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1.
BMC Pediatr ; 24(1): 61, 2024 Jan 19.
Artigo em Inglês | MEDLINE | ID: mdl-38243173

RESUMO

BACKGROUND: Human milk fortifier (HMF) composition has been optimized recently. But clinical evidence of its safety and efficacy is limited in Chinese population. The aim of this study was to evaluate effects of a new HMF in growth, nutritional status, feeding intolerance, and major morbidities among very preterm (VPT) or very low birth weight (VLBW) infants in China. METHODS: VPT/VLBW infants admitted from March 2020 to April 2021 were prospectively included in the experimental (new HMF, nHMF) group, who received a new powdered HMF as a breast milk feeding supplement during hospitalization. Infants in the control group (cHMF) admitted from January 2018 to December 2019, were retrospective included, and matched with nHMF group infants for gestational age and birth weight. They received other kinds of commercially available HMFs. Weight gain velocity, concentrations of nutritional biomarkers, incidence of major morbidities, and measures of feeding intolerance were compared between the two groups. RESULTS: Demographic and clinical characteristics of infants in nHMF and cHMF groups were comparable. Weight gain velocity had no significant difference between the nHMF (14.0 ± 3.5 g/kg/d) and the cHMF group (14.2 ± 3.8 g/kg/d; P = 0.46). Incidence of morbidities, including necrotizing enterocolitis, bronchopulmonary dysplasia, retinopathy of prematurity, culture-confirmed sepsis, and feeding intolerance during hospitalization between nHMF and cHMF, were similar (all P-values > 0.05). The time to achieve full enteral feeding [13.5 (10, 21) days] in the nHMF group was significantly shorter than that in the cHMF group [17 (12, 23) days, HR = 0.67, 95%CI: 0.49, 0.92; P = 0.01]. Compared with cHMF group, the decrease of blood urea nitrogen level over time in nHMF group was smaller (ß = 0.6, 95%CI:0.1, 1.0; P = 0.01). CONCLUSIONS: The new HMF can promote growth of preterm infants effectively without increasing the incidence of major morbidity and feeding intolerance. It can be used feasible in Chinese VPT/VLBW infants. TRIAL REGISTRATION: This study was registered on ClinicalTrials.gov (NCT04283799).


Assuntos
Enterocolite Necrosante , Leite Humano , Lactente , Feminino , Recém-Nascido , Humanos , Estudos Retrospectivos , Lactente Extremamente Prematuro , Alimentos Fortificados , Recém-Nascido de muito Baixo Peso , Aumento de Peso , Enterocolite Necrosante/epidemiologia , Fórmulas Infantis
2.
Environ Res ; 245: 117987, 2024 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-38141918

RESUMO

Intense human activities have significantly altered the concentrations of atmospheric components that enter ecosystems through wet and dry deposition, thereby affecting elemental cycles. However, atmospheric wet deposition multi-elemental stoichiometric ratios are poorly understood, hindering systematic exploration of atmospheric deposition effects on ecosystems. Monthly precipitation concentrations of six elements-nitrogen (N), phosphorus (P), sulfur (S), potassium (K), calcium (Ca), and magnesium (Mg)-were measured from 2013 to 2021 by the China Wet Deposition Observation Network (ChinaWD). The multi-elemental stoichiometric ratio of atmospheric wet deposition in Chinese terrestrial ecosystems was N: K: Ca: Mg: S: P = 31: 11: 67: 5.5: 28: 1, and there were differences between vegetation zones. Wet deposition N: S and N: Ca ratios exhibited initially increasing then decreasing inter-annual trends, whereas N: P ratios did not exhibit significant trends, with strong interannual variability. Wet deposition of multi-elements was significantly spatially negatively correlated with soil nutrient elements content (except for N), which indicates that wet deposition could facilitate soil nutrient replenishment, especially for nutrient-poor areas. Wet N deposition and N: P ratios were spatially negatively correlated with ecosystem and soil P densities. Meanwhile, wet deposition N: P ratios were all higher than those of ecosystem components (vegetation, soil, litter, and microorganisms) in different vegetation zones. High input of N deposition may reinforce P limitations in part of the ecosystem. The findings of this study establish a foundation for designing multi-elemental control experiments and exploring the ecological effects of atmospheric deposition.


