中国热带地区住院儿童眼病临床特征

目的:探讨中山大学中山眼科中心海南眼科医院5年间收治住院儿童眼病的病种、好发年龄段、性别比例等问题,为儿童眼病的预防和治疗提供临床依据。方法:选择2013年1月-2018年8月我院收治的3~15岁儿童眼病患者2 036例,对相关因素进行分析。结果:共统计患儿2 036例,男女比例1. 6∶1。斜视、眼外伤、上睑下垂为排名前三的主要病种。结论:积极重视儿童眼病,定期对儿童行眼科检查,及早治疗原发病,根据不同年龄段,预防儿童眼病的发生,保护儿童视功能的发育。

中国中亚热带地区的水土流失

在调查研究的基础上,对我国中亚热带地区水土流失的现状、原因、危害和特点等进行了简要分析,认为中亚热带地区水土流失具有面积大、范围广,原因多、危害重,历史久、发展快,以及治理难、恢复慢等诸多特点。对认识中亚热带地区水土流失的基本规律及采取有效防治对策和措施具有重要参考价值。

中国中亚热带地区湿地资源面临的问题及对策

中国中亚热带地区湿地资源丰富。目前,该地区湿地资源存在面积缩小、容积锐减、质量下降、结构受损和功能退化等诸多问题。为实现中国亚热带地区湿地资源的保护和可持续利用,必须采取以下对策和措施:一是提高认识;二是加强法制;三是搞好规划;四是重视保护;五是循环利用;六是增加投入;七是强化研究。

我国热区全国“一村一品”示范村镇发展现状与路径

党中央、国务院高度重视乡村产业发展,“一村一品”是促进乡村产业振兴的重要手段。利用农业农村部认定的全国“一村一品”示范村镇相关数据,以中国热区为研究视野,从全国“一村一品”示范村镇数量、区域分布、主导产业和产品类型、年度获批情况等方面系统梳理热区“一村一品”示范村镇发展现状;研究探讨热区全国“一村一品”与国家地理标志产品、中国特色农产品优势区产品、全国名特优新农产品名录产品、全国乡村特色产品目录产品、中国农业品牌目录产品之间的品牌关系;在此基础上,剖析热区“一村一品”发展中存在的缺乏统筹规划、主导产业规模小、品牌效应不够明显、产业化水平低、缺乏能人带动等主要问题,并从坚持规划引领、构筑质量安全体系、强化品牌培育、壮大新型经营主体、提高农民组织化水平等方面提出发展路径。

我国热区地理标志产品发展现状及对策研究

地理标志作为区域经济的一种特色品牌,是解决新时期"三农"问题的一个重要途径。从地理标志产品结构数量、标准制定、专用标志使用、产品产值等方面全面总结了热区9省地理标志保护产品的发展现状,分析了热区地理标志产品保护的特点,提出促进热区地理标志产品发展的对策建议:完善地理标志保护管理体制机制;积极挖掘地理标志资源,注重培育特色资源;加强地理标志产品质量安全体系建设;优化运作模式,实施"龙头"战略;加强宣传与培训;建立健全的地理标志产品社会化服务体系等。

中国热带黏菌的已知种类

我国广东、广西、云南和台湾4省区的南部及海南、香港和澳门全境均在北回归线以南,属于地理上的热带。为了全面系统地开展我国热带地区黏菌资源的多样性和分类学研究,文中通过标本采集、鉴定和复核以及文献考证研究了已知的发生于中国热带地区的黏菌种类,对一些物种分类地位和名称变化进行了更新,同时记述了每个物种的生境和在我国热带地区的分布。结果表明:中国热带地区现知黏菌6目13科35属160种,其中,广东南部为23种,广西南部为61种,海南为33种,云南南部为67种,台湾南部为26种,香港为66种,澳门为10种。从黏菌的目级水平来看,中国热带地区现知黏菌鹅绒菌目1种,刺轴菌目5种,无丝菌目22种,团毛菌目32种,绒泡菌目73种,发网菌目27种。

