Anthropogenic activity shapes the assemble and co-occurrence pattern of microbial communities in fishing harbors around the Bohai Economic Circle.

This study aimed to elucidate the effects of coastal environmental stress on the composition of sediment bacterial communities and their cooccurrence patterns in fishing harbors around the Bohai Economic Circle, China. Compared with the natural sea area, fishing harbors contained higher levels of organic pollution (organic pollution index = 0.12±0.026) and considerably reduced bacterial richness and evenness. The distributions of sediment microbial communities clustered along the pollutant concentration gradients across fishing harbors. Betaproteobacteria dominated (76%) organically polluted fishing harbors, which were mostly disturbed by anthropogenic activities. However, the harbors also revealed the absence of numerous pathogenic (Coxiella and Legionella) and photosynthetic (Synechococcus and Leptolyngbya) bacteria. Abundant genera, including Thiobacillus and Arenimonas, exhibited a positive correlation with total phosphorus and a negative correlation with total nitrogen in sediments. Meanwhile, Sulfurovum, Psychrobacter, and Woeseia showed the opposite trend. Pollutant accumulation and anthropogenic activities caused the decrease in the sediment microbial diversity and dispersal ability and promoted convergent evolution. Severely polluted harbors with simplified cooccurrence networks revealed the presence of destabilized microbial communities. In addition, the modularity of bacterial networks decreased with organic pollution. Our results provide important insights into the adjustment mechanism of microbial communities to community organization and functions under environmental pollution stress. Overall, this study enhanced our understanding of how microbial communities in coastal sediments adapted and survived amidst anthropogenic activities like oily effluent discharges from large ships, wash water, domestic sewage, garbage, and fisheries wastes. It also examined their resilience to future contamination.

Unprecedented phytoplankton blooms in autumn/winter in the southern Bohai Sea (China) due to high Yellow River discharge: Implications of extreme rainfall events.

The occurrence of abnormal phytoplankton blooms is one of the significant changes in coastal ecosystems due to climate change. However, the underlying mechanism of such blooms remains poorly understood due to the complexity of the system. In this study, the data from numerous observations was used to elucidate the unprecedented phytoplankton blooms in the autumn and winter of 2021 in Laizhou Bay, a typical aquaculture bay in the southern Bohai Sea of China. The abundance of phytoplankton cells increased by more than tenfold in the southern waters compared to that in the same period from 2019 to 2020. The phytoplankton bloom was first observed in winter in the Bohai Sea, with the cell abundance in the southern bay exceeding 108 cells L-1 in December 2021. The diversity and evenness of phytoplankton communities decreased in the southern area. Cerataulina pelagica was the dominant algae, comprising 69 % of the total phytoplankton in October and 99 % in December. In autumn 2021, the largest flood of the Yellow River in recent decades occurred. This was attributed to extreme rainfall events within the river basin. The input of substantial riverine nutrients played a significant role in promoting phytoplankton blooms. Correlation analysis indicated the important cumulative impact of the Yellow River on phytoplankton blooms rather than a direct short-term effect. Numerical modeling results indicated that exceptionally high Yellow River discharge in autumn could significantly affect the entire bay from autumn to the following spring. This study may contribute to understanding the abnormal phytoplankton blooms in coastal waters and provide valuable insights for environmental management in river basins and coastal waters.

Atmospheric fine particles in a typical coastal port of Yangtze River Delta.

