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| 1 | Molecular Fingerprints of Soil Organic Matter in a Typical Freshwater Wetland in Northeast China显示文摘Natural wetlands are known to store huge amounts of organic carbon in their soils. Despite the importance of this storage,uncertainties remain about the molecular characteristics of soil organic matter(SOM), a key factor governing the stability of soil organic carbon(SOC). In this study, the molecular fingerprints of SOM in a typical freshwater wetland in Northeast China were investigated using pyrolysis gas-chromatography/mass-spectrometry technology(Py-GC/MS). Results indicated that the SOC, total nitrogen(TN),and total sulfur contents of the cores varied between 16.88% and 45.83%, 0.93% and 2.82%, and 1.09% and 3.79%, respectively. The bulk δ^13C and δ^15N varied over a range of 9.85‰, between –26.85‰ and –17.00‰, and between –0.126‰ and 1.002‰, respectively. A total of 134 different pyrolytic products were identified, and they were grouped into alkyl(including n-alkanes(C:0) and n-alkenes(C:1),aliphatics(Al), aromatics(Ar), lignin(Lg), nitrogen-containing compounds(Nc), polycyclic aromatic hydrocarbons(PAHs), phenols(Phs), polysaccharides(Ps), and sulfur-containing compounds(Sc). On average, Phs moieties accounted for roughly 24.11% peak areas of the total pyrolysis products, followed by Lg(19.27%), alkyl(18.96%), other aliphatics(12.39%), Nc compounds(8.08%), Ps(6.49%), aromatics(6.32%), Sc(3.26%), and PAHs(1.12%). Soil organic matter from wetlands had more Phs and Lg and less Nc moieties in pyrolytic products than soil organic matters from forests, lake sediments, pastures, and farmland.δ^13 C distribution patterns implied more C3 plant-derived soil organic matter, but the vegetation was in succession to C4 plant from C3 plant. Significant negative correlations between Lg or Ps proportions and C3 plant proportions were observed. Multiple linear analyses implied that the Ar and Al components had negative effects on SOC. Alkyl and Ar could facilitate ratios between SOC and total nitrogen(C/N), while Al plays the opposite role. Al was positively related to the ratio of dissolved organic carbon(DOC) to SOC. In summary, SOM of wetlands might characterize by more Phs and lignin and less Nc moieties in pyrolytic products. The use of Pyrolysis gas-chromatography/mass-spectrometry(Py-GC/MS) technology provided detailed information on the molecular characteristics of SOM from a typical freshwater wetland. | LI Zhe ZHANG Zhongsheng XUE Zhenshan SONG Xiaolin ZHANG Hongri WU Haitao JIANG Ming LYU Xianguo | 2019 | Chinese Geographical Science2019，29，4： | 4 |
| 2 | Effects of Tidal Channels and Roads on Landscape Dynamic Distribution in the Yellow River Delta, China显示文摘Landscape characters in estuarine regions generally controlled by tidal regimes and human activities like road construction.In this work,tidal channels and road construction in the Yellow River Delta(YRD)were extracted by visual interpretation methods so as to decipher impacts of tidal channel development and road construction on landscape patch change during 1989–2016.Spatial distribution history of three wetlands,which covered by Phragmites australis(freshwater marsh,FM),Suaeda salsa(salt marsh,SM),and mudflats(MD)were also established.Results indicated that tidal channel,number,frequency,and fractal dimension were all the maximum in 2003,and the minimum in 1998,respectively.Road length,number,and density showed increasing trend during 1989–2016.MD were the predominant landscape type,followed by FM and SM during 1989-2016.Principal component analysis implied two extracted factors,F1 and F2,which could represent 91.93% of the total variations.F1 mainly proxied tidal channel development,while F2 represented road construction.A multiple linear regression analysis showed positive effects of both F1 and F2 on FM patch numbers and negative impacts on SM patch areaes with R^2 values of 0.416 and 0.599,respectively.Tidal channels were negatively related to MD patch numbers,while roads were positively related to that.In any case,road construction showed larger impacts on landscape type shifting than that of tidal channel development in the YRD. | YU Xiaojuan ZHANG Zhongsheng XUE Zhenshan WU Haitao ZHANG Hongri | 2020 | Chinese Geographical Science2020，30，1： | 2 |
| 3 | RESEARCH ARTICLE Open Access Investigating clinical characteristics and prognostic factors in patients with chronic osteomyelitis of humerus显示文摘Background:Chronic osteomyelitis in the humerus,which has complex neuroanatomy and a good soft tissue envelope,represents a unique clinical challenge.However,there are relatively few related studies in the literature.This article retrospectively reviewed a large case series with the aims of sharing our management experiences and further determining factors associated with the outcomes.Methods:Twenty-eight consecutive adult patients with a mean age of 36 years were identified by reviewing the osteomyelitis database of our clinic centre.The database was used to prospectively identify all osteomyelitis cases between 2013 and 2017,and all data then was retrospectively analysed.Results:The mean follow-up period was 35 months(range 24–60).The aetiology was trauma in 43%(12)of the patients and haematogenous in 57%(16)of the patients,and Staphylococcus aureus was a solitary agent in 50%(14)of the patients.Host-type(Cierny’s classification)was IA in 8,IIIB in 11 and IVB in 9 patients.All patients required debridement followed by the placement of a temporary antibiotic-impregnated cement spacer(rod).Seventeen patients received a cement-coated plate for internal fixation after debridement,and 13 patients needed bone grafts when the spacer was staged removed.All patients attained an infection-free bone healing state at the final follow-up.The final average DASH(disabilities of the arm,shoulder and hand)score was 18.14±5.39,while 6 patients(two developed traumatic olecranarthritis,four developed radial nerve injuries)showed the lowest levels of limb function(p=0.000)and were unemployed.Three patients(type I;significant difference between type I versus type III and type IV patients,p<0.05)experienced recurrence after debridement and underwent a second revision,which was not related to the bone graft(p=0.226)or plate fixation(p=0.050).Conclusions:Humeral chronic osteomyelitis can be treated with general surgery and anti-infective therapy;medullary(type I)infection presents a challenge,and the antibiotic-coated cement plate provides favourable fixation without increasing recurrence of infections.Clinicians should be aware of potential iatrogenic nerve injuries when treating these patients with complicated cases,and an experienced surgeon may improve the outcome. | Hongri Wu Shengpeng Yu Jingshu Fu Dong Sun Shulin Wang Zhao Xie Yungui Wang | 2019 | Burns & Trauma2019，7，1： | 0 |
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