We report the results of 50G, 100G, 200G, 400G un- repeatered transmission aimed at achieving the longest distance without any inline active elements, this system realizes record single-carrier 50 ...Gb/s (PM-BPSK), 100 Gb/s (PS-QPSK), 200 Gb/s (PM-8QAM) and 400 Gb/s (PM-64QAM) unrepeatered transmission over 670.64 km with 103.95 dB span loss, 653.35 km with 101.27 dB span loss, 601.93 km with 93.3 dB span loss, and 502.13 km with 77.83 dB span loss, respectively. This is achieved using optimized high-order Raman pumps, cascaded RGUs and coherent modulation format with concatenated FEC. G.654.E fiber with ultra-low loss & 130 μm 2 effective area is used as span fiber.
Background and aims
Interactive effect of warming and precipitation addition on litter decomposition is still scarce. Moreover, nonlinear response of its temperature sensitivity to warming is not ...demonstrated due to lack of warming gradient experiment in situ.
Methods
we performed a warming gradient experiment (0, ~0.25–0.5, ~1, ~2, and ~4 °C, respectively) using infrared heaters and a precipitation addition treatment in a fully-factorial design for 2-years on the Tibetan Plateau. The responses of mass loss of litter components (i.e. organic matter (OM), soluble cell content (SCC), lignin, cellulose (Ce), hemi-cellulose (Hce), total organic carbon (OC)) and nutrients (total nitrogen (TN) and total phosphorus (TP)) to warming and precipitation addition were determined over 2-years.
Results
We found that warming significantly increased annual mass losses of all litter components in both treatment years. Precipitation addition significantly increased annual mass losses of OM, SCC, OC, TN and TP only in the first year due to drought. There were no interactive effects between warming and precipitation addition on litter component decomposition in the semi-arid alpine region. Temperature sensitivities were lowest when soil temperature increased by a mean of about 2.3 °C. There was an inverse relationship between the temperature sensitivity of organic matter decomposition and quality of litter carbon compounds.
Conclusions
Our results suggest that soil temperature effects may override soil moisture effects on litter decomposition in the alpine region, and the nonlinear temperature sensitivity of litter decomposition should be estimated using warming gradients. Lower quality of litter carbon compounds had higher temperature sensitivity of organic matter decomposition.
•HY grapefruit contained more phenols and flavonoid than pomelo.•ST pomelo contained more abundant volatiles, more protein and vitamin C.•ST pomelo had the highest sucrose content and total sugars ...content.•MY pomelo contained the highest amount of organic acids.•ST and HY possessed stronger antioxidant activities than other four varieties.
China, the largest pomelo producer, has many famous pomelo varieties. However, there has been limited research on the comparative of chemical compositions and antioxidant activities among different pomelo varieties from China. In the work, five pomelo varieties and one grapefruit variety from China were studied by investigating their chemical composition and antioxidant activity. Volatiles in dichloromethane extract of pomelo peels were measured using gas chromatography - mass spectrometry. Shatianyu pomelo contained 27 volatile compounds, was the most abundant in volatiles. Total protein, phenols, and flavonoid were determined by spectrophotometry. Changshanhuyou grapefruit contained more phenols and flavonoids, while Shatianyu pomelo contained more protein. The amount of vitamin C, sugars, and organic acids were evaluated using liquid chromatography. Shatianyu pomelo had the highest amount of vitamin C and sugars, and the lower amount of organic acids. Guanximiyu pomelo had the highest amount of organic acids. Shatianyu pomelo and Changshanhuyou grapefruit possessed the higher antioxidant activities as compared to other four pomelo varieties. The antioxidant activities of pomelo pulp had no obvious correlation with the amount of total phenols, total falconoid, and vitamin C. This study is helpful to understand the nutritional value and health function of six Chinese famous pomelo varieties.
Coarse woody debris (CWD) is an important component of the forest carbon cycle, acting as a carbon pool and a source of CO₂ in temperate forest ecosystems. We used a soda-lime closed-chamber method ...to measure CO₂ efflux from downed CWD (diameter ≥5 cm) and to examine CWD respiration (R CWD) under field conditions over 1 year in a temperate secondary pioneer forest in Takayama forest. We also investigated tree mortality (input to the CWD pool) from the data obtained from the annual tree census, which commenced in 2000. We developed an exponential function of temperature to predict R CWD in each decay class (R ² = 0.81–0.97). The sensitivity of R CWD to changing temperature, expressed as Q ₁₀, ranged from 2.12 to 2.92 and was relatively high in decay class III. Annual C flux from CWD (F CWD) was extrapolated using continuous air temperature measurements and CWD necromass pools in the three decay classes. F CWD was 3.0 (class I), 17.8 (class II), and 13.7 g C m⁻² year⁻¹ (class III) and totaled 34 g C m⁻² year⁻¹ in 2009. Annual input to CWD averaged 77 g C m⁻² year⁻¹ from 2000 to 2009. The budget of the CWD pool in the Takayama forest, including tree mortality inputs and respiratory outputs, was 0.43 Mg C ha⁻¹ year⁻¹ (net C sink) owing to high tree mortality in the mature pioneer forest. The potential CWD sink is important for the carbon cycle in temperate successional forests.
