Spatial variation of potentially toxic elements in different grain size fractions of marine sediments from Gulf of Mannar, India

Marine sediments of the Gulf of Mannar (GoM), India are contaminated by potential toxic elements (PTEs) due to anthropogenic activities posing a risk to the existing fragile coral ecosystem and human health. The current study aimed to assess the distribution of PTEs (arsenic—As; cobalt—Co; copper—Cu, molybdenum—Mo; lead—Pb; and zinc—Zn) in marine sediments of different grain size fractions, viz., medium sand (710 μm), fine sand (250 μm), and clay (<63 μm) among the different coastal regions of Pamban, Palk Bay, and Rameswaram coasts of GoM, using grain size as one of the key factor controlling their concentrations. The concentrations of PTEs were measured in the different size fractions of sediment using inductively coupled plasma mass spectrophotometer. The order of accumulation of all PTEs in the three fractions was ranked as Zn > Cu > Pb > As > Co > Mo and in the three locations as Rameswaram > Palk Bay > Pamban. The concentration of PTEs in Palk Bay and Rameswaram coast was significantly different (P?<?0.05), when compared to Pamban coast. Measured geoaccumulation index (I _geo) and contamination factor (CF) indicated significant enrichment of Co and Pb from Rameswaram coast when compared to other two coasts. Although the concentration of Co was low but the measured I _geo and CF values indicated significant enrichment of this PTE in Rameswaram coast. The increased input of PTEs in the coastal regions of GoM signifies the need to monitor the coast regularly using suitable monitoring tools such as sediments to prevent further damage to the marine ecosystem.     

Sandbar-regulated hydrodynamic influences on river hydrochemistry at Mengabang Telipot River, Peninsular Malaysia

Influences of river hydrodynamic behaviours on hydrochemistry (salinity, pH, dissolved oxygen saturations and dissolved phosphorus) were evaluated through high spatial and temporal resolution study of a sandbar-regulated coastal river. River hydrodynamic during sandbar-closed event was characterized by minor dependency on tidal fluctuations, very gradual increase of water level and continual low flow velocity. These hydrodynamic behaviours established a hydrochemistry equilibrium, in which water properties generally were characterized by virtual absence of horizontal gradients while vertical stratifications were significant. In addition, the river was in high trophic status as algae blooms were visible. Conversely, river hydrodynamic in sandbar-opened event was tidal-controlled and showed higher flow velocity. Horizontal gradients of water properties became significant while vertically more homogenised and with lower trophic status. In essence, this study reveals that estuarine sandbar directly regulates river hydrodynamic behaviours which in turn influences river hydrochemistry.     

Elemental contamination in urban parks of Rawalpindi/Islamabad—a source identification and pollution level assessment study

The soil quality of urban parks is of vital importance as the children playing in the parks get themselves easily contaminated. A study was conducted to assess the level of elemental pollution caused by constant urbanization and industrialization, in various parks of Islamabad and Rawalpindi. The soil samples, collected from 14 urban parks of Islamabad and Rawalpindi areas, were analysed for their elemental concentrations. In each sample, 32 elements were quantified using semi-absolute k (0)-instrumental neutron activation analysis and flame atomic absorption spectrophotometry. The quality of analysis was assured by analysing the International Atomic Energy Agency (IAEA) reference material IAEA-S7 (soil). The pollution level was assessed by enrichment factor, pollution load index and our suggested indicator called "average toxic element concentration". The elemental concentrations measured in the parks of two cities were compared by t test. Four sources of different elements in the soils were identified by employing principal component analysis and cluster analysis. The results of multivariate techniques grouped all parks into four classes. The use of enrichment factor indicated the presence of Ni at slightly higher level in all parks while the pollution load index revealed that the parks of Rawalpindi were relatively more polluted as compared to that of Islamabad. The hot spot areas of elemental concentration were closely related to high traffic conditions.     

Salt marsh macrophyte Phragmites australis strategies assessment for its dominance in mercury-contaminated coastal lagoon (Ria de Aveiro, Portugal)

Introduction and aims

The dominance of a plant species in highly metal-contaminated areas reflects its tolerance or adaptability potential to these scenarios. Hence, plants with high adaptability and/or tolerance to exceptionally high metal-contaminated scenarios may help protect environmental degradation. The present study aimed to assess the strategies adopted by common reed, Phragmites australis for its dominance in highly mercury-contaminated Ria de Aveiro coastal lagoon (Portugal).

