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Fluoroquinolone antibiotics (FQs) are one of the most widely used antibiotics, which are new pollutants with 'pseudo persistence' in the environment, causing great ecological risks. FQs could change the structure and function of microbial communities and affect nitrogen cycling mediated by microorganisms. Consequently, FQs would change the composition of various types of nitrogen in the environment and exert a significant impact on the global nitrogen cycling. We encapsulated the distribution of FQs in the environment and its impacts on nitrogen cycling mediated by microorganisms, explained the role of FQs in each key process of nitrogen cycling, aiming to provide an important reference for revealing the ecological effects of FQs. Generally, FQs could be detected in various environmental media, with significant differences in the concentration and types of FQs in different environments. Ofloxacin, norfloxacin, ciprofloxacin, and enrofloxacin are the four types of FQs with the highest detection frequency and concentration. The effect of FQs on nitrogen cycling deeply depends on typical characteristics of concentration and species. FQs mainly inhibit nitrification by reducing the abundance of amoA gene related to ammoxidation process and the abundance and composition of ammoxidation bacteria. FQs inhibits nitrification by reducing the abundance and composition of microbial communities. The denitrification process is mainly inhibited due to the reduction of the activity of related enzymes and the abundance of genes such as narG , nirS , norB , and nosZ genes, as well as the abundance and composition of denitrifying functional microorganisms. The process of anammox is restricted due to the reduction of the abundance, composition and hzo gene abundance of anaerobic anammox bacteria. FQs lead to the reduction of active nitrogen removal and the increase of N 2 O release in the environment, with further environmental problems such as water eutrophication and greenhouse effect. In the future, we should pay attention to the effects of low concentration FQs and complex antibiotics on the nitrogen cycling, and focus on the effects of FQs on the changes of nitrogen cycle-related microbial monomers and communities.

Sulfonamides (SAs) are the first broad-spectrum synthetic antimicrobial agents used in human health and veterinary medicine. The majority of SAs entering human body is discharged into aquatic environment in the form of parent material or metabolites. The residues of SAs and their metabolites in the aquatic environment and the development of drug resistance can be serious threats to ecosystems and human health. We summarized recent advances in the research of SAs. The main metabolite types of SAs and the distribution characteristics of metabolites in different aquatic environments were introduced. The ecotoxicology of SAs metabolites, especially the distribution and hazards of sulfonamide resistance genes ( sul -ARGs), were discussed with emphasis. Finally, the future research works were proposed. This paper could provide basic information for further research on SAs.

Synthetic fluoroquinolones (FQs) are the third most commonly used antibiotics in the world and play an extremely important role in antibacterial drugs. The excessive use and discharge will alter ecological environment, with consequence on human health and global sustainable development. It is therefore of great significance for scientific use and management of FQs to systematically understand their biogeochemical behavior and eco-environmental effects. After drug administration in humans and animals, only a small part of FQs are transformed in vivo . The main transformation processes include formylation, acetylation, oxidation and cleavage of piperazine ring, defluorination and decarboxylation of aromatic core ring, etc . About 70% of the original drug and a small amount of transformed products would be migrated to the environment through excretion. After entering the environment, FQs and their transformation products mainly exist in environmental media such as water, soil and sediment, and undergo migration and transformation processes such as adsorption, photolysis and biodegradation. Adsorption facilitates transfer of FQs from medium to another. The photolysis mainly affects the C7-amine substituents of FQs, whereas the core structure of FQs remains intact. Biodegradation mainly refers to the degradation of FQs by microorganisms and microalgae, including piperazine modification of the piperazine ring such as acetylation and formylation, partial or complete ring cleavage, core structure decarboxylation, defluorination and conjugation formation. The migration and transformation processes of FQs cannot completely eliminate them from the environment. Instead, they would become "pseudo-persistent" pollutants, which seriously affect the behavior, growth and reproduction of algae, crustaceans and fish, change biogeochemical cycle, destroy aquatic environment, and stimulate microbial resistance and the generation of resistance genes. In the future, more in-depth studies should be conducted on the environmental behavior of FQs and their impacts on ecological environment, the risk assessment of microbial resistance and resistance genes of FQs, and the mechanism and effect of micro-biodegradation of FQs.