Biomass, litterfall and the nutrient fluxes in Chinese fir stands of different age in subtropical China

Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.), a fast-growing, ever-green conifer tree with high yield and excellent quality, is the most important tree species of timber plantations in subtropical China. We investigated the characteristics of biomass, litterfall and nutrient fluxes in the 8, 14 and 24 year-old stands, representing the young, middle-aged and mature stands. The results showed that Chinese fir plantations in central Fujian province had high productivity, and the proportion of stem mass in total biomass was between 50%-70%. Chinese fir was low nutrient-return tree species with litterfall. Nutrient withdrawal from senescing needles was a strong age-dependence for nitrogen, phosphorous and potassium in Chinese fir. With a management system of such short-rotation and continuously pure-crop planting, harvesting timber can lead to great nutrient loss, which may be one of the causes for site degradation.

Study on the Introduction and Screening of Cut Roses in the Tropical Coastal Area of China

[Objective] This study aimed to select suitable cultivars of cut roses with prominent comprehensive performance which is suitable for the commercial promotion in the tropical region of South Hainan Province,including Sanya and the low-altitude area.[Method] Introduction experiment and production test were designed to observe the agronomic and economic traits of cultivars in a rose resources nursery established in Sanya.[Result] Through observation in the resources garden,18 varieties were chosen to conduct the introduction experiment,of which 8 varieties were selected to accomplish the production test.The results of the production test showed that ＇Vendela＇,＇Golden Emblem＇,＇Samantha＇ and ＇Tineke＇ showed the best adaptability;the cut flower quality of ＇Carola＇,＇Black Magic＇ and ＇Golden Emblem＇ belonged to the first grade;the yield of ＇Movie Star＇,＇Golden Emblem＇ and ＇Black Magic＇ was more than one million per hm2;except ＇Golden Emblem＇,the vase life of the other seven cultivars was more than 10 days;＇Carola＇,＇My Choice＇ and ＇Perfume White＇ had better disease-and insect-resistance;＇Carola＇,＇Vendela＇,＇Rouge Meilland＇,＇Tineke＇,＇Golden Emblem＇,＇Samantha＇,＇Perfume White＇,＇Saiun＇,＇Asagumo＇ and ＇Double Delight＇ were more resistant to blackspot,while ＇Black Magic＇,＇Versilla＇,＇Alec＇s Red＇ and ＇Movie Star＇ were less resistant to blackspot.[Conclusion] Cultivars of cut roses were able to grow and develop normally in the tropical coastal area of Hainan Province,including South Hainan and Sanya,where it was appropriate for the production of cut roses.However,it is necessary to pay attention to the prevention and control of thrips and blackspot.＇Black Magic＇,＇Carola＇,＇Vendela＇,＇Rouge Meilland＇,＇Golden Emblem＇,＇Tineke＇,＇Movie Star＇ and ＇Samantha＇ showed best comprehensive performance,which were thus worthy of large-scale popularization in Hainan Province.

Aggregate Stability and Its Relationship with Some Chemical Properties of Red Soils in Subtropical China

The stability of aggregates in the surface soil is crucial to soil erosion and runoff generation. Thus, to understand the stability and the breakdown mechanisms of soil aggregates as well as the relationship between aggregate stability and selected soil chemical properties, such as different forms of Fe and Al oxides, organic matter, CEC and clay content, the aggregates of slightly and severely eroded red soils derived from Quaternary red clay in subtropical China were analyzed using the routine wet sieving…

Using GIS Spatial Distribution to Predict Soil Organic Carbon in Subtropical China

Spatial distribution of organic carbon in soils is difficult to estimatebecause of inherent spatial variability and insufficient data. A soil-landscape model for a region,based on 151 samples for parent material and topographic factors, was established using a GISspatial analysis technique and a digital elevation model (DEM) to reveal spatial distributioncharacteristics of soil organic carbon (SOC). Correlations between organic carbon and topographicfactors were analyzed and a regression model was established to predict SOC content. Results forsurface soils (0-20 cm) showed that the average SOC content was 12.8 g kg^(-1), with the SOC contentbetween 6 and 12 g kg^(-1) occupying the largest area and SOC over 24 g kg^(-1) the smallest. Also,soils derived from phyllite were the highest in the SOC content and area, while soils developed onpurple shale the lowest. Although parent material, elevation, and slope exposure were allsignificant topographic variables (P < 0.01), slope exposure had the highest correlation to SOCcontent (r = 0.66). Using a multiple regression model (R^2 = 0.611) and DEM (with a 30 m X 30 mgrid), spatial distribution of SOC could be forecasted.