In recent decades, coastal ports have experienced rapid development and become an important economic and ecological hub in China. Atmospheric particle is a research hotspot in atmospheric environmental sciences in inland regions. However, few studies on the atmospheric particle were conducted in coastal port areas in China, which indeed suffers atmospheric particle pollution. Lack of the physicochemical characteristics of fine particles serves as an obstacle toward the accurate control for air pollution in the coastal port area in China. Here, a field observation was conducted in an important coastal port city in Yangtze River Delta from March 6 to March 19, 2019. The average PM2.5 concentration was 63.7 ± 27.8 µg/m3 and NO3-, SO42-, NH4+, and organic matter accounted for ~60% of PM2.5. Fe was the most abundant trace metal element and V as the ship emission indicator was detected. Transmission electron microscopy images showed that SK-rich, soot, Fe, SK-soot and SK-Fe were the major individual particles in the coastal port. V and soluble Fe were detected in sulfate coating of SK-Fe particles. We found that anthropogenic emissions, marine sea salt, and secondary atmosphere process were the major sources of fine particles. Backward trajectory analysis indicated that the dominant air masses were marine air mass, inland air mass from northern Zhejiang and inland-marine mixed air mass from Shandong and Shanghai during the sampling period. The findings can help us better understand the physicochemical properties of atmospheric fine particles in the coastal port of Eastern China.

Histone deacetylase 5 promotes the migration and invasion of hepatocellular carcinoma via increasing the transcription of hypoxia-inducible factor-1α under hypoxia condition.

Hypoxia plays a critical role in the progression and metastasis of hepatocellular carcinoma by activating the key transcription factor, hypoxia-inducible factor-1. This study aims to identify the novel mechanisms underlying the dysregulation of hypoxia-inducible factor-1α in hepatocellular carcinoma. We found that histone deacetylase 5, a highly expressed histone deacetylase in hepatocellular carcinoma, strengthened the migration and invasion of hepatocellular carcinoma cells under hypoxia but not normoxia condition. Furthermore, histone deacetylase 5 induced the transcription of hypoxia-inducible factor-1α by silencing homeodomain-interacting protein kinase-2 expression, which was also dependent on hypoxia. And then knockdown of hypoxia-inducible factor-1α decreased the expressions of mesenchymal markers, N-cadherin, and Vimentin, as well as matrix metalloproteinases, MMP7 and MMP9; however, the epithelial marker, E-cadherin, increased. Phenotype experiments showed that the migration and invasion of hepatocellular carcinoma cells were impaired by knockdown of histone deacetylase 5 or hypoxia-inducible factor-1α but rescued when eliminating homeodomain-interacting protein kinase-2 in hepatocellular carcinoma cells, which suggested the critical role of histone deacetylase 5-homeodomain-interacting protein kinase-2-hypoxia-inducible factor-1α pathway in hypoxia-induced metastasis. Finally, clinical analysis confirmed the positive correlation between histone deacetylase 5 and hypoxia-inducible factor-1α in hepatocellular carcinoma specimens and a relatively poor prognosis for the patients with high levels of histone deacetylase 5 and hypoxia-inducible factor-1α. Taken together, our findings demonstrated a novel mechanism underlying the crosstalk between histone deacetylase 5 and hypoxia-inducible factor-1 in hepatocellular carcinoma.

Platelet biogenesis and functions require correct protein O-glycosylation.

Platelets express a variety of membrane and secreted glycoproteins, but the importance of glycosylation to platelet functions is poorly understood. To explore the importance of O-glycosylation, we generated mice with a targeted deletion of Cosmc in murine endothelial/hematopoietic cells (EHC) (EHC Cosmc(-/y)). X-linked Cosmc encodes an essential chaperone that regulates protein O-glycosylation. This targeted mutation resulted in lethal perinatal hemorrhage in the majority of mice, and the surviving mice displayed severely prolonged tail-bleeding times and macrothrombocytopenia. EHC Cosmc(-/y) platelets exhibited a marked decrease in GPIb-IX-V function and agonist-mediated integrin αIIbß3 activation, associated with loss of interactions with von Willebrand factor and fibrinogen, respectively. Significantly, three O-glycosylated glycoproteins, GPIbα, αIIb, and GPVI normally on platelet surfaces that play essential roles in platelet functions, were partially proteolyzed in EHC Cosmc(-/y) platelets. These results demonstrate that extended O-glycans are required for normal biogenesis of the platelets as well as the expression and functions of their essential glycoproteins, and that variations in O-glycosylation may contribute to altered hemostasis.

Effect of hydrodynamic and ecosystem conditions on persistent organic pollutant temporal-spatial variations in the Yellow Sea.

