Morphological,physiological and biochemical responses of two Australian biotypes of Parthenium hysterophorus to different soil moisture regimes

Parthenium weed is a problematic invasive species in several countries around the world. Although it is considered to be a highly invasive species within Australia, not all biotypes of parthenium weed exhibit the same ability in regard to aggressive colonization and distribution. Differences among biotypes, particularly in regard to environmental ranges as a possible basis for this variation, have not always been elucidated. To determine whether drought tolerance could be a factor in biotype demographics, we quantified the biological responses of two Australian parthenium weed biotypes known to differ in invasive ability Clermont (“high”) and Toogoolawah (“low”) to 100, 75 and 50% of soil water holding capacity (WHC). The Clermont biotype had greater vegetative growth, seed production and chlorophyll content than Toogoolawah, across all moisture levels. Net photosynthesis, stomatal conductance, internal CO₂ concentration, seed production per plant, 1000 seed weight and subsequent germination percentage were also higher for Clermont than for Toogoolawah and were maximum at 75% WHC. Clermont plants also had higher total soluble sugar, phenolics and free proline content than Toogoolawah, and a significant increase in the levels of all of these biochemicals was observed at 50% WHC. In conclusion, Clermont grew and reproduced better than Toogoolawah across all moisture regimes consistent of enhanced invasive ability of this biotype. Overall, the ability of parthenium weed to maintain good growth, physiology and seed production under moisture stress may enable it to colonize a wide range of Australian environments.

     

Emerging trends in photodegradation of petrochemical wastes: a review

Various human activities like mining and extraction of mineral oils have been used for the modernization of society and well-beings. However, the by-products such as petrochemical wastes generated from such industries are carcinogenic and toxic, which had increased environmental pollution and risks to human health several folds. Various methods such as physical, chemical and biological methods have been used to degrade these pollutants from wastewater. Advance oxidation processes (AOPs) are evolving techniques for efficient sequestration of chemically stable and less biodegradable organic pollutants. In the present review, photocatalytic degradation of petrochemical wastes containing monoaromatic and poly-aromatic hydrocarbons has been studied using various heterogeneous photocatalysts (such as TiO₂, ZnO and CdS. The present article seeks to offer a scientific and technical overview of the current trend in the use of the photocatalyst for remediation and degradation of petrochemical waste depending upon the recent advances in photodegradation of petrochemical research using bibliometric analysis. We further outlined the effect of various heterogeneous catalysts and their ecotoxicity, various degradation pathways of petrochemical wastes, the key regulatory parameters and the reactors used. A critical analysis of the available literature revealed that TiO₂ is widely reported in the degradation processes along with other semiconductors/nanomaterials in visible and UV light irradiation. Further, various degradation studies have been carried out at laboratory scale in the presence of UV light. However, further elaborative research is needed for successful application of the laboratory scale techniques to pilot-scale operation and to develop environmental friendly catalysts which support the sustainable treatment technology with the “zero concept” of industrial wastewater. Nevertheless, there is a need to develop more effective methods which consume less energy and are more efficient in pilot scale for the demineralization of pollutant.     

Irrigation Water Allocation Using an Inexact Two‐Stage Quadratic Programming with Fuzzy Input under Climate Change

Agricultural irrigation accounts for nearly 70% of the total water use around the world. Uncertainties and climate change together exacerbate the complexity of optimal allocation of water resources for irrigation. An interval‐fuzzy two‐stage stochastic quadratic programming model is developed for determining the plans for water allocation for irrigation with maximum benefits. The model is shown to be applicable when inputs are expressed as discrete, fuzzy or random. In order to reflect the effect of marginal utility on benefit and cost, the model can also deal with nonlinearities in the objective function. Results from applying the model to a case study in the middle reaches of the Heihe River basin, China, show schemes for water allocation for irrigation of different crops in every month of the crop growth period under various flow levels are effective for achieving high economic benefits. Different climate change scenarios are used to analyze the impact of changing water requirement and water availability on irrigation water allocation. The proposed model can aid the decision maker in formulating desired irrigation water management policies in the wake of uncertainties and changing environment.     

