Shares in Talvivaara Mining tumbled by a fifth after the Finnish miner said it was assessing all available options for additional funding after its liquidity position weakened more than expected.The company once lauded for its pioneering metals extraction process known as bioheapleaching has been rocked by a series of waste water leaks.It said that excess water in its older heaps had continued to dilute metal grades in the leach solution throughout the third quarter while the market environment had remained challenging due to the weak nickel price.Chief Executive Officer Pekka Pera said: "Despite our intensive efforts to revive the older heaps from the effects of excess water, we have only achieved moderate success which in turn has limited our production volumes through the year. "This together with the weak nickel price has impacted our liquidity position more than anticipated and in order to secure sufficient financial flexibility and liquidity going forward, we are now assessing all available options for additional funding."Talvivaara has been cutting its headcount to save money. It shed 68 members of staff through redundancy and retirement and reduced the headcount by a further 96 through not renewing temporary contracts.Shares in the company were down 20% to 6.85p.TB