Environmental changes in Jiaozhou Bay of northern China during the past 90 years using metals and biogenic elements in sediments

Metals and biogenic elements were analyzed from surface sediments and a 100 cm core collected from Jiaozhou Bay in July 2009, to determine how the environment has changed over the past 90 years due to increasing anthropogenic influences in this region. High concentrations of biogenic silica (BSi) represented the dominance of diatoms in the bay. Most metals were lower than the marine sediment quality guidelines; however, Hg, Zn, and Mn were at polluted levels. The vertical profiles of biogenic elements and metals in the sediment core suggest that the most significant environmental changes occurred since the 1990s, and three stages could be defined: (1) before 1950, characterized by low concentrations of biogenic elements and metals; (2) between 1950 and 1990, displaying an obvious increase of Hg and a slow increase of biogenic elements; (3) after 1990, reflected by a significant increase of total organic carbon (TOC), total nitrogen (TN), total phosphate (TP), and most metals, but a decrease of BSi. Correlation and principal component analyses indicated that most metals originated from lithogenic sources, industrial and domestic discharges as well as maricultural activities.     

Biochemical Changes in Decomposing Leaves of Mangroves

Nylon bags containing yellow leaves of Rhizophora apiculata and Avicennia marina, were immersed for 80 days from August to October, 1996. the decomposing leaves were collected every 10 days and analysed for dry weight loss and six biochemical parameters: tannins, total amino acids, total sugars, total nitrogen, total lipids and fatty acid profile. the leaf weight initially decreased very rapidly by about 50% of the start in two species of mangroves within 10 days. Similar changes were observed with tannins, total amino acids and sugars. However, the concentration of nitrogen increased significantly with decomposition. There was no significant change in total lipid and fatty acid profile. the highest concentration of fatty acid in the decomposing leaves was palmitic acid (16:0). Unsaturated fatty acids such as, 18:1 w7c and 18:1 w9c were found to be present in decomposing leaves of both species.     

Climate changes and overstory recruitment of larch at the northern timberline in the Yamal Peninsula

Studies on overstory recruitment of the Siberian larch (Larix sibirica Ledeb.) in open larch forests depending on the time of seedling establishment (1880–1980) have been performed in the northern timberline ecotone on the Yamal Peninsula. Two periods of active larch establishment have been revealed: from 1900 to 1935 and from 1950 to 1970. A comparison of these data with the results of instrumental observations on temperature and precipitation has shown that the overstory recruitment of larch in valleys of northern rivers is largely dependent on July air temperatures in the first years of tree life, when seedlings grow 10–20 cm high.     

Changing institutions for environmental policy and politics in New Era China

ABSTRACT

The evolution of Chinese environmental policy and politics can be better understood in the broader context of institutional changes that have taken place since the late 1970s. In this study, an analytical framework was established to analyze how overall institutional changes were reflected in the roles of relationships between governmental and non-governmental actors engaged in environmental governance. Institutional changes were observed at three levels: informal institutions (cultural traditions, and political ideology); formal institutions (the polity, political system, property rights, and judiciary); and governing mechanisms (structures, regulatory approaches, and incentives). This analysis of interactions between institutional changes and the changing environmental process explained not only the drives and constraints behind China’s environmental policy evolution so far but also shed light on future challenges and opportunities.     

滹沱河超采区地下水回补的水化学效应研究

由于长期超采地下水,导致滹沱河冲洪积平原地下水位持续下降,水质恶化,为缓解滹沱河超采区水资源矛盾,2018年开始实施了河道回补工程,回补水源为黄壁庄水库水和“南水北调”水.为了研究回补后地下水化学效应变化,应用水文地球化学、水文学和统计学等理论方法,开展了现场动态监测、地下水化学检测工作.结果表明:①实施滹沱河补水后地下水位上升显著,滹沱河沿线地下水位平均回升5.83 m;2019年较2015年滹沱河超采区地下水位平均回升5.93 m,地下水漏斗形状发生改变,地下水向漏斗中心汇集已不明显.②滹沱河多年受上游高硫酸盐水源补给的影响,滹沱河沿岸分布HCO₃·SO₄-Ca·Mg型地下水,并在HCO₃·SO₄-Ca·Mg型水两侧形成了条带状的HCO₃·SO₄·Cl-Ca·Mg型水.与2015年相比,2019年HCO₃-Ca·Mg型水的面积减少了20.6%,HCO₃·SO₄·Cl-Ca·Mg型水和HCO₃·SO₄-Ca·Mg型水的面积增加了13.6%.③河道补给有效缓解了地下水环境恶化,区域地下水中硫酸盐平均含量基本持平,氯化物浓度、TDS（溶解性总固体）浓度、总硬度呈下降趋势;受上游黄壁庄水库补水影响,滹沱河沿岸附近地下水中硫酸盐的浓度升高,高浓度的硫酸盐主要分布在滹沱河、石津灌渠及黄壁庄水库副坝附近,随着补水的不断推进,水位持续回升,在水动力作用下,其有向下游扩散的趋势.研究显示,科学合理地选择补水水源与回补方式是减缓该地区地下水硫酸盐污染及保持地下水可持续利用的有效方式.      

