通过残留水再利用绿化干旱城市:智利北部的多学科项目

本文描述了智利北部的一个项目,其目的是促进处于普遍缺水及土壤和水中含盐量高条件下的干旱地区适当绿地和花园的发展.现场研究试验了选定的本地和引入的观赏植物的适合性.植物生长、水和土壤质量、海洋飞沫、气候、废水处理以及灌溉作业问题等是专门研究和探讨的课题.     

Experiments on vertical transverse mixing in a large-scale heterogeneous model aquifer

Vertical transverse mixing is known to be a controlling factor in natural attenuation of extended biodegradable plumes originating from continuously emitting sources. We perform conservative and reactive tracer tests in a quasi two-dimensional 14 m long sand box in order to quantify vertical mixing in heterogeneous media. The filling mimics natural sediments including a distribution of different hydro-facies, made of different sand mixtures, and micro-structures within the sand lenses. We quantify the concentration distribution of the conservative tracer by the analysis of digital images taken at steady state during the tracer-dye experiment. Heterogeneity causes plume meandering, leading to distorted concentration profiles. Without knowledge about the velocity distribution, it is not possible to determine meaningful vertical dispersion coefficients from the concentration profiles. Using the stream-line pattern resulting from an inverse model of previous experiments in the sand box, we can correct for the plume meandering. The resulting vertical dispersion coefficient is approximately approximately 4 x 10(-)(9) m(2)/s. We observe no distinct increase in the vertical dispersion coefficient with increasing travel distance, indicating that heterogeneity has hardly any impact on vertical transverse mixing. In the reactive tracer test, we continuously inject an alkaline solution over a certain height into the domain that is occupied otherwise by an acidic solution. The outline of the alkaline plume is visualized by adding a pH indicator into both solutions. From the height and length of the reactive plume, we estimate a transverse dispersion coefficient of approximately 3 x 10(-)(9) m(2)/s. Overall, the vertical transverse dispersion coefficients are less than an order of magnitude larger than pore diffusion coefficients and hardly increase due to heterogeneity. Thus, we conclude for the assessment of natural attenuation that reactive plumes might become very large if they are controlled by vertical dispersive mixing.     

Effect of Fe0 quantity on the efficiency of integrated microbial-Fe0 treatment processes

Batch experiments were conducted with different reaction systems to investigate how the treatment efficiency of integrated microbial-Fe0 processes is affected by the amount of Fe0 added. Abiotic experiments with hexavalent chromium and carbon tetrachloride mixtures corroborated that different pollutants could compete for reactive sites on the iron surface, which would hinder specific degradation rates when the available Fe0 surface area is relatively small (e.g., 11 m(2) l(-1)). In such cases, reductive precipitation of chromium could occlude reactive sites and significantly inhibit removal efficiency. Microbial participation in the cleanup process was also influenced by the amount of Fe0 added. Increasing the Fe0 dose (and thus the available surface area) had a stimulatory effect possibly due to a higher production of cathodic H2, which can be used as electron donor for reductive biotransformation of many pollutants. However, high Fe0 doses had an inhibitory effect due to a corrosion-induced increase in pH beyond the optimum range of the bacteria. This suggest that there may be a system-specific, optimum quantity of Fe0 that satisfies availability requirements to preclude contaminant competition for reactive sites and biological requirements for H2 production while minimizing inhibitory increases in pH. Results also confirmed extensive RDX mineralization in bioaugmented (but not in abiotic) Fe0 systems, and support the notion that permeable reactive iron barriers performance might be enhanced by the participation of some microorganisms.     

A new hazard index of complex mixtures integrates bioconcentration and toxicity to refine the environmental risk assessment of effluents