Coastal seas are important pools of persistent organic pollutants (POPs) discharged from land. Considering the complex conditions in coastal seas and various biochemical features of POPs, special temporal-spatial variations in POPs have been reported. To understand these variations, we developed a three-dimensional hydrodynamic-ecosystem-POP coupled model and applied it to the Yellow Sea. We selected two POP species (polychlorinated biphenyl congener 153 (PCB-153) and decabromodiphenyl ether (BDE-209)), which have different biochemical properties, as target materials. The dissolved PCB-153 simulated concentration was high in late spring and low in autumn, whereas that of BDE-209 was high in summer and low in winter. Both PCB-153 and BDE-209 showed high particle-bound concentrations in early spring. In summer, dissolved PCB-153 accumulated at the sea bottom, whereas dissolved BDE-209 accumulated at the sea surface. Seasonal and spatial variation differences in the two POPs are likely caused by greater Henry's Law Constant (H') and bioconcentration factor (BCF) of PCB-153 than that of BDE-209, which leads to higher volatilization and stronger absorption by the particles for PCB-153 than BDE-209. As a component of such differences, the "biological pump" of PCB-153 in the central Yellow Sea is more apparent than that of BDE-209.

Atmospheric deposition and river runoff stimulate the utilization of dissolved organic phosphorus in coastal seas.

In coastal seas, the role of atmospheric deposition and river runoff in dissolved organic phosphorus (DOP) utilization is not well understood. Here, we address this knowledge gap by combining microcosm experiments with a global approach considering the relationship between the activity of alkaline phosphatases and changes in phytoplankton biomass in relation to the concentration of dissolved inorganic phosphorus (DIP). Our results suggest that the addition of aerosols and riverine water stimulate the biological utilization of DOP in coastal seas primarily by depleting DIP due to increasing nitrogen concentrations, which enhances phytoplankton growth. This "Anthropogenic Nitrogen Pump" was therefore identified to make DOP an important source of phosphorus for phytoplankton in coastal seas but only when the ratio of chlorophyll a to DIP [Log10 (Chl a / DIP)] is larger than 1.20. Our study therefore suggests that anthropogenic nitrogen input might contribute to the phosphorus cycle in coastal seas.

Epigenetic silencing of the chaperone Cosmc in human leukocytes expressing tn antigen.

Cosmc is the specific molecular chaperone in the endoplasmic reticulum for T-synthase, a Golgi ß3-galactosyltransferase that generates the core 1 O-glycan, Galß1-3GalNAcα-Ser/Thr, in glycoproteins. Dysfunctional Cosmc results in the formation of inactive T-synthase and consequent expression of the Tn antigen (GalNAcα1-Ser/Thr), which is associated with several human diseases. However, the molecular regulation of expression of Cosmc, which is encoded by a single gene on Xq24, is poorly understood. Here we show that epigenetic silencing of Cosmc through hypermethylation of its promoter leads to loss of Cosmc transcripts in Tn4 cells, an immortalized B cell line from a male patient with a Tn-syndrome-like phenotype. These cells lack T-synthase activity and express the Tn antigen. Treatment of cells with 5-aza-2'-deoxycytidine causes restoration of Cosmc transcripts, restores T-synthase activity, and reduces Tn antigen expression. Bisulfite sequencing shows that CG dinucleotides in the Cosmc core promoter are hypermethylated. Interestingly, several other X-linked genes associated with glycosylation are not silenced in Tn4 cells, and we observed no correlation of a particular DNA methyltransferase to aberrant methylation of Cosmc in these cells. Thus, hypermethylation of the Cosmc promoter in Tn4 cells is relatively specific. Epigenetic silencing of Cosmc provides another mechanism underlying the abnormal expression of the Tn antigen, which may be important in understanding aberrant Tn antigen expression in human diseases, including IgA nephropathy and cancer.

Cosmc is an essential chaperone for correct protein O-glycosylation.