多维视角下新型城市化对中国二氧化碳排放影响的时空变化特征

城市化和碳排放之间关系密切,现有研究多从单一维度来衡量城市化,而忽略了城市化的多维性.本文从人口、经济、社会、空间和生态5个维度建立了新型城市化的评价体系,利用中国30个省、自治区和直辖市2004—2016年的面板数据,基于熵值法和地理加权回归（GWR）模型,从多维视角下研究了新型城市化对中国二氧化碳排放影响的时空变化特征,结果表明：①北京的新型城市化水平最高,东部沿海地区的新型城市化水平高于西部、西南和东北地区.②新型城市化对碳排放有显著促进作用.人口城市化、社会城市化和生态城市化对碳排放的影响存在明显的区域差异,在不同地区分别表现出促进作用和抑制作用,经济城市化和空间城市化对碳排放有显著促进作用.③人口城市化对碳排放影响的空间集聚性呈现出从西南、南部及东部地区往北部、东北部转移的特征.经济城市化对碳排放影响的空间集聚性呈现出从南部往东部沿海及东北地区逆时针转移的特征.社会城市化对碳排放影响的空间集聚性呈现出从南部、西南地区往西部及东北部顺时针转移的特征.空间城市化对碳排放影响的空间集聚性呈现出从北部、东北部地区往西部、西南地区逆时针转移的特征.生态城市化对碳排放影响的空间集聚性呈现出从东部往中西部转移的特征.     

中国农业发展与环境变迁

我国农业历史悠久,农业人口众多,人类活动尤其是农业发展对地理环境的影响极大。我国地理环境在时间与空间上都有很大差异。我国的环境变迁是自然条件与人类活动相互作用的结果。有些环境变化是“积极的”,如土地开发与绿洲建设、水利与灌溉、作物与家畜驯化、平原森林的营造等等,但更多环境变化是“消极的”,如旱灾、洪涝灾害、流沙、盐渍化、森林破坏、动物灭绝、土壤侵蚀、山地灾害等等。当地理环境利用得当时,积极的环境变化将占主导;但若利用不当或利用过度,消极的环境变化将最终占优势。     

贵州农业“两旱”的气候特征及其防御

研究了对贵州农业有重要影响的春旱、夏旱两种灾害性天气的气候规律，指出了贵州春旱呈西重东轻，夏旱则呈东重西轻的地区分布特点．并在分析其危害的基础上，提出了“两旱”灾害的防御措施。     

温室效应与全球变化（二）：应当限制哪些温室气体的排放？

自有大气层以来就有温室效应。工业革命以来，大量人为温室气体的排放使温室效应增强，全球海平面上升和气温上升。人类对这一过程的认识还有很大的不确定性。本文综述了到目前为止对这一问题进行科学研究的结论，指出在控制温室效应和全球变化的问题上，最困难也是最基本的难题是减少二氧化碳的排放。     

Old distribution procedure of both water and matter fluxes in floodplains of western Europe: Impact on present vegetation

In France and the United States it has been shown that strong linkages exist between vegetation and alluvial landforms within homogeneous river stretches characterized by geomorphological processes, flood duration, flood magnitude, flood frequency, and sediment size. Furthermore, perturbations induced by man (such as embankments and damming) have been shown to have an effect on both succession and plant distribution patterns. Yet, in numerous cases it is not possible to find either the communities or the plants whose presence might be predicted by reference to the river section characteristics (such as straight, braided, anastomosed, or meandering channels) or by reference to perturbation effects well known in piedmont valleys (such as variations of the water-table depth, variations of magnitude, and frequency and duration of floods). Unexpected species, new communities, and even new successional sequences are often observed. The presence of new alluvial forms explains these differences. An “artificial” substratum generated by an old human perturbation (limited in the time) has been established in the past; consequently, the natural distribution patterns of water and matter flows have been disturbed. Archive research has enabled a classification of abandoned systems that were commonly used during the 16th, 17th, 18th, and 19th centuries on European floodplains. Several case studies were chosen in order to illustrate and explain the importance of stream corridor history. The example of the Isère River valley, downstream from Albertville, is chosen to highlight the heterogeneity of the vegetation mosaïc pattern outside the dikes. The historical reconstruction explains the role of the additional disturbances that cause deviation from the system evolution patterns.