Assuntos
Ecossistema , Nitrogênio , Humanos , Nitrogênio/análise , Fósforo/análise , Enxofre , Solo , China
3.
Sci Total Environ ; 898: 165629, 2023 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-37467980

RESUMO

Organic nitrogen (N) is an important component of atmospheric reactive N deposition, and its bioavailability is almost as important as that of inorganic N. Currently, there are limited reports of national observations of organic N deposition; most stations are concentrated in rural and urban areas, with even fewer long-term observations of natural ecosystems in remote areas. Based on the China Wet Deposition Observation Network, this study regularly collected monthly wet deposition samples from 43 typical ecosystems from 2013 to 2021 and measured related N concentrations. The aim was to provide a more comprehensive assessment of the multi-component characteristics of atmospheric wet N deposition and reveal the influencing factors and potential sources of wet dissolved organic N (DON) deposition. The results showed that atmospheric wet deposition fluxes of NO3-, NH4+, DON and dissolved total N (DTN) were 4.68, 5.25, 4.32, and 13.05 kg N ha-1 yr-1, respectively, and that DON accounted for 30 % of DTN deposition (potentially up to 50 % in remote areas). Wet DON deposition was related to anthropogenic emissions (agriculture, biomass burning, and traffic), natural emissions (volatile organic compound emissions from vegetation), and precipitation processes. The wet DON deposition flux was higher in South, Central, and Southwest China, with more precipitation and intensive agricultural activities or more vegetation cover, and lower in Northwest China and Inner Mongolia, with less precipitation and human activities or vegetation cover. DON was the main contributor to DTN deposition in remote areas and was possibly related to natural emissions. In rural and urban areas, DON may have been more influenced by agricultural activities and anthropogenic emissions. This study quantified the long-term spatiotemporal patterns of wet N deposition and provides a reference for future N addition experiments and N cycle studies. Further consideration of DON deposition is required, especially in the context of anthropogenic control of NO2 and NH3.

4.
J Environ Manage ; 334: 117511, 2023 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-36801691

RESUMO

The rapid growth of energy-intensive and high-emission industries has propelled China's economy but has also led to massive levels of air pollutant emissions and ecological problems, such as acid deposition. Despite recent declines, atmospheric acid deposition in China is still severe. Long-term exposure to high levels of acid depositions has a substantial negative impact on the ecosystem. Evaluating these hazards and incorporating this issue into planning and decision-making processes is critical to achieving sustainable development goals in China. However, the long-term economic loss caused by atmospheric acid deposition and its temporal and spatial variation in China is unclear. Hence, the aim of this study was to assess the environmental cost of acid deposition in the agriculture, forestry, construction, and transportation industries from 1980 to 2019, using long-term monitoring, integrated data, and the dose-response method with localization parameters. The results showed that the estimated cumulative environmental cost of acid deposition was USD 230 billion, representing 0.27% of the gross domestic product (GDP) in China. This cost, was particularly high for building materials, followed by crops, forests, and roads. Temporally, the environmental cost and the ratio of environmental cost to GDP decreased from their peaks by 43% and 91%, respectively, because of emission controls targeting acidifying pollutants and promotion of clean energy. Spatially, the largest environmental cost occurred in developing provinces, indicating that more stringent emission reduction measures should be implemented in these regions. These findings highlight the huge environmental costs behind rapid development; however, the implementation of reasonable emission reduction measures can effectively reduce these environmental costs, providing a promising paradigm for other undeveloped and developing countries.