Materials and methods

Both plant samples and the sediments vegetated by monospecific stand of Phragmites australis were collected in five replicates from mercury-free (reference) and contaminated sites during low tide between March 2006 and January 2007. The sediments?? physico-chemical traits, plant dry mass, uptake, partitioning, and transfer of mercury were evaluated during growing season (spring, summer, autumn, and winter) of P. australis. Redox potential and pH of the sediment around roots were measured in situ using a WTW-pH 330i meter. Dried sediments were incinerated for 4?h at 500??C for the estimation of organic matter whereas plant samples were oven-dried at 60??C till constant weight for plant dry mass determination. Mercury concentrations in sediments and plant parts were determined by atomic absorption spectrometry with thermal decomposition, using an advanced mercury analyzer (LECO 254) and maintaining the accuracy and precision of the analytical methodologies. In addition, mercury bioaccumulation and translocation factors were also determined to differentiate the accumulation of mercury and its subsequent translocation to plant parts in P. australis.

Results and conclusions

P. australis root exhibited the highest mercury accumulation followed by rhizome and leaves during the reproductive phase (autumn). During the same phase, P. australis exhibited ??5 times less mercury-translocation factor (0.03 in leaf) when compared with the highest mercury bioaccumulation factor for root (0.14). Moreover, seasonal variations differentially impacted the studied parameters. P. australis?? extraordinary ability to (a) pool the maximum mercury in its roots and rhizomes, (b) protect its leaf against mercury toxicity by adopting the mercury exclusion, and (c) adjust the rhizosphere-sediment environment during the seasonal changes significantly helps to withstand the highly mercury-contaminated Ria de Aveiro lagoon. The current study implies that P. australis has enough potential to be used for mercury stabilization and restoration of sediments/soils rich in mercury as well.     

Genotypic variation of nitrogen use efficiency in Indian mustard

This experiment was conducted to investigate the variation of nitrogen efficiency (NE), nitrogen uptake efficiency (UE), physiological nitrogen use efficiency (PUE) among Indian mustard genotypes, grown under N-insufficient and N-sufficient conditions. Nitrogen efficiency varied from 52.7 to 92.8. Seed yield varied from 1.14 t ha(-1) to 3.21 t ha(-1) under N-insufficient condition, while 2.14 t ha(-1)-3.33 t ha(-1) under N-sufficient condition. Physiological basis of this difference was explained in terms of nitrogen uptake efficiency and physiological nitrogen use efficiency, and their relationship with the growth and yield characteristics. While nitrogen uptake efficiency was positively correlated with plant biomass (0.793**), leaf area index (0.664*), and leaf nitrogen content (0.783**), physiological nitrogen use efficiency is positively correlated with photosynthetic rate (0.689**) and yield (0.814**). This study suggests that genotype having high nitrogen uptake efficiency and high physiological nitrogen use efficiency might help in reducing the nitrogen load on soil without any penalty on the yield.     

The role of infrastructure,socio-economic development,and food security to mitigate the loss of natural disasters

Environmental Science and Pollution Research - This study shows the impact of risk (hazard, exposure, and vulnerability) and resilience (infrastructure, information and communication technology,...     

Revitalization of tourism and hospitality sector: preempting pandemics through lessons learned

Environmental Science and Pollution Research - The devastating effects of the COVID-19 pandemic have left many repercussions for the tourism industry to preempt any future catastrophe of this...     

Industrial hygiene and toxicity studies in unorganized bone-based industrial units

A large variety of ornamental and decorative items are manufactured from bone waste by various unorganized sectors in India. An initial survey indicated that workers were exposed at various phases of final product. The subjects (12 industrial units) were tested for total suspended particulate matter (TSPM), particulate matter <10  $\upmu $ m (PM₁₀), and particulate matter <2.5  $\upmu $ m (PM_2.5). Prevalent levels of TSPM ranged between 2.90 and 5.89 mg m^???3. Respirable fractions of occupational dust as PM₁₀ and PM_2.5 were found in the range of 0.30?C2.08 and 0.26?C0.50 mg m^???3, respectively. Cytotoxicity study was conducted using hemolysis as a sensitive marker. In an in vitro study, rat RBCs were exposed to the concentration of 25?C1,000  $\upmu $ g/ml for 15?C120 min. A considerable variation was observed in the hemolytic activity of samples collected from different areas. At 500  $\upmu $ g/ml concentration, the hemolytic activity (12 h) was found to be in the range of 18?C25%. Due to limitation in sample mass of respirable fractions, only one concentration (100  $\upmu $ g/ml/2 h) was used for comparative study on hemolysis of RBCs caused by PM₁₀ and PM_2.5. Interestingly, the hemolytic activity was more at PM_2.5 than PM₁₀ and TSPM. These results suggest that the respirable particles are capable of reaching deep into the respiratory system. The finding is significant notably when there are no standards available in occupationally exposed populations. This is the first such study. Data could be of importance to policy makers and regulators.