Characterisation of sequential leachate discharges of mining waste rock dumps in the Tinto and Odiel rivers

Mining waste rock dumps (WRDs) are potential sources of pollution, which after rainfall produce leachate discharges, loaded with acid mining drainage (AMD). The discharges generally occur in two phases: initial rapid leaching over a period of 1-7 days, followed by a period of variable duration during which leaching decelerates. The relative preponderance of each phase depends on the characteristics of the WRD, including its antecedent hydrological condition, and the temporal pattern and amount of rainfall.     

Influence of compost amendment rate and level of compaction on the hydraulic functioning of soils

There has been widespread interest in using compost to improve the hydrologic functions of degraded soils at construction sites for reducing runoff and increasing infiltration. The objective of this study was to determine the effects of compost amendment rate on saturated hydraulic conductivity (K_s) and water retention in order to identify target compost rates for enhancing soil hydrologic functions. Samples were prepared with three soil textures (sandy loam, silt loam, and sandy clay loam), amended with compost at 0%, 10%, 20%, 30%, 40%, and 50%. All soils were tested at a porosity of 0.5 m³/m³, and the sandy loam was further tested at high (0.55 m³/m³) and low (0.4 m³/m³) porosities. The K_s and water retention data were then used to model infiltration with HYDRUS-1D. With increasing compost amendment rate, K_s and water retention of the mixtures generally increased at the medium porosity level, with more compost needed in heavier soils. As porosity decreased in the sandy loam soil, the amount of compost needed to improve K_s rose from 20% to 50%. Water distribution in pore fractions (gravitational, plant-available, and unavailable water) depended on texture, with only the highest compost rates increasing plant-available water in one soil. Results suggest soil texture should be taken into consideration when choosing a compost rate in order to achieve soil improvement goals. Hydrologic benefits may be limited even at a high rate of compost amendment if soil is compacted.     

Effect of selected and non-selected urban waste compost on the initial growth of corn

Brazil produces approximately 242,000 t of waste per day, 76% of it being dumped outdoors and only 0.9% recycled, including composting, which is an alternative still little known in Brazil. In search of a better destination for residues produced by domestic activities, composting stands as a feasible alternative. Organic compost from waste may be used for various purposes, among which are soil recovery, commercial production, pastures, lawns and reforestry and agriculture. However, the quality of the compost determines the growth and the development of plants. The effect of compost made from urban waste on corn plant (Zea mays L.) growth was investigated. Two types of compost were used: the selected compost (SC), produced from organic waste selectively collected; and the non-selected compost (NSC), taken from a 15-year-old cell from the Canabrava land-fill, located in Salvador, Bahia, Brazil (altitude 51 m, 12°22′–13°08′S, 38°08′–38°47′W). Corn was seeded in polyethylene pots, with soil-compost mixing substrate in the proportion of 0, 15, 30, 45 and 60 t ha⁻¹ equivalent doses. Chemical analyses of the compost and growth properties of the plant like chlorophyll content; height and stem diameter; aerial and radicular dry biomasses, were used to evaluate compost quality. Plants cultivated with SC presented a superior gain, being of 52.5% in stem diameter, 71.1 and 81.2% in root and stem biomasses, respectively. Chlorophyl content alterations were observed in plants from treatments using 30 t compost ha⁻¹ dose onwards. Conventional and multivariate statistical methods were used to evaluate these results. The beneficial action of organic compost in plant growth was confirmed with this research.     

水泥粉尘对夹江城区降雨pH值的影响

本文通过实验测试和理论计算，说明了夹江县城区降雨pH值偏高是由于水泥粉尘影响造成的，通过测试数据计算了水泥厂周围区域每天承受水泥污染的数量。     

pH值对废水中氨氮监测结果的影响

在相同水温条件下,采用中华人民共和国国家环境保护标准HJ537—2009（（水质氨氮的测定蒸馏一中和滴定法》测量水中氨浓度时,不同的pH值会对废水中氨氮浓度的监测结果造成影响。pH值对测定水样氨氮含量监测结果的影响呈先增大后下降的趋势,在pH值为6。0～7．4之间测定水样氨氮含量最大。     

Effect of pH and alum dosage on the efficiency of microalgae harvesting via flocculation technique

Microalgae biomass is well known as a potential sustainable product for bio-based industry, which has reported encountering numerous difficulties during biomass harvesting and recovering. This study examined the effect of pH (5–12) and alum dosage (30–180 mg/L) for microalgae Botryococcus sp. harvested via flocculation technique. The optimum pH condition for Botryococcus sp. harvesting was measured to be 9.2, and the alum dosage was 100 mg/L. Both optimum values successfully harvested up to 95% microalgae biomass. This study revealed that flocculation efficiencies for alum are highly dependent on the range of pH and coagulant dosage that were applied during the process. Use of flocculation technique with alum as a coagulant represents a convenient technique for Botryococcus sp. biomass harvesting and is recommended for use in both small- and large-scale biomass industries.     