Cosmc is a molecular chaperone thought to be required for expression of active T-synthase, the only enzyme that galactosylates the Tn antigen (GalNAcalpha1-Ser/Thr-R) to form core 1 Galbeta1-3GalNAcalpha1-Ser/Thr (T antigen) during mucin type O-glycan biosynthesis. Here we show that ablation of the X-linked Cosmc gene in mice causes embryonic lethality and Tn antigen expression. Loss of Cosmc is associated with loss of T-synthase but not other enzymes required for glycoprotein biosynthesis, demonstrating that Cosmc is specific in vivo for the T-synthase. We generated genetically mosaic mice with a targeted Cosmc deletion and survivors exhibited abnormalities correlated with Tn antigen expression that are related to several human diseases.

Interannual variations in the nutrient cycle in the central Bohai Sea in response to anthropogenic inputs.

In recent decades, there has been growing concern regarding the effects of human activities on the coastal nutrient cycle. However, interannual variations in the coastal nutrient cycle in response to anthropogenic nutrient input have rarely been quantified. In this study, a hydrodynamic-ecological model capable of describing the nitrogen and phosphorus cycles was used to analyze interannual variations in the nutrient cycle in the central Bohai Sea, a typical semi-enclosed sea in the Northwest Pacific. The results showed an increasing trend of dissolved inorganic nitrogen and particulate nitrogen from 1998 to 2017, whereas different forms of phosphorus showed no obvious interannual variations. The annual nutrient budgets were also quantitatively estimated from 1998 to 2017. This indicates that atmospheric nitrogen deposition plays an important role in interannual variations in the nitrogen cycle. A large amount of nitrogen from anthropogenic inputs was mainly removed by sedimentation processes instead of increasing the standing stock of nitrogen in the sea. With the reduction of anthropogenic inputs, the model showed that a variety of forms of nitrogen concentration decreased linearly, whereas phosphorus concentration increased slightly. Therefore, although environmental governance can effectively alleviate water eutrophication, it is necessary to avoid the situation where the dissolved inorganic nitrogen concentration in the sea becomes too low for phytoplankton to grow, which may determine the primary productivity and eventually affect fishery resources.

Safety and Efficacy of Combined Imbrication Axle Reconstruction and Z-Type Titanium Plate Fixation for Hinge Fracture Displacement During Open-Door Laminoplasty.

BACKGROUND: Open-door laminoplasty is a classical decompression method used to treat cervical spondylotic myelopathy. However, hinge fracture displacement (HFD) is a common occurrence during this procedure. The current study aimed to investigate the safety and efficacy of a combined imbrication axle reconstruction and Z-type titanium plate fixation method for HFD during open-door laminoplasty. METHODS: In total, 617 patients with cervical spondylotic myelopathy who underwent C3-C7 open-door laminoplasty from March 2015 to October 2018 were included in this retrospective study. Overall, 73 patients developed HFD during surgery. Of these, 43 underwent combined imbrication axle reconstruction and Z-type titanium plate fixation (IRZF group) and 30 underwent traditional titanium plate fixation (TF group). Data such as the operative time, intraoperative blood loss volume, and distribution of fractured hinges were recorded. Both groups were compared in terms of improvement in neurologic function, cervical curvature index, hinge fusion rate, incidence of C5 palsy, severity of axial symptoms, and development of complications. RESULTS: The operative time and intraoperative blood loss were slightly higher in the IRZF group than in the TF group; however, the differences were not significant (p > 0.05). Furthermore, there was no significant difference between the groups in terms of the number of fractured segments and the distribution of fractured hinges (p > 0.05). The cervical curvature index did not decline in the two groups (p > 0.05). The IRZF group had a higher hinge fusion rate than the TF group at 3 (79.6 vs. 57.1%) and 12 (93.9 vs. 74.3%) months postoperatively (p < 0.05). There was no significant difference in the incidence of C5 palsy between the two groups (9.3 vs. 6.7%; p > 0.05). However, the TF group had more severe axial symptoms than the IRZF group (p < 0.05). The neurologic function of the two groups increased postoperatively as per the Japanese Orthopaedic Association scoring system (p < 0.05). Nevertheless, there was no significant difference in terms of neurologic function at any observational time point (p > 0.05). One patient in the TF group with hinge nonunion underwent laminectomy due to lamina displacement into the spinal canal and nerve root compression. CONCLUSION: In patients with HFD, IRZF facilitates a more intimate contact between the lamina and the lateral mass and, therefore, achieves fractured hinge fusion without additional surgical trauma. This technical improvement can significantly promote neurologic recovery, decrease the severity of axial symptoms, and prevent the development of spinal cord or nerve root recompression.

