Impact of Atmospheric Long Range Transport of Lead,Mercury and Cadmium on the Swedish Forest Environment

Emissions of Hg, Pb, and Cd to air aretransported over wide areas in Europe and deposited far awayfrom their sources. About 80% of the atmospheric depositionof these metals in south Sweden originate from emissions inother countries. As a result of the increased anthropogenicdeposition the concentrations of Hg, Pb, and Cd in the morlayer of forest soils have increased considerably, mainlyduring the 20th century. Although the atmosphericdeposition of these elements has declined during the mostrecent decades, the reduction of the input of Hg and Pb isnot sufficient to prevent a further accumulation. Theconcentrations of Hg and Pb are still increasing by ca. 0.5and ca. 0.2% annually in the surface layer of forest soils.In contrast, the Cd concentration is currentlydecreasing in a large part of Sweden as a result of bothdeposition decreases and enhanced leaching induced by soilacidification. The accumulation factors of Hg and Pb,especially in the forest topsoils of south Sweden, arealready above those at which adverse effects on soilbiological processes and organisms have been demonstrated instudies of gradients from local emission sources andlaboratory assessment. There are also indications of sucheffects at the current regional concentrations of Hg and Pbin mor layers from south Sweden, judging from observationsin field and laboratory studies. There is an apparent riskof Pb induced reduction in microbial activity over parts ofsouth Sweden. This might cause increased accumulation oforganic matter and a reduced availability of soil nutrients.At current concentrations of Hg in Swedish forest soils,effects similar to those of Pb are likely. Increasedconcentrations of these elements in organs of mammals andbirds have also been measured, though decreases have beendemonstrated in recent years, related to changes inatmospheric deposition rates. As a result of current andpast deposition in south Sweden, concentrations of Hg infish have increased about fivefold during the 20thcentury. This implies risks for human health, when fish frominland waters are used for food. Although the concentrationof Hg in fish has decreased ca. 20% during the last decade,probably as a result of the reduced deposition, the levelstill exceeds the general limit (0.5 mg kg^-1) in about half(ca. 40 000) of the Swedish lakes. In order to reduceconcentrations in fish to the level recommended, and avoidfurther accumulation of Hg in soils, the atmosphericdeposition has to be reduced to ca. 20% of the current deposition rate. This can only be achieved by international co-operation.     

Aminocyclopyrachlor sorption-desorption and leaching from three Brazilian soils

This study aimed to evaluate the sorption-desorption and leaching of aminocyclopyrachlor from three Brazilian soils. The sorption-desorption of ¹⁴C-aminocyclopyrachlor was evaluated using the batch method and leaching was assessed in glass columns. The Freundlich model showed an adequate fit for the sorption-desorption of aminocyclopyrachlor. The Freundlich sorption coefficient [K_{f (sorption)}] ranged from 0.37 to 1.34 µmol ^(1–1/n) L^1/n kg^?1 and showed a significant positive correlation with the clay content of the soil, while the K_{f (desorption)} ranged from 3.62 to 5.36 µmol ^(1–1/n) L^1/n kg^?1. The K_{f (desorption)} values were higher than their respective K_{f (sorption)}, indicating that aminocyclopyrachlor sorption is reversible, and the fate of this herbicide in the environment can be affected by leaching. Aminocyclopyrachlor was detected at all depths (0?30 cm) in all the studied soils, where leaching was influenced by soil texture. The total herbicide leaching from the sandy clay and clay soils was <0.06%, whereas, ～3% leached from the loamy sand soil. The results suggest that aminocyclopyrachlor has a high potential of leaching, based on its low sorption and high desorption capacities. Therefore, this herbicide can easily contaminate underground water resources.     

利用TaPL3模型计算p,p''-DDTDDT在天津地区的长距离传输潜力

利用TaPL3(Version 3．00)模型计算了天津地区p，p’-DDT通过大气和水体的长距离传输潜力(LRTP)．通过灵敏度分析，确定了模型的关键参数．利用蒙特卡罗方法对模型结果进行了不确定性分析．结果表明，天津地区p，p’-DDT通过大气的LRlP为473～762km，均值为579km；通过水体的LRTP为940～10958km，均值为2254km．通过大气的LRTP的结果分布比通过水体的LRTP更集中．与国外同类结果比较，通过大气的LRTP略低，而通过水体的LRTP则明显偏低．     

鄱阳湖水流运动与污染物迁移路径的粒子示踪研究

湖泊水流运动和污染物的迁移路径对湖泊水质起着关键作用。采用水动力和粒子示踪耦合模型,并结合野外粒子示踪实验来调查鄱阳湖洪水季节空间水流运动和污染物迁移路径。模拟结果显示,流域五河点源入湖污染物和湖区空间面源分布污染物均会沿着不同方向迅速进入湖泊主河道,在快速水流推动下逐渐向北部湖区迁移,但部分污染物因东北部湖湾区存在顺时针方向环流而发生长时间滞留和富集。野外粒子示踪实验同样表明,东北部湖湾区污染物迁移路径随着该湖区水流运动表现得复杂多变,除了可以明显观察到顺时针方向的污染物运动,还可以发现污染物向湖岸边界和湖汊迁移,最终滞留在东北部湖湾区,而康山湖区污染物在快速水流推动下主要沿主河道向西北主湖区迁移,未发现污染物进入东北部湖湾区的迹象。鄱阳湖洪水季节水流运动和污染物迁移路径具有枯水期水流-污染物传输特性。模拟得出鄱阳湖洪水期的平均换水周期约89 d,表明其可能需要近3个月时间才能彻底完成一次换水。研究成果可为大型通江湖泊"江湖关系变化"研究提供参考,对保护"一湖清水"、保障长江中下游水环境安全具有重要现实意义。     

