Investigation of Corrosion Damages caused by Air Pollutans in Western Japan and Those Countermeasures.

(1)调查了日本西部地区酸雨对建筑物和文物的腐蚀破坏，以及森林退化问题。据调查，在奈良东大寺的大博町，铜制镀金的“HAKKAKU TORO”被污染燃烧产生的氯化物和硫氧化物产生的酸雨腐蚀，造成了文化遗产的损坏。在冈山县、广岛市和山口县的高速公路上发现了大量的死松树。广岛大学的Nakane教授提出了附着在松树叶子上的酸液和分解成雾和露珠的空气污染物降低了光合作用的功能，而且凋谢的松树容易受到一些有害昆虫的攻击。(2)我们在山口县的几个点测量了雨水的pH值。山口大学工学院的pH值为4.38 ~ 6.25，Shyuho镇的pH值为4.72，Heki镇的pH值为4.38 ~ 5.79。在日本海附近的Heki镇，雨水酸化明显。(3)研究了锈蚀对碳钢酸雨腐蚀的光催化作用。在人工酸雨中对碳钢进行紫外线照射。锈蚀后的碳钢在紫外光照射下的腐蚀损失增加了20% ~ 40%，锈蚀对腐蚀的光催化作用随着浸泡时间的延长而增大。电化学阳极极化曲线证实了铁锈的光催化作用。极化到0 mV诱发0.3 mA/？光响应电流密度。在此基础上，提出了锈蚀对碳钢酸雨腐蚀光催化作用的增强机理。

(1) We investigated acid rain corrosion damages of structures and cultural assets, and forest decline in western Japan which has became a serious problem. It has been found a damage of cultural assets that gold plated HAKKAKU TORO made of copper in DAIBUTSUDEN OF NARA-TODAIJI was corroded by chlorinic species due to pollution combustion and by acid rain due to sulfuric oxides. A great number of dead pine trees have been found along high ways in Okayama, Hiroshima and Yamaguchi Prefectures. Prof. Nakane of Hiroshima University proposes an thought that acid falls adherent to pine leaves and air pollutants solved into fog and dew drops decrease the function of photosynthesis and that declined pine trees are easily attacked by a few harmful insects.(2) We measured pH values of rain at several points in Yamaguchi Prefecture. pH values were 4.38 to 6.25 at Faculty of Engineering of Yamaguchi University, 4.72 at a point in Shyuho Town and 4.38 to 5.79 at a point in Heki Town. Acidification of rain was remarkable in Heki Town near Japan Sea.(3) We investigated the photocatalystic effect of rust on acid rain corrosion of a carbon steel. Ultra-Violet(UV) light was irradiated to the carbon steel in artificial acid rain. Corrosion loss of the rusted carbon steel increased 20 to 40% due to UV irradiation and the photocatalystic effect of rust on corrosion became larger with immersion time. Electrochemical anodic polarization curves confirmed the photocatalystic effect of rust. Porarization to 0 mV induced 0.3 mA/? of light response current density. From the results, we proposed a enhacement mechanism of the photocatalystic effect of rust on acid rain corrosion of a carbon steel.