Assuntos
Poluentes Atmosféricos , Poluentes Ambientais , Ecossistema , China , Poluentes Atmosféricos/análise , Florestas , Desenvolvimento Econômico
6.
Environ Res ; 214(Pt 3): 114084, 2022 11.
Artigo em Inglês | MEDLINE | ID: mdl-35973460

RESUMO

Silicon (Si) is considered a "quasi-essential" nutrient element for plants and is also an essential nutrient for some phytoplankton. Except for the silicate provided by weathering, atmospheric deposition has gradually become an important supplementary method for Si nutrients to enter the ecosystem. However, national observational studies on atmospheric silicon deposition have not yet been reported. Herein, based on the China Wet Deposition Observation Network, we continuously collected monthly wet deposition samples from 43 typical ecosystems from 2013 to 2020 and measured the content of dissolved silica (dSi) in precipitation to quantify the spatiotemporal patterns of Si wet deposition in China. The results showed that the mean annual dSi wet deposition in China during 2013-2020 was approximately 2.07 ± 0.27 kg ha-1 yr-1. Atmospheric dSi deposition was higher in Southwest, North, and South China but lower in the Northwest and Northeast China, which was mainly regulated by precipitation and soil available Si content. There was no significant annual variation trend in dSi deposition during 2013-2020 in China, which showed disorderly fluctuations from year to year. This study revealed the spatiotemporal patterns of atmospheric dSi deposition in China for the first time, which can provide unique scientific data to explore the potential effect of dSi deposition on carbon sequestration in aquatic ecosystems. A comprehensive evaluation of the nutrient balance of aquatic ecosystems from the perspective of nitrogen, phosphorus, and silicon stoichiometry is required in the future.


Assuntos
Ecossistema , Monitoramento Ambiental , China , Nitrogênio/análise , Silício
7.
Environ Sci Technol ; 56(18): 12898-12905, 2022 09 20.
Artigo em Inglês | MEDLINE | ID: mdl-36026692

RESUMO

Iron (Fe), molybdenum (Mo), and vanadium (V) are the main components of the three known biological nitrogenases, which constrain nitrogen fixation and affect ecosystem productivity. Atmospheric deposition is an important pathway of these trace metals into ecosystems. Here, we explored the deposition flux, spatiotemporal pattern, and influencing factors of atmospheric wet Fe, Mo, and V deposition based on China Wet Deposition Observation Network (ChinaWD) data from 2016 to 2020. Our results showed that atmospheric wet Fe, Mo, and V deposition was 7.77 ± 7.24, 0.16 ± 0.11, and 0.13 ± 0.12 mg m-2 a-1 in Chinese terrestrial ecosystems, respectively, and revealed obvious spatial patterns but no significant annual trends. Wet Fe deposition was significantly correlated with the soil Fe content. Mo and V deposition was more affected by anthropogenic activities than Fe deposition. Wet Mo deposition was significantly affected by Mo ore reserves and waste incineration. V deposition was significantly correlated with domestic biomass burning. This study quantified wet Fe, Mo, and V deposition in China for the first time, and the implications of atmospheric trace metal deposition on biological nitrogen fixation were discussed.


Assuntos
Oligoelementos , Vanádio , China , Ecossistema , Monitoramento Ambiental/métodos , Ferro/metabolismo , Molibdênio , Nitrogênio/metabolismo , Solo , Vanádio/metabolismo
8.
Environ Res ; 202: 111787, 2021 11.
Artigo em Inglês | MEDLINE | ID: mdl-34339690

RESUMO

Long-term atmospheric nitrogen (N) deposition increases bioavailable N in terrestrial ecosystems, thereby influencing ecosystem productivity. However, how N deposition and its components (i.e., NO3--N and NH4+-N) influence the spatial pattern of productivity in terrestrial ecosystems in China remains unknown. Here, we utilize published data including carbon (C) fluxes from eddy flux tower (gross ecosystem productivity, ecosystem respiration, and net ecosystem productivity) and the corresponding climate and N deposition data for 60 typical ecosystems in China. The objective was to investigate the effect of N deposition on ecosystem productivity and explore the variations of N use efficiency (NUE). Our results reveal that atmospheric total N deposition is significantly correlated with C fluxes of terrestrial ecosystems in China. Ecosystems respond variably to different components of N deposition. In detail, forest ecosystem marginally correlated with NO3--N and wet deposition, while grassland ecosystem significantly correlated with NH4+-N and dry deposition. NUE of productivity induced by N deposition in Chinese terrestrial ecosystems was 53.95 ± 40.30 g C g-1 N, and it was influenced by precipitation and aridity index. This study quantifies the contribution of total N deposition and its associated components to productivity in terrestrial ecosystems in China, offering vital information for regional C and N management.