Amino sugars (AS) are one of the important biochemical components in the natural organic matter pool. Clarifying the sources and transformations of AS would facilitate our understan-ding of the microbial regulation of organic matter. As an emerging technology, compound-specific isotope analysis of amino sugars (CSIA-AS) provides more detailed dynamic information of indivi-dual AS in natural environment. Here, we systematically summarized the determination methods of CSIA-AS and gave an overview on innovative applications in the cycling of AS. CSIA-AS can be performed by gas chromatography-isotope ratio mass spectrometry (GC-IRMS) and ion chromatography-isotope ratio mass spectrometry (IC-IRMS). Each method has its own advantages and disadvantages, but reliable results can be achieved after calibration. The mean residence time of AS is relatively low in soil organic matter, and the bacterial-derived muramic acid possesses a higher minera-lization rate than glucosamine, galactosamine, and mannosamine. The source and metabolic transformation of AS are affected by the substrate, which is related to the specific response of microbial community to different carbon and nitrogen sources. The promotion of CSIA-AS technology requires further optimization of method and integration with other approaches such as microbial screening to decipher the source, transformation, fate and regulatory mechanisms of organic matter.

There is a big imbalance between the input and output of oceanic nitrogen in global ocean nitrogen cycles, because a part of the fixed nitrogen is reduced to N 2 or N 2 O and then lost from the ocean. Oxygen minimum zone (OMZ) is the most important area for nitrogen loss, which could lose fixed nitrogen up to 40 to 450 Tg·a -1 through the denitrification and anammox. A summary of the two main roles of nitrogen loss in the different OMZ sea areas reveals that heterotrophic denitrification dominates in eastern tropical Pacific, Arabian Sea, and marine sediments. The autotrophic denitrification has been found in Chile, Peru's coastal waters, and Arabian waters. In the Black Sea, the Benguela upwelling in southwestern Africa, and the northern coast of Chile, anaerobic ammonia oxidation is strong, with greater effects on the continental shelf than that in the ocean. In addition to the loss of nitrogen, nitrogen fixation, nitrification, and dissimilatory nitrate reduction to ammonium may affect the imbalance of nitrogen budget in the OMZ. The effects of nitrogen fixation can't be ignored. The total amount of nitrogen fixed in the global OMZ can reach 15-40 Tg·a -1 , which is an important supplement to the loss of nitrogen in OMZ. Disentangling the relative contribution of denitrification and anammox to the loss of nitrogen, ascertaining the formation mechanism and quantitative evaluation method of N 2 O (another product of nitrogen loss) are the most important challenges in the current study of OMZ. Focusing on the existing problems, we put forward corresponding research ideas with references for related studies of the OMZs in the ocean.

As important components of marine organic matters especially of organic nitrogen, amino acids play an important role in organic matter cycles owing to their lability. The concentration, composition, and distribution of amino acids have been widely used to indicate the degradation state of organic matters in particulates and sediments of marine. Here, the distribution, influencing factors of amino acids and their role in indicating degradation of organic matters were systematically summarized. Gly, Glu, Ala, and Asp were the major components of amino acids in marine particulates and sediments. The contents of amino acids in the particles and sediments showed a decreasing tendency from the coastal waters to the open sea, and adecreased with the water depth. The lower value of %AA-C/TOC, %AA-N/TN and degradation index (DI) based on changes in the composition of amino acids indicated the higher degradation degrees of organic matters. The reactivity index (RI) and ratios of D-AA and L-AA (D/L) based on non-protein amino acids and D-AA were used to indicate the degradation of organic matter according to the bacterial transformation of amino acids, in which RI value closer to 0, higher D/L, and lower ratios of protein amino acids to non-protein amino acids (Asp/β-Ala and Glu/γ-Aba) indicated the higher degree of degradation in organic matters. The migration and transformation of amino acid were mainly affected by dissolved oxygen, nutrient concentrations, sources of organic matter, depositional environments and microbial activities. Further studies should focus on the synergistic effects of particles and sediments, and also the effects and the specific regulatory roles of microorganisms on amino acids.

As a typical semi-closed bay, Jiaozhou Bay, is remarkably affected by human activities. Biogenic elements transported into the oceans by the atmospheric deposition of anthropogenic particles can lead to profound impacts on the ecosystem of Jiaozhou Bay. In this paper, the researches of atmospheric dry and wet depositions in the Jiaozhou Bay were systematically summarized from the following three aspects: study methods, variation characteristics of the fluxes and their influencing factors and the ecological effects of atmospheric deposition. The concentrations and fluxes of nitrogen species in atmospheric dry and wet depositions were very high in the Jiaozhou Bay compared with other bays, estuaries and marginal seas around the world. The dissolved inorganic nitrogen (DIN) was the main component of the total dissolved nitrogen (TDN) and the dissolved organic nitrogen (DON) accounted for 22%-31% of TDN. However, the concentrations and fluxes of phosphate and silicate species were very low. The atmospheric deposition fluxes of (NO 3 - -N+NO 2 - -N) were slightly higher than terrestrial inputs, while the fluxes of NH 4 + -N, PO 4 3- -P and SiO 3 2- -Si were very low compared with terrestrial inputs. The concentration of total suspended particulates (TSP) in the air, the intensity of the emission sources, precipitation amount and meteorological conditions are the major factors influencing the atmospheric depositions of biogenic elements, which can increase the primary productivity, change the structure of nutrients and the structure of phytoplankton communities in surface seawater and further promote the succession of phytoplankton dominant species from diatom to dinoflagellate in the Jiaozhou Bay. On that basis, the future research should be focused on constructing the monitoring network for atmospheric dry and wet depositions, accurately quantifying the deposition rates of aerosol particles of different forms and sizes, recognizing the ecological effects and biogeochemical mechanisms of atmospheric depositions of biogenic elements and discriminating the mechanisms, fluxes and influencing factors of atmospheric deposition biogenic elements via indirect approaches such as overland runoff, sheetflood and permeation etc. It is significant for illuminating the effects of anthropogenic activities on the coastal waters as well as understanding the bio-geochemical processes of biogenic elements in marginal seas by elucidating atmospheric depositions of biogenic elements in the Jiaozhou Bay.