The influence of diesel—truck exhaust particles on the kinetics of the atmospheric oxidation of dissolved sulfur dioxide by oxygen

The automobile exhausts are one of the major sources of particulate matter in urban areas and these particles are known to influence the atmospheric chemistry in a variety of ways. Because of this, the oxidation of dissolved sulfur dioxide by oxygen was studied in aqueous suspensions of particulates, obtained by scraping the particles deposited inside a diesel truck exhaust pipe (DEP). A variation in pH showed the rate to increase with increase in pH from 5.22 to about ～6.3 and to decrease thereafter becoming very slow at pH?=?8.2. In acetate-buffered medium, the reaction rate was higher than the rate in unbuffered medium at the same pH. Further, the rate was found to be higher in suspension than in the leachate under otherwise identical conditions. And, the reaction rate in the blank reaction was the slowest. This appears to be due to catalysis by leached metal ions in leachate and due to catalysis by leached metal ions and particulate surface both in suspensions. The kinetics of dissolved SO₂ oxidation in acetate-buffered medium as well as in unbuffered medium at pH?=?5.22 were defined by rate law: k _obs ?=?k ₀?+?k _cat [DEP], where k _obs and k ₀ are observed rate constants in the presence and the absence of DEP and k _cat is the rate constant for DEP-catalyzed pathway. At pH?=?8.2, the reaction rate was strongly inhibited by DEP in buffered and unbuffered media. Results suggest that the DEP would have an inhibiting effect in those areas where rainwater pH is 7 or more. These results at high pH are of particular significance to the Indian subcontinent, because of high rainwater pH. Conversely, it indicates the DEP to retard the oxidation of dissolved SO₂ and control rainwater acidification.

     

Study of cyanide removal from contaminated water using zinc peroxide nanomaterial

The present study highlights the potential application of zinc peroxide(ZnO_2)nanomaterial as an efficient material for the decontamination of cyanide from contaminated water. A process patent for ZnO_2 synthesis has been granted in United States of America(US Patent number 8,715,612; May 2014),South Africa,Bangladesh,and India. The ZnO_2 nanomaterial was capped with polyvinylpyrrolidone(PVP)to control the particle size. The PVP capped ZnO_2nanomaterial(PVP-ZnO_2)before and after adsorption of cyanide was characterized by scanning electron microscope,transmission electron microscope,X-ray diffractometer,Fourier transform infrared spectroscopy and time of flight-secondary ion mass spectrometry. The remaining concentration of cyanide after adsorption by PVP-ZnO_2 was determined using ion chromatograph. The adsorption of cyanide over PVP-ZnO_2 was also studied as a function of p H,adsorbent dose,time and concentration of cyanide. The maximum removal of cyanide was observed in p H range 5.8–7.8 within 15 min. The adsorption data was fitted to Langmuir and Fruendlich isotherm and it has been observed that data follows both the isotherms and also follows second order kinetics.     

Impact of riverbank filtration on treatment of polluted river water

The impact of riverbank filtration (RBF) on the treatment of water from the River Yamuna at Mathura, which has disagreeable visual properties, has been investigated. The dissolved organic carbon (DOC) and colour of the river water were 4.0–6.8 mg/L and 40–65 colour units (CU), respectively. Pre-chlorination is in practice to improve raw water quality. Chlorine doses as high as 60 mg/L ahead of the water treatment units reduced colour by about 78%. Removal of DOC and UV-absorbance was less than 18%. In comparison to direct pumping of the river water, collection of water through RBF resulted in the reduction of DOC, colour, UV-absorbance and fecal coliforms by around 50%. However, riverbank filtrate did not conform to the drinking water quality standards. Therefore, riverbank-filtered water along with the Yamuna water were ozonated for different durations. To reduce DOC to the desired level, the dose of ozone required for the riverbank filtrate was found to be considerably less than the ozone required for the river water. RBF as compared to direct pumping of Yamuna water appears to be effective in improving the quality of the raw water.