Sources, Toxicity and Detection Techniques of Semicarbazide: A Review

Semicarbazide has become an important pollutant in the environment,but there was no comprehensive literature on its advances.In this review,the source,biotoxicity and detection methods are summarized.Among the sources is the material of chemical reaction,a metabolite of nitrofurazone,food processing(production by azobisformamide and hypochlorite treatment),endogenous substances,etc.Semicarbazide is demonstrated to be accumulative and reproductive toxicity,mutagenicity and genotoxicity,endocrine disruptors,and neurotoxicity.There are still many controversies on the effect of genotoxicity and no clear result on the carcinogenic mechanism.HPLC-MS/MS is the mainstream of the detection methods.Other methods,including HPLC,immunoassay method,biosensor method,electrochemical detection,capillary electrophoresis technique,and spectral techniques mainly,have become less and less in recent years.On all these counts,to reduce the content of semicarbazide in the environment,the key is to control the use of nitrofurazone as the banned drug effectively.Meanwhile the toxicity data should be supplemented to reveal its toxic mechanism.

Climate-Related Variations in Autumn Cohort of Japanese Common Squid Todarodes pacificus

The Japanese common squid Todarodes pacificus is widely distributed in the Sea of Japan,the East China Sea and the Northwest Pacific Ocean,and is largely exploited by the Asia-Pacific countries.In this study,the impacts of regime shift of the Pacific Decadal Oscillation(PDO)during 1977-2015 on the autumn cohort of T.pacificus were assessed by examining the variations in vertical water temperatures at depths of 0 m(Temp_0 m),50 m(Temp_50 m)and 100 m(Temp_100 m)and the distribution pattern of preferred spawning ground(SSG).Spatial and temporal correlation analysis revealed that the PDO index exhibited a significantly negative relationship with vertical water temperatures at different depths and was negatively related to catch-per-unit-effort(CPUE)and stock biomass of T.pacificus.In addition,water temperatures in the specific three water layers were positively associated with CPUE.The PDO regime shift strongly affected the thermal condition and spawning ground of T.pacificus.Comparing to the negative PDO,the waters from the surface to the deep became cool in the positive PDO phase;correspondingly,the area of SSG largely contracted at different depths.Consequently,the CPUE and stock biomass of T.pacificus profoundly decreased.From the results it can be concluded that the PDO regime shift-driven changes in vertical thermal condition and SSG ranges can yield substantial impacts on T.pacificus abundance.

A Comparison of MODIS LST Retrievals with <i>in Situ</i>Observations from AWS over the Lambert Glacier Basin, East Antarctica

Satellite-derived surface temperature data is increasingly required to supplement the limited weather stations for the assessment of temperature trend over the data-sparse Antarctic Ice Sheet. To accomplish this, it is essential to assess the relationship and difference between satellite-based land-surface temperature (LST) retrieval and air temperature observation. In this study, we made a comparison between monthly averaged LST from Moderate Resolution Imaging Spectroradiometer (MODIS) and the corresponding air temperature at the nominal heights of 1 m and 2 m from automatic weather stations (AWSs) over the Lambert Glacier basin, East Antarctica. This comparison reveals a statistically significant correlation between the two types of temperature measurements with correlation coefficient (R) above 0.6. Also, the time difference between satellite overpass and air temperature observation is not critical for the R values. Although MODIS LST evidently deviates from air temperature (Mean difference fluctuates from 2.87°C to 8.08°C) probably due to the temperature inversion effect, heterogeneity in surface emissivity, representative of AWS measurements and satellite self limitation. MODIS LST measurements have a great potential for the accurate evaluation or monitoring of regional air temperature over Antarctica, and thus better improve current reconstruction of spatial and temporal reconstruction variability in Antarctic temperature.

Zooplankton community variations in response to summer hypoxia in Sishili Bay,North Yellow Sea,China

Hypoxia may cause severe disturbances to coastal ecosystems.The potential effects of summer hypoxia on zooplankton communities in Sishili Bay,China,was investigated in three cruises conducted during the summer from 2015 to 2017.Comparative analysis was performed on zooplankton communities at hypoxic and normoxic sites.Results show that the number and abundance of zooplankton species at hypoxic sites were lower than those at normoxic sites.Copepods exhibited greater dominance at the hypoxic sites compared to the normoxic sites,suggesting a higher tolerance to low oxygen concentrations than other taxonomic groups.Specifically,Oithona spp.was particularly prevalent at hypoxic sites and displayed a negative correlation with dissolved oxygen concentration at sea bottom.Additionally,the zooplankton community at hypoxic sites also exhibited lower Shannon-Wiener diversity and Margalef richness indices.The normalized biovolume size spectrum of the hypoxic sites showed steep slopes,suggesting a shift towards smaller species and lower transfer efficiency in pelagic food webs for the zooplankton community.

Bacterial communities associated with hydromedusa Gonionemus vertens in diff erent regions in Chinese coastal waters

Bacteria communities in cnidarian jellyfi sh can be harmful to many important aquaculture species,as they can be key vectors of bacterial pathogens.However,our knowledge of bacterial communities associated with jellyfi sh in culture ponds and their potential roles in the regulation of aquaculture species remains unclear.In this study,sequencing based on the bacterial 16S rRNA gene was used to investigate the composition and variation of the bacterial communities associated with hydromedusa Gonionemus vertens in sea cucumber culture ponds and natural marine environment.The associated bacterial communities of G.vertens from the culture ponds in the Yellow Sea and Bohai Sea had signifi cantly diff erent compositions,when compared with those from ambient seawater environment.Furthermore,bacterial communities associated with G.vertens had similar diversity and composition in culture ponds and natural marine environment in the Yellow Sea.There were 31 unique bacterial biomarkers identifi ed in three locations.The major communities were highly abundant in Kiloniellales,Octadecabacter,Polynucleobacter,and Polaribacter,and are related to the environmental information processing.Pathogen candidates such as Vibrionales and Chlamydiales had notably low relative abundances(<1%).The venom of the jellyfi sh was considered responsible for damage to the aquaculture.This study provides important data to help assess the impact of cnidarians-associated bacterial communities on pond aquaculture and the infl uences on material cycling and energy fl ow in marine ecosystems.

Climatology of stable isotopes in Antarctic snow and ice:Current status and prospects

Stable isotopic composition in Antarctic snow and ice is commonly regarded as one of invaluable palaeoclimate proxies and plays a critically important role in reconstructing past climate change.In this paper we summarized the spatial distribution and the controlling factors of δD,δ18O,d-excess and 17O-excess in Antarctic snow and ice,and discussed their reliability and applicability as palaeoclimate proxies.Recent progress in the stable isotopic records from Antarctic deep ice cores was reviewed,and perspectives on bridging the current understanding gaps were suggested.