Utilization of UV‐A and UV‐C radiation in advanced oxidation processes with the intention of removing color and organic matter from the gross leachate of a stabilized sanitary landfill

The present work investigated color and biochemical oxygen demand (COD) removal from treated landfill leachate via advanced oxidative processes (AOPs) artificially emitted. The AOP H₂O₂/UV, TiO₂/UV, and photolysis were tested in two bench‐scale photoreactors: The first one with UV‐C lamp and the other with UV‐A lamp associated or not with coagulation / flocculation pretreatment. Crude leachate samples with pH ranging from 8 to 3 were used, and time varied in 30, 45, and 60 minutes. Experiments were performed in two stages: step 1 with a 20 mL volume from each sample and step 2 with repetition of the best results from the previous step, adopting the 150 mL volume. In step 1, the AOP applied in the crude leachate sample showed the best results, standing out H₂O₂/UV‐C with 30 minutes and TiO₂/UV‐A with 60 minutes. In step 2, H₂O₂/UV‐C had a 60% color removal and 25% COD reduction, while TiO₂/UV‐A had a 10% color removal and 20% COD reduction. Therefore, the H₂O₂/UV‐C process was the most efficient, because the complex characteristics of the effluent interfered in the TiO₂/UV‐A efficiency, but it is necessary to eliminate the process interferences. The use of artificial radiation is a viable alternative; however, it can be costly, being relevant in the associations between processes with artificial UV and solar UV, as the natural radiation becomes more attractive and allows the process operating costs reduction.     

绵阳市大气降水pH值时空分布及酸雨成因研究

通过对绵阳市9个测点1998－1999年大气降水监测数据的统计分析，并结合历史数据，对大气降水pH值的时空分布及酸雨成因进行了研究。结果表明：绵阳市大气降水酸化严重，除主要受本地区大气污染影响外，还受大气中、长距离输送的影响。     

宜宾市酸雨pH值预测的偏最小二乘回归分析

酸雨pH值受酸性离子(有机酸、无机酸)和碱性离子的影响。这些影响因素之间存在多重相关性。用一般最小二乘回归法建模预测pH值,估计参数存在着很大的误差,而且物理意义明显不足。本文以宜宾市区2002-2003年的27组降雨监测数据作为样本数据,应用偏最小二乘回归技术建立pH值预测模型,克服了自变量之间的多重相关性的问题。与最小二乘回归法相比更具有先进性,计算结果更为可靠;在确定了模型可行性后,分析比较了影响宜宾市区酸雨pH值的离子的重要性和离子来源。     

Impervious surface as an indicator of pH and specific conductance in the urbanizing coastal zone of New Jersey, USA

Impervious surface is often used as an indicator of non-point source pollution in urban areas due to the strong relationship between percent impervious surface cover and water-quality impacts. In many cases, a threshold effect exists where water quality rapidly degrades above a given percent cover, but the exact threshold level appears to vary across regions. This study explores the relationship between pH, specific conductance, and percent impervious surface cover in the urbanizing coastal zone of New Jersey (USA) to determine the nature of the relationship in the region. The results of the analysis suggest the system is very sensitive to impervious surface, with a threshold potentially existing between 2.4% and 5.1% impervious surface cover. An examination of future conditions suggests that by 2020 water quality in more than 50% of the catchments in the study area will be negatively impacted by non-point source pollution associated with impervious surface.     