Novel Three-Holed Titanium Plate Fixation during Open Door Laminoplasty for Cervical Spondylotic Myelopathy: Comparison with Conventional Titanium Plate.

OBJECTIVE: For reconstructing the posterior cervical muscular-ligament complex, attachment points and various modified techniques were designed and applied in clinical practice. This study investigated the clinical and radiographic outcomes of open door laminoplasty with modified centerpiece mini-plate fixation and extensor attachment point reconstruction in the treatment of cervical spondylotic myelopathy (CSM). METHODS: Sixty-nine patients with CSM who underwent C3-C7 open door laminoplasty at our hospital from January 2016 to May 2018 were divided into two groups: 37 and 32 patients underwent laminoplasty with modified and conventional centerpiece titanium plate fixation (MPF and CPF groups), respectively. Changes in cervical spinal angle (CSA), cervical range of motion (ROM), posterior cervical muscle atrophy, neurological function (Japanese Orthopaedic Association [JOA] score), Neck Disability Index (NDI), and axial symptom severity were compared between the two groups. RESULTS: There were no significant differences in operative duration (136.7 ± 23.9 vs 128.3 ± 21.5 min, t = 1.525, p > 0.05), volume of intraoperative blood loss (275.9 ± 33.1 vs 268.2 ± 31.6 ml, t = 0.984, p > 0.05), lamina open angle (41.2° ± 4.5° vs 39.4° ± 4.1°, t = 1.726, p > 0.05), and spinal cord drift distance (2.4 ± 0.3 vs 2.3 ± 0.4 mm, t = 1.184, p > 0.05) between the two groups. After surgery, JOA score significantly increased (p < 0.05), and neurological recovery rates were similar (62.7% vs 63.4%, t = 0.208, p > 0.05). The NDI score was significantly decreased in both the groups (p < 0.05); however, the MPF group recovered to a greater degree than the CPF group (8.3 ± 1.2 vs 9.8 ± 1.4) (t = 4.793, p < 0.05). There was no significant change in cervical ROM postoperatively compared with preoperatively in either group (p > 0.05). CSA decreased from 21.7° ± 2.8° to 18.3° ± 2.1°, and posterior cervical muscle cross-sectional area decreased from 35.2 ± 4.9 cm2 to 31.0 ± 4.1 cm2 in the CPF group (p < 0.05), but no significant change was observed in the MPF group (20.6° ± 2.5° to 20.4° ± 2.6°and 35.9 ± 5.1 to 34.1 ± 4.6 cm2 , respectively) (p > 0.05). Postoperative axial symptom severity was significantly worse in the CPF group than in the MPF group (Z = -2.357, p < 0.05). CONCLUSIONS: As an improvement to the conventional titanium plate, the modified centerpiece titanium plate effectively provides an attachment point for the posterior muscle-ligament complex, reducing posterior cervical muscle atrophy and improving neck function, without inflicting additional surgical trauma.

Quantifying evolution of soot mixing state from transboundary transport of biomass burning emissions.