土壤有机质（SOM）是衡量农业生产力和土壤整体健康的重要指标，对促进区域粮食安全和缓解全球变暖下的粮食危机具有重要意义。为揭示1984—2009年广西全域SOM变化情况，基于广西第二次土壤普查项目（1984年）和广西测土配方施肥项目（2009年）两期数据，利用地统计学、动态度、分布指数等方法分析了广西土壤表层SOM时空演变特征及其在不同海拔高度上的分布状况。结果显示，近30年广西SOM总体含量大幅提升，各含量等级已由零散交错的不均匀分布演变为相对集中的连片分布，分布面积呈现：等级4（20~30 g·kg-1）>等级5（30~40 g·kg-1）>等级6（>40 g·kg-1）>等级3（10~20 g·kg-1）>等级1（≤6 g·kg-1）>等级2（6~10 g·kg-1），等级4和等级5所占比例分别由1984年的28.20%和18.73%提升至2009年的38.09%和36.19%。在变化速率方面，等级2减少最为迅速，动态度为-3.76%，等级5增加最为迅速，动态度为3.73%，各等级动态度表现为等级2>等级5>等级1>等级3>等级4>等级6。在不同海拔高度上，除等级4和等级6外，其余等级的分布指数曲线均发生了较大变动。在海拔≤200 m的区域，等级3始终保持着高优势位特征，而等级6对海拔变动保持较强的选择性，随海拔上升其优势位愈发明显。研究表明，广西SOM各含量等级及空间分布均存在较大差异，海拔是其重要的影响因素。Soil organic matter(SOM)is an important indicator of agricultural productivity and soil health, which plays a significant role in promoting regional food security and alleviating the food crisis under global warming. Based on the data from the second soil investigation project(1984)and the soil testing and formulated fertilization project(2009)in Guangxi, temporal and spatial evolution characteristics
We measured the forest biomass and biometrically derived net primary production (NPP) in a cool-temperate deciduous forest stand beneath a flux tower. NPP was calculated as the sum of the living ...biomass of new-season tissue in all organs (
B) and biomass of new-season tissue lost due to death (
L). Annual leaf-litter production was adopted as
L. We regarded the total tree growth in the stand as
B, and examined three methods for estimating
B to discuss the practicality of continuous measurement of NPP to compare with corresponding estimates of eddy-covariance based net ecosystem exchange (NEE). The three methods were diameter at breast height (DBH)–growth allometry by stem analysis of sample trees (SA method), DBH–growth allometry by core sample analysis of sample trees (CS method) and direct measurement of stem growth by tree census (TC method). The total annual tree growth in the forest stand estimated by the SA, CS and TC methods was 2.26, 1.60 and 2.38
Mg
ha
−1, respectively, and NPP was 5.64, 4.98 and 5.74
Mg
ha
−1. The slope of the regression of DBH against annual tree growth was slightly smaller for the CS method than for the SA method; the CS method underestimated the growth of several sample trees that had no clear main stem and, as a result, greatly underestimated B. To estimate B, the SA and CS methods depend on the use of DBH–growth allometry. Thus, it is difficult to determine species-dependent growth in natural mixed forests by these methods if only a few sample trees are used. In contrast, the TC method can directly and continuously measure the growth of all tree stems. Therefore, the TC method is the most suitable method for measuring NPP through annual measurements of tree diameter and leaf-litter production allowing for direct comparison with eddy-covariance based estimate of NEE.