Changes in Soil Properties of Paddy Fields Across a Cultivation Chronosequence in Subtropical China

Rice production plays a crucial role in the food supply of China and a better understanding of the changes in paddy soil fertility and the management effects is of practical importance for increasing rice productivity. In this study, field sampling in a typical red soil region of subtropical China, Jiangxi Province, was used to observe changes in the soil physical, chemical, and biological properties in a cultivation chronosequence of paddy fields. After cultivation, clay (< 0.002 mm) content in the soil…

Soil Fertility in Agroforestry System of Chinese Fir and Villous Amomum in Subtropical China

A trial of interplanting and non-interplanting villous amomum (Amomum villosum Lour.) under the canopy of Chinese fir (Cunninghamia lanceolata Hook.) at age 22 was established in Sanming, Fujian of China, and a survey on soil fertility was carried out 10 years after its establishment. Compared with the control (non-interplanting), the properties of soil humus in agroforestry system were ameliorated, with a higher level of humification and resynthesis of organic detritus. The soil microbial population and enzymatic activities were both higher under the influence of villous amomum. Both the nutrient supplying and nutrient conserving capacities of the soil were improved. This agroforestry system exhibited an advantage of improved soil fertility as well as an accelerated growth of Chinese fir, it was, therefore, a sustainable management system suited for Chinese fir in South China.

Nutrient Discharges from a Typical Watershed in the Hilly Area of Subtropical China

Agriculture is still the biggest contributor of non-point source (NPS) pollution to water bodies andrunoff discharges of nutrients and other chemicals are one of the most important pathways. This studywas conducted during 1998～1999 in a typical watershed with complex agriculture and forestry systems aswell as dotted farmer villages, in a transitional region between the mid- and northern subtropical zones ofChina. Continuous sampling of stream water was performed regularly at a weekly frequency, with additionalsampling after all major rainfall events. The discharges of N and P nutrients and suspended materials weremeasured and the total and area-averaged annual discharges of all components were calculated. The resultsshowed an uneven seasonal distribution of nutrient discharges with summer storms contributing most tothe total fluxes. This study demonstrated a high dependence of runoff volume on rainfall but the overallrunoff coefficients were dependent on land use type and watershed size. The area-averaged annual dischargesvaried greatly among the sub-watersheds with different sizes and land use structures. This is the first studyestimating the area-averaged annual discharges of N and P in the hilly areas of subtropical China, which were1.5 g m-2 a-1 and 0.1 g m-2 a-1, respectively, providing important reference values for the assessment ofregional agricultural non-point source pollution.

Effects of Chinese Fir，Loblolly Pine and Deciduous Oak Forests on Nutrient States of Soils in Northern Subtro－pics of China

This paper deals with a study on the effects of Chinese fir, loblolly pine and deciduous oak forests on thenutrient status of soils in northern subtropics of China, adopting the principle of forest ecology in the caseof similar climate and soil type. The experimental area was situated in the Xiashu Experimental Centre ofForest, where the soil is yellow-brown soil derived from siliceous slope wash. Sample plots of these 3 standswere established to study the nutrient status in litter, the amount of nutrient uptake by roots, the quantityof nutrient output by percolating water outside the deep layer of soil, and the seasonal dynamics of availablenutrient in surface soil. It was shown that the intensity of nutrient cycling in soil under deciduous oak wasthe highest, and the effect of oak in improving soil fertility was the best. The result of improving soil fertilityby Chinese fir was the most inferior, though the intensity of nutrient cycling under that stand was higherthan that under loblolly pine stand. The influence of loblolly pine on the improvement of soil fertility wasbetter than that of Chinese fir, in spite of its lowest intensity of nutrient cycling.