Assuntos
Ecossistema , Nitrogênio , Carbono/análise , Ciclo do Carbono , China , Nitrogênio/análise
9.
Sci Total Environ ; 795: 148849, 2021 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-34246133

RESUMO

Ecological stoichiometry is an efficient tool for exploring the balance and cycling of coupled elements (e.g., carbon [C], nitrogen [N], and phosphorus [P]). Therefore, C:N:P ratios are essential input parameters in most ecological models of productivity or C cycling. However, previous C:N:P ratios estimated using the species arithmetic means exhibit high uncertainty when used as direct model parameters. In this study, we comprehensively calculated C:N:P ratios from organs to ecosystems for 66 typical natural ecosystems in China (e.g., forests, grasslands, and deserts) using the community biomass-weighted mean (CWM), with the consistently measured element data of 3229 site-species combination. The C:N:P ratios were 427:19:1, 885:13:1, 9549:33:1, and 797:18:1 in the leaves, branches, trunks, and roots of terrestrial ecosystems, respectively. Furthermore, the ratios were 91:4:1, 919:17:1, 1121:25:1, and 55:4:1 in ecosystems, plant communities, litter, and soils, respectively. Significant differences were observed in C:N:P ratios among different ecosystem types and biomes, with generally higher ratios in forests. Moreover, the latitudinal patterns of C:N ratios exhibited no obvious trends, whereas both C:P and N:P ratios decreased significantly with increasing latitude, especially in forests. Environmental conditions explained 15.4-86.6% of the spatial variation of C:N:P ratios from organs to ecosystems. In summary, this study systematically demonstrates the variations in biome-scale C:N:P stoichiometry in terrestrial ecosystems, as well as their influencing factors, using the CWM. More importantly, this study provides a systematic dataset of C:N:P ratios from plot to biome scale that can be used to improve relevant ecological models.


Assuntos
Ecossistema , Fósforo , China , Florestas , Nitrogênio/análise , Fósforo/análise
10.
Sci Total Environ ; 755(Pt 2): 143372, 2021 Feb 10.
Artigo em Inglês | MEDLINE | ID: mdl-33183803

RESUMO

Stable soil pH is a key property in maintaining an ecosystem's structure, function, and sustainability. Increasing atmospheric deposition and grassland use on the Tibetan Plateau (TP) may increase the soil acidification risk, but we lack such information to date. Here, we evaluated the soil acidification risk in the TP, by comparing it with that in the Mongolia Plateau (MP) and applying the acid-base balance principles on atmospheric inputs, soils, and plants from 1980 to 2019. Cumulative acid input was lower in the TP than in the MP. Sulfur contributed more to acidity than nitrogen and atmospheric deposition contributed more to acidity than grassland use. Acid input was mainly influenced by local industry, animal husbandry and transportation in the MP, while in the TP it was also affected by the long-distance transportation of pollutants from South Asia and southern China. Overall, the TP was less acid-sensitive than the MP because of higher inorganic carbon content. However, soils in the southeastern TP, covering 21% of the total area, were acid-sensitive due to low levels of soil exchangeable base cation (EBCs) and lack of calcium carbonate. Coincidentally, the southeastern region has the highest concentration of acid input in the TP due to more rapid development and stronger influence of adjacent high acid deposition regions than others. Therefore, the acidification risk to the southeastern region is much higher than to other regions of the TP and the MP; in this region, the EBCs are likely to be depleted approximately 95 years earlier than in the MP. The findings of this study provide insights into the response of the TP to global change. For the ecosystem sustainability of southeastern TP, control of atmospheric acid deposition, especially sulfur deposition, in both local and adjacent regions and nations is required.

