本研究では、道路で移動する観察者が湖面のように面的に展開する視対象物を俯瞰することを想定する。本研究の目的は、視点場と視対象との相対的位置関係で定まる見えの「大きさ」、「バランス」、「奥行き」を数式表現し、パレート最適の概念を用いて景観に特徴のある視点位置を特定する手法を提案することにある。そして、この手法を諏訪湖及び宍道湖周辺地域の道路網へ適用し、俯瞰景観に優れた場所を選定する。特に本研究では、視点場から全方向への視線を考え湖面を向く視線の分布に着目する。この分布を視点を原点とする単位球上で表現し、球面へ投影された湖面形状の面積や長さを活用して視点位置を評価する。

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In the present study, we investigated the Polycyclic Aromatic Hydrocarbons (PAHs) at the representative eutrophic lake “Lake Suwa”, which has drastically eutrophicated since 1960s by inflow of domestic and industrial effluents. We also investigated PAHs in river sediments, road dusts, suspended solids and air particles of the catchment area of Lake Suwa.
We showed that the concentrations of Σ17PAHs in the lake sediments and river sediments were 364±129 ng/g-dry and 157±194 ng/g-dry, respectively. On the other hand, the concentrations of Σ17PAHs in sediments were relatively high in the northeast part of Lake Suwa.
One of the major PAHs in the sediment of Lake Suwa was perylene. It would be mainly produced from precursor substances (such as perylenequinone) in anoxic lake sediment. On the other hand, the major sources of other PAHs (except perylene) were considered to be both petrogenic and pyrogenic source as diesel exhaust matter and asphalt. They entered the Lake Suwa through rivers and finally precipitated to lake sediment.

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