Constructed wetlands (CWs) and algae tanks are regarded as promising polishing steps to treat wastewaters for the removal of persistent organic pollutants, such as pharmaceuticals and personal care products (PPCPs). In this systematic review, we provide a synthesis of the relationship between the presence of the most widely studied PPCPs in domestic wastewater and the conformation of the CWs and algae tanks constructed to treat them. The six drugs most commonly found in the reviewed articles were caffeine, carbamazepine, diclofenac, ibuprofen, ketoprofen, and naproxen. Removal efficiency of the PPCPs was evaluated by means of the following selected parameters: hydraulic retention time (HRT), system flow rate, temperature, inflow concentration, and average removal rate. The average removal rate of PPCPs in CWs showed a positive and moderate relationship with the HRT (r = 0.346). A different flow configuration and plant species acted better for different target compounds. The average concentration reduction ranged from 80% for caffeine to zero reduction levels in some conformations for carbamazepine, diclofenac, and ketoprofen. There was a wide variation in the concentration reduction of different plant genera or unplanted tanks, ranging from 81% (caffeine using Phragmites sp.) to no reduction in an unplanted tank for diclofenac. The algae tanks were more efficient in removing most of the six target compounds than the wetlands. Removal rates ranged from 50% for ketoprofen to 16% for naproxen. According to our results, a combination of CW systems and algae tanks might be an effective alternative for the removal of PPCPs from domestic wastewater.

This paper investigated the photodegradation of oxytetracycline (OTC) in the presence of dissolved organic matter (DOM) and chloride ions, which is relevant to the estuary environment. The separate effects of chloride ions and DOM on the photodegradation of OTC were first studied, and then, the combined effects were studied. The photodegradation of OTC showed a tendency to decrease with increasing DOM levels: a low concentration of DOM (< 2 mg/L) enhanced the degradation of OTC, and a high concentration of DOM (> 5 mg/L) inhibited it. The addition of chloride ions (10–500 mmol/L) to DOM solutions (20 mg/L) significantly increased the degradation rate of OTC. The observed promotion effects may be a consequence of the participation of reactive chlorine species. Quenching experiments verified that the main active species in the presence of chloride ions and DOM are radicals including Cl•/Cl₂•⁻ and HO•. These results indicate a promotion of OTC degradation in saline water compared with fresh water, and this finding is important to better understand the environmental fate of OTC in estuarine and coastal waters.

The issues of heavy metal contamination in water sources have been increasing substantially along with the rapid pace of industrial revolution. Lead, particularly, is one of the heavy metals that received considerable attention lately due to its frequent detection in the environment and hazardous effects. Although conventional water treatment processes had been utilized for ages, it is still a challenge to remove lead in the treatment plant effectively. In line with the advancement of chemistry and nanotechnology, the study on hydroxyapatite (HAp) nanopowder made from fish waste (skin, bones, and scales) has brought to its beneficial use as an adsorbent for lead removal in water. This paper reviews on the sources, occurrences, and health effects of lead as well as the treatment of lead using HAp adsorbent for its removal in water.

Magnetic Fe₃O₄ assembled on nanoscale zero-valent iron (nZVI) supported on an activated carbon fiber (ACF) to form nanoscale magnetic composites (nZVI-Fe₃O₄/ACF) for removing Cr(VI) and Cu(II) from aqueous solution through a permeable reactive column was synthesized via an in situ reduction method. The nZVI-Fe₃O₄/ACF composites and the interaction between nZVI-Fe₃O₄/ACF and both Cr and Cu ions were characterized by field emission scanning electron microscopy (FESEM) with EDX, TEM, XRD, and XPS. Batch experiments were used to analyze the effects of main factors on Cr(VI) removal and investigate the simultaneous removal of Cr(VI) and Cu(II) through a permeable reactive column. The results indicated that the ACF and Fe₃O₄ can inhibit the agglomeration and enhance the dispersibility of nZVI, and Fe₃O₄ and nZVI displayed good synergetic effects. The removal efficiency of Cr(VI) improved with the increase amount of Fe₃O₄ in the nZVI-Fe₃O₄/ACF composites. With low initial concentration of Cr(VI) and acidic conditions, ~ 90% of 20.0 mg·L⁻¹ Cr(VI) in the solution was removed after 60 min. The removal of Cr(VI) was also affected by coexisting ions. The removal efficiency of 10.0 mg·L⁻¹ Cu(II) was ~ 100% after 45 min of reaction, and the presence of Cu(II) can accelerate the reduction of Cr(VI). The simultaneous removal mechanisms of Cr(VI) and Cu(II) by the nZVI-Fe₃O₄/ACF composites also were proposed.