11.
Environ Pollut ; 262: 114335, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32179227

RESUMO

Atmospheric wet deposition of base cations (BCs) plays a significant role in providing plant nutrients and buffering acidification. However, the temporal dynamic of wet BC deposition in China during the past two decades remain unclear. Here, we used long-term monitoring and literature data since 2000 to assess the temporal dynamics (seasonal and inter-annual variation), spatial patterns, main influencing factors, source apportionment, and capacity to neutralize the acidity of wet BC depositions at site, regional, and national scales. The results showed that total wet deposition of BCs was, on average, 2.12 keq ha-1 yr-1, where Ca2+ accounted for 65.57% of the total deposition, followed by Na+ (13.21%), Mg2+ (13.68%), and K+ (7.55%). Qinghai-Tibet had significantly lower BC deposition fluxes than northern, southern, and central China, as well as Inner Mongolia. Exchangeable BCs in soil, PM10 in the atmosphere, energy consumption, and cement production are significantly related to wet BC deposition, which account for 79.17% of the variation in the spatial deposition of BC. Influenced by the strategies to control acid rain and particulate matter in China, interannual variations showed a stabilization trend after a continuous decline from 2000 to 2017, which can be explained by inter-annual changes in PM10, energy consumption and cement production. Statistical methods confirmed that 45.95% of wet BC deposition was derived from crustal contributions, 27.78% from sea salt sources, and 26.27% from anthropogenic sources. Furthermore, we found that wet deposition of BCs neutralized 84.85% of the acidity due to NO3- and SO42- depositions. Under the emissions reduction strategy, there has been a decrease in the deposition of BC. However, SO42- and NO3- depositions decreased faster than BC deposition, which buffered a higher proportion of acidic depositions. Our findings contribute to an improved understanding of wet BC deposition in China, an evaluation of their capacity to neutralize acidity, and important parameters for acidification models.


Assuntos
Poluentes Atmosféricos/análise , Cátions , China , Monitoramento Ambiental , Tibet
12.
Environ Pollut ; 258: 113739, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31874437

RESUMO

Nitrogen (N) deposition in China may increase due to urbanization and economic growth. Current research has considered the ecological significance under the assumption of increasing N deposition. Atmospheric N deposition tending toward levelling or declining has been observed in China. Such potential recovery and responses of high N loads ecosystems under decreasing atmospheric N deposition scenarios have yet to be adequately investigated. This work reviews existing literature to consider possible responses of carbon (C) sequestration, biodiversity and species composition, soil acidification, and greenhouse emissions in ecosystems responding to recent patterns of N deposition. Potential effects of N composition and internal ratios may be further explored through state-of-the-art N addition experiments and model development.


Assuntos
Poluentes Atmosféricos/análise , Nitrogênio/análise , Biodiversidade , Sequestro de Carbono , China , Ecossistema , Monitoramento Ambiental , Gases de Efeito Estufa , Solo
13.
Front Pediatr ; 7: 166, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31134166

RESUMO

Objectives: To investigate the association between serum N-terminal pro-B-type natriuretic peptide (NT-proBNP) level on the first day of life and a composite outcome of bronchopulmonary dysplasia (BPD) or death in a cohort of infants born before 32 weeks of gestation. Methods: We retrospectively identified infants born before 32 weeks of gestation who had serum NT-proBNP levels measured when they were admitted to the Neonatal Intensive Care Unit shortly after birth. The outcome of BPD or death was assessed at 36 weeks of postmenstrual age. The association of serum NT-proBNP levels with BPD or death was evaluated. Receiver operator characteristic (ROC) curve analysis was used to evaluate the predictive performance of serum NT-proBNP levels. Results: A 100 and 47 preterm infants had serum NT-proBNP levels measured on the first day of life. Serum NT-proBNP level was significantly higher in preterm infants who developed moderate/severe BPD or died [3,855 (2,567-6,369) vs. 1,259 (950-2,035) in control infants, P < 0.001]. On binary regression analysis, a high natural logarithm of serum NT-proBNP levels was associated with increased risk of moderate/severe BPD or death adjusted for gestational age, birth weight, birth weight z-score, and Apgar scores at 1 and 5 min (odds ratio [OR] = 5.195, 95% confidence interval [CI] 2.667-10.117, P < 0.001). ROC analysis identified a NT-proBNP level of 2002.5 pg/mL to have 87.5% sensitivity and 74.7% specificity for predicting moderate/severe BPD or death. The area under the curve (AUC) was 0.853 (95% CI 0.792-0.914). Conclusion: Serum NT-proBNP level measured on the first day of life is a promising biomarker for predicting the development of moderate/severe BPD or death in preterm infants. Our findings warrant a larger prospective study to incorporate measurement of NT-proBNP in prognosticating outcomes in very preterm infants.

