异丁烯选择氧化制备甲基丙烯醛催化剂

采用共沉淀法制备了掺杂Sb的Mo—Bi-Fe—Co—Cs—Ce—K—O混合氧化物催化剂，并将该催化剂用于异丁烯（1B）选择氧化制备甲基丙烯醛（MAL）；采用X射线衍射和BET法对催化剂进行了表征，并在固定床反应器中考察了Sb添加量、气态空速、V（IB）：V（空气）对催化剂性能的影响。实验结果表明，掺杂Sb的Mo—Bi—Fe—Co—Cs—Ce—K—O催化剂的成分为CoMoO4，Bi2Mo3O12,FeMoO4，Bi2Mo2O9；Sb的掺杂改变了Bi2Mo3O12的晶体结构，进而影响催化剂的性能，抑制了产物MAL的过度氧化，提高了MAL的收率。当n（Sb）：n（Mo）=0．03时，催化剂的性能最好，此时催化剂的组成为Mo12Bi1.6Fe1Co8Ce0.4·Cs0.4K0.2Sb0.36，在该催化剂用量5mL、反应温度380℃、气态空速4500h^-1、V（IB）：V（空气）=6：94的最优反应条件下，IB的转化率为95．3％，MAL的选择性和收率分别为71．7％，68．3％

异丁烯选择氧化制备甲基丙烯醛催化剂

采用共沉淀法制备了掺杂 Sb 的 Mo-Bi-Fe-Co-Cs-Ce-K-O 混合氧化物催化剂,并将该催化剂用于异丁烯(IB)选择氧化制备甲基丙烯醛(MAL);采用 X 射线衍射和 BET 法对催化剂进行了表征,并在固定床反应器中考察了 Sb 添加量、气态空速、V(IB):V(空气)对催化剂性能的影响。实验结果表明,掺杂 Sb 的 Mo-Bi-Fe-Co-Cs-Ce-K-O 催化剂的成分为CoMoO_4,Bi_2Mo_3O_(12),FeMoO_4,Bi_2Mo_2O_9;Sb 的掺杂改变了 Bi_2Mo_3O_(12)的晶体结构,进而影响催化剂的性能,抑制了产物 MAL 的过度氧化,提高了 MAL 的收率。当 n(Sb):n(Mo)=0.03时,催化剂的性能最好,此时催化剂的组成为 Mo_(12)Bi_(1.6)Fe_1Co_8Ce_(0.4)·Cs_(0.4)K_(0.2)Sb_(0.36),在该催化剂用量5 mL、反应温度380℃、气态空速4 500 h~(-1)、V(IB):V(空气)=6:94的最优反应条件下,IB 的转化率为95.3%,MAL 的选择性和收率分别为71.7%,68.3%

Food web characteristics of seagrass beds in intertidal of Dongying and Yantai,Shandong Province

为了探明海草床内主要生物类群间的营养关系以及食物网结构,作者于2018年8月分别在东营黄河口潮间带和烟台西海岸潮间带海草床采集大型底栖生物样品,采用δ13C和δ15N稳定同位素方法,对生物样品的碳、氮同位素组成进行了测定和分析。结果表明:东营海草床内生物的δ13C、δ15N值范围分别为–21.99‰至–12.13‰和5.23‰–11.05‰,烟台海草床内生物的δ13C、δ15N值范围分别为–18.11‰至–14.06‰和6.60‰–10.22‰。东营海草床主要生物的营养级范围为2.00–3.85,烟台海草床主要生物的营养级范围为2.00–3.15。根据δ15N值计算所得的营养级图分析可知两区域海草床内初级消费者主要为滤食性双壳类和多毛类,次级消费者为植食性或杂食性甲壳类,肉食性鱼类和腹足类。与近海海域大型底栖生物食物网相比,海草床内底栖生物的营养级均值普遍较低

FOOD WEB STRUCTURE OF MACROBENTHOS IN THE INTERTIDAL ZONE OF YANGMA ISLAND, YANTAI, CHINA

To understand the nutrient relationship, food web structure, and their seasonal changes in major benthic communities in Yangma Island, Yantai, Shandong, samples of macrobenthos, sediment particles(SOM), suspended organic matter(POM), phytoplankton, and zooplankton were collected in the intertidal zone of the island in spring(March) and summer(July) 2019. Stable isotopes of carbon and nitrogen in the macrobenthos were measured and analyzed. Results show that the δ13 C and δ15 N values of macrobenthos were ?20.23‰— ?12.99‰, 5.32‰—10.45‰ in spring and ?21.91‰— ?9.88‰, 7.01‰—14.17‰ in summer, respectively. The stable isotopes values were greater in summer than those in spring, and the values of the same macrobenthos species changed seasonally. The trophic level of major macrobenthos species in spring and summer was 1.98—3.49 and 1.89—4.00, respectively. The nutrient levels of the same macrobenthos in two seasons showed no significant change(P>0.05). The nutrition delivery sequence from low to high was filter feeding mollusk → polychaete → crustacean, which was consistent with the direction of energy flow

Impacts of Spartina alterniflora invasion on the benthic food web in the Yellow River Delta during autumn

Spartina alterniflora was introduced into the Yellow River Delta(YRD)in 1990 with the purpose of shore protection and siltation accretion.However,it spread rapidly and became a severe threat to the local coastal wetland ecosystem.To assess the impacts of S.alterniflora invasion on the benthic food web,we sampled the potential food sources of macrobenthos in November 2020,analyzed the trophic level and the benthic food web structure based on stable isotope technique.Results showed that the average delta~(13) C values of macrobenthic food sources followed an order:sediment organic matter(SOM)>S.alterniflora >benthic microalgae >particulate organic matter(POM)>Suaeda salsa.The average delta~(15) N values significantly differed among food sources,ranging from 1.24 to 9.03.The trophic levels of different macrobenthos ranged from 1.73 to 4.19,of which the bivalve species was the lowest one.S.alterniflora and the decayed debris were the most important food sources for macrobenthos,but without any impact on the trophic level structure of macrobenthos.In conclusion,Spartina alterniflora invasion distinctly changed the composition of food sources of macrobenthos through a bottom-up effect,which would probably impact the local food web structure in the YRD wetland

Species composition and long-term variation of macrobenthos in intertidal zone and offshore areas of the Yellow River Delta

The Yellow River Delta wetlands play a major role in protecting the biodiversity and ecological function of the Bohai Sea. To understand the species diversity and spatial-temporal dynamics of macrobenthic community in this region, five surveys were carried out in intertidal zone and offshore areas in August and November 2016, May, August and November 2017, respectively. Results showed that 187 macrobenthic species were identified in surveyed areas, of which, 119 species were found in the intertidal zone and 99 in offshore areas. Obvious variation was found in the spatio-temporal distribution pattern of species composition. Compared to historical records, individuals of certain species presented a miniaturization trend in body size. The dominant species composition also has undergone an obvious change from large-sized crustacean and mollusc species toward small-sized polychaete, bivalve and crustacean species. Possible factors responsible for these changes are complex, including a decrease of water inflow and sediment transport by the Yellow River combined with human activities (overfishing and increasing exploitation) and other factors, e.g., salinity decrease and the invasion of Spartina alterniflora happened in the Yellow River Delta