Application of Remote Sensing in Study of Slope Land Use and Soil Erosion in Subtropic Region of China

This paper introduces briefly two remote sensing case studies on land use in the subtropic region of China. One is on slope land use in the Yangtze River Three Gorges area. This is a large area of 60497 km2.First of all, geometric correction and supervised classification were conducted for ten scenes of Landsat-5 TM or MSS images. The resolution of the processed images is 50 m ×50 m on ground. By the classification the land use/cover categories in this area were discriminated. Then the croplands including rice fields and upland fields were extracted from the land use/cover maps. Simultaneously the slope grade maps were prepared based on the topographic maps. Overlaying the slope grade maps and the cropland maps, the area and percentage of the croplands in different slope grades were determined. This case study indicated that 71.5% of the uplands was situated on the slope above 15° and 25% on the slope above 25° in this area. It is dangerous, and urgent cultivation or engineering measures should be taken. Another case study is on soil erosion in Linshan County of Guangxi Province. Airphoto interpretation and supervised classification of a Landsat TM image were carried out for discriminating land cover/use categories in an area of 3557.8 km2.And the soil erosion intensity grades were determined according to the land cover/use maps and slope maps.It wed discovered that the land suffering soil erosion accounted for 2404.0 km2, 67.6% of the total area of the county. Necessary measures to control soil erosion should be taken also.

Polycyclic Aromatic Hydrocarbons in Agricultural Soils of the Southern Subtropics,China

The contributions of persistent organic pollutants （POPs） from the subtropical regions of China to pollution of the global environment have been paid great attention; however, little is known about the state of POPs in agricultural ecosystems within these regions of China. This study primarily revealed the state of the contamination and distribution of polycyclic aromatic hydrocarbons （PAH） in agricultural soils in the subtropical regions. 115 surface soils （0-20 cm） were sampled in the breadbaskets of these regions. The concentrations and types of PAH were determined using gas chromatography linked to mass spectrometry （GC-MS）. The total PAH concentrations ranged from 22.1 to 1 256.9 ng g^-1 with a mean of 318.2 ± 148.2 ng g^-1. In general terms, the current PAH concentrations were lower than most PAH levels reported in a number of investigations from different countries and regions. PAH isomer ratios indicated that pyrolytic origins, such as fossil fuel combustion related to vehicle tail gas and industrial emissions, were the dominant sources of PAH in the southern subtropical areas of China. Although PAH concentrations decreased with decreasing pollution, population, and traffic density, to a great extent PAH compositions were similar throughout subtropical soils, with naphthalene, phenanthrene, fluoranthene, and benzo（b）fluoranthene being dominant.

Distribution and Assessment of Soil and Land Degradation in Subtropical China—A Case Study of the Dongxi River Basin, Fujian Province *1

Some alternative methods for estimating soil erosion rates rapidly were used to elucidate the relationship between the land use types and land degradation. The 137 Cs content, magnetic susceptibility, aggregate stability, and soil properties were studied in the Dongxi River Basin, a mountainous area of western Fujian. A plot of 137 Cs inventory (Y) against slope angle (X) shows a strong inverse log log relationship ( r = -0.83 ), indicating that much more soil erosion occurs on steeper slopes. Average soil loss (in thickness of top soil per year) in the past 30 years for arable slope crest, arable slopes and tea plantation slopes are 1.6 , 10.4 and 8.0 mm year -1 respectively. The surface layer enrichment factor of magnetic susceptibility (Y) in soil also shows an inverse log log relationship ( r =-0.63), indicating a similar tendency with the relationship between the 137 Cs inventory (Y) against slope angle (X). The physical and chemical properties of soils among different land use types show different degraded characteristics at different significant levels.