14.
Environ Sci Pollut Res Int ; 25(24): 24417-24425, 2018 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-29909532

RESUMO

China is one of three global hotspots for nitrogen (N) deposition, which has concerned scientists and the public. While previous studies on N deposition in China have focused on its composition, spatial pattern, and interannual dynamics, its monthly dynamics in different regions remain unclear, hindering our ability to evaluate its ecological effects. Therefore, we obtained monthly wet N deposition data from196 sites after continuous network observations and published data in China and analyzed the monthly dynamics of NH4+-N, NO3--N, and dissolved inorganic N (DIN=NH4+-N+NO3--N) deposition fluxes on site, regional, and national scales. We observed that the deposition fluxes of NH4+-N, NO3--N, and DIN in China showed clear monthly patterns and regional differences. In Northern China, wet N deposition predominantly showed a unimodal trend, whereas in Southern China, it revealed a bimodal trend or irregular fluctuations. During 2000-2016, NH4+-N, NO3--N, and DIN deposition fluxes were estimated as 9.09, 6.12, and 15.21 kg N ha-1 year.-1, respectively. Our findings enhance our understanding of atmospheric wet N deposition, and can serve as a reference for N deposition simulation experiments in different regions, and for generating long-term N deposition data for model optimization. Regional differences in the monthly dynamics of wet N deposition should be emphasized to accurately evaluate its ecological effects on terrestrial ecosystems in different regions.


Assuntos
Poluentes Atmosféricos/análise , Nitrogênio/análise , Compostos de Amônio/análise , Atmosfera , China , Ecossistema , Monitoramento Ambiental , Nitratos/análise
15.
Environ Pollut ; 231(Pt 1): 182-190, 2017 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-28800487

RESUMO

Atmospheric acid deposition is a global environmental issue. China has been experiencing serious acid deposition, which is anticipated to become more severe with the country's economic development and increasing consumption of fossil fuels in recent decades. We explored the spatiotemporal variations of acid deposition (wet acid deposition) and its influencing factors by collecting nationwide data on pH and concentrations of sulfate (SO42-) and nitrate (NO3-) in precipitation between 1980 and 2014 in China. Our results showed that average precipitation pH values were 4.59 and 4.70 in the 1990s and 2010s, respectively, suggesting that precipitation acid deposition in China has not seriously worsened. Average SO42- deposition declined from 40.54 to 34.87 kg S ha-1 yr-1 but average NO3- deposition increased from 4.44 to 7.73 kg N ha-1 yr-1. Specifically, the area of severe precipitation acid deposition in southern China has shrunk to some extent as a result of controlling the pollutant emissions; but the area of moderate precipitation acid deposition has expanded in northern China, associated with rapid industrial and transportation development. Furthermore, we found significant positive correlations between precipitation acid deposition, energy consumption, and rainfall. Our findings provide a relatively comprehensive evaluation of the spatiotemporal dynamics of precipitation acid deposition in China over past three decades, and confirm the idea that strategies implemented to save energy and control pollutant emissions in China have been effective in alleviating precipitation acid deposition. These findings might be used to demonstrate how developing countries could achieve economic development and environmental protection through the implementation of advanced technologies to reduce pollutant emissions.


Assuntos
Poluentes Atmosféricos/análise , Poluição do Ar/estatística & dados numéricos , Atmosfera/química , China , Conservação dos Recursos Naturais , Monitoramento Ambiental/métodos , Combustíveis Fósseis , Nitratos/análise , Sulfatos/análise
16.
Sci Rep ; 7(1): 7492, 2017 08 08.
Artigo em Inglês | MEDLINE | ID: mdl-28790341

