On the potential of pristine Cocos nucifera L. tissues for green desalination

Coconut palm tree (Cocos nucifera L.) tissues were used as a readily available, low-cost and green adsorbent to desalinate seawater. The tree bark (CB), husk (CH), leaves (CL) and roots (CR) were examined in their fresh (F) and dry (D) forms. The salinity removal (adsorption) efficiency followed the trend: F_CB ≈ F_CR > F_CL > D_CR > F_CL > D_CR. The sorbents from the coastal region desalinated more efficiently than those from a non-coastal region. Also, the fresh tissues were more effective and efficient than the dry parts. The salinity retention ability (desalination : desorption) follows the trend: F_CR (22.2) > F_CB (19.0) ≫ D_CR (12.3) > D_CB (11.0) > D_CL (6.14) ≈ F_CL (6.10) > F_CH (4.3) > D_CH (2.1). Moreover, the desalination fitted the pseudo-second-order kinetics than the pseudo-first-order, suggesting the predominance of chemisorption over physical removal. Overall, water pH, conductivity, total dissolved solids and dissolved oxygen (DO) correlated positively and strongly with desalination. By contrast, the density and redox potential correlated negatively, whereas temperature and DO showed no definite influence. Conclusively, F_CR and F_CB are the most suitable coconut palm tree tissues for desalination. Future studies should include chemical characterization of the tissues and system optimization for upscaling. This article is part of the theme issue 'Developing resilient energy systems'.

In-kitchen aerosol exposure in twelve cities across the globe

Poor ventilation and polluting cooking fuels in low-income homes cause high exposure, yet relevant global studies are limited. We assessed exposure to in-kitchen particulate matter (PM_2.5 and PM₁₀) employing similar instrumentation in 60 low-income homes across 12 cities: Dhaka (Bangladesh); Chennai (India); Nanjing (China); Medellín (Colombia); São Paulo (Brazil); Cairo (Egypt); Sulaymaniyah (Iraq); Addis Ababa (Ethiopia); Akure (Nigeria); Blantyre (Malawi); Dar-es-Salaam (Tanzania) and Nairobi (Kenya). Exposure profiles of kitchen occupants showed that fuel, kitchen volume, cooking type and ventilation were the most prominent factors affecting in-kitchen exposure. Different cuisines resulted in varying cooking durations and disproportional exposures. Occupants in Dhaka, Nanjing, Dar-es-Salaam and Nairobi spent > 40% of their cooking time frying (the highest particle emitting cooking activity) compared with ∼ 68% of time spent boiling/stewing in Cairo, Sulaymaniyah and Akure. The highest average PM_2.5 (PM₁₀) concentrations were in Dhaka 185 ± 48 (220 ± 58) μg m^-3 owing to small kitchen volume, extensive frying and prolonged cooking compared with the lowest in Medellín 10 ± 3 (14 ± 2) μg m^-3. Dual ventilation (mechanical and natural) in Chennai, Cairo and Sulaymaniyah reduced average in-kitchen PM_2.5 and PM₁₀ by 2.3- and 1.8-times compared with natural ventilation (open doors) in Addis Ababa, Dar-es-Salam and Nairobi. Using charcoal during cooking (Addis Ababa, Blantyre and Nairobi) increased PM_2.5 levels by 1.3- and 3.1-times compared with using natural gas (Nanjing, Medellin and Cairo) and LPG (Chennai, Sao Paulo and Sulaymaniyah), respectively. Smaller-volume kitchens (<15 m³; Dhaka and Nanjing) increased cooking exposure compared with their larger-volume counterparts (Medellin, Cairo and Sulaymaniyah). Potential exposure doses were highest for Asian, followed by African, Middle-eastern and South American homes. We recommend increased cooking exhaust extraction, cleaner fuels, awareness on improved cooking practices and minimising passive occupancy in kitchens to mitigate harmful cooking emissions.

Phytoremediation potentials of Eichhornia crassipes for nutrients and organic pollutants from textile wastewater

We used live water hyacinth (WH, Eichornnia crassipes) to purify effluents from textile factories and monitored changes in the physicochemical properties, organic pollutants, and WH biomass. Although the water plant could not thrive in the highly polluted effluents after eight weeks, it achieved 55, 91, 53, 84, 96, 53, and 55% removal efficiency for total Kjeldahl-N (tK-N), NH₃-N, organic-N, PO₄^3-, SO₄^2-, Cl^-, and hardness, respectively. Likewise, the biomass growth showed a positive and strong correlation with NH₃-N (0.998), tK-N (0.956), organic-N (0.923), pH (0.853), and EC (0.712). In contrast, chemical oxygen demand and total oil and grease (TOG) evinced negative and strong correlations of -0.994 and -0.807, respectively. Further, Cl^- correlated mildly (-0.38), while alkalinity (0.154) and water hardness (-0.296) were less influential on the biomass growth. From the removal models, an average of 312 ± 7.7 g of WH would ensure 100% remediation of the nutrients in 29.2 ± 2.5 days. Except for organic-N, the removal kinetics generally favors pseudo-first-order, suggesting the sorbates' concentration and contact time as the limiting factors. Conclusively, WH is a phytoremediator of high potentials for industrial textile effluents, provided the effluents are conditioned at optimum concentration before contact with mature WH of sufficient biomass weight. Novelty statement Eichhornia crassipes was used for simultaneous removal of nutrients and organics from textile effluents. The influence of the macrophte's biomass weight and maturity on the remediation process were examined. Also, the limiting parameters that govern the remediation process were investigated via statistical correlation and kinetic study.

