The legacy of large dams in the United States

The sustainability of large dams has been questioned on several grounds. One aspect that has been less explored is that the development of dams and reservoirs often enables agricultural expansion and urban growth, which in turn increase water consumption. As such, dam development influences, while being influenced by, the spatial and temporal distribution of both supply and demand of water resources. In this paper, we explore the interplay between large dams, patterns of population growth and agricultural expansion in the United States over the past two centuries. Based on a large-scale analysis of spatial and temporal trends, we identify three distinct phases, in which different processes dominated the interplay. Then, we focus on agricultural water use in the Southwest region (Arizona, California and Nevada) and explore chicken-and-egg dynamics where water supply partly meets and partly fuels water demand. Lastly, we show that the legacy of dams in the United States consists of a lock-in condition characterized by high levels of water consumption, especially in the Southwest, which leads to severe water crises and groundwater overexploitation when droughts occur.     

An ethnobotanic garden

With the help of local schools and the Mount Subasio Park Community, the Assisi Nature Council has created a small ethnobotanic garden in the centre of the ancient city of Assisi, Italy. This short paper describes the opening of the garden and the philosophy which promoted its construction.     

Enhanced photocatalytic activity using GO/TiO<Subscript>2</Subscript> catalyst for the removal of DCA solutions

This work aimed to optimize high-performance photocatalysts based on graphene oxide/titanium dioxide (GO/TiO₂) nanocomposites for the effective degradation of aqueous pollutants. The catalytic activity was tested against the degradation of dichloroacetic acid (DCA), a by-product of disinfection processes that is present in many industrial wastewaters and effluents. GO/TiO₂ photocatalysts were prepared using three different methods, hydrothermal, solvothermal, and mechanical, and varying the GO/TiO₂ ratio in the range of 1 to 10%. Several techniques were applied to characterize the catalysts, and better coupling of GO and TiO₂ was observed in the thermally synthesized composites. Although the results obtained for DCA degradation showed a coupled influence of the composite preparation method and its composition, promising results were obtained with the photocatalysts compared to the limited activity of conventional TiO₂. In the best case, corresponding to the composite synthesized via hydrothermal method with 5% of GO/TiO₂ weight ratio, an enhancement of 2.5 times of the photocatalytic degradation yield of DCA was obtained compared to bare TiO₂, thus opening more efficient ways to promote the application of photocatalytic remediation technologies.     

Finished leather waste chromium acid extraction and anaerobic biodegradation of the products

Due to the amounts of chromium in the leachate resulting from leather leaching tests, chromium sulfate tanned leather wastes are very often considered hazardous wastes. To overcome this problem, one option could be recovering the chromium and, consequently, lowering its content in the leather scrap. With this objective, chromium leather scrap was leached with sulfuric acid solutions at low temperature also aiming at maximizing chromium removal with minimum attack of the leather matrix. The effects of leather scrap dimension, sulfuric acid and sodium sulfate concentration in the solutions, as well as extraction time and temperature on chromium recovery were studied, and, additionally, organic matrix degradation was evaluated. The best conditions found for chromium recovery were leather scrap conditioning using 25 mL of concentrated H₂SO₄/L solution at 293 or 313 K during 3 or 6 days. Under such conditions, 30–60 ± 5% of chromium was recovered and as low as 3–6 ± 1% of the leather total organic carbon (TOC) was dissolved. Using such treatment, the leather scrap area and volume are reduced and the residue is a more brittle material showing enhanced anaerobic biodegradability. Although good recovery results were achieved, due to the fact that the amount of chromium in eluate exceeded the threshold value this waste was still hazardous. Thus, it needs to be methodically washed in order to remove all the chromium de-linked from collagen.     

Nickel and copper accumulation strategies in Odontarrhena obovata growing on copper smelter-influenced and non-influenced serpentine soils: a comparative field study

The present investigation is the first in situ comparative study for the identification of Ni and Cu accumulation strategies involved in Odontarrhena obovata (syn. Alyssum obovatum (C.A. Mey.) Turcz.) growing in Cu-rich smelter-influenced (CSI) and non-Cu-influenced (NCI) sites. The total and Na₂EDTA (disodium ethylenediaminetetraacetic acid)-extractable metal concentration in soils and plant tissues (roots, stem, leaves and flowers) were determined for CSI and NCI sites. High concentrations of total Ni, Cr, Co and Mg in the soil suggest serpentine nature of both the sites. In spite of high total and extractable Cu concentrations in CSI soil, majority of its accumulation was restricted to O. obovata roots showing its excluder response. Since the translocation and bioconcentration factors of Ni?>?1 and the foliar Ni concentration?>?1000 μg g^?1, it can be assumed that O. obovata has Ni hyperaccumulation potential for both the sites. No significant differences in chlorophyll content in O. obovata leaves were observed between studied sites, suggesting higher tolerance of this species under prolonged heavy metal stress. Furthermore, this species from CSI site demonstrated rather high viability under extreme technogenic conditions due to active formation of antioxidants such as ascorbate, free proline and protein thiols. The presence of Cu in higher concentration in serpentine soil does not exert detrimental effect on O. obovata and its Ni hyperaccumulation ability. Thus, O. obovata could act as a putative plant species for the remediation of Cu-rich/influenced serpentine soils without compromising its Ni content and vitality.

     

Perspective on the Therapeutic Applications of Algal Polysaccharides

Journal of Polymers and the Environment - Algae are an enormous source of polysaccharides and have gained much interest in human flourishing as organic drugs. Algal polysaccharides have aroused...     

Role of green innovation,trade and energy to promote green economic growth: a case of South Asian Nations

Environmental Science and Pollution Research - The objective of this study is to contribute to the existing debate of green economic growth by empirically investigating the role of cleaner energy...     

Response to lead pollution: mycorrhizal Pinus sylvestris forms the biomineral pyromorphite in roots and needles

Environmental Science and Pollution Research - The development of mycorrhized pine seedlings grown in the presence of lead was assessed in order to investigate how higher plants can tolerate lead...     

Developing the interaction matrix technique as a tool assessing the impact of traffic on air quality

This paper develops a technique which can be used as a preliminary tool for assessing air quality related to urban traffic. It combines a Geographic Information System (GIS) with an interaction matrix-type methodology based on a system analysis approach. The matrix identifies and quantifies interactions between all selected variables involved in a system as well as their interaction with the system as a whole. This matrix is used to determine the weightings to apply to spatial datasets within a GIS to develop a pollution vulnerability map. The focus of the paper is to introduce and assess a more versatile coding of the interaction matrix with respect to previously used coding. A case study is presented in which the modified interaction methodology is applied to data for a busy urban location. The resulting vulnerability map, in terms of pollution vulnerable hot spots, was compared to a pollution map derived from an advanced dispersion model. The interaction matrix technique with GIS can be used as a tool complementary to sophisticated numerical modelling and has potential as an analytical tool to evaluate multidisciplinary systems.