RESUMO

Rewetting after precipitation events plays an important role in regulating soil carbon (C) and nitrogen (N) turnover processes in arid and semiarid ecosystems. Here, we conducted a 48-h rewetting simulation experiment with measurements of soil C and N mineralization rates (R C and R N, respectively) and microbial biomass N (MBN) at high temporal resolution to explore the pulse responses of R C and R N. R C and R N responded strongly and rapidly to rewetting over the short term. The maximum R C value (because of pulse effects) ranged from 16.53 to 19.33 µg C gsoil-1 h-1, observed 10 min after rewetting. The maximum R N varied from 22.86 to 40.87 µg N gsoil-1 h-1, appearing 5-6 h after rewetting. The responses of soil microbial growth to rewetting were rapid, and the maximum MBN was observed 2-3 h after rewetting. Unexpectedly, there was no correlation between R C, R N, and MBN during the process of rewetting, and R C and R N were uncoupled. In sum, the pulse responses of R C, R N, and microbial growth to simulated rewetting were rapid, strong, and asynchronous, which offers insights into the different responses of microbes to rewetting and mechanisms behind microbes.


Assuntos
Carbono/química , Consórcios Microbianos/fisiologia , Nitrogênio/química , Microbiologia do Solo , Solo/química , Água/química , Biomassa , China , Clima Desértico , Ecossistema , Modelos Estatísticos
17.
Glob Chang Biol ; 23(8): 3393-3402, 2017 08.
Artigo em Inglês | MEDLINE | ID: mdl-28055123

RESUMO

How to assess the temperature sensitivity (Q10 ) of soil organic matter (SOM) decomposition and its regional variation with high accuracy is one of the largest uncertainties in determining the intensity and direction of the global carbon (C) cycle in response to climate change. In this study, we collected a series of soils from 22 forest sites and 30 grassland sites across China to explore regional variation in Q10 and its underlying mechanisms. We conducted a novel incubation experiment with periodically changing temperature (5-30 °C), while continuously measuring soil microbial respiration rates. The results showed that Q10 varied significantly across different ecosystems, ranging from 1.16 to 3.19 (mean 1.63). Q10 was ordered as follows: alpine grasslands (2.01) > temperate grasslands (1.81) > tropical forests (1.59) > temperate forests (1.55) > subtropical forests (1.52). The Q10 of grasslands (1.90) was significantly higher than that of forests (1.54). Furthermore, Q10 significantly increased with increasing altitude and decreased with increasing longitude. Environmental variables and substrate properties together explained 52% of total variation in Q10 across all sites. Overall, pH and soil electrical conductivity primarily explained spatial variation in Q10 . The general negative relationships between Q10 and substrate quality among all ecosystem types supported the C quality temperature (CQT) hypothesis at a large scale, which indicated that soils with low quality should have higher temperature sensitivity. Furthermore, alpine grasslands, which had the highest Q10 , were predicted to be more sensitive to climate change under the scenario of global warming.


Assuntos
Ciclo do Carbono , Mudança Climática , Pradaria , Solo/química , Carbono , China , Florestas , Temperatura
18.
Glob Chang Biol ; 23(4): 1575-1584, 2017 04.
Artigo em Inglês | MEDLINE | ID: mdl-27562684

RESUMO

Forests store a large part of the terrestrial vegetation carbon (C) and have high C sequestration potential. Here, we developed a new forest C sequestration (FCS) model based on the secondary succession theory, to estimate vegetation C sequestration capacity in China's forest vegetation. The model used the field measurement data of 3161 forest plots and three future climate scenarios. The results showed that logistic equations provided a good fit for vegetation biomass with forest age in natural and planted forests. The FCS model has been verified with forest biomass data, and model uncertainty is discussed. The increment of vegetation C storage in China's forest vegetation from 2010 to 2050 was estimated as 13.92 Pg C, while the average vegetation C sequestration rate was 0.34 Pg C yr-1 with a 95% confidence interval of 0.28-0.42 Pg C yr-1 , which differed significantly between forest types. The largest contributor to the increment was deciduous broadleaf forest (37.8%), while the smallest was deciduous needleleaf forest (2.7%). The vegetation C sequestration rate might reach its maximum around 2020, although vegetation C storage increases continually. It is estimated that vegetation C sequestration might offset 6-8% of China's future emissions. Furthermore, there was a significant negative relationship between vegetation C sequestration rate and C emission rate in different provinces of China, suggesting that developed provinces might need to compensate for undeveloped provinces through C trade. Our findings will provide valuable guidelines to policymakers for designing afforestation strategies and forest C trade in China.


