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| 1 | Behavior of sulfate in preparation of single light rare earth carbonate by Mg(HCO_(3))_(2) precipitation method显示文摘The precipitation of the water-leaching solution of Baotou mixed rare earth(RE) concentrate roasted with sulfuric acid using ammonium bicarbonate for producing RE carbonate produces a mass of ammonia-nitrogen wastewater because of the relatively low solubility of rare earth sulfate.To solve the serious problem of ammonia-nitrogen pollution,new precipitators need to be developed urgently so as to meet the requirements of environmental protection and impurities content of the product(SO_(4)^(2-)<1.8 wt% in RE carbonates products).In this paper,we studied the effects of feeding modes on the behavior of SO_(4)^(2-) during the preparation of light RE carbonate(RE=La,Ce,Pr,Nd) from their sulfate solutions using Mg(HCO_(3))_(2) as a precipitant.The results indicate that the contents of SO_(4)^(2-) in the La and Ce precipitates using positive feeding mode exceed 16 wt% because of the formation of La_(2)(CO_(3))2.15(-SO_(4))0.85·4 H_(2)O and Ce_(2)(CO_(3))_(2).15(SO_(4))0.85·3H_(2)O,while those of the Pr and Nd precipitates are 4 wt%-5 wt% since they exist in the form of n-carbonate.The precipitates prepared using synchronous feeding mode are all RE carbonate with only 4 wt%-5 wt% of SO_(4)^(2-) enclosed in the precipitation.The content of SO_(4)^(2-) in the RE carbonate obtained using reverse feeding mode is the lowest.Among them,the content of SO_(4)^(2-) in La precipitate is only 1.40 wt%.Both synchronous and reverse feeding modes can effectively reduce the content of SO_(4)^(2-)in RE carbonate,which provides theoretical guidance for the preparation of qualified light RE carbonate products by Mg(HCO3)2 precipitation method. | Meng Wang Xiaowei Huang Zongyu Feng Chao Xia Deliang Meng Zonghe Yu | 2021 | Journal of Rare Earths2021，39，7： | 3 |
| 2 | Phylogenetic diversity and bioactivity of culturable deepsea-derived fungi from Okinawa Trough显示文摘Deep-sea sediments are now recognized as a home for rich and largely microbial community.Recently,it has been believed in an increasing number of studies that bacteria could be abundant in deepsea sediments of many types;however,fungi in deep-sea sediments remain relatively unknown.The phylogenetic diversity and bioactivity of culturable deep-sea-derived fungi from Okinawa Trough sediments were investigated in traditional method combined with fungal identification of molecular biology in this study.A total of 76 isolates belonged to 15 fungal taxa were recovered in a harsh condition of low nutrient and low temperature,indicating that the fungal communities in deep-sea sediments from Okinawa Trough were relatively abundant and diversified.Aspergillus,Cladosporium,and Penicillium were the dominant fungal genera,while Mycosphaerella,Purpureocillium,and Schizophyllum were relatively rare in the deep-sea sediments from Okinawa Trough.Among the six genera recovered,Mycosphaerella was firstly recovered from deep-sea sediments in this study.Moreover,about 75%of the extracts from the 15 fungal representative isolates displayed distinct bioactivity against at least one indicator bacterium or marine macrofouler,emphasizing the potentials of these deep-sea-derived fungi from Okinawa Trough as producers of bioactive metabolites.Notably,isolates Cladosporium oxysporum SCSIO z001 and Penicillium citrinum SCSIO z049 displayed a wide spectrum of bioactivities,isolates Cladosporium cladosporioides SCSIO z015,Cladosporium sphaerospermum SCSIO z030,and Penicillium verruculosum SCSIO z007 exhibited a strong anti-bacterial-growth activity,and isolate Penicillium chrysogenum SCSIO z062 displayed a strong anti-larval-settlement activity.These results suggest that these isolates deserved further study as potential sources of novel bioactive metabolites. | Xiaoyong ZHANG Yiyang LI Zonghe YU Xiao LIANG Shuhua QI | 2021 | Journal of Oceanology and Limnology2021，39，3： | 0 |
| 3 | Effect of diets on the feeding behavior and physiological properties of suspension-feeding sea cucumber Cucumaria frondosa显示文摘The suspension-feeding sea cucumber Cucumaria frondosa has become commercially important in recent years.Finding proper diets is the first important step for intensive aquaculture of this sea cucumber.In this study,adult C.frondosa were exposed to one of the following diet treatments:control(no diet provided),two powdered seaweeds(Ascophyllum nodosum and Saccharina latissima),a commercially available microalgal diet(shellfish diet)and natural seston.The effects of diets on the feeding behavior and physiological properties of sea cucumbers were investigated after a 5-week rearing period.Results show that sea cucumbers fed with shellfish diet exhibited a significantly higher tentacle insertion rate(1.80±0.20 insertion/min)than these fed with seaweed powders,and there was no significant different between the two groups fed by seaweed powders.No significant difference was found on the fecal production rate among the feeding groups.The minimum oxygen consumption rate was observed in the control group(5.76±0.99μg O2/(g·h)),which is significantly lower than individuals fed with A.nodosum,shellfish diet,and natural seston;however,no significant difference was shown between those of control and S.latissimi groups.The maximum ammonium excretion rate was found in the A.nodosum group(0.03±0.01μmol/(g·h)),which is significantly higher than other groups.The minimum O/N ratio was observed in the A.nodosum group(14.57±1.04),which is significantly lower than the S.latissima,shellfish diet,and natural seston groups.Individuals fed with seaweed powders had similar physiological properties with these fed with microalgae diet and natural seston,indicating that A.nodosum and S.latissima can be explored as promising diets for intensive aquaculture of C.frondosa. | YU Zonghe ROBINSON Shawn MACDONALD Bruce LANDER Terralynn SMITH Craig | 2020 | Journal of Oceanology and Limnology2020，38，3： | 0 |
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