Influence of the environmental behavior and ecological effect of cropland heavy metal contaminants by CO2 enrichment in atmosphere

Recently, the impacts of increasing atmospheric CO2 level on the terrestrial ecological system have been intensively studied. The higher the CO2 concentration, the higher the risk of destabilizing vulnerable carbon pool on ecological safety. Metabolism, biomass, activity, and diversity of microbial communities in soils can be significantly altered by the CO2 enrichment. For instance, it may accelerate carbonate weathering, vary the rhizospheric exudation, and enhance the amount of available C from the upper soil layer. However, how the CO2 enrichment would influence food safety such as species transformation and bioavailability of heavy metals in soils is remained unanswered. The bioavailability of heavy metals is strongly affected by bio-factors in addition to the physiochemical conditions of soils. Different physiological mechanisms and states control plant uptake of heavy metals. The enrichment of CO2 influences physiological functionalities of plants, and in turn, is expected to have impacts on the bioaccumulation of pollutants and the stress adjustment system of plants. Currently, in China soil is heavily polluted, in most cases, combined by organic pollutants and heavy metals. Studies of the environmental behavior and ecological effect of Cu in soil under elevated CO2 levels were conducted in China FACE （Free Air Carbon Dioxide Enrichment） from June to October 2005 using pot experiments. Results showed that the accumulation of Cu and Cd in leaves, stems, roots, and grains of rice growing in Cu contaminated soils was significantly lowered, indicating that the bioavailability of heavy metals in soils decreases with increasing CO2 concentration.     

大武水源地地下水生物降解烃污染物的机理

近几年的环境调查研究表明,山东省淄博市大武地下水水源地上游邻近石化厂区出现严重的地下管道石油污染物持续泄漏的现象。堠皋—柳杭地段地下水环境在成为集中污染区的同时,水化学环境也发生了迥然的变化：地下水中电子接受体溶解氧、ＮＯ－３几乎未检出,ＳＯ４２－呈低值分布。这是因为地下水中存在微生物降解烃污染物的作用所致,其作用机理包括需氧降解、脱硝降解、脱硫降解以及有Ｆｅ３＋参与的降解作用。然而由于该地段需氧降解、脱硝降解难以持续自行进行,导致生物降解污染物的速度降低。进一步研究生物降解速度,以提高地下水中电子接受体的浓度,增强微生物的活性,将有利于治理方案的制订与实施。     

Coring artifacts and contaminant inventories in lake sediment

Sediments of Lake 382, Experimental Lakes Area, Canada, were sampled at six sites using a 5-cm Wildco KB core sampler (KB), a similar device incorporating a ball check valve (BC), and a 0.2 m by 1.2 m flat-faced aluminum freeze core sampler (FC). Cores were sectioned at 1-cm intervals to a depth of 15 cm. Contaminant (²¹⁰Pb and ¹³⁷Cs) concentrations (Bq g^-1) were measured by gamma spectroscopy, and inventories (Bq cm^-2) were calculated following standard methods. Sediments collected using FC, BC and KB had similar contaminant concentrations, however, cores collected by FC and BC had lower estimated inventories than KB cores. Differences between estimates appear to be caused by differences in the water content (WC) of core material. Laboratory studies confirm that FC sediments have higher WC than tube-cored sediment. We hypothesize that ice crystal formation increases the WC of freeze cores, resulting in lower contaminant inventories. Loss of surficial sediment caused by a bow wave may have a similar effect on BC samples. We conclude that KB core gear is appropriate for sampling sediments to measure contaminant concentrations and inventories in recently deposited sediments.     

Using resource management plans to protect organic production in New Zealand

Abstract: The focus of this article is on examining how resource management plans prepared under the Resource Management Act 1991 can be used to control the effects of activities for the purpose of preserving the integrity of an organic farm. The article examines effects that can potentially threaten an organic farm and identifies methods that could be employed in a District or Regional Plan to avoid or mitigate those effects. It concludes that the use of resource management plans represents a substantial opportunity to secure the position of the organic farm in New Zealand.     

Investigations on Diffusion Characteristics of Granite and Chalk Rock Mass

Contaminant transport through fractured rock mass is predominated by diffusion. This is due to the continuous interaction of the mobile water present in the fracture network and relatively immobile pore water, which is adsorbed on the surface and in the rock matrix itself. Even though the advective flow through the fracture network is high, besides sorption of rock mass, the diffusive exchange into the rock mass leads to significant retardation of contaminant transport. Hence, for describing contaminant transport in fractured rock mass, more precisely, the effect of retardation attributed to the matrix diffusion must be taken in account. With this in view, a methodology, which can be employed for determination of the diffusion characteristics of the rock mass, has been developed and its details are presented in this paper. Validation of the methodology has been demonstrated with the help of Archie’s law.     