Incomplete combustion of fossil fuels and biomass burning emit large amounts of soot particles into the troposphere. The condensation process is considered to influence the size (Dp) and mixing state of soot particles, which affects their solar absorption efficiency and lifetimes. However, quantifying aging evolution of soot remains hampered in the real world because of complicated sources and observation technologies. In the Himalayas, we isolated soot sourced from transboundary transport of biomass burning and revealed soot aging mechanisms through microscopic observations. Most of coated soot particles stabilized one soot core under Dp < 400 nm, but 34.8% of them contained multi-soot cores (nsoot ≥ 2) and nsoot increased 3-9 times with increasing Dp. We established the soot mixing models to quantify transformation from condensation- to coagulation-dominant regime at Dp ≈ 400 nm. Studies provide essential references for adopting mixing rules and quantifying the optical absorption of soot in atmospheric models.

Influence of fixed titanium plate position on the effectiveness of open-door laminoplasty for cervical spondylotic myelopathy.

BACKGROUND: During open-door laminoplasty, the position of the bone gutter is not fixed, and when the gutter migrates inward, the outer end of the titanium plate must be fixed on the lamina edge. It is unclear whether this will affect the clinical efficacy. This study aimed to observe the influence of the titanium plate fixation position on the effectiveness of open-door laminoplasty for cervical spondylotic myelopathy (CSM). METHODS: A total of 98 patients with CSM who underwent open-door laminoplasty from August 2016 to October 2019 were included in this retrospective study. Fifty-five patients had the titanium plate fixed on the lateral mass (lateral mass group), and 43 patients had the titanium plate fixed on the lamina edge (lamina group). The opening angle, opening width, occurrence of hinge fracture, spinal cord drift distance, cervical curvature index (CCI), neurological function recovery (JOA score), neck function (NDI), C5 palsy and severity of axial symptoms were observed and compared between the two groups. RESULTS: The opening angle in the lamina group was significantly larger than that in the lateral mass group, while the opening width and the spinal cord drift distance were significantly smaller than those in the lateral mass group (P < 0.05). The occurrence of hinge fracture in the lamina group was significantly higher than that in the lateral group (25.6% and 9.1%, respectively) (P < 0.05). The CCI was maintained well in both groups (P > 0.05), and there was no significant difference between the groups (P > 0.05). After surgery, the JOA score significantly increased in both groups (P < 0.05), and the neurological recovery rates were similar between the two groups (62.6% vs. 64.5%). The NDI score significantly decreased in both groups (P < 0.05), but the lateral mass group recovered to a greater degree than the lamina group (P < 0.05). The occurrence of C5 palsy was 2.3% in the lamina group and 14.5% in the lateral mass group, and there was a significant difference between the groups (P < 0.05). Postoperative axial symptom severity was significantly worse in the lamina group than in the lateral mass group (P < 0.05). CONCLUSIONS: In open-door laminoplasty, it is feasible to fix the titanium plate on the lateral mass or to the lamina due to the same neurological function recovery. However, fixing it to the lamina will increase the opening angle and decrease the opening width, making the hinge prone to fracture and increasing the severity of postoperative axial symptoms.

A novel fluorescent assay for T-synthase activity.

Loss of T-synthase (uridine diphosphate galactose:N-acetylgalactosaminyl-α1-Ser/Thr ß3galactosyltransferase), a key enzyme required for the formation of mucin-type core 1 O-glycans, is observed in several human diseases, including cancer, Tn syndrome and IgA nephropathy, but current methods to assay the enzyme use radioactive substrates and complicated isolation of the product. Here we report the development of a novel fluorescent assay to measure its activity in a variety of tumor cell lines. Deficiencies in T-synthase activity correlate with mutations in the gene encoding the molecular chaperone Cosmc that is required for folding the T-synthase. This new high-throughput assay allows for facile screening of tumor specimens and other biological material for T-synthase activity and could be used diagnostically.

Seasonal variations of nutrient concentrations and their ratios in the central Bohai Sea.

