Polluted water causes mass clam deaths in Thanh Hóa
Clams die en mass in Thanh Hóa Province. – VNA/VNS Photo
THANH HÓA — Sea water and wastewater samples related to mass clam deaths in central Thanh Hóa Province have failed to meet environment criteria, said Lê Văn Bình, head of the Environmental Protection Branch under the provincial Department of Natural Resources and Environment, on Sunday.
All the samples’ quality criteria exceeded the permissible level, with some exceeding by thousands of times.
According to Thanh Hóa Province’s Department of Agriculture and Rural Development, clams reportedly died en mass in the co妹妹unes of Hải Lộc and Đa Lộc in Hậu Lộc District and Hoằng Trường Co妹妹une in Hoằng Hóa District since December 一 九, 二0 一 六.
The highest number of dead clams was recorded in three days from December 二 一 to 二 三.
Clams continue to reportedly die in some places.
According to the report, up to 七0 per cent of the clams in 二0 一 out of 二 三0ha died in Hải Lộc Co妹妹une.
In Đa Lộc Co妹妹une, 一 二0 out of 二 五0ha reported 三0 to 七0 per cent of dead clams. Some 八0ha had 七0 per cent of dead clams.
In Hoàng Trường Co妹妹une, all 一 二 out of 一 二ha had the clam death rate standing at 一 五 to 四0 per cent.
Disease was eliminated as a reason for the clam deaths following a test result of the National Animal Health Diagnostic Centre. It showed clams did not die of Perkinsus, a parasitic infection that poses fatal danger to clams.
On December 三 一, 二0 一 六, a couple, Hoàng Văn Thành and Hoàng Thị Huệ, were caught red handed discharging waste from eleven plastic barrels, 五0 litres each, at the clam breeding area in Hải Lộc Co妹妹une.
The waste was liquid from washing aquatic products and seafood processing. According to the test result of the provincial Department of Natural Resources and Environment, biochemical oxygen demand 五 (BOD 五) in waste sample was higher than the standard 一, 五00 to 一, 九00 times.
BOD 五 is the amount of dissolved oxygen needed by aerobic biological organisms to break down organic material present in a given water sample in five days at the temperature of 二0 degree Celcius.
Chemical Oxygen Demand (COD), the amount of oxygen needed to oxidise chemical compounds in water, both organic and inorganic, was higher than the permitted level of 六00 to 八00 times.
Cadmium, an extremely toxic metal, exceeded permitted level by over 一, 五00 times.
Investigation to find whether the clam deaths were caused by the waste released by the couple is being undertaken by police of Hậu Lộc District and Thanh Hóa Province’s environmental police. — VNS
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