[:ja]意外と知られていませんが、世界最大（面積は374,000 km2、日本の国土面積377,835km2よりわずかに狭い）のカスピ海は塩湖です。
塩分濃度は北部と南部では異なり、北部ではヴォルガ川などの流入で塩分が薄く、南部ではイランからの流入河川が少ないため塩分が濃くなっています。ちなみに、湖全体の平均塩分濃度は1.2%で、海水のほぼ1/3です。
カスピ海はロシア、アゼルバイジャン、イラン、トルクメニスタン、カザフスタンの5ヶ国に囲まれ、大量の原油埋蔵量から、はやくも10世紀には油井が掘られていました。
カスピ海では漁業も盛んであり、ロシアの内水面漁業の漁獲高の4分の1を占めますが、近年では、水質汚染により、大打撃を受けているとの報告があります。
主因は油田関係で、アゼルバイジャン・バクー沖の油田、トルクメニスタン沖の油田製油所から放出される汚染物質で、北部のウラル川からの汚染物質、イランからの汚泥も汚染に寄与していると報告されています。
参考文献： Caspian Sea
ウェブ地球儀で地球俯瞰画像を見る： LiVEARTH
[Earthview Wonders] No.117: Caspian Sea
Not many people know the fact that the Caspian Sea is a salt lake, largest of the kind (374,000 km2, comparative with the area of Japan (377,835km2)).
The salinity of the lake differs in locations, lower in the northern area with the inflow of Volga River and higher in the southern area. The average salinity is approximately 1.2%, 1/3 of seawater.
The Caspian Sea is surrounded by Russia, Azerbaijan, Iran, Turkmenistan and Kazakhstan, and crude oil was spotted as early as 10th century. Further, the Capsian Sea is the crucial source of fishing for the region, and accounts for 25% of the Russian domestic fishing.
However, the Caspian Sea suffer from serious pollution due to the discharge of pollutants from oil field, refinery mills, sewage of inflowing rivers.
Reference: Caspian Sea
See earthview photo gallery with web-globe: LiVEARTH[:en][Earthview Wonders] No.117: Caspian Sea
Not many people know the fact that the Caspian Sea is a salt lake, largest of the kind (374,000 km2, comparative with the area of Japan (377,835km2)).
The salinity of the lake differs in locations, lower in the northern area with the inflow of Volga River and higher in the southern area. The average salinity is approximately 1.2%, 1/3 of seawater.
The Caspian Sea is surrounded by Russia, Azerbaijan, Iran, Turkmenistan and Kazakhstan, and crude oil was spotted as early as 10th century. Further, the Capsian Sea is the crucial source of fishing for the region, and accounts for 25% of the Russian domestic fishing.
However, the Caspian Sea suffer from serious pollution due to the discharge of pollutants from oil field, refinery mills, sewage of inflowing rivers.
Reference: Caspian Sea
See earthview photo gallery with web-globe: LiVEARTH[:]