A new methodology to evaluate the overall environmental hazard of unknown mixtures, based on bioconcentration potential and toxicity, was developed using a combination of two methodologies: 1) the estimation of the octanol-water partition coefficient (K(ow)) using reverse-phase high performance liquid chromatography (RP-HPLC) and 2) the toxicity identification evaluation (TIE). Forty seven compounds with known K(ow) and different molecular structures where used for the calibration of the log K(ow) in relation to the retention time in reverse-phase high performance liquid chromatography (RP-HPLC). A linear regression with an R(2)=0.81 and an sd=0.69 was established between log K(ow) and RP-HPLC retention time. This K(ow) estimation method was furthermore validated using seven additional compounds, showing acceptable estimations of the log K(ow) of unknown substances. Two different mixtures were tested, one containing 3,4 Dichloroaniline, Diazinon and 4-Nonylphenol and another one containing a mixture of 16 pesticides. Both mixtures were first tested as a whole effluent and then fractionated and tested, using a miniaturized Daphnia magna test. An equation is presented, that combines both methodologies and establishes a relative hazard index RHI, ranging from 1 to 10 for any particular mixture of chemicals. The results show how the method presented can refine the security factors that could be included in the environmental risk assessment of effluents in the future.     

An inhibitor of urease activity effectively reduces ammonia emissions from soil treated with urea under Mediterranean conditions

Urea is an important source of ammonia (NH₃) emissions to the atmosphere from agricultural soils. Abatement strategies are necessary in order to achieve NH₃ emission targets by reducing those emissions. In this context, a field experiment was carried out on a sunflower crop in spring 2006 with the aim of evaluating the effect of the N-(n-butyl) thiophosphoric triamide (NBPT) in the mitigation of volatilized NH₃ from a urea-fertilised soil. Ammonia emission was quantified, using the integrated horizontal flux (IHF) method, following application of urea with and without the urease inhibitor NBPT. Urea and a mixture of urea and NBPT (0.14%, w/w) were surface-applied at a rate of 170 kg N ha⁻¹ to circular plots (diameter 40 m). The soil was irrigated with 10 mm of water just after the application of urea to dissolve and incorporate it into the upper layer of soil. Over the duration of the measurement period (36 days) three peaks of NH₃ were observed. The first peak was associated with hydrolysis of urea after irrigation and the others with the increase of ammonia in soil solution after changes in atmospheric variables such as wind speed and rainfall. The total NH₃ emission during the whole experiment was 17.3 ± 0.5 kg NH₃–N ha⁻¹ in the case of urea treated soils and 10.0 ± 2.2 kg NH₃–N ha⁻¹ where NBPT was included with the urea (10.1 and 5.9%, respectively, of the applied urea–N). The lower NH₃ emissions from plots fertilised with urea + NBPT, compared with urea alone, were associated with a reduction in urease activity during the first 9 days after inhibitor application. This reduction in enzymatic activity promoted a decrease in the exchangeable NH₄⁺ pool.     

Ecosystem-based adaptation to climate change: defining hotspot municipalities for policy design and implementation in Brazil

We developed an indicator that defines priority municipalities in order to facilitate the deployment of preventive policies and strategies for ecosystem-based adaptation to climate change (EbA) in Brazilian municipalities. Based on the premises that poor people are the population most vulnerable to climate change and that conservation and sustainable use of biodiversity and ecosystems are adaptive to climate change, our indicator uses three parameters: (1) poverty, (2) proportion of natural-vegetation cover, and (3) exposure to climate change. Thus, we searched for Brazilian municipalities that simultaneously belonged to the quartile of municipalities with the highest percentage of poverty, the quartile with the highest percentage of natural-vegetation cover, and the quartile with the highest exposure indices in two global climate models (Eta-HadGEM, Eta-Miroc). We found 398 (7.1%) EbA hotspots among 5565 Brazilian municipalities, which comprise 36% of the total area of native remnants in the country and are home to 22% of the poor people in Brazil. In their majority, these municipalities cover significant portions of the Amazon, Cerrado, Caatinga, and Atlantic forest, and indeed, these regions are recognised as some of the most vulnerable to climate change in the world. Considering the relevance of these biomes for the global water and nutrient cycle (Amazon), global food security (Cerrado), vulnerability to desertification (Caatinga), and biodiversity (all) we discuss the adaptive strategies in place, the need to bring them to scale, and existing policy gaps. Finally, in an effort to guide international and national investment and policies, we discuss how the approach described here can be applied to societies inhabiting tropical forests, savannas, and semiarid zones in other parts of the world. In particular, we propose that the indicator developed here is a simple and fast way to achieve early detection of priority municipalities for deployment of EbA action and policies, particularly in tropical developing countries.     

