times greater than at Ikuno, but the T-P loads were the same.
    The ratios of the T-N and T-P loads for the wet depositions from every event and the total depositions were 60% and 70%, respectively. Therefore, it was judged that the loads for the total depositions were better than the loads for the wet depositions from every event for estimating the total input to the non-point sources.
  • 広瀬 明彦, 鎌田 栄一, 西川 秋佳, 紅林 秀雄, 江馬 眞, 安藤 正典, 黒川 雄二, 長谷川 隆一
    2001 年 24 巻 5 号 p. 308-316
    発行日: 2001/05/10
    公開日: 2007/02/22
    ジャーナル フリー
    Humans could be exposed to formaldehyde, a by-product of drinking water disinfectants, by both oral intaki and inhalation. The guideline value of formaldehyde in drinking water was established by WHO in 1992, and the guideline for air quality was also published by WHO in 2000. However, the inhalation exposure was not incorporated into WHO drinking water guideline establishment. In this article, we re-evaluated oral toxicity and inhalation toxicity studies in addition to the latest information, and calculated Tolerable Daily Intake (TDI) via oral administration and tolerable air concentration via inhalation. Then, the human health risk of formaldehyde was assessed via an oral administration and via an inhalation, separately.
    For oral administration, TDI for general toxicity was calculated an 0.15 mg·kg-1·d-1 from NOAEL of 15 mg·kg-1·d-1, divided by uncertainty factor (UF) of 100 because of the lack of oral carcinogenicity. A 10% benchmark dose of 0.3 mg·m-3 in general inhalation toxicity and a NOAEL of 2.5 mg·m-3 in inhalation carcinogenicity were selected as the starting points for calculation of tolerable air concentration. The tolerable air concentrations based on general toxicity and carcinogenicity study were calculated as 0.037 mg·m-3 divided by UF of 8 and 0.031 mg·m-3 divided by UF of 80, respectively. Based on the above TDI or tolerable air concentrations, we assessed the risk of formaldehyde in drinking water, using two exposure scenario, and concluded that the detected levels of formaldehyde in the recent national investigation reports might not affect to human health.
  • カゼインの役割
    鈴木 祥広, 丸山 俊朗
    2001 年 24 巻 5 号 p. 317-324
    発行日: 2001/05/10
    公開日: 2007/02/22
    ジャーナル フリー
    Foam separation using a coagulant (iron or aluminum) and milk casein is effective for removing suspended matter such as kaolin particles, suspended solids in wastewater, and phytoplankton. However, the function of casein in this separation is unclear. In this study, to clarify the role of casein in coagulation and foam separation, the characteristics of casein adsorption onto flocs that were made up of kaolin and Fe(OH)3 and the removal of suspended substances by the separation were investigated.
    Both of adsorbing casein onto the flocs as a collector and remaining casein in the solution as a frother were necessary in order to obtain the high removal rate (above 90%). The optimum pH range was 6.8-7.6. The required amount of adsorbing casein onto the flocs was 0.5g-casein/g-Fe. To obtain more than 90% turbidity removal from the suspended solution of kaolin (200mg·l-1), greater than 5mg·l-1 of residual casein with 10mg-Fe·l-1 of coagulant dosage was needed. The amounts of adsorbing casein and the concentration of residual casein were estimated from the adsorption rate of casein. The suitable dosage of casein and the mixing time for the foam separation were determined by the adsorption rate.
  • 永淵 修, 海老瀬 潜一, 浮田 正夫, 井上 隆信
    2001 年 24 巻 5 号 p. 325-330
    発行日: 2001/05/10
    公開日: 2007/02/22
    ジャーナル フリー
    To clarify the runoff characteristics of the pesticide applied paddy fields to water environment, detail dynamic behavior of herbicide daimuron was investigated based on daily change for concentration of pesticide in pooled water and soil water. The concentration of daimuron was reached maximum within 24 hr. after application, its concentration was corresponding with the theory value. After reaching the maximum concentration, the concentration was rapidly decreased according as a pseudo first-order rate curve. Also, after rainfall events, daimuron concentration of the pooled water was increased. These results indicated that the sorption and desorption occurred the interface between pooled water and surface soil. The pesticide concentration of soil water was reached maximum concentration at 10-14 days after application. The reaching volume were lesser compared with the surface runoff volume, daimuron has 1/173 ratio. These results showed that daimuron was discharged from paddy field by the surface runoff.
feedback
Top