地下酸性水威胁到约翰尼斯堡用水安全

Rapidly rising acidic water in the abandoned gold mines under Johannesburg in South Africa could leak out early next year, the water ministry¹ warns.

南非水利部发出警告，约翰尼斯堡地下废弃金矿中酸性水水位正快速上涨，可能会在明年渗漏出来。

Its report recommends building pumps and monitoring stations immediately.

The toxic² liquid has been building up in mine shafts³ which were dug more than a century ago and stretch for many kilometres under the city.

Trevor Manuel, a minister in the president's office, reassured⁴ residents that there was no cause for panic.

The BBC's Milton Nkosi in Johannesburg says the report, compiled by a group of experts in December, was published by the Department of Water Affairs on its website on Thursday.

The panel of experts warn that if the water is allowed to continue to rise, it will start decanting⁵（倾析，移注） in low-lying areas in the vicinity of the former mine at Gold Reef City, popular with tourists.

The report states that water with low pH readings - the measure that indicates the acidity⁶ or alkalinity（碱性） of a solution - will affect property and infrastructure⁷.

It recommends that acid mine drainage（排水） intervention⁸ be made in the western, central and eastern basins as a matter of urgency.

The basins referred to are areas of interconnected mining tunnels underlying⁹ Johannesburg and surrounding areas.

The government has said it is feasible（可行的） to have pump stations by March 2012.