The utilization of construction and demolition waste materials for the radionuclide immobilization by sorption processes was investigated. Given that the liquid radioactive waste usually has a complex composition and that effects of competition may significantly influence the efficiency of the treatment, the Simplex Centroid experimental design was used to explore ions sorption from multi-component solutions. For the purpose of this study, the common components of construction and demolition waste, such as pathway concrete and different bricks samples, were used along with the multi-component Sr²⁺, Co²⁺, and Ni²⁺ ions solutions. The equations for the prediction of metal ions sorption capacities were derived. The coefficients that correspond to the linear and interaction terms were obtained using a special cubic model. Likewise, by analysis of variance, statistically significant terms of the obtained polynomial were defined. The investigation has shown that the most effective sorption was onto the pathway concrete for all three cations, while the highest sorption capacity was found for Co²⁺ ions. Also, it has been determined that concerning Sr²⁺ ion removal there was a competition with coexisting Co²⁺ and Ni²⁺ ions, reducing its sorption capacity, while sorption of Co²⁺ and Ni²⁺ occurred more independently on other cations in multi-component solutions. Based on the obtained results, the applied experimental design can be efficiently used for the description of competitive sorption process and could be a powerful tool for the prediction of cation immobilization in liquid radioactive waste treatment.

Malva sylvestris L. is a widely consumed edible-medicinal plant growing all around the world. The aim of our study was the determination of the concentration levels of heavy metals in M. sylvestris L. samples and their extracts from polluted and non-polluted locations in Niš, Republic of Serbia. The analysis of heavy metals was performed by the AAS (Atomic Absorption Spectroscopy) method from soil, plants, and extracts. The heavy metals content (Fe, Cu, Mn, Ni, Pb, Zn, and Cd) in the soil and plants from the contaminated site is increased, but the coefficients of metal uptake are not significantly different in plants from polluted and non-polluted areas. The highest content of metals was found in aqueous, then water-alcoholic, and the smallest content was determined in alcoholic solutions. The content of the tested metals is within the limits recommended by international organizations, so the plant and its extracts can be safely used.

Global trade plays an imperative role in the world economy that yields environmental degradation. Therefore, the current paper’s ambitions are to explore the trade–air pollution nexuses by introducing the value-added trade (VT) concept from a global value chain stance. The value-added trade (VT) indicator is constructed by the World Input-Output (WIOD) classifications database. Owing to scanty data accessibility, the sample set is reduced to 39 countries covering the period from 1995 to 2009. Furthermore, this paper is also contributing by including the eight different pathways of per capita air pollution in terms of ammonia (NH3), carbon monoxide (CO), carbon dioxide (CO₂), methane (CH₄), nitrogen oxides (NOₓ), nitrous oxide (N₂O), sulphur oxides (SOₓ) and non-methane volatile organic compounds (NMVOC) respectively. The valuable outcomes from empirical analysis have been found; Firstly, it explores that the preliminary stage of the development of value-added trade (VT) has a positive impact on air-bonds pollution. However, in the later stage of the economic development, trade improves the environmental quality as the square of value-added trade (VT²) has a negative impact on air pollution. Moreover, it also elaborates that the magnitude impact of trade on carbon monoxide (CO) air pollution is more than the other seven air pollutants. Thirdly, the inverted U-shape in the trade–air pollution Environmental Kuznets Curve (EKC) hypothesis, the non-linear relationship between trade and pollution is also validated in all eight air pollutants indicators. Policy proposals for green economy that underlines the global value chain stance and environmental factors in the growing economy are proposed.

