Providing access to clean, reliable, and affordable energy by adopting hybrid power systems is important for countries looking to achieve their sustainable development goals. This paper presents an optimization method for sizing a hybrid system including photovoltaic (PV), wind turbines with a hydroelectric pumped storage system. In this paper, the implementation of different optimization techniques has been investigated to achieve optimal sizing of grid-connected hybrid renewable energy systems. A comprehensive study has been carried out between Whale Optimization Algorithm (WOA), Water Cycle Algorithm (WCA), Salp Swarm Algorithm (SSA), and Grey Wolf optimizer (GWO) to validate each one. Moreover, the optimal sizing of the system’s components has been studied using real-time information and meteorological data of Ataka region located in Egypt. The purpose of the optimization process is to minimize the cost of energy from this hybrid system while satisfying the operation constraints including high reliability of the hybrid power supply, small fluctuation in the energy injected to the grid, and high utilization of the photovoltaic and wind complementary properties. MATLAB software package has been used to evaluate each optimization algorithm for solving the considered optimization problem. Simulation results proved that WOA has the most promising performance over other techniques.

Ecological quality assessment (EQA) is important for regional socio-economic development and its sustainability. To assess the status of land ecological quality more precisely, an ecological quality assessment system with 11 indicators of ecological stability, ecosystem service function, and habitat stress was established using the analytic hierarchy process for Guangdong Province, a highly urbanized region of China. Remotely sensed data were mainly used to quantify the 11 indicators and acquire regional EQA graphs at high spatial resolution. In addition, we used the spatial autocorrelation measure Moran’s I to capture dynamic signatures of spatial organization of ecological quality in the study area. The results show that the ecological quality of the study area is heterogeneous spatially but relatively consistent in different regions. Significant positive spatial autocorrelation for EQI in Guangdong was revealed by global Moran’s I. Potential ecological hot spot or cold spot were detected based on the spatial clustering patterns that were obtained by local Moran’s I. Lands with low ecological quality is mainly distributed in economically developed areas such as the Pearl River Delta and coastal cities in eastern and western Guangdong, while those with high ecological quality are mostly situated in northern mountainous areas that have lush vegetation. The low assessment scores for Guangdong, especially for the Pearl River Delta, are highly correlated with large populations and degrees of industrial agglomeration; this is mainly because urbanization and economic development jeopardize the environment. The presented case study can facilitate information provision and targeted strategy making for environmental protection. This study provides a helpful approach to assess and to analyze the ecological status in the future research. In contrast with methods that employ a single metric and limited data, the assessment system proposed in this study expands the potential application of the remotely sensed data and enriches the methodological system for EQAs.

The deposition of toxic metals in the ecosystem contributes to the exposure and bioaccumulation of metals in the food chain, thus affecting human health. This study aimed to access the distribution of metal pollution emitted from automobiles in the dust, soil, and plant samples collected from the roadsides of national highways. Furthermore, metals were also determined in fuels and vehicular emissions. High contents of Pb, Cd, Cr, Cu, Fe, Mn, and Zn were found in roadsides as compared to control (35 km away from roads). The comparison among plants indicated that Calotropis procera and Rumex dentatus contained significantly higher metals than other plants. The concentrations of Pb, Cd, Cr, and Fe in plants were above the safe limits of the WHO/FAO. Significant and positive correlations were found between Cr, Cu, Fe, Pb, and Zn in the dust and soil samples and Cd and Cr in dust and plants. According to the results of the PCA analysis, all metals formed the first two components explaining 89.5% of the total variance. The source of these metals was attributed to automobile exhaust and dust depositions. The findings of the present study suggest that roadside plants are heavily infested with heavy metals due to vehicular smoke pollution, so the consumption of vegetation facing vehicular pollution may lead to certain physiological disorders and diseases. Graphical abstract