Geospatial assessment of oil spill pollution in the Niger Delta of Nigeria: An evidence-based evaluation of causes and potential remedies

Based on the archival data on oil facilities, oil spill incidents, and environmental conditions, we researched the plausible causes of oil spill disasters in the Niger Delta of Nigeria between 2006 and 2019. The data were analyzed for geospatial and statistical patterns, using ArcGIS and R programming platforms, respectively. A fuzzy logic algorithm was employed to generate three oil spill disaster models (hazard, vulnerability, and risk). Ordinary Least Square algorithm was adopted to model the relationships between oil spill and two sets of predictor variables: oil facilities (oil well, flow station, and pipeline) and disaster models. We found that, during the 23 years, the Niger Delta experienced 7940 oil spill incidents, of which 67% occurred onshore. A total of 4,950, 501, 855 episodes were attributed to sabotage, corrosion, and equipment failure, with 87%, 62%, and 45% occurring onshore, respectively. Besides, 81% of the 5320 onshore oil spill cases were attributed to sabotage, while corrosion and equipment failure accounted for mere 6% and 7% of the incidents, respectively. The estimated average risk index (R = 0.20) shows that the risk of an oil spill disaster in the Niger Delta is low. Whereas, 5% of the region is characterized by a high risk of oil spill disaster. Furthermore, the regression model infers that the oil spillages exhibit a positive relationship with disaster models and oil facilities at α = 0.10. However, only 16% of the incidents were explained by disaster models, while the oil facilities account for 23% of the total cases, indicating the influence of other factors. To avert further socio-environmental damage in the Niger-Delta, oil theft and sabotage should be curbed, polluted areas are remediated, and an all-inclusive socio-economic development is prioritized.

Agro-Climato-Edaphic Zonation of Nigeria for a Cassava Cultivar using GIS-Based Analysis of Data from 1961 to 2017

To investigate the optimal cultivation conditions for cassava cultivar (TMS98/0505) in Nigeria, we employed agro-ecological zoning to delineate the cultivated lands. Using GIS-based multi-criteria analysis, we researched the influence of some meteorological and soil parameters on the clone cultivation. From the multiple-parameter climato-edaphic zoning map, an average yield of 26 t ha⁻¹ was estimated. The dry Rainforest and southern Guinea Savanna account for 80% of the favorable zones. However, with irrigation, the cultivar would yield optimally in the northern marginal zones. Further, the significant climatic parameters are sunshine hour (t = 3.292, α = 0.0064) and rainfall (t = 2.100, α = 0.0575). Thus, the potentials of a location for cassava cultivation in Nigeria largely depend on the soil conditions, sunshine hour, and rainfall. Generally, the cassava yield correlates strongly (+0.88) with the suitability map. Considering future climate variability based on the annual rainfall data, we projected an average annual rainfall range of 565–3,193 mm between 2070 and 2099. Likewise, the projected range of daily temperature for 2046–2100 is 24.57–31.94 °C. Consequently, with currently allotted farmlands, Nigeria can double her current cassava production through soil fertility enhancement and irrigation.

Sorptive process and breakthrough behavior of odorous volatile compounds on inert surfaces

The use of glass impinger is an important device for sampling and handling when measuring volatile organic compounds (SVOCs). Thus, it is important to check for possible analyte losses to the inner glass surface when carrying out sample analysis with the aid of impinger system. In this research, we evaluated the sorptive loss patterns of vapor-phase semi-volatile organic compounds [SVOCs (n = 10): acetic acid (ACA), propionic acid (PPA), i-butyric acid (IBA), n-butyric acid (BTA), i-valeric acid (IVA), n-valeric acid (VLA), phenol (PhAl), p-cresol (p-C), indole (ID), and skatole (SK)] on inert surfaces of an impinger in reference to sampling bags. The gaseous standard of these SVOCs (48–406 ppb) in polyester aluminum (PEA) bags was passed through an empty impinger in 1 L steps. The exiting SVOCs were collected on three-bed sorbent tubes for subsequent analysis by thermal desorption-gas chromatography-mass spectroscopy (TD-GC-MS). Impinger wall sorption capacities ranged from 2.0 to 21.0 ng cm⁻². The 10% breakthrough adsorption capacities on the impinger wall for acids, phenols, and indoles ranged from 1.21 ± 0.15 to 5.39 ± 0.79, 0.92 ± 0.12 to 13.4 ± 2.25, and 4.47 ± 0.42 to 5.23 ± 0.35 ng cm⁻², respectively. The observed sorptive patterns suggest that the sorptive losses of the volatile fatty acids, phenols, and indoles can occur very effectively at low ppb levels onto a glass surface.