Accurate estimation of the storage and spatial distribution of carbon in forest ecosystems is essential when studying the role of these ecosystems in global warming. Appropriate methods and reliable ...data are thus necessary. In this study, we developed a precise, unifying estimation method and assessed seven components of carbon storage in a cool-temperate deciduous forest ecosystem in central Japan. This method is based on detailed dividing of carbon pools in forest ecosystem, unifying, and systemic survey and estimate for each divided carbon component using precise and suitable methods, respectively. Data and methods used include tree census and allometry method between diameter at breast height (DBH)–biomass for tree, spectral reflectance measurement using a handy-type spectroradiometer for floor vegetation (
Sasa), standing dead tree census (diameter at breast height and tree height) and allometry method between DBH–biomass and geometric calculation, detailed dry weight surveys for litter and coarse woody debris, detailed soil profile survey using profile digging and profile sampler measurement. The total carbon storage in the ecosystem equaled 440.6
t
C
ha
−1. Of the aboveground mass, 71.4
t
C
ha
−1 was stored in living trees, 5.3
t in standing dead trees, and 2.8
t in
Sasa senanensis (the understory vegetation). Of the belowground mass, 19.6
t
C
ha
−1was stored in living roots, 1.8
t in the roots of the standing dead tree, 15.3
t in plant litter, 6.1
t in coarse woody debris, and 318.3
t in the mineral soil. Carbon was stored unevenly throughout the ecosystem, and storage varied as a function of topography. The minimum and maximum amounts of stored carbon were 125.1 and 726.9
t
C
ha
−1, respectively; the highest and lowest amounts were found in a valley (average, 556.7
t
C
ha
−1) and on a west-facing slope (average, 381.3
t
C
ha
−1), respectively. Compared with other ecosystems, carbon storage in this forest ecosystem was higher in the soil and lower in the vegetation. The results also demonstrate the importance of gravels and stones in the soil and of standardizing the soil sampling depth.
The effects of combined contaminated soils containing cadmium (Cd) and ciprofloxacin (CIP) on the human gut microbiota are demonstrated using an in vitro test. Uncontaminated soil samples were ...artificially polluted with Cd and CIP using three different treatments (CK: 0 mg·kg−1; CIPI: 5 mg·kg−1, CIPII: 25 mg·kg−1, and Cd: 80 mg·kg−1). An experiment was performed to investigate the effect of Cd and CIP on the human colon microbiota using two aging times (D30: Day 30; D60: Day 60), and then the method of high-throughput 16S rRNA gene sequencing was used. In this study, we observed five phyla: Proteobacteria, Firmicutes, Synergistetes, Bacteroidetes, and Actinobacteria in colon microbial community. In addition, our results indicated that the relative abundances of the gut bacteria varied at the phylum level. Nevertheless, a slight decline in the relative abundance of Bacteroidetes among all the sets (compared to the D30-CK + Cd set) was revealed, and the lowest decline percentage of 90% was observed in the D60-CIPI + Cd set. Our results validated that the relative abundance of Rhodococcus increased with an increase in the CIP concentration in D30. In addition, this may disrupt normal physiological functions of the intestine after exposure to contaminated soil via the mouth. This study provides a theoretical basis for human risk assessment of oral exposure to Cd and CIP contaminated soils.
Display omitted
•Soils containing CIP and Cd can change the gut microbiota community structure from the phylum to the genus level.•There were differences in the structure of the gut microbiota community with the different aging times.•Soil containing CIP and Cd can change the function of colon.
With the increasing demands of livestock production, grasslands are under pressure from over‐intensified grazing. Phosphorus (P) and nitrogen (N) fertilization is widely employed to meet the nutrient ...demands of heavy grazing. Although soil ammonia‐oxidizers play a critical role in determining N dynamics after fertilizer application, their responses to fertilization are still not well understood in steppe grassland systems. Here, the individual and combined effects of N (0, 7.5 and 15 g N m−2 year−1) and P (0, 3.27, 6.55 and 13.09 g P m−2 year−1) applications on soil ammonia‐oxidizers were explored in the Tibetan alpine steppe. Ammonia‐oxidizing archaea (AOA) and bacteria (AOB) abundance and community composition were examined using qPCR, terminal restriction fragment length polymorphism and clone libraries. Results showed that AOB diversity was significantly increased by N fertilization and decreased by P fertilization. The abundance of AOB was significantly increased by N fertilization and its interactive effects with P application. In contrast, AOA community diversity and abundance remained unaffected by either N or P application. The AOB abundance and diversity were affected by the direct effects of N fertilization, as well as its indirect effects of N application through available N and ammonium (NH4+), and further analysis showed that NH4+ and pH were the main factors. The changes to the ammonia‐oxidizing community altered the total N content of plants and the N:P ratio of Gramineae. Plant P properties were influenced by P addition, which also interacted with soil pH and available N to indirectly affect AOB. Overall, AOB exhibited stronger responses to N and P fertilization of alpine steppe grassland than AOA, and appear to play a critical role in plant nutrient absorption under fertilization management.
Highlights
Effects of N and P application on AOA and AOB communities were evaluated.
AOB, not AOA, responded to N or P, and their interaction, and NH4+ and pH were regulators of AOB.
N application affected AOB community, resulting in changes to plant nutrient absorption.
P addition affected plant tissue stoichiometry, and thus affected AOB community.
