Effect of the Mercury and Methyl Mercury on Retard Vegetable’s
Growth and Accumulation Status
M-Y. Chen1, C-S. Lin1*
National Ping-Tung University of Science and Technology,
Dept. of Food Science
Abstract
In recent years, accumulation of harmful heavy metals like mercury in the soil,
has become one of the major toxic metal pollution in farm land. Two major categories
of mercury, organic mercury and inorganic mercury, may affect crops with mercury
accumulation. To understand the absorption of mercury and methyl mercury by leaf
vegetables, and the scope of plants’ injuries, the Pak-choi, Field mustard and
Ching-geeng were tested by the way of hydroponic cultivation and soil cultivation.
Mercury (0, 0.04, 0.08, 0.12, 0.16, 0.2 μg/mL) and methyl mercury (0, 0.04, 0.08,
0.12, 0.16, 0.2 μg/mL) in medium of hydroponic cultivation and mercury(0, 0.5, 1
μg/g)，methyl mercury(0, 0.5, 1 μg/g) in soil cultivation are used for 30 days’
cultivation. Effects of mercury and methyl mercury on seed germination rates were
tested. High concentration of methyl mercury 0.2-0.1 μg/mL, and 0.2-0.1 μg/mL of
mercury hindered Pak-choi, Field mustard and Ching-geeng seeds germination.
Results showed that the three plants will accumulate mercury and methyl mercury.
The absorption level of methyl mercury was higher than mercury in Pak-choi, which
absorbed slightly higher than in other two kinds of vegetables. Higher mercury and
methyl mercury concentrations severely inhibited the growth in the experiment, while
the highest absorption rate of Pak-choi was the most serious. In methyl mercury
detection found that the accumulation of mercury and did not transfer into methyl
mercury. Leaves color showed mercury and methylmercury decreased the brightness
(L* value), green (-b* value) and increased yellowness (b* value) and methylmercury
group discolored much more severe than the mercury group. Plant dry matter weights
decreased, including protein, ash and crude fiber content, due to the increase in plant
water content. The vitamin C contents increased along with the increase of
concentration of mercury and methyl mercury, methyl mercury group had much
higher vitamin C than the mercury group. Tested plants facing mercury and
methylmercury stress may produce vitamin C to resist the toxicity. Chlorophyll
content of plants also decreased along with increasing mercury and methylmercury
concentrations, methylmercury group is the worst. Analysis of plant essential minerals
showed that mercury and methylmercury inhibited their absorption. The greater
concentrations inhibit the greater mineral’s absorption, as compared with control
group. Overall, mercury and methyl mercury can hinder plant growth, cause etiolated
leaf, decline vegetable quality and block the absorption of essential elements.
Methylmercury accumulation and it’s toxicity were higher than the equivalent
concentration of mercury in the test.
Keywords: Methyl mercury; Mercury; Absorption rate; Accumulation capacity; Leaf
vegetable
*Corresponding author. NO. 1,Shuefu Rd., Neipu, Pingtung, Taiwan,
phone+886-8-7740224, fax +886-8-7740218, cslin@mail.npust.edu.tw