The present study evaluated the sequential biodiesel-bioethanol production from seaweeds. A total of 22 macroalgal species were collected at different seasons and screened based on lipid and carbohydrate contents as well as biomass production. The promising species was selected, based on the relative increase in energy compounds (REEC, %), for further energy conversion. Seasonal and annual biomass yields of the studied species showed significant variations. The rhodophyte Amphiroa compressa and the chlorophyte Ulva intestinalis showed the highest annual biomass yield of 75.2 and 61.5 g m⁻² year⁻¹, respectively. However, the highest annual carbohydrate productivity (ACP) and annual lipid productivity (ALP) were recorded for Ulva fasciata and Ulva intestinalis (17.0 and 3.0 g m⁻² year⁻¹, respectively). The later was selected for further studies because it showed 14.8% higher REEC value than Ulva fasciata. Saturated fatty acids (SAFs) showed 73.4%, with palmitic acid as a dominant fatty acid (43.8%). Therefore, biodiesel showed high saturation degree, with average degree of unsaturation (ADU) of 0.508. All the measured biodiesel characteristics complied the international standards. The first route of biodiesel production (R1) from Ulva intestinalis showed biodiesel recovery of 32.3 mg g⁻¹ dw. The hydrolysate obtained after saccharification of the whole biomass (R2) and lipid-free biomass (R3) contained 1.22 and 1.15 g L⁻¹, respectively, reducing sugars. However, bioethanol yield from R3 was 0.081 g g⁻¹ dw, which represented 14.1% higher than that of R2. Therefore, application of sequential biofuel production using R3 resulted in gross energy output of 3.44 GJ ton⁻¹ dw, which was 170.9% and 82.0% higher than R1 and R2, respectively. The present study recommended the naturally-grown Ulva intestinalis as a potential feedstock for enhanced energy recovery through sequential biodiesel-bioethanol production.

Phytoplankton-derived particulate matter (PPM) is the active component of the solid particles in eutrophic shallow lakes. To date, understanding of the degradation characteristics of PPM and the effect of degradation products on nutrient cycling in water are limited. In this study, field observations and simulation experiments were carried out to elaborate the nutrient transformation during phytoplankton-derived particulate matter deposition in the cyanobacterial blooming area of Lake Taihu. Results showed that the deposition of the PPM was strongly facilitated by the cyanobacterial bloom and the sediment resuspension. The main variation characteristics of phosphorus (P) species in PPM are shown in the increase of Ortho-P and the decrease of biodegradable phosphorus (Poly-P, DNA-P) during the deposition of PPM. The degradation of the PPM resulted in the release of dissolved nitrogen (N) and P to the water body. The conversion of easily degradable particulate N and P in the PPM to ammonium nitrogen (NH₃-N) and soluble reactive phosphorus were believed to be responsible for this phenomenon. The cycling of nutrients and the cyanobacterial bloom status might therefore be altered because of the deposition and degradation of PPM. More considerations should be given on this process in future works.

The aim of the present study was to assess physico-chemical water parameters, granulometric sediment characteristics and concentrations of trace and macroelements in the water and sediments of the Ilova River. Samplings were conducted at three sampling sites (near villages Maslenjača, Ilova and Trebež) along the Ilova River, differing in the source and intensity of the anthropogenic influence. This study indicated disturbed environmental conditions, most pronounced in the downstream part of the river (Trebež village) impacted by the activity of fertilizer factory. Water from the Ilova and Maslenjača villages was of good quality, whereas COD, nitrates and phosphates exceeded the good quality levels in Trebež village. Trace and macroelement concentrations in water were mostly below thresholds set by environmental quality standards at all locations, but levels of Al, As, Cd and Ni were few times higher in Trebež village than at other locations. Metal contamination assessment of sediments (trace and macroelement concentrations, contamination and enrichment factor, pollution load index) confirmed deteriorated environmental quality in Trebež village. However, the overall assessment performed in this study revealed that anthropogenic impact was still not particularly strong in the Ilova River ecosystem. Nevertheless, the observed water and sediment characteristics serve as a warning and suggest that stricter protection measures should be initiated, including continuous monitoring and comprehensive quality assessment of the downstream part of the Ilova River, especially because it is a part of the protected area of the Lonjsko Polje Nature Park.

Nowadays, determining the factors influencing carbon dioxide emissions is a crucial issue for policymakers. So, this study examines Porter and pollution haven’s hypothesis via foreign direct investment, financial development, and energy consumption in 14 countries of the MENA region during 2004–2016, using panel quantile regression that estimated the impact of these factors in quantiles of 0.1, 0.25, 0.5, 0.75, and 0.9. Also, the effect of population, trade openness, and economic growth variables has been investigated as controlling variables on CO₂ emissions. The results of the research show that the impact of energy consumption, economic growth, and total population on all quantiles of carbon dioxide emission is positive and significant. Still, the effect of direct foreign investment on the amount of CO₂ emissions is negative and only significant at 0.1, 0.5, and 0.75 quantiles, which supports Porter's hypothesis. Based on this hypothesis, the foreign direct investment entrance helps reduce the environmental pollution of the host country. Also, the effect of financial development on 0.25, 0.5, 0.75, and 0.9 quantile carbon dioxide emissions is negative and significant. Finally, the trade openness variable has a positive and significant effect on the quantiles of 0.1 and 0.9 CO₂ emissions.