The Bohai Sea is a typical semi-enclosed sea in the northwest Pacific, which is subject to serious eutrophication due to human activities. Similar to hydrographic variables such as water temperature and salinity, the nutrient concentrations and ratios in the Bohai Sea also exhibit seasonal variations. However, the effects of external inputs, biological processes, and benthic processes on these seasonal variations have not been quantified to date. To address this issue, a physical-biological coupled model was developed to capture the seasonal nutrient cycling in the central Bohai Sea. The simulation results revealed apparent seasonal variations in the concentrations of dissolved inorganic nitrogen (DIN), dissolved inorganic phosphorus (DIP), and dissolved silicate (DSi). The N/P ratio (as the molar ratio of DIN/DIP) also exhibited an apparent seasonal variation, with the maximum and minimum values in surface water occurring in summer (>100) and winter (<30), respectively. The Si/N ratio (as the molar ratio of DSi/DIN) was slightly higher in summer than in other seasons. The budget for three types of nutrient indicated that the biological processes determined the seasonal variations in nutrient concentrations and the N/P ratio. The external inputs of nutrients via river input, atmospheric deposition, and sediment release were probably important in summer when they could alleviate the reduced nutrient concentrations due to biological processes. To maintain a reasonable nitrogen budget, it was necessary to include benthic nitrogen loss, which removed a large amount of inorganic nitrogen in summer and autumn. In addition, the variation of N/P ratio of phytoplankton uptake can reduce the ratio of DIN to DIP in surface water by ~20 in summer as compared to the calculation with a fixed N/P ratio (16:1) in phytoplankton uptake.

Fine particles from village air in northern China in winter: Large contribution of primary organic aerosols from residential solid fuel burning.

Rural residential emissions contribute significantly to regional air pollution in China, but our understanding on how residential solid fuel burning influences the village outdoor air quality is limited. In this study, we compared the fine particulate matter (PM2.5) composition and individual particle characteristics from 11 to 18 January 2017 at a village and an urban site in northern China. At the village site, each day was divided into four periods: cooking (07:30-10:00; 16:00-17:00), daytime (10:00-16:00), heating (17:00-24:00), and midnight (00:00-07:30) periods. The highest PM2.5 concentration occurred during the cooking period (236 ± 88 µg m-3), which was characterized by high concentrations of K+ and abundant primary OM-K particles (i.e., organic matter mixed with K-salts) emitted from residential biomass burning. The second highest PM2.5 concentration was found during the heating period (161 ± 97 µg m-3), and the PM2.5 contained abundant spherical primary OM particles (i.e., tarballs) emitted from residential coal burning. The primary emissions from residential solid fuel burning resulted in 75% of the village OM by mass consisting of primary OM and 67% of the village aerosol particles by number internally mixing with primary OM particles. The village PM2.5 composition was different from that of the urban PM2.5, with the former containing more OM (47% vs 32%) and less secondary inorganic ions (30% vs 46%). Individual primary OM-K and tarballs were abundant in the village air. These results suggest a large contribution of village residential emissions in the winter to village air pollution. Our study highlights that the residential health in villages of northern China should be paid more attention because of high PM2.5 concentrations and abundant toxic particles during the cooking and heating periods per day in winter.

Overview of primary biological aerosol particles from a Chinese boreal forest: Insight into morphology, size, and mixing state at microscopic scale.

Biological aerosols play an important role in atmospheric chemistry, clouds, climate, and public health. Here, we studied the morphology and composition of primary biological aerosol particles (PBAPs) collected in the Lesser Khingan Mountain boreal forest of China in summertime using transmission electron microscopy (TEM) and scanning electron microscopy (SEM). C, N, O, P, K, and Si were detected in most of the PBAPs, and P represented a major marker to discriminate the PBAPs. Of all detected particles >100 nm in diameter, 13% by number were identified as PBAPs. We found that one type of PBAPs mostly appeared as similar rod-like shapes with an aspect ratio > 1.5. Size distribution of the rod-like PBAPs displays two typical peaks at 1.4 µm and 3.5 µm, which likely are bacteria and fungal particles. The second most PBAPs were identified as fungal spores with ovoid, sub-globular or elongated shapes with a smooth surface and small protuberances with their dominant size range of 2-5 µm. Moreover, we found some large brochosomal clusters containing hundreds of brochosomes with a size range of 200-700 nm and a shape like a truncated icosahedron. We estimated that mass concentration of PBAPs approximately 1.9 µg m-3 and contributed 47% of the in situ PM2.5-10 mass. The detection frequency and concentration of PBAPs were higher at night than in the daytime, suggesting that the relative humidity dramatically enhanced the PBAPs emissions in the boreal forest. Our study also showed that the fresh PBAPs displayed weak hygroscopicity with a growth factor of ~1.09 at RH = 94%. TEM analysis revealed that about 20% of the rod-like PBAPs were internally mixed with metal, mineral dust, and inorganic salts in the boreal forest air. This work for the first time provides the overview of individual PBAPs from nanoscale to microscale in Chinese boreal forest air.