Environmental Contaminants in Blood, Hair, and Tissues of Ocelots from the Lower Rio Grande Valley, Texas, 1986–1997

The ocelot (Felis pardalis) isan endangered neotropical cat distributed within asmall range in the Lower Rio Grande Valley (LRGV), inTexas, U.S.A. Studies of the impacts of environmentalcontaminants in wild cats are few. Approximately onefourth of the estimated population (about 100) ofocelots in the LRGV was sampled to evaluate theimpacts of chlorinated pesticides, polychlorinatedbiphenyls, and trace elements on the population. Hairwas collected from 32 ocelots trapped between 1986–1992,and blood was collected from 20 ocelots trappedbetween 1993–1997. A few blood samples were obtainedfrom individuals recaptured two or three times. Tissue samples from 4 road-killed ocelots were alsoanalyzed. DDE, PCBs, and Hg were some of the mostcommon contaminants detected in hair and blood. MeanHg levels in hair ranged from 0.5 to 1.25 g g^-1 dw,Se from 1.5 to 3.48 g g^-1 dw, and Pb from 0.56 to26.8 g g^-1 dw. Mean DDE concentrations in plasma ranged from 0.005 g g^-1 ww to 0.153 g g^-1 ww, and PCBs ranged from 0.006 g g^-1 ww to 0.092 g g^-1 ww. Mean Hg levels in red blood cells rangedfrom 0.056 g g^-1 dw to 0.25 g g^-1 dw. Concentrations of DDE, PCBs, or Hg, did not increasesignificantly with age, although the highestconcentrations of DDE and Hg were found in olderanimals. Overall, concentrations of DDE, PCBs, and Hgwere low and at levels that currently do not pose anythreat to health or survival of the ocelot. This isfurther supported by good reproduction of the ocelotin the LRGV, where adult females averaged about 1.5kittens/litter. Thus, it seems that the current majorthreat to recovery of the ocelot in the LRGV may behabitat loss, although potential impacts of newgeneration pesticides, such as organophosphorus andcarbamate insecticides need further study.     

多种聚氧乙烯牛脂胺混合物MON 0818的水生环境危害评估：实验室急性暴露实验基础上的物种敏感度分布

本实验利用标准短期(48- 96 h)实验室测试测定了包括初级生产者，底栖无脊椎动物，水蚤类动物，软体动物和鱼类在内的15种水生生物对于MON 0818的敏感性。MON 0818是一种商业表面活性剂，由多种聚氧乙烯牛脂胺混合而成。此外本实验使用模糊网纹蚤(Ceriodaphnia dubia)潜在的长期(8 d)毒性，确定了暴露浓度。长期毒性测试中未在任何终端指标中发现显著效果。利用得出的数据和文献记载得到物种敏感度在4种暴露条件下的分布，通过对比物种敏感度分布进行了tier-1危害评估。评估显示在本研究规划下(以综述为原型，研究林业除草剂；12 L标准每公顷，等于4.27 kg每公顷) 最差的情况(无意中以最大标签使用速率直接过量喷洒到15 cm深的水体中)会造成中等危害(43.1%的物种处于暴露中，高于中位有效浓度水平)。在更多以最大使用速率使用的典型情况下，受到损害的物种降至20.9%(6 L标准每公顷，相当于2.14 kg每公顷)，在更频繁的雇佣施用速率(2.5 L标准每公顷，相当于0.89 kg每公顷)下，受损物种比例降至6.9%。通过草甘膦在环境中的最大测定浓度计算得到MON 0818的浓度，最终受损物种比例(3.8%)则小于此浓度下受损物种比例(5%)。
精选自Jose L. Rodriguez-Gil, Ryan Prosser, David Poirier, Linda Lissemore, Dean Thompson, Mark Hanson, Keith R. Solomon. Aquatic hazard assessment of MON 0818, a commercial mixture of alkylamine ethoxylates commonly used in glyphosate-containing herbicide formulations. Part 1: Species sensitivity distribution from laboratory acute exposures. Environmental Toxicology and Chemistry: Volume 36, Issue 2, pages 501–511, July 2017. DOI: 10.1002/etc.3559
详情请见http://onlinelibrary.wiley.com/wol1/doi/10.1002/etc.3559/full