Effect of Slash Burning on Nutrient Removal and Soil Fertility in Chinese Fir and Evergreen Broadleaved Forests of Mid-Subtropical China

A Chinese fir forest (Cunninghamia lanceolata, CF) and an evergreen broadleaved forest (EB) located inFujian Province, southeastern China, were examined following slash burning to compare nutrient capital andtopsoil properties with pre-burn levels. After fire, nutrient (N, P and K) removal from burning residues wasestimated at 302.5 kg ha-1 in the CF and 644.8 kg ha-1 in the EB. Fire reduced the topsoil capitals of totalN and P by about 20% and 10%, respectively, in both forests, while K capital was increased in the topsoils ofboth forests following fire. Total site nutrient loss through surface erosion was 28.4 kg (N) ha-1, 8.4 kg (P)ha-1 and 328.7 kg (K) ha-1 in the CF. In the EB, the losses of total N, P and K were 58.5, 10.5 and 396.3kg ha-1, respectively. Improvement of soil structure and increase in mineralization of nutrients associatedwith increased microbe number and enzyme activities and elevated soil respiration occurred 5 days after fire.However, organic matter and available nutrient contents and most of other soil parameters declined one yearafter fire on the burned CF and EB topsoils. These results suggest that short-term site productivity canbe stimulated immediately, but reduced subsequently by soil and water losses, especially in South China,where high-intensity precipitation, steep slopes and fragile soil can be expected. Therefore, the silviculturalmeasurements should be developed in plantation management.

Goethite Morphologies of Some Soils in South of Central China

The morphologies of goethites in latosol, red soils, yellow-brown soil and the paddy soils developed from red soils were studied in comparison with the morphology of synthetic goethite by means of the X-ray distraction, transmission electron microscopy and energy dispersive X-ray analysis. The synthetic goethite displayed acicular particles elongated in the c-direction. The goethites in the latosol, red soils and yellowbrown soil were platy particles stretched in two directions or isodimensional particles, and those in the paddy soils from red soils were acicular, short columnar, platy or isodimensional particles. Various morphologies of the goethites probably suggested their different dominant crystal faces, surface charge distribution and surface adsorption characteristics.

1.4-nm Intergrade Mineral in Soils of Snbtropical China:A Review

This paper is a review of some advances in the studies on 1.4-nm intergrade mineral of soils in sub-tropical China. 1) 1.4-nm intergrade mineral occurs ubiquitously in soils of subtropical China. The 1.4-nmrnineral in red soil and yellow soil is mainly 1.4-nm intergrade mineral, and in acidic yellow-brown soil (pH< 5.5) is verniiculite alone or 1.4-nm intergrade mineral together with vermiculite. The distribution and thecontent of 1 .4-nm intergrade mineral in the mountain soils are more widespread and higher than those of thecorresponding soils in horizontal zone. 2) The interlayer material of 1.4-nin intergrade mineral ui these soilsappears to be hydroxy-Al polymers instead of hydroxy-Fe, proto-imogolite or kaolin-like material. There isa significant positive correlation between Al amount extracted from the soil with sodium citrate after DCBextraction and pH value of the citrate solution after the extraction. The citrate can also extract a certainamount of silicon from the soil, but the silicon may not come from interlayer of 1.4-nm intergrade mineral.3) It was seldom studied that either vermiculite or smectite did the natural 1.4-nm intergrade mineral comefrom in soil, or it was commonly thought to come from vermiculite. A recent report has revealed that itcan come from smectite. There are some different behaviors between the 1.4-nm intergrade mineral derivedfrom vermiculite and that from smectite. For example, they exert different influences on the formation ofgibbsite. The 1.4-nm intergrade mineral derived from smectite may promote the formation of gibbsite in theyellow soil. 4) The type of 1.4-nm minerals in soils. i.e., vermiculite or 1.4-nm intergrade mineral, may besignificant to soil properties, such as soil acidity, exchangeable Al, electric charge aiiiount and specific surfacearea. Therefore, the management for the soil in which 1.4-nm mineral is mainly 1.4-nm intergrade mineralor vermiculite should be dealt with differently.