中日美三国成年人体质监测指标体系的演变及比较分析

该研究通过文献资料法、逻辑分析法对中、日、美三个国家的成年人体质监测指标体系进行纵向和横向的比较,总结分析三个国家的异同之处及外延意义,为完善我国成年人体质测试指标体系提供理论支持和参考、借鉴依据。结果显示:受文化、地域、种族等客观因素影响中日两国对体质的定义及范畴相似性比美国高;三个国家对成年人体质监测都经历了三个阶段进行纵向比较分析。

后疫情时代农民工就业状况分析

本文以河南省安阳市2021年农民工外出就业为例。从安阳市经济发展整体情况和当地吸纳就业渠道和规模状况等三个方面入手,深入分析了后疫情时代农民工外出就业状况,以此为其他地区提供有益借鉴。

赣州市酸雨污染特征及原因研究

本文选取2006—2015年赣州市降水pH值、酸雨频率、降水主要离子等数据,通过计算Spearman秩相关系数分析近年来赣州市的酸雨变化趋势。结果表明,赣州市在酸雨污染防治方面采取了有效措施,治理成效明显。但是,赣州市大气污染有向煤烟型与机动车尾气、工业盐酸混合型过渡的趋势,有必要加强工业燃煤、机动车尾气、企业排放废气的治理工作。

基于GEE平台的海岛地表覆盖提取及变化监测——以苏拉威西岛为例

随着海洋在国家政治、经济、资源等方面重要性的提升,对海岛开发利用、管理和保护等具有重要意义的海岛地表覆盖研究逐渐受到关注。针对传统的大范围地表覆盖提取速度慢、效率低的问题,基于Google Earth Engine(GEE)地学大数据平台,以作为生态重点保护区的印度尼西亚的苏拉威西岛为研究区,开展海岛地表覆盖提取及变化监测研究。基于GEE平台对Landsat TM/OLI遥感影像进行辐射校正、影像去云、镶嵌裁剪等预处理,构建海岛地表覆盖分类体系(包括人造地表、裸地、水体、湿地、草地、林地、耕地7个类别),采用随机森林(Random Forest,RF)算法提取2000~2018年苏拉威西岛地表覆盖信息,并从结构及类型变化、时空变化、动态变化3个角度分析苏拉威西岛地表覆盖的变化特征及变化驱动因素。研究表明:GEE在对海岛进行影像处理和地表覆盖信息提取方面具有处理数据量大、效率高的优势。随机森林分类精度较高,研究区2000年、2015年和2018年分类总体精度分别为91%、88%、85%,Kappa系数分别为0.89、0.86、0.82。变化监测研究发现苏拉威西岛的主要地类为林地和耕地,两者占整个海岛地表面积的85%以上。在2000~2018年期间受移民计划以及禁止非法砍伐政策的影响,林地面积呈先减(减少7982.29 km^(2))后增(增加9079.17 km^(2))的态势,耕地面积不断萎缩(共减少14267.35 km^(2))且主要流向林地、草地和人造地表。人造地表的变化最为活跃且其面积显著增加,主要驱动力为人口的迁移以及经济的发展。研究结果为生态型海岛的土地资源合理开发及应用、生态环境的保护、气候与环境变化等研究奠定了基础。

Dissolved Organic Carbon Dynamics and Controls of Planted Slash Pine Forest Soil in Subtropical Region in Southern China

Soil dissolved organic carbon （DOC） is an active fraction of the soil organic carbon （SOC） pool and links terrestrial and aquatic systems. The degradation of DOC can affect carbon cycling, nutrient dynamics and energy supply to microorganism, and consequently change biogeochemical processes. This study investigated the vertical and seasonal variability of soil DOC concentrations and its controls in a 23-year-old planted slash pine （Pinus elliottii） forest at Qianyanzhou Forest Experimental Station （QFES） in Southern China. Soil solutions were collected at bimonthly intervals at depths of 10, 20 and 30 cm by a mechanical-vacuum extractor from November 2007 to March 2009, and at monthly intervals at depths of 10, 30 and 50cm from April 2009 to October 2010. The DOC concentrations were determined with a total organic carbon （TOC） analyzer. Mean （±standard deviation） DOC concentrations at depths of 10cm, 20cm, 30cm and 50cm were 12.4±4.4, 10.6±6.3, 8.7±2.6, and 8.0±5.9 mg L^-1, respectively. Both seasonal and spring means of DOC concentration showed a decreasing trend with increasing depth, while there was no clear trend for the summer, autumn, or winter seasons. DOC concentrations during spring, summer, autumn and winter ranged from 4.8 to 21.5, 4.9 to 26.2, 5.4 to 17.1, 4.9 to 14.6 mg L-1, respectively, their mean DOC concentrations were 10.2, 10.5, 10.8 and 8.3 mg L 1, respectively. No consistent pattern of seasonal variability of DOC concentrations at different depths was observed. No obvious relationship between organic carbon content of forest litter and DOC concentration was found. There was a positive linear relationship between SOC and DOC concentration （R2=0.19, p〈0.01）, which showed that SOC was one of the main controls of DOC. A positive exponential relationship existed between soil temperature at 5 cm and DOC concentrations at 10 cm depth in slash pine, masson pine （Pinus massoniana） and Chinese fir （Cunninghamia lanceolata） planted forests （R2=0.12, p〈0.01）. DOC concentrations showed a negative linear relationship with soil moisture at all depths in slash pine forest （R2=0.15, p〈0.001）, and DOC concentrations at depth of 10 cm demonstrated a negative exponential relationship with soil moisture at 5 cm depth in three planted forests （R2=0.13,/）〈0.001）. Precipitation in sampling months and mean seasonal DOC concentration were not correlated. However, a more detailed analysis of precipitation events at different times before sampling and seasonal DOC concentration showed that the timing of precipitation events prior to sampling had different effects on seasonal DOC concentrations at different depths. Our study highlights the importance of DOC dynamics for the carbon cycle in planted slash pine forest and it provides evidence for evaluating the effects of ecological restoration in subtropical red soil region.