1. Heavy metals concentration of Fecal Solids of Recirculating Aquaculture System for Renewal Feed Resource for
Sea Cucumber
Anisuzzaman Md, Feng Jin, Ga-Hyun Kang, Jong-Kuk Choi, Byong–dae Choi ,and Seok-joong Kang*
Department of Seafood and Aquaculture Science, Gyeongsang National University, Korea
Introduction
Results & Discussion
Table 1. The concentration of different heavy metals in faecal solids and sea cucumber (PPM)
The environmental pollution, caused by fecal solids from the recirculating aquaculture system (RAS), has been getting worse throughout the world. That is why it needs a fundamental solution in an urgent manner. However, fecal solid of RAS have high concentration of different heavy metals. In this study, we investigate heavy metals how much concentration in fecal solids and how much concentration in sea cucumber for the food safety. For this study, three samples such as fecal solid, fermented feed feeding sea cucumber and natural sea cucumber were used. We have decided to look into the concentration of different heavy metals such selenium, arsenic, lead, cadmium, chromium, mercury in above mentioned samples on the basis of feed standard and Korean food standard codex.
Fecal solids
Sea cucumber
(Fermented feed )
(Natural)
Arsenic
Not Detected
0.404
0.332
Chromium
39.404
0.968
0.553
Lead
7.759
0.431
0.161
Mercury
Cadmium
1.539
Selenium
1.760
0.121
0.039
In the faecal solids, arsenic was not detected, chromium was ppm which was within the acceptable limit. The acceptable limit of chromium is less than 100ppm (formula feed basis). Lead was 10ppm whereas acceptable limit is less than 7.759ppm (formula feed basis) and mercury was not detected. On the other hand, in the faecal solids cadmium was higher than the acceptable limit. Cadmium was 1.539ppm whereas allowable threshold 1.0ppm(formula feed basis except fish and another animals). However, in case of cadmium in the premix feed acceptable limit is less than 50ppm and selenium was 1.760ppm which was below acceptable standards 2ppm (formula feed basis).
Materials and Methods
As for the feed of the experiment, faecal solids of the rainbow trout farming were collected from the RAS, located in Chungju, Chungcheongbuk-do. Duplicate samples were used. In the heavy metal analysis, arsenic, chromium, lead, mercury, cadmium and selenium were analyzed by wet digestion method using Perkin Elmer ICP-OES 2000DV instrument.
Wet Digestion Method:
5g of pre-treatment sample was taken into decompose flask and then added distilled water up to the moisture content of 80%and 20ml HNO3 acid into the sample, mixed and kept in room temperature for 15 minutes and then added 10ml H2SO4 acid and gently heated. When the mixture started to darken, added 30ml HNO3 acid by continuously heating. After that, when the mixture was completely decomposed its changed color from pale yellow to colorless and after cooling, 40ml distilled water was added. Heating was continued until the white smoke of SO2 was generated and then sample was cooled. Afterwards, certain amount of the prepared sample solution was analyzed. For analysis 50 ml sample put into the digestion tube and added mixture of HNO3 (1 + 1) 1ml, HCl (1 + 1) 0.5ml into the digestion tube . After that, digestion tube was heated at 950C temperature until the total volume of sample concentrated into 25ml on the heating digestion block. Then the tube cape was closed and refluxed for 30 minutes. The refluxed sample was cooled. Soon after the liquid adjustment sample was analyzed using a PerkinElmer ICP-OES 2000DV (Made in USA) device, RF power was set to 1300 watts. The Plasma Flow was a 15 ℓ / min, Sample Flow rate was set to 1.5 ml / min.
Fig. 1. Recirculating Aquaculture System (RAS) for sea cucumber
Fig. 2. Feeding fermented feed
Conclusion
Our results have shown that different heavy metals existing in faecal solids having below the determining acceptable limits. For the reason, faecal solids as a renewal feed resource are good and safe for sea cucumber culture.
Acknowledgments
This study was supported by Renewable sea cucumber feed of faecal solids released in effluents from RAS(recirculating aquaculture system) from the Korea Institute of Marine Science&Technology.
References
Hseu ZY Evaluating heavy metal contents in nine composts using four digestion methods. Bioresource technology
Akinyele IO, Shokunbi OS Comparative analysis of dry ashing and wet digestion methods for the determination of trace and heavy metals in food samples. Food chemistry