巴西亚马孙流域热带森林的开垦与大豆生产:以朗多尼亚州维列纳市为例

近来巴西大豆生产的增长引发了环境保护团体以及一些学者对于亚马孙盆地的热带自然环境正在向大豆种植地转换的关注.大豆生产的支持者则认为大豆是区域的一种可行性农产品;对于环境的关注是没有根据的,因为新的大豆种植地正在替代已经被砍伐的林地或者是转换了的土地.两种观点虽被提出却都没有对大豆生产扩充区的土地利用与土地覆被(LULC)状况进行过综合研究与估量.本案例研究是在巴西的朗多尼亚州,亚马孙盆地西南部的维列纳市(Vimena),通过遥感手段对1996～2001年以来该市大豆种植面积的大幅度增加所伴随的土地利用与土地覆被变化状况进行评估.结果表明虽然森林变成了大豆生产基地,但是大部分的大豆生产的增长归功于对已有土地的微量扩充、已伐林地的转换以及更高的单位产量.     

1952-2016年长江经济带天然与人为氮输入时空演变

过量氮输入是水体氮污染的关键驱动因子，解析氮输入的结构和时空变化模式成为氮素环境管理的重要基础和难点.基于1952—2016年长江经济带各地区氮活动数据，分别构建了天然氮输入和人为氮输入模型，评估了氮输入负荷的时空变化特征.结果表明：①长江经济带氮输入负荷总体越过EKC曲线拐点进入由增长向下降的发展阶段，拐点出现在人均GDP为35777~36299元·人^-1时，发生时间为"十二五"时期，主要原因是化肥和食物输入下降；②氮输入负荷存在显著的时空差异，东部地区表现为倒U型，中部为S型，西部为J型，表明氮负荷存在从东向西的空间转移，西部地区成为氮输入负荷增长的热点地区，这与东部地区化肥施用量下降有关；③人为输入是长江经济带氮输入的主要来源，输入量及其占总输入的比例均呈现显著的增长趋势，空间上表现为从西到东部逐步递增的变化规律，与氮驱动力分布一致；④植被的多年平均固氮量为1771 kg·km^-2·a^-1，其中，非农作物的固氮速率为763 kg·km^-2·a^-1，植被固氮量的年际波动较小，天然输入对长江经济带总体氮输入影响较小.     

Enhanced removal of high-As(Ⅲ) from Cl(-Ⅰ)-diluted SO4(-Ⅱ)-rich wastewater at pH 2.3 via mixed tooeleite and(Cl(-Ⅰ)-free) ferric arsenite hydroxychloride formation

An advanced cost-saving method of removal of high-As(Ⅲ) from SO₄(-Ⅱ)-rich metallurgi cal wastewater has been developed by diluting the SO₄(-Ⅱ) content with As(Ⅲ)-Cl(-Ⅰ)-rich metallurgical wastewater and then by the direct precipitation of As(Ⅲ) with Fe(Ⅲ) at pH2.3.As(Ⅲ) removal at various SO₄(-Ⅱ)/Cl(-Ⅰ) molar ratios and temperatures was investigated The results showed that 65.2–98.2%of As(III) immobilization into solids occurred at the SO₄(Ⅱ)/Cl(-Ⅰ) mo...     

Climatic variations in the Eastern Mediterranean Sea area

A very dry climate which prevailed during the last glacial maximum of the Pleistocene from India to the Sahara, was replaced by variable weather conditions with alternating more or less humid phases, starting from the Pleistocene-Holocene transition period and lasting up to about 3000 years ago, when present arid conditions set in. A particularly wet phase is recognized throughout the region some 5000 years ago. Phase shifts within the region and in particular changes in rain distribution patterns, are interpreted as due to shifting spheres of influence of the monsoonal circulation, of Atlantic depressions and moisture originating from the Mediterranean Sea. The condition of the Mediterranean Sea itself, which is influenced by runoff and melt waters from the European Continent and by the Nile floods, as well as by the eustatic sea-level changes, is not a good indicator of local climate conditions.