Glutathione and its dependent enzymes’ modulatory responses to toxic metals and metalloids in fish—a review

Toxic metals and metalloid are being rapidly added from multiple pathways to aquatic ecosystem and causing severe threats to inhabiting fauna including fish. Being common in all the type of aquatic ecosystems such as freshwater, marine and brackish water fish are the first to get prone to toxic metals and metalloids. In addition to a number of physiological/biochemical alterations, toxic metals and metalloids cause enhanced generation of varied reactive oxygen species (ROS) ultimately leading to a situation called oxidative stress. However, as an important component of antioxidant defence system in fish, the tripeptide glutathione (GSH) directly or indirectly regulates the scavenging of ROS and their reaction products. Additionally, several other GSH-associated enzymes such as GSH reductase (GR, EC 1.6.4.2), GSH peroxidase (EC 1.11.1.9), and GSH sulfotransferase (glutathione-S-transferase (GST), EC 2.5.1.18) cumulatively protect fish against ROS and their reaction products accrued anomalies under toxic metals and metalloids stress conditions. The current review highlights recent research findings on the modulation of GSH, its redox couple (reduced glutathione/oxidised glutathione), and other GSH-related enzymes (GR, glutathione peroxidase, GST) involved in the detoxification of harmful ROS and their reaction products in toxic metals and metalloids-exposed fish.     

Ozone levels in the empty quarter of Saudi Arabia—application of adaptive neuro-fuzzy model

In arid regions, primary pollutants may contribute to the increase of ozone levels and cause negative effects on biotic health. This study investigates the use of adaptive neuro-fuzzy inference system (ANFIS) for ozone prediction. The initial fuzzy inference system is developed by using fuzzy C-means (FCM) and subtractive clustering (SC) algorithms, which determines the important rules, increases generalization capability of the fuzzy inference system, reduces computational needs, and ensures speedy model development. The study area is located in the Empty Quarter of Saudi Arabia, which is considered as a source of huge potential for oil and gas field development. The developed clustering algorithm-based ANFIS model used meteorological data and derived meteorological data, along with NO and NO₂ concentrations and their transformations, as inputs. The root mean square error and Willmott’s index of agreement of the FCM- and SC-based ANFIS models are 3.5 ppbv and 0.99, and 8.9 ppbv and 0.95, respectively. Based on the analysis of the performance measures and regression error characteristic curves, it is concluded that the FCM-based ANFIS model outperforms the SC-based ANFIS model.     

Oxidized starch solutions for environmentally friendly aircraft deicers

Deicers currently used for aircraft deicing, including ethylene glycol and propylene glycol, pose significant threats to surface waters, as a result of high biochemical oxygen demand (BOD) and toxicity to aquatic organisms. Oxidized starch may provide a less toxic deicer with lower BOD. The freezing point depression of starch formulations oxidized using hydrogen peroxide and catalysts (i.e., catalyzed hydrogen peroxide [H2O2] propagations-CHP) was 28 degrees C, and viscosities similar to those of commercial deicers were achieved after post-treatment with granular activated carbon. The most effective oxidized starch formulation exerted a 5-day BOD up to 6 times lower than glycol deicers (103 versus 400 to 800 g O2/L). Toxicity to Ceriodaphnia dubia for this formulation (48-hour lethal concentration, 50% [LC50] of 2.73 g/L) was greater than pure propylene glycol (13.1 g/ L), but lower than propylene glycol deicer formulations (1.02 g/L). Organic acids were identified by gas chromatography/mass spectrometry as the primary constituents in the oxidized starch solution. The proposed deicing system would provide effective deicing while exerting minimal environmental effects (e.g., lower toxicity to aquatic organisms and lower BOD). Furthermore, these deicers could be made from waste starch, promoting sustainability.     

Changing air quality in Delhi,India: determinants,trends, and policy implications

Air pollution is a major environmental problem in urban areas worldwide. Delhi, the capital city of India, is no exception to the universal pattern of deteriorating urban air quality with concentration of pollutants being well above the recommended WHO levels. The magnitude and urgency of the problem as a global environmental issue needs a systematic understanding of the potential causes of pollution and their contribution to air quality. In the present study, ambient air quality data (1987–2006) of SO₂, NO₂, SPM, and RSPM were analyzed to asses the changing air quality in the study area and to evaluate the effect of measures taken to control it. The primary data were collected from 1,583 households to examine the relationship between outdoor and indoor pollution level. Based on the data, the current study concludes that despite the implementation of different pollution-controlling measures, the pollutants, especially the particulate pollutants, were well above the standard limits set by CPCB. Integration between technological and social approach of urban planning is required to mitigate and manage urban environmental problems in sustainable manner.     

Variations in breeding success and daily nest survival of Whiskered Tern (<Emphasis Type="Italic">Chlidonias hybrida</Emphasis>) at two Iranian colonies

Variations in breeding success of the Whiskered Terns (Chlidonias hybrida) were studied in two wetlands; Anzali (2005 and 2008) and Zarivar (2007–2008) in north and west Iran. Nesting success was modeled and compared using information-theoretic approach implemented in program Mark in order to assess effects of colony locations, years and nest initiation dates on the probability of daily nest survival. Clutch size did not vary between colonies and years. Breeding success varied between colonies (Zarivar > Anzali), and years only in Anzali (2005 > 2008). Overall daily nest survival was 0.977. (95% LCI 0.973, UCI 0.981), equivalent to a Mayfield nest survival of 0.317. (95% LCI 0.255, UCI 0.387). Egg-laying periods and colony site were important covariates affecting the daily survival rates (Σω _i = 0.86 and Σω _i = 0.83, respectively), while, the support for the effect of year was less (Σω _i = 0.41). We concluded that Lake Zarivar provides a more favorable nesting location for Whiskered Terns probably because of little changes in rainfall and water depth during the breeding seasons which influence breeding performance.     