分形法估算分散性污染物的运移时间

污染物运移的分形模型导出一个新的适于任意浓度的污染物运移时间公式.对于一个高度非均质含水层中逐渐形成的污染羽,新公式预算出低浓度更早到达的测点.污染峰或羽的运移时间一般经常从达西定律中采用估算平均孔隙流速法得到,而此估算仅仅提供平均浓度(或污染脉冲的峰值浓度)的运移时间信息.近来,计算出任意浓度的运移时间是一个很直接的过程,并且对一个无反应污染物而言,其突破曲线部分的方程被发展.在文中,我们推导出这些方程去概括污染物运移的分形模型.     

昆明盆地孔隙水的化学特征及其演化规律

昆明盆地为一碳酸盐岩基底背景上形成的断陷盆地.研究区内孔隙水中Ca2+、HCO3-在阳、阴离子中占有绝对优势,水化学类型以HCO3-Ca、HCO3-Ca·Mg、HCO3·Cl-Ca等为主.受不同区域人为活动影响,地下水各离子组分空间分异较大,水化学类型由盆地边缘向盆地中心呈现出复杂化.在平面上,从盆地边缘向盆地中部的冲湖积平原方向,地下水矿化度具有东西过渡分带的特点,以矣六乡-小板桥-巫家坝-联盟镇为界,东部矿化度较低,西部则相对偏高.20年来,随城市化进程的加快,孔隙水水质的演变朝着正负两方面发展,盆地西山、草海一带生态环境有所好转,地下水矿化度在逐年降低,而地下水恶化的区间向着城市的外围边缘转移.冲湖积平原区,地下水矿化度变化不大.地下水化学类型的变异在很大程度上显示了地表土地利用方式的改变对地下水环境演变的影响.因子分析法的结果表明,地下水中Mg2+、HCO3-、Ca2+、Na+、Cl-、SO42-等离子的来源很大程度上显示自然演化的结果,而NO3-、K+、PO 4 3-等离子的来源主要受农业和生活污水的影响.地下水化学组分中Mg2+、Na+、Cl-、SO 4 2-和K+同时受到自然作用和外界污染的影响,以COD为代表的工业污染在一定程度上影响了地下水中Cl-、SO42-和K+的浓度及其分布.     

Impact of irrigation implementation on hydrology and water quality in a small agricultural basin in Spain

Abstract

Irrigation practice has increased considerably recently and will continue to increase to feed a growing population and provide better life standards worldwide. Numerous studies deal with the hydrological impacts of irrigation, but little is known about the temporal evolution of the affected variables. This work assesses the effects on a gully after irrigation was implemented in its hydrological basin (7.38 km²). Flow, electrical conductivity, nitrate concentration and exported loads of salts and nitrates were recorded in Lerma gully (Zaragoza, Spain) for eight hydrological years (2004–2011), covering the periods before, during and after implementation of irrigation. Non-parametric statistical analysis was applied to understand relationships and trends. The results showed the correlation of irrigation with flow and the load of salts and nitrates exported, although no significant relationship with precipitation was detected. The implementation of irrigation introduced annual trends in flow (3.2 L s^-1, +23%), salinity (–0.38 mS cm^-1, –9%), and nitrate concentration (5.4 mg L^-1, +8%) in the gully. In addition, the annual loads of contaminants exported increased (salts and nitrates, 27.3 Mg km^-2 year^-1, +19%, and 263 kg NO₃^–-N km^-2 year^-1, +27%, respectively). The trends presented a strong seasonal pattern, with higher and more significant trends for the irrigation season. The changes observed were different from those of larger irrigation districts or regional basins, due to the differences in land use and irrigation management. It is important to understand these changes in order to achieve an adequate management of the environment and water resources.

Editor Z.W. Kundzewicz

Citation Merchán, D., Causapé, J., and Abrahão, R., 2013. Impact of irrigation implementation on hydrology and water quality in a small agricultural basin in Spain. Hydrological Sciences Journal, 58 (7), 1400–1413.     

核废料及有毒化学废料的地质处理问题

为了防止核废料及有毒化学废料进入生物圈污染人类所赖以生存的环境,自从70年代末以来,对核废料和有毒化学废料的地质处理发生了很大的兴趣。文中讨论了几种有关的溶质运移模型。并指出这些模型应用于实际野外问题时的主要困难在于各种参数的现场测定。同时,文中也指出了在这个领域中的数学模型技术和野外测试技术正在迅速发展之中,本文讨论的范围仅限于多孔介质及等价多孔介质中的溶质运移问题。