Mechanism of Acidification that Progresses in Library Collections of Books Made of Alkaline Paper

Acidification mechanisms of paper were examined, studying 120 pairs of identical copies of books published from 1971 to 2010 housed in two Japanese university libraries. The pH at the edges of the alkaline paper lowered from 7.5 to 6.4 after 5–10 years and to 5.8 after 10–15 years after publication. The pH bottomed at 5.4 at the edges and at 7.0 in the centre of the sheet. Acid paper showed higher pH at the edges than in the centre of the sheet. The edge pH of the alkaline paper of books stored on an above-ground floor was lower due to more exposure to incoming open air with pollutants compared to paper stored in the basement. Elemental analysis suggested nitrogen oxide deposition, but could not prove sulphur oxide deposition at the edges of the paper. The position-dependent acidification is presumed to relate to the deposition tendency of air pollutants contained in open air, and accordingly the edge pH dropped dramatically. In the 1980s, alkaline paper was increasingly used in the production of books, and it was assumed that no more book acidification was to occur; however, this study concludes that even in alkaline paper, acidification processes will take place over time.

ĐÁNH GIÁ ẢNH HƯỞNG CỦA MỘT SỐ GIẢI PHÁP CÔNG TRÌNH ĐẾN TRAO ĐỔI NƯỚC VÀ VẬN CHUYỂN BÙN CÁT KHU VỰC ĐẦM NẠI (NINH THUẬN)

With the area of only about 700 ha, Nai lagoon has a great contribution to ecology as well as socioeconomic development of Ninh Hai disctrict and Phan Rang-Thap Cham city (Ninh Thuan province). However, the deposition tendency has occurred recently, making the lagoon shallower. It also causes the decrease in water exchange as well as environmental degradation in this area. Therefore, solutions that increase water exchange and reduce the deposition rate in the Nai lagoon are necessary. Based on the Delft3D model with MORFAC approach, this paper gives some assessments on the impact of coastal engineering solution on water exchange and sediment transport. The simulation scenarios include as extending present jetties to 165 m long, extending present jetties combined with dredging lagoon inlet, extending only northeast jetty to 260 m long combined with dredging lagoon inlet, and dredging all lagoon area. The results show that the change in water exchange is very small (almost below 1%), except in the case of dredging the entire lagoon area, water exchange decreases about 10% (due to the increase of the lagoon water volume) compared with the present. Sediment flux balance at cross-section MCI (Tri Thuy bridge) also changes slightly under influence of coastal engineering works. On the other hand, sediment flux from the coastal zone into the inlet (cross-section 2- MCII) and alongshore to Southwest (cross-section MCIII) have strongly decreased. Especially, in the scenario of extending northeast jetty combined with and dredging the inlet zone, net sediment flux into the inlet decreases from 637 m3/day to 180 m3/day (droughty year) and from 535 m3/day to 80 m3/day in the flood year.