Residues from mining, as metabasalt powder from amethyst exploration, can be used to improve soil properties. Although there is a high-load content of clay minerals in metabasalt, the effects of this residue on cooper (Cu²⁺) and zinc (Zn²⁺) sorption and desorption have not been studied. The aim of this work was to evaluate Cu²⁺ and Zn²⁺ sorption capacity of metabasalt powder and to discuss the mineralogical behavior facing this phenomenon. This residue sorption capacity was compared to reference clay minerals under two Cu²⁺ and Zn²⁺ concentrations (8 and 16 cmolc/kg) in a competitive system (Cu²⁺ + Zn²⁺). The sorption capacity was estimated by sequential desorption using cation exchange resin. A survey of mineralogical and Cu²⁺ and Zn²⁺ concentrations was performed on metabasalt before and after sorption, and after desorption tests. All materials sorbed higher amounts of Cu²⁺ than Zn²⁺. The sorption magnitude decreased in the following order: metabasalt > montmorillonite > illite > kaolinite. Cu²⁺ and Zn²⁺ desorption from metabasalt is lower than the standard clay minerals, since the metabasalt sorption sites are expandable interlayers of clay minerals. The relevance and application of our findings are critical in providing information for the management of metabasalt residue, suggesting potential use as a remediation agent in contaminated water, especially those with high Cu²⁺ and Zn²⁺ loading. It also suggests that the Cu²⁺ and Zn²⁺ enrichment of this residue could potentially be used for converting the metabasalt into a useful source of slow nutrient supply for agricultural soils.

A pot experiment was performed to examine the role of foliar applied mannitol (M) in chromium (Cr) stress alleviation in different maize cultivars. Two maize cultivars, one tolerant (6103) and one sensitive (9108) to chromium stress, were grown in soil treated with three concentrations of Cr (0, 5, and 10 mg kg⁻¹) and three levels of mannitol (0, 50, and 100 mg L⁻¹). Chromium stress decreased the overall growth of plants by reducing the plant height, root/shoot dry weight, chlorophyll contents, and enzymatic activities, while exacerbated the severity of reactive oxygen species in both maize cultivars. Chromium-induced reduction in growth attributes of maize plants was relatively higher in sensitive cultivar than that of tolerant one. Uptake of Cr by the plants and its translocation from roots to shoots increased with increasing concentration in the soil. However, foliar application of mannitol significantly alleviated the Cr stress and improved growth, biomass, and photosynthetic pigments of maize plants. Mannitol also considerably reduced Cr contents in leaves and roots of both cultivars. Hence, it is concluded that mannitol can be helpful for crops grown on heavy metal, especially Cr, contaminated soils for remediation purpose.

Forest soils (mainly soil organic carbon) play an important role in the retention of nitrogen and mercury, and loss of the forest floor during wildfires can stimulate N and Hg losses. In this paper, we investigate long-term impacts of forest fire on soil N and Hg concentrations at Acadia National Park (ANP) in Maine. Acadia National Park experienced a severe fire in 1947. Within the national park, Hadlock Brook watershed was left unburned, whereas most of Cadillac Brook watershed was intensely burned, with substantial loss of the forest floor. Post-fire regeneration in Cadillac was mostly as hardwood species, whereas vegetation in Hadlock remained predominantly softwood. We sampled soils in both watersheds in 2015, approximately 70 years after the fire. The soils were analyzed for total carbon (TC), total nitrogen (TN), total mercury (THg), and methylmercury (MeHg) content. Compared to Hadlock, Cadillac soils had ~ 50% lower TC, ~ 40% lower TN, and ~ 50% lower THg content, reflecting the loss of forest floor 70 years ago. Methylmercury concentrations in Cadillac were approximately 2 times the concentrations in Hadlock, indicating that conditions were more conducive to methylation, potentially due to differences in forest type. Long-term comparisons of stream DOC, NO₃⁻, and THg concentrations between the two watersheds demonstrated that concentrations were significantly lower in Cadillac Brook, reflecting greater retention in Cadillac and a legacy of lower atmospheric deposition in the hardwood as compared to softwood watershed. This study provides insights on the multi-decadal recovery from a stand-replacing disturbance and underscores the persistence of altered soil biogeochemistry.