Long-term trends in airborne SO2 in an air quality monitoring station in Seoul, Korea, from 1987 to 2013

Atmospheric concentration of sulfur dioxide (SO₂) was intermittently measured at an air quality monitoring (AQM) station in the Yong-san district of Seoul, Korea, between 1987 and 2013. The SO₂ level was compared with other important pollutants concurrently measured, including methane (CH₄), carbon monoxide (CO), nitric oxide (NO), nitrogen dioxide (NO₂), ozone (O₃), and particulate matter (PM₁₀). If split into three different periods (period 1, 1987-1988, period 2, 1999-2000, and period 3, 2004-2013), the respective mean [SO₂] values (6.57 ± 4.29, 6.30 ± 2.44, and 5.29 ± 0.63 ppb) showed a slight reduction across the entire study period. The concentrations of SO₂ are found to be strongly correlated with other pollutants such as CO (r = 0.614, p = 0.02), which tracked reductions in reported emissions due to tighter emissions standards enacted by the South Korean government. There was also a clear seasonal trend in the SO₂ level, especially in periods 2 and 3, reflecting the combined effects of domestic heating by coal briquettes and meteorological conditions. Although only a 16% concentration reduction was achieved during the 27-year study duration, this is significant if one considers rapid urbanization, an 83.2% increase in population, and rapid industrialization that took place during that period.

IMPLICATIONS

Since 1970, a network of air quality monitoring (AQM) stations has been operated by the Korean Ministry of Environment (KMOE) for routine nationwide monitoring of air pollutant concentrations in urban/suburban areas. To date, the information obtained from these stations has provided a platform for analyzing long-term trends of major pollutant species. In this study, we examined the long-term trends of SO₂ levels and relevant environmental parameters monitored continuously in the Yong-san district of Seoul between 1987 and 2013. The data were analyzed over various time scales (i.e., monthly, seasonal, and annual intervals). The results obtained from this study will allow us to assess the effectiveness of abatement strategy and to predict future concentrations trends in association with future abatement strategies and technologies.

Engineered nano particles: Nature, behavior, and effect on the environment

Increased application of engineered nano particles (ENPs) in production of various appliances and consumer items is increasing their presence in the natural environment. Although a wide variety of nano particles (NPs) are ubiquitously dispersed in ecosystems, risk assessment guidelines to describe their ageing, direct exposure, and long-term accumulation characteristics are poorly developed. In this review, we describe what is known about the life cycle of ENPs and their impact on natural systems and examine if there is a cohesive relationship between their transformation processes and bio-accessibility in various food chains. Different environmental stressors influence the fate of these particles in the environment. Composition of solid media, pore size, solution chemistry, mineral composition, presence of natural organic matter, and fluid velocity are some environmental stressors that influence the transformation, transport, and mobility of nano particles. Transformed nano particles can reduce cell viability, growth and morphology, enhance oxidative stress, and damage DNA in living organisms.

Air ionization as a control technology for off-gas emissions of volatile organic compounds

High energy electron-impact ionizers have found applications mainly in industry to reduce off-gas emissions from waste gas streams at low cost and high efficiency because of their ability to oxidize many airborne organic pollutants (e.g., volatile organic compounds (VOCs)) to CO₂ and H₂O. Applications of air ionizers in indoor air quality management are limited due to poor removal efficiency and production of noxious side products, e.g., ozone (O₃). In this paper, we provide a critical evaluation of the pollutant removal performance of air ionizing system through comprehensive review of the literature. In particular, we focus on removal of VOCs and odorants. We also discuss the generation of unwanted air ionization byproducts such as O₃, NOx, and VOC oxidation intermediates that limit the use of air-ionizers in indoor air quality management.

Toward a better understanding of the impact of mass transit air pollutants on human health

Globally, modern mass transport systems whether by road, rail, water, or air generate airborne pollutants in both developing and developed nations. Air pollution is the primary human health concern originating from modern transportation, particularly in densely-populated urban areas. This review will specifically focus on the origin and the health impacts of carbonaceous traffic-related air pollutants (TRAP), including particulate matter (PM), volatile organic compounds (VOCs), and elemental carbon (EC). We conclude that the greatest current challenge regarding urban TRAP is understanding and evaluating the human health impacts well enough to set appropriate pollution control measures. Furthermore, we provide a detailed discussion regarding the effects of TRAP on local environments and pedestrian health in low and high traffic-density environments.