Lake Baikal 貝加爾湖

Lake Baikal， a lake located in the southern part of eastern Siberia in Russia. It is the oldest existing freshwater lake on Earth， as well as the deepest continental body of water， having a maximum depth of 1，620 meters. Its area is some 31，500 km2， with a length of 636 km and a width of 48 km on average. It is also the worlds largest freshwater lake by volume， containing about one-fifth of the fresh water on Earths surface， some 23.6 trillion m3. Into Lake Baikal flow more than 330 rivers and streams， including the Selenga， Barguzin， Upper Angara， Chikoy， and Uda.

Baikal is surrounded by mountains， some of which rise more than 2，000 meters above the lakes surface. The sedimentary strata on the floor of the lake may be as much as 6，100 meters thick. In 1862， flood caused by a quake inundated about 200 km2 in the northern Selenga delta， creating a new bay in Baikal known as Proval Bay.

The lake hollow is not symmetrical， having steep slopes on the western shores and gentler slopes on the eastern. Baikal contains some 27 islets and islands. The influx of water into the lake is mainly from rivers， chiefly the Selenga. The only outflow is through the Angara River， a tributary of the Yenisey.

Baikals climate is much milder than that of the surrounding areas. Winter air temperatures are on average ?21℃， and August temperatures average 11℃. The lake surface freezes in January and thaws in May or June. The water temperature at the surface in August is between 10℃ and 12℃ and reaches 20℃ in the offshore shallows. Waves can be as high as 4.6 meters. The water is very clear， from the surface one can see to 40 meters. Its salinity is low， and it contains a few minerals.

貝加爾湖位于俄羅斯東西伯利亞南部，是地球上現(xiàn)存最古老的淡水湖，也是最深的陸地水體，最深處達(dá)1620米。貝加爾湖長636千米，平均寬48千米，面積約3.15萬平方千米。貝加爾湖也是世界上體積最大的淡水湖，蓄水量約23.6萬億立方米，約占全球地表淡水總量的五分之一。有330多條河川注入貝加爾湖，包括色楞格河、巴爾古津河、上安加拉河、奇科伊河和烏第河。

貝加爾湖被群山環(huán)繞，其中一些山高出湖面2000多米。湖底沉積物厚度可能達(dá)到6100米。1862年，一場因地震引發(fā)的洪水淹沒了色楞格河三角洲北部約200平方千米的土地，在貝加爾湖形成了一個新的湖灣——普羅瓦爾灣。

湖中的凹陷構(gòu)造不對稱，西岸坡陡，東岸坡緩。貝加爾湖中大約有27座島嶼。注入湖中的水大部分來自河流，主要為色楞格河。而唯一的外流出口是葉尼塞河的支流安加拉河。

貝加爾湖的氣候比周邊地區(qū)要溫和很多。冬季的平均氣溫為?21℃，8月平均氣溫為11℃。湖面在1月結(jié)冰，5月或6月解凍。8月份湖面水溫在10℃—12℃，近岸淺灘達(dá)到20℃。浪花可高達(dá)4.6米。貝加爾湖湖水清澈，能見度可達(dá)40米。湖水鹽度較低，含少量礦物質(zhì)。

Plant and animal life in the lake is rich and various. There are between 1，500 and 1，800 animal species at different depths， and hundreds of plant species live on or near the surface. The majority of the species are unique to Baikal. The one mammal species is the Baikal seal. There are more than 320 bird species in the Baikal area.

Industries along the shores of Baikal include mining （mica and marble）， the manufacture of cellulose and paper， shipbuilding， fisheries， and timber. There are many mineral springs， and lots of visitors come here for the curative properties of the waters. A pulp and paper mill built on Lake Baikals southern shore in 1966 drew strong protests from local scientists because its wastes were polluting the water， and in 1971 the government adopted a law to protect the lake from polluting emissions.

The protection of natural resources in the area began with the establishment of the Barguzinsky Nature Reserve in 1916， subsequently there were added two nature reserves and two wildlife reserves， and two national parks. The Lake Baikal Coastal Protection Zone， covering the lake and its environs （a total of 88，000 km2）， was created in 1987， and the same area was listed as a UNESCO World Heritage Site in 1996.

湖中動植物種類繁多，在不同深度生活著1500到1800種動物，湖面或近湖面水域則生活著數(shù)百種植物，大多數(shù)物種為貝加爾湖的特有物種。湖中還生活著一種哺乳動物——貝加爾海豹。貝加爾湖地區(qū)有320多種鳥類。

貝加爾湖沿岸工業(yè)包括采礦業(yè)（云母和大理石）、纖維素和紙張制造業(yè)、造船業(yè)、漁業(yè)和木材加工業(yè)。該地區(qū)的礦泉資源豐富，具有水療效果，許多游客慕名而來。1966年，貝加爾湖南岸建起了一家紙漿造紙廠，但遭到了當(dāng)?shù)乜茖W(xué)家的強(qiáng)烈抗議，因為工廠的廢棄物會污染水體。1971年，政府通過了一項法令，以保護(hù)貝加爾湖免受污染排放的侵害。

貝加爾湖地區(qū)的自然資源保護(hù)始于1916年巴爾古津斯基自然保護(hù)區(qū)的設(shè)立，隨后又相繼增加了兩個自然保護(hù)區(qū)、兩個野生動物保護(hù)區(qū)，以及兩個國家公園。貝加爾湖海岸保護(hù)區(qū)創(chuàng)建于1987年，包括湖泊及其周邊地區(qū)（總面積為8.8萬平方千米）。1996年，該地區(qū)被聯(lián)合國教科文組織列入世界遺產(chǎn)名錄。

Word Bank

volume /'v?lju?m/ n. 體積；容積

How do you measure the volume of a gas？

slope /sl??p/ n. 斜坡；坡地

thaw /θ??/ v. 解凍，融化

Its starting to thaw.

shallows /'??l??z/ n. （河海的）淺水處，淺灘

At dusk more fish come into the shallows.