Improving Water Resistance of Soy-Based Adhesive by Vegetable Tannin

In this research tannic acid was used to prepare soy-based adhesives for making plywood and fiber board. The different resin formulations were analyzed by Differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and its derivative as a function of temperature (DTG) and Fourier Transform Infra-red (FTIR) spectroscopy. The results showed that the addition of tannic acid to soy-based adhesive decreased soy-based adhesive viscosity and its pH. The DSC analysis showed that the denaturation temperature of soy-based adhesives decrease by adding tannic acid. The TGA and DTG curves showed that the thermal degradation of soy flour starts above 146 °C. The FTIR spectroscopy results also showed that the soy flour amino acids appeared to react well with tannic acid. Furthermore, delamination and shear strength test results showed the good water resistance of plywood bonded with soy-based tannic acid-modified adhesive. The mechanical and physical properties such as MOR, MOE, IB, and water resistance of fiberboard were improved, by adding tannic acid to the soy-based adhesive.     

Effects of water shortage in Kabul River network on the plain areas of Khyber Pakhtunkhwa,Pakistan

Kabul River is a shared resource of Pakistan and Afghanistan and is a major source of economy for both countries. It is used for irrigation, power generation, fishery, hunting, and recreation. This study explored human-induced impact on Kabul River and its associated wetlands. For an in-depth study, the area situated between the two tributaries of Kabul River, i.e., Shalam and Naguman Rivers, was selected. The focus of the study was to find out reduction in the wetland areas, its causes, and associated impacts. For this purpose, a survey was conducted in 10 villages selected randomly in 10 union councils. The study revealed that anthropogenic activities, such as wetland farming, grazing residential encroachment, and industrial development, have caused severe alteration in the wetland of the study areas. The results revealed that before the 1990s, 33.55% area of the study area was wetland. Due to regular decrease in the flow of the Kabul River System and human encroachment, it has engulfed 68.40% of the total wetland leaving behind only 10.60% wetland. This can be termed as a big ecological disturbance. In the long run, this will have negative effects on both the countries. It is therefore recommended to give proper attention to this important wetland, positioning between Shalam and Naguman Rivers and to conserve it. One of the solutions is to regulate the natural flow of Kabul River.     

Organochlorine pesticides in the surrounding soils of POPs destruction facility: source fingerprinting,human health,and ecological risks assessment

Environmental Science and Pollution Research - The elimination of persistent organic pollutants (POPs) obsolete pesticides stockpiles, particularly the organochlorine pesticides (OCPs), is one of...     

Empirics on heterogeneous links among urbanization,the intensity of electric power consumption,water-based emissions,and economic progress in regional China

Environmental Science and Pollution Research - This study investigates the heterogeneous causal linkages between urbanization, the intensity of electric power consumption, water-based pollutant...     

Genotypic Variation in the Phytoremediation Potential of Indian Mustard for Chromium

The term “phytoremediation” is used to describe the cleanup of heavy metals from contaminated sites by plants. This study demonstrates phytoremediation potential of Indian mustard (Brasicca juncea (L.) Czern. & Coss.) genotypes for chromium (Cr). Seedlings of 10 genotypes were grown hydroponically in artificially contaminated water over a range of environmentally relevant concentrations of Cr (VI), and the responses of genotypes in the presence of Cr, with reference to Cr accumulation, its phytotoxity and anti-oxidative system were investigated. The Cr accumulation potential varied largely among Indian mustard genotypes. At 100 μM Cr treatment, Pusa Jai Kisan accumulated the maximum amount of Cr (1680 μg Cr g⁻¹ DW) whereas Vardhan accumulated the minimum (107 μg Cr g⁻¹ DW). As the tolerance of metals is a key plant characteristic required for phytoremediation purpose, effects of various levels of Cr on biomass were evaluated as the gross effect. The extent of oxidative stress caused by Cr stress was measured as rate of lipid peroxidation. The level of thiobarbituric acid reactive substances (TBARS) was enhanced at all Cr treatments when compared to the control. Inductions of enzymatic and nonenzymatic antioxidants were monitored as metal-detoxifying responses. All the genotypes responded to Cr-induced oxidative stress by modulating nonenzymatic antioxidants [glutathione (GSH) and ascorbate (Asc)] and enzymatic antioxidants [superoxide dismutase (SOD), ascorbate peroxidase (APX), and glutathione reductase (GR)]. The level of induction, however, differed among the genotypes, being at its maximum in Pusa Jai Kisan and its minimum in Vardhan. Pusa Jai Kisan was grown under natural field conditions with various Cr treatments, and Cr-accumulation capacity was studied. The results confirmed that Pusa Jai Kisan is a hyperaccumulator of Cr and hypertolerant to Cr-induced stress, which makes this genotype a viable candidate for use in the development of phytoremediation technology of Cr-contaminated sites.