Water conservancy project on the Yellow River modifies the seasonal variation of Chlorophyll-a in the Bohai Sea.

The Water Sediment Regulation Scheme (WSRS) is a unique engineering measure that has been regularly performed to reduce reservoir sedimentation and increase the flood capacity of the Yellow River in China since 2002. As a side effect, the WSRS greatly increases the monthly input flux of nutrients to the Bohai Sea (BHS) in summer, potentially exacerbating eutrophication levels therein and subsequently affecting the growth of phytoplankton. However, its influence on the Chlorophyll-a (Chl-a) dynamics over the BHS is still poorly understood. In this study, two approaches were adopted to investigate it: 1) long-term in-situ observations and satellite-derived data of surface Chl-a were used to study its seasonal variations before and since 2002, and 2) one 1D physical-biological coupled model was developed to evaluate the impact of WSRS on seasonal Chl-a. The results showed that the surface Chl-a exhibited two peaks in spring and autumn until 2002, but has exhibited only one peak in spring-summer since 2002. Satellite-derived Chl-a concentrations in spring-summer since 2002 have increased by 56% compared to those until 2002. The simulated results showed that the change in Yellow River discharge induced by the WSRS has resulted in the appearance of high concentrations of Chl-a in summer over the Central Bohai Sea since 2002. The WSRS increased the ratio of added Chl-a owing to the riverine nutrients to total Chl-a by 19% compared to that until 2002. Overall, WSRS greatly affects the seasonal cycling of Chl-a in the Bohai Sea, and the side effect needs to be considered.

Dynamics of phytoplankton and nutrient uptake following dust additions in the northwest Pacific.

Dust deposition can supply nutrients that affect marine phytoplankton, but changing trophic statuses of the surface ocean increase the complexity of interpreting the process. In this study, four onboard incubation experiments amended with various nutrients and dust were performed in the Kuroshio Extension (KE) and Kuroshio-Oyashio transition (TR) of the northwest Pacific (NWP), which are characterised by lower and higher trophic statuses, respectively. According to the nutrient-addition experiments, phytoplankton were limited by nitrogen (N) in the KE, and limited by iron (Fe) or co-limited by Fe and phosphorus (P) in the TR. Dust additions supplied a considerable amount of N and Fe but negligible amount of P to stimulate phytoplankton growth, as indicated by chlorophyll a (Chl a) concentration. In the KE incubations, dust additions enhanced the shift of phytoplankton size structure towards larger cells from dominantly pico-sized (0.2-2 µm) Chl a to comparable contributions from each size class (i.e. pico-, nano-: 2-20 µm, micro-: >20 µm). On the basis of the large shift of size structure towards nano- or micro-phytoplankton in the unamended control treatments in the TR, dust additions furtherly promoted the shift towards micro-phytoplankton becoming the dominant contributor to the total Chl a. The collective analysis of the data from experiments in both regions revealed that, the extent of phytoplankton growth stimulation and the shift towards larger cells were enhanced gradually with increasing amounts of nutrient uptake (including N, P, and silicon). The nutrient uptake ratios of phytoplankton converged towards the Redfield ratio in comparison to the wider range of nutrient ratios in the dust-amended seawater. This study suggested consistencies in the dynamic of phytoplankton growth, shift of size structure, and nutrient uptake following dust additions in the KE and TR, although the trophic status and limiting nutrient varied between these two regions.