Specific Conductance and pH as Indicators of Watershed Disturbance in Streams of the New Jersey Pinelands, USA

/ We used linear regression to independently and jointly relate specific conductance and pH measured at New Jersey Pinelands stream sites to the percentage of altered land in a watershed. Percentage altered land included developed and agricultural land uses and represented watershed disturbance for a given site. Median values calculated for a 2-year period (September 1992 through August 1994) characterized pH and specific conductance at the study sites. We found the relationships between the median values for both water-quality measures and percentage altered land for a site to be consistent across subregion and dominant altered-land use. Our results also demonstrated that the water-quality/altered-land relationships developed using median values were similar to relationships developed using data from any single-sample period within the entire study period. Individually, pH and specific conductance explained 48% and 56%, respectively, of the variability in watershed disturbance among study sites. The joint use of pH and specific conductance explained 79% of the watershed disturbance variability among sites. The joint use of these easily obtained water-quality measures can provide a quick assessment of instream water-quality impacts from upstream watershed disturbance at any Pinelands stream site. Additionally, a range in pH and specific conductance, and hence a range in ambient water quality, can be predicted for a given altered-land percentage or a change in existing altered-land conditions.     

Snowmobile impact on old field and marsh vegetation in Nova Scotia,Canada: An experimental study

A study was carried out in Nova Scotia, Canada, to experimentally assess the effect of snowmobiles on old field and marsh vegetation. Snowmobile treatments ranging from a single pass to 25 passes (five passes on five separate days) were administered. The first pass by a snowmobile caused the greatest increase in snow compaction-roughly 75% of that observed after five sequential passes. Snowmobile treatment resulted in highly significant increases in snow retention in spring. Frequency was more important than intensity in this regard.Standing crop and species composition were measured the following summer. Standing crop in the field showed a significant reduction with increasing snowmobile use; frequency of treatment (p < 0.01) was more important than intensity (p = 0.125).Stellaria graminea, Aster cordifolius, Ranunculus repens, andEquisetum arvense all showed significant (p < 0.05) differences in percent cover resulting from the treatment. Marginally significant changes were observed inAgrostis tenuis andPhleum pratense Marsh vegetation showed no significant effects of snowmobile treatment. This may have been because of solid ice cover during the winter.The literature is critically reviewed. It is concluded that snowmobile use can have a highly significant effect upon natural vegetation. Management suggestions are made.     

酸雨pH预测的偏最小二乘回归模型

酸雨pH值受酸性离子[SO4^2-]、[NO3^-]和碱性离子[Ca^2 ]、[NH4^ ]等的影响。这些影响因素之间存在多重相关性。用一般最小二乘回归法建模预测pH值，估计参数存在着很大的误差且物理意义明显不足。应用偏最小二乘回归技术建立pH值预测模型，克服了自变量之间的多重相关性的问题，因而更具有先进性，计算结果更为可靠。以我国17个城市pH值预测为例，探讨偏最小二乘法的优势，并与最小二乘回归法进行了比较。     

An experimental study to explore WTP for aviation carbon offsets: the impact of a carbon tax on the voluntary action

As Australia recently introduced a mandatory carbon price, this paper provides a rare perspective of how such institutional changes influence consumer preferences for voluntary climate action. When examined using three contingent valuation questions, the results show that the compliance mechanism induces a substantial reduction in the number of air travellers who are willing to pay extra for voluntary carbon offsets and in the payment amount, although the crowding-out effect is incomplete. A disproportionately larger welfare benefit is attached to the carbon offsets for a domestic flight than its international counterpart. Overall empirical findings advocate the continued role of voluntary programmes.     

等离子体技术在环境污染治理中的应用研究

阐述了等离子体的产生机理、方法、分类及特点,从大气污染、水污染和固体废物三方面论述了等离子体技术在环境污染治理中的应用进展,展现了等离子体技术在废物处理中的应用前景。     

Betaine removal during thermo- and mesophilic aerobic batch biodegradation of beet molasses vinasse: influence of temperature and pH on the progress and efficiency of the process

The key issue in achieving a high extent of biodegradation of beet molasses vinasse is to establish the conditions for the assimilation of betaine, which is the main pollutant in this high-strength industrial effluent. In the present study, aerobic batch biodegradation was conducted over the temperature range of 27-63°C (step 9°C), at a pH of 6.5 and 8.0, using a mixed culture of bacteria of the genus Bacillus. Betaine was assimilated at 27-54°C and the pH of 8.0, as well as at 27-45°C and the pH of 6.5. The processes where betaine was assimilated produced a high BOD(5) removal, which exceeded 99.40% over the temperature range of 27-45°C at the pH of 8.0, as well as at 27°C and the pH of 6.5. Maximal COD removal (88.73%) was attained at 36°C and the pH of 6.5. The results indicate that the process can be applied on an industrial scale as the first step in the treatment of beet molasses vinasse.     