Frontier science and challenges on offshore carbon storage

● The main direct seal up carbon options and challenges are reviewed. ● Ocean-based CO₂ replacement for CH₄/oil exploitation is presented. ● Scale-advantage of offshore CCS hub is discussed. Carbon capture and storage (CCS) technology is an imperative, strategic, and constitutive method to considerably reduce anthropogenic CO₂ emissions and alleviate climate change issues. The ocean is the largest active carbon bank and an essential energy source on the Earth’s surface. Compared to oceanic nature-based carbon dioxide removal (CDR), carbon capture from point sources with ocean storage is more appropriate for solving short-term climate change problems. This review focuses on the recent state-of-the-art developments in offshore carbon storage. It first discusses the current status and development prospects of CCS, associated with the challenges and uncertainties of oceanic nature-based CDR. The second section outlines the mechanisms, sites, advantages, and ecologic hazards of direct offshore CO₂ injection. The third section emphasizes the mechanisms, schemes, influencing factors, and recovery efficiency of ocean-based CO₂-CH₄ replacement and CO₂-enhanced oil recovery are reviewed. In addition, this review discusses the economic aspects of offshore CCS and the preponderance of offshore CCS hubs. Finally, the upsides, limitations, and prospects for further investigation of offshore CO₂ storage are presented.     

稀土元素在水体食物链生物中迁移的摸拟研究

本文用动态和静态摸拟系统分别研究了稀土元素在小球藻-大型溞-鲤鱼食物链生物上的迁移。结果表明:水生生物对稀土的生物积累作用有从水体直接摄取和从食物间接摄取两种方式,但稀土元素在该食物链上无生物放大作用,生物体中积累的稀土量和水环境中残余的稀土浓度从轻稀土向重稀土递减,稀土元素在水环境中迁移的最重要形式可能是物理-化学迁移。     

Analyzing the relationships between travel mode indicators and the number of passenger transport fatalities at the city level

Objective: A number of efforts have been conducted on travel behavior and transport fatalities at the neighborhood or street level, and they have identified different factors such as roadway characteristics, personal indicators, and design indicators related to transport safety. However, only a limited number of studies have considered the relationship between travel behavior indicators and the number of transport fatalities at the city level. Therefore, this study explores this relationship and how to fill the mentioned gap in current knowledge.

Method: A generalized linear model (GLM) estimates the relationships between different travel mode indicators (e.g., length of motorway per inhabitants, number of motorcycles per inhabitant, percentage of daily trips on foot and by bicycle, percentage of daily trips by public transport) and the number of passenger transport fatalities. Because this city-level model is developed using data sets from different cities all over the world, the impacts of gross domestic product (GDP) are also included in the model.

Conclusions: Overall, the results imply that the percentage of daily trips by public transport, the percentage of daily trips on foot and by bicycle, and the GDP per inhabitant have negative relationships with the number of passenger transport fatalities, whereas motorway length and the number of motorcycles have positive relationships with the number of passenger transport fatalities.     

粉煤灰浆中碳酸钙沉淀反应动力学

利用设计的试验装置研究了燃煤电厂粉煤灰浆中碳酸钙沉淀反应动力学 .该试验装置可以有效地完成灰与水的瞬间混合 ,并通过设计的特殊真空取样装置完成灰浆的快速取样 .取样完成后 ,迅速通过离心、快速密闭过滤措施 ,实现灰与水的分离 ,从而终止体系中所发生的沉淀反应 ,制取清水样品供测试 .采用此法 ,首次以粉煤灰浆水相中的总无机碳含量为检测因子 ,直接测得了该体系中碳酸钙沉淀反应的动力学数据 .根据动力学数据特征 ,提出了能够表征该反应动力学规律的数学表达式 ,并经数学推导、计算机拟合求得了针对具体动力学数据的表达式参数 .     

基于数值模拟的河道再生水补充区地下水监测网构建

再生水作为改善城市景观用水纳入河道,可其对地下水具有潜在的污染风险。通过构建区域地下水数值模型,应用质点追踪技术,计算出永定河补水区在河湖受水后地下水5 a运移1.47 km、20 a运移6.32 km,年均运移0.32 km。在数值模拟的基础上,依据地下水运移轨迹,结合区域水文地质条件,将研究区划分为核心监控区、二级监控区和控制监控区3个地下水监测分区,并提出各分区地下水监测井的布设原则及布设方式,实现地下水环境监测网络的优化。