Selenium (Se) is beneficial for plant growth under different stressful conditions. In this study, we investigated the protective effects of Se supply from Cd-induced damages in tall fescue under Cd stress. Tall fescue seedlings (40 days old) were treated with Cd (30 mg/L, as CdSO₄·8/3 H₂O) and Se (0.1 mg/L, as Na₂SeO₃) individually and in combination using 1/2 Hoagland’s solution system for 7 days. Various physiological parameters, photosynthetic behaviors, and gene expressions were measured. The results showed that Cd-stressed plants displayed obvious toxicity symptoms such as leaf yellowing, decreasing plant height, and root length. Cd stress significantly increased the malondialdehyde (MDA) content and electrolyte leakage (EL), and remarkably reduced the chlorophyll and soluble protein content, antioxidant enzyme activities, and photosynthetic efficiency. Cd stress significantly inhibited the expression of two photosynthesis-related genes (psbB and psbC), but not psbA. In addition, it significantly inhibited the expression of antioxidant system-related genes such as ChlCu/ZnSOD, CytCu/ZnSOD, GPX, and pAPX, but significantly increased the expression of GR. However, Se improved the overall physiological and photosynthetic behaviors of Cd-stressed plants. Se significantly enhanced the chlorophyll and soluble protein content and CAT and SOD activities, but decreased MDA contents, EL, and Cd content and translocation in tall fescue under Cd stress. Furthermore, under Cd stress, Se increased the expression of psbA, psbB psbC, ChlCu/ZnSOD, CytCu/ZnSOD, GPx, and PAPx. The result suggests that Se alleviated the deleterious effects of Cd and improved Cd resistance in tall fescue through upregulating the antioxidant system, photosynthesis activities, and gene expressions.

This study explores the contamination potential of groundwater due to the use of sodium chloride (NaCl) in the wintertime. The research was conducted in two Iranian cities, Malayer and Hamedan, where groundwater is the major source of water for drinking and irrigating purposes. However, the amount of deicing salt used in the former is about 10 times less than that used in the latter. The assessment of geochemical dataset from 2004 to 2018 revealed no significant trend in the groundwater characteristics of Malayer where the water quality indices were in the range of WHO and USEPA permissible limits. In contrast, the indices had a continually increasing trend (~ 2.3% annually) in Hamedan’s supply wells over the same period and particularly near the urban areas that showed higher levels (> 5 times on average) than those observed in Malayer. This could mainly be ascribed to the influx of halite. Based on the USSL diagram, the water samples retrieved from the latter system were mostly classified as C3-S1 (decreasing the soil fertility) and even as C4-S2 (harmful for agriculture activities). Chloride contamination rates also reached 250 mg/L, which could negatively affect the water potability and threaten the aquatics microorganisms. In this region, a rather similar distribution of NaCl and arsenic was observed, implying mobilization of toxic trace metals with the increased salt encroachment into the aquifer. Based on such findings, it is suggested that in snow-influenced cities (e.g., Hamedan), new approaches for winter maintenance be considered to prevent the gradual deterioration of water resources.

An objective understanding of the current situation and influencing factors of rural green development in China is an important prerequisite for effective formulation making of green development policies. Based on the panel data of 31 provinces of China from the year 1997 to 2017, this paper constructs and measures the rural green development efficiency (RGDE) based on Driving-Force, Pressure, State, Influence, Response (DPSIR) model and super-efficiency slacks-based measure (SBM) model. The results show that, the overall RGDE in China is fluctuating and rising from 1997 to 2017, and there are some differences between and within regions. The RGDE in developed areas is higher than that in developing areas, and coastal areas are higher than that in inland areas. The entire country, eastern, central, and western regions show σ convergence, which indicates that the RGDE is getting better, but there is no absolute β convergence, that means there is no “catch-up effect” between regions, but the gradient divergence showed central > eastern > western. At the same time, there is no conditional β convergence; the initial RGDE has a positive impact on the growth rate of RGDE, and the financial self-sufficiency rate promotes the growth of RGDE of the whole country and the western region, but inhibits the improvement of RGDE of the eastern region. The per capita GDP, mechanization degree, and agricultural industrial structure in rural areas did not promote the growth of RGDE. Based on the results, this paper puts forward some policy suggestions, such as promoting the classified implementation of rural green development policies, strengthening the top-level design, optimizing the existing agricultural mechanism and system, and guiding and standardizing the farmers’ green production behavior.