An empirical study on the public perception and acceptance of hydrogen energy in Taiwan

In this study, we extract factors by using factor analysis and then adopt them in a regression analysis to investigate the public perception and acceptance of hydrogen energy in Taiwan. Six reliable factors were extracted from the exploratory factor analysis of 29 5-point Likert-type items. Our regression results show that the public perception of hydrogen energy as a green energy, public belief in domestic hydrogen industries being able to conform to international safety standards, and public perception of the cost advantage of hydrogen gas over petroleum have significantly positive effects on support for the development of hydrogen energy in Taiwan. While people have a high level of concern about the safety of hydrogen and its associated technologies, the unsafe perceptions of hydrogen and its associated technologies have no significant effects on their support. In particular, public belief in domestic hydrogen industries being able to conform to international safety standards is a powerful factor that enhances support for hydrogen energy development.     

An experimental and numerical investigation into the impact of dissolution/precipitation mechanisms on CO2 injectivity in the wellbore and far field regions

Carbon dioxide capture and storage (CCS) technology is gaining credibility as the best short to medium term solution for significantly reducing net carbon emissions into the atmosphere. From a capacity point of view, deep saline aquifers offer the greatest potential for CO₂ storage. In this respect, well injectivity is considered a key technical and economical issue. Rock/fluid interactions – dissolution/precipitation of minerals, in particular carbonates – are currently considered as one of the principal reasons for wellbore injectivity changes in aquifers.This research investigated the mechanisms involved in injectivity losses through experimental and theoretical methods. The impact on injectivity of permeability changes occurring at various distances from the wellbore was studied using an idealised CO₂ injection well flow model. A new experimental set-up was used to investigate the effect on dissolution/precipitation mechanisms of the pressure and temperature changes that the fluid is subjected to as it advances from the wellbore.Numerical modelling of the injection wellbore has shown that changes in the petrophysical properties of the reservoir several metres away from the wellbore can still have a significant impact on injectivity. As indicated by the experimental research carried out, pressure and temperature gradients that exist inside the reservoirs may lead to re-precipitation in the far field, however no significant permeability and porosity changes were detected to suggest major losses of injectivity due to these effects.     

Ambivalence and conservation behaviour: An exploratory study on the recycling of metal cans

As resource conservation is an imperative for sustainable development, it is crucial to achieve a deeper understanding of the factors involved in people's decisions to recycle. This is even more so because the level of environmental concern is usually higher than the level of ecological behaviours. In this paper we take this fact as indicating that decision-making regarding conservation behaviours happens in the context of an internal debate where contradictory ideas are weighed up and the possibility of ambivalence arises. The main aim of this paper is therefore to explore how contradiction and ambivalence impact upon the attitudes, intentions and pro-ecological behaviours of the private sphere. The paper focuses specifically on the separation and deposition of metal cans, and compares the predictive capacity of beliefs, attitudes and intentions for two groups of respondents – one with a high and another with a low level of ambivalence, as assessed with a direct measure. The role of personal identity and the influence of structural constraints are also explored. Results demonstrate a clear moderating effect of experienced ambivalence, and show how beliefs, particularly negative ones, present a higher predictive capacity of the attitude in the high-ambivalence group, and personal identity plays a relevant role in predicting behaviour in both groups. We discuss the importance of pursuing the study of ambivalence when analysing decision-making in the conservation area.     

An exploratory study of the effect of high and low fascination environments on attentional fatigue

According to attention restoration theory attentional fatigue can be renewed in environments where fascinating stimuli are present as they evoke effortless attention and allow directed attention to rest and be restored. The present study hypothesizes that performing an attention-orienting task in a state of attentional fatigue costs less in a high fascination than in a low fascination condition. In the former attentional shifts are expected to be facilitated because one can function in the involuntary mode. The high fascination condition is also expected to facilitate attention in the coding process and therefore to affect the likelihood of stimulus material to be remembered. To this end 31 subjects were mentally fatigued by performing a sustained attention test. Then they performed an ad hoc attention-orienting task inspired by Posner's paradigm and applied to 40 photographs of environments already assessed for their fascination value. Finally they performed an incidental memory task. As expected, only in the high fascination condition did participants show a significant benefit (reaction time reduction) in shifting attention between trials. The role of fascination on recall is less clear since it interacts with the naturalness of the scene.