Assuntos
Sequestro de Carbono , Florestas , Biomassa , Carbono , China , Árvores
19.
Chemosphere ; 164: 128-133, 2016 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-27588571

RESUMO

Industrialization and urbanization have led to increasingly serious levels of atmospheric heavy metal pollution, which is one of the main sources of heavy metals to terrestrial ecosystems. Therefore, it is essential to quantify atmospheric fluxes and explore their potential effects on natural ecosystems and human welfare. We monitored water-soluble heavy metals (lead (Pb), cadmium (Cd), and chromium (Cr)) in rainfalls on a monthly basis in 2013 and 2014, at 31 field stations located in typical natural Chinese ecosystems. The average soluble Pb, Cd, and Cr deposition was 1.90 ± 1.54, 0.28 ± 0.25, and 0.96 ± 0.48 mg m-2 yr-1, respectively, with a large variation among the different sites. Generally, the atmospheric deposition of soluble Pb, Cd, and Cr was higher in the southwest, central, south, and north China than in the northwest and northeast China, Inner Mongolia, and Qinghai-Tibet. As expected, the atmospheric heavy soluble metal deposition fluxes were significantly correlated with the number of vehicles (Ps < 0.1). The wet deposition of soluble Pb and Cr was positively correlated with oil and coal consumption, unlike Cd deposition. Moreover, soluble Pb and Cd in atmospheric wet deposition were positively correlated with the contents of Pb and Cd in soil at different regions. In this study, atmospheric heavy metal deposition through rainfall in typical natural ecosystems in China is assessed at the national scale, alerting potential ecological hazards resulting from an increasing atmospheric heavy metal deposition and providing a basis for future studies.


Assuntos
Metais Pesados/análise , Poluentes do Solo/análise , China , Ecossistema , Monitoramento Ambiental
20.
Zhongguo Dang Dai Er Ke Za Zhi ; 18(2): 99-104, 2016 Feb.
Artigo em Chinês | MEDLINE | ID: mdl-26903053

RESUMO

OBJECTIVE: To investigate the incidence, clinical features, and treatment of perinatal cytomegalovirus (CMV) infection, as well as the factors affecting the therapeutic effect of ganciclovir. METHODS: The clinical data of 237 infants who were hospitalized and diagnosed with perinatal CMV infection from 2008 to 2012 were retrospectively analyzed. RESULTS: The clinical features of infants with perinatal CMV infection and the proportion of such infants in all hospitalized infants showed no significant differences across the five years. In most infants, two or more systems were involved, and CMV hepatitis plus CMV pneumonia was most common (43.1%). The results of pathogen detection showed that the percentage of the infants with positive blood CMV-IgM and blood/urine CMV-DNA was 3.8%, while 90.3% of all infants had positive blood CMV-IgM alone and 5.9% had positive blood/urine CMV-DNA alone. A total of 197 infants were treated with ganciclovir, and the cure rate was 88.3%. An abnormal history of pregnancy (OR=6.191, 95% CI: 1.597-24.002) and liver involvement before medication (OR=3.705, 95% CI: 1.537-8.931) were the independent risk factors affecting the therapeutic effect of ganciclovir in infants with perinatal CMV infection. CONCLUSIONS: The epidemiological characteristics of perinatal CMV infection have remained generally stable for the last 5 years. CMV often involves several organs or systems, especially the liver and lung. Ganciclovir has a significant efficacy in the treatment of perinatal CMV infection, and an abnormal history of pregnancy and liver involvement before medication can increase the risk of ganciclovir resistance in infants with perinatal CMV infection.


Assuntos
Infecções por Citomegalovirus/virologia , Citomegalovirus/fisiologia , Doenças do Recém-Nascido/virologia , Antivirais/uso terapêutico , Citomegalovirus/isolamento & purificação , Infecções por Citomegalovirus/tratamento farmacológico , Infecções por Citomegalovirus/epidemiologia , Feminino , Ganciclovir/uso terapêutico , Humanos , Lactente , Recém-Nascido , Doenças do Recém-Nascido/tratamento farmacológico , Doenças do Recém-Nascido/epidemiologia , Fígado/virologia , Masculino , Estudos Retrospectivos
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