Abstract: Jellyfish bloom has been increasing in Chinese seas and decomposition after jellyfish bloom has great influences on marine ecological environment. We conducted the incubation of Nemopilema nomurai decomposing to evaluate its effect on carbon, nitrogen and phosphorus recycling of water column by simulated experiments. The results showed that the processes of jellyfish decomposing represented a fast release of biogenic elements, and the release of carbon, nitrogen and phosphorus reached the maximum at the beginning of jellyfish decomposing. The release of biogenic elements from jellyfish decomposition was dominated by dissolved matter, which had a much higher level than particulate matter. The highest net release rates of dissolved organic carbon and particulate organic carbon reached (103.77 ± 12.60) and (1.52 ± 0.37) mg · kg⁻¹ · h⁻¹, respectively. The dissolved nitrogen was dominated by NH₄⁺-N during the whole incubation time, accounting for 69.6%-91.6% of total dissolved nitrogen, whereas the dissolved phosphorus was dominated by dissolved organic phosphorus during the initial stage of decomposition, being 63.9%-86.7% of total dissolved phosphorus and dominated by PO₄³⁻-P during the late stage of decomposition, being 50.4%-60.2%. On the contrary, the particulate nitrogen was mainly in particulate organic nitrogen, accounting for (88.6 ± 6.9) % of total particulate nitrogen, whereas the particulate phosphorus was mainly in particulate. inorganic phosphorus, accounting for (73.9 ±10.5) % of total particulate phosphorus. In addition, jellyfish decomposition decreased the C/N and increased the N/P of water column. These indicated that jellyfish decomposition could result in relative high carbon and nitrogen loads.

Coastal salt marsh has higher potential of carbon sequestration, playing an important role in mitigating global warming, while coastal saline soil is the largest organic carbon pool in the coastal salt marsh carbon budget. To study the carbon deposition and burial in this soil is of significance for clearly understanding the carbon budget of coastal salt marsh. This paper summarized the research progress on the deposition and burial of organic carbon in coastal salt marsh from the aspects of the sources of coastal salt marsh soil organic carbon, soil organic carbon storage and deposition rate, burial mechanisms of soil organic carbon, and the relationships between the carbon sequestration in coastal salt marsh and the global climate change. Some suggestions for the future related researches were put forward: 1) to further study the underlying factors that control the variability of carbon storage in coastal salt marsh, 2) to standardize the methods for measuring the carbon storage and the deposition and burial rates of organic carbon in coastal salt marsh, 3) to quantify the lateral exchange of carbon flux between coastal salt marsh and adjacent ecosystems under the effects of tide, and 4) to approach whether the effects of global warming and the increased productivity could compensate for the increase of the organic carbon decomposition rate resulted from sediment respiration. To make clear the driving factors determining the variability of carbon sequestration rate and how the organic carbon storage is affected by climate change and anthropogenic activities would be helpful to improve the carbon sequestration capacity of coastal salt marshes in China.

At present, chemical approaches are the main tools adopted to assess the contaminated sediments along China's coast. However, with the crucial progress of weight of evidence (WOE) approach in both logic and practice, this approach is getting available to be applied in the sediment quality assessment of our coastal ecosystem. By incorporating the levels of evidences such as sediment chemistry, toxicity and benthic community ecology, WOE forms an integrated approach to assess the potential adverse biological effects of environmental stressors mainly toxic substances by reconciling the information from multiple relevant lines of evidences and by weighing the data quality, study design, and other factors, being the sole means currently available to characterize the actual sediment quality and to reach an environmental decision. This paper reviewed the history of sediment quality assessment and the progress of WOE research in coastal sediment, summarized the variety of WOE definitions and interpretive techniques with reliability analysis, and discussed the limitations of WOE in theory and practice. Several improvement suggestions were proposed associated with the prospects of WOE research to advance the coastal sediment quality assessment in China.