Research On The Effects Of Ni Complexes To The Formation And Micro-structure Of Pearl In The Indoor Closed System For Pearl Cultivation

Pearl, is a kind of precious jewelry of organic matter, high-quality pearls have alwaysbeen in short supply in the domestic and international high-end market, so how to improvethe quality of pearls has become a hot area in pearl research. In order to explore a methodto breed high-quality pearls, effects of Ni complex of [Ni（C₇H₇N₂O₄）₂（H₂O）₂]3H₂O tomicrostructure of the pearl under a indoor closed system was studied. Firstly the indoorclosed system was established and breeding technology of Pinctada martensii under thissystem was researched. A new kind of Ni complex named2-ethyl-4,5-imidazole dioctylphthalate nickel through hydrothermal synthesis method, its structure was thencharacterized. Based on the algae-shellfish-pearl transfer way, toxic effects to algae andpearl breeding shell, effects of biochemical indicators and alkaline phosphatase activity ofPinctada martensii, as well as the pearl structure of the complex were researched, the roleit played in pearl breeding was revealed.The main conclusions obtained in this paper are as follows:1. Pinctada martensii indoor pearl breeding management（1） The effects of placement on growth and mortality rate of Pinctada martensii. PlacePinctada martensii at the bottom and hanging in the breeding cylinder respectively.Between the two modes, shell length growth rate was not statistical significant, shell heightgrowth rate variance was more and more large by the increase of time; when the shell wasat the bottom, shell width growth rate was higher than hanging and mortality rate waslower.（2） The effects of stocking density on growth and mortality rate of Pinctada martensii. Thegrowth rate was in contrast with stocking density, when the stocking density was20/cylinder, average growth rate of shell height was0.15mm/d, which was the maximal,when the stocking density was40/cylinder, average growth rate of shell height was theslowest, growth rate was0.101mm/d. shellfish mortality increased with the increasing ofstocking density, mortality was maximal when stocking density was40/cylinder, this wassignificantly higher than other density groups （p<0.05）. （3） The trend of water quality indicators over time. Nitrite nitrogen changed little in first35d, decreased significantly during35-70d. The content of amino nitrogen, BOD and CODshowed a clear upward trend in the first30d of the experiment, BOD content in the30-60dwas significantly reduced, amino nitrogen and COD content in the30-90d amplitude insmall.（4） The trend of growth and mortality of Pinctada martensii over time. In different stage ofexperiment, Shell width growth rate changed little, shell length and shell height growthrate were more obvious changed. In the first30d of test, mortality was maximal, after35dmortality decreased, in70-90d, mortality gently increased.2. Synthesis and characterization of Ni complexUse2-ethyl-4,5-imidazole dioctyl phthalate as ligand compounds to reaction withNi（NO₃）₂and a new Ni complex [Ni（C₇H₇N₂O₄）₂（H₂O）₂]3H₂O was obtained, its structurewere characterized. The crystallographic asymmetric structural unit of the complex wascomposed with a H₂EIDC-ligand, a central metal ions Ni （II）, a combined water and a halffree water molecules. Each of the central metal ions Ni （II） and two N atoms （N1, N1i,） inthe equatorial plane along with two O atoms （O1, O1i） made up two double teeth chelatingfive-membered rings （the two N and two O came from two different H₂EIDC-ligandmolecules, respectively） and formed a regular octahedron with two axial O atoms （O5, O5i）from the bound water molecules.3. Toxicological research of Ni²⁺and Ni complexes to algaeChoose96h-EC50as the index to evaluate toxic effects to algae. Through theestablishment of the linear regression equation about probability unit-mass concentration,concentration96h-EC50of Ni²⁺and Ni complexes that inhibit the growth of algae wasobtained, which was8.147mg/L and105.682mg/L respectively. χ2test of dose-responseequation between the concentration logarithm of Ni²⁺and Ni complex and probability unitswas played, the degree of fitting was sound.4. Acute toxic effects of Ni complexes of Pinctada martensiiUsing hydrostatic test and gastric disorder test, toxicity test of Ni complexes toPinctada martensii was played. with the rise of the concentration and the test time,sensitivity of Pinctada martensii to the Ni complexes rise also, half-lethal dose of48h,72hand96h was78.52mg/L,18.32mg/L and9.441mg/L, respectively. The safe dose was3.926mg/L,0.916mg/L and0.471mg/L.5. Accumulation of Ni in Pinctada martensii in the transfer process and its effects toenzymeFeeding the Pinctada martensii with algae （the concentration of Ni complexes was 0.006mg/L）enriched with Ni complex, determine Ni content and alkaline phosphataseactivity of the pallium and visceral mass, the results show that: accumulation of Ni ofexperimental group in the pallium and visceral mass was increased, in20-60daccumulation of Ni in pallium was fast and the maximum rate of accumulation of Ni invisceral mass appeared in30-50d. ALP activity in the visceral mass was significantlyhigher than in the pallium, enzyme activity in both pallium and visceral mass ofexperimental group were significantly increased. Growth rate of enzyme activity in palliumwas minimum in0-30d and was maximum to visceral mass in30-45d.6. Biochemical changes of Pinctada martensii in transfer processFeeding the Pinctada martensii with algae（the concentration of Ni complexes was0.006mg/L） enriched with Ni complex, blood biochemical changes of Pinctada martensiiin food origin transfer process. The results showed: there was a significant rise in alkalinephosphatase, globulin and Mg by the extension of time and a significant decrease of ureanitrogen and Zn. Contents of triglycerides, glucose and lactate dehydrogenase change littleover time.7. Effects of Ni complexes on the microstructure of pearly layerCompared pearl surface micro-structure both from the blank group and groups fedwith different concentration of Ni complexes, analysis results showed that: when theconcentration of Ni complexes was0.006mg/L, the glossiness of the pearls,the dgree oforder as well as the size uniformity of surface aragonite crystal were the best, aragonitelayer surface was even and its micro-layers were of dense structure; On the contrary,aperture of aragonite tablet was fuzzy, micro-layers of aragonite structure were loose,disappearance and stagger of layers were exsisted, delaminated thick fragments were filledbetween layers.