Ologe Lagoon is one of Lagos, Nigeria’s five major lagoons, which provide essential ecosystem services such as agriculture, fishing, transportation, salt and sand mining, tourism, and industrial development. There are concerns, however, that the lagoon’s water may not be safe for the ecosystem functions it offers. As a result, the physicochemical properties, heavy metal concentrations, and microbial loads of water samples from the lagoon, as well as their health risks, were examined in this study. Physicochemical analysis showed that calcium, chloride, nitrates, sulphate, dissolved oxygen, acidity, alkalinity, total dissolved solid, and total suspended solid were present within the World Health Organization permissible limits, but not so for phosphate and temperature. The heavy metal analysis revealed that the water had non-permissible levels of iron, cadmium, chromium, nickel, manganese, and copper, but lead was normal. The microbiological examination showed abnormal bacteria counts, while coliform and fungus were not detected. The average daily oral and dermal exposure to cadmium, chromium, and nickel were higher than the recommended daily intake, but iron, lead, and copper were within the limits. The hazard quotient of oral and dermal exposure to cadmium, dermal exposure to chromium, and oral exposure to manganese were higher than the recommended limit (> 1). The carcinogenic risks of Cd, Cr, and Ni were also greater than the acceptable limit. The results obtained indicate that Ologe Lagoon’s water is unsafe for the lagoon’s ecosystem functions. Relevant agencies should ensure that waste is treated before being discharged into the lagoon.

Agricultural intensification is associated with the use of great amounts of agrochemicals that may result in the accumulation of metals in soils, and –subsequently—agricultural products and food chain. Nowadays, this is a major concern for many Iranian agricultural products, necessitating scientific researches on the issue. Therefore, the present study has been conducted to evaluate the level of metal contamination in some agricultural products of Torbat-e Jam, Iran, with the following purposes: (i) to determine concentrations of cadmium (Cd), nickel (Ni), and lead (Pb) in melon (Cucumis melo var. inodorus), sugar beet (Beta vulgaris), and maize (Zea mays) as well as water and soils of some farms in Torbat-e Jam, Iran; and (ii) to examine chemical fertilizers as a possible source of heavy metals' contamination. To do so it has taken some samples from soils, irrigation waters, chemical fertilizers, and crops, measuring their heavy metals contents by means of atomic absorption spectrometry. Results show that heavy metals' concentrations in groundwater and soil were lower than the adopted global standards. Among fertilizers, only Cd content of triple-superphosphate was higher than the standards, leading to a substantial buildup of Cd in the soil, compared to Pb. The greater use of potassium fertilizer has increased Pb concentration in the soil samples of maize farms during the growing season. Among all elements, Pb had the greatest transfer coefficient. It seems that current farm management practices as well as excessive use of chemical fertilizers may further the contamination and loss of soil quality in agricultural systems of the region.

This research aims to study the effect of Mycorrizal fungus and Plant-Growth-Promoting Bacteria (PGPB) on Cadmium (Cd) uptake by one-year-old Eucalyptus Camaldulensis seedlings. The treatments have involved three levels of heavy metal (0, 30, and 60 mg/kg) for Cd, and three bacterial levels (no bacteria (B0), Bacillus (Ba105), and Pseudomonas (Ps36, Ps448)), inoculated with mycorrhizal fungus Glomus mosseae (M1) and non-inoculated with fungus (M0). Results show that absorption of these elements in plant increased as Cd concentration in soil became more. Inoculation by Ps448 bacteria had an incremental effect on Cd uptake by 90%, compared to the non-inoculated (control) samples. Moreover, inoculation of the plants with mycorrhizal fungus increased Cd uptake by 24%, compared to the control. Also, it has been observed that plant resistance to metal stress and plant growth under such conditions ascended in treatments wherein inoculation happened with mycorrhizal fungus and bacteria. The highest Cd heavy metal uptake has been observed in Eucalyptus (shoots and roots), treatment (C2B2M1) with 648.19 micrograms per one seedling in pot. According to the obtained results, Eucalyptus with biological factors (fungi and bacteria) has the ability to clean and purify the contaminated soil with Cd heavy metal.

Environmental pollution with heavy metals has a negative impact on lawn grasses. Heavy metals are one of the priority pollutants of anthropogenic ecosystems. Earlier, plants Agrostis stolonifera, resistant to cadmium, were obtained using biotechnological method. Plants that are resistant to one heavy metal may be cross-resistant to another. The assessment of the resistance of plants obtained by biotechnological methods to other heavy metals is of practical value. The object of our study was to lawn grass - Agrostis stolonifera L. The aim of this work was to assess the tolerance of the next generation descendants  of the regenerant  Agrostis stolonifera, resistant to cadmium, to one of the most phytotoxic heavy metals - copper. Cadmium -tolerant plants were more resistant to copper. The tolerance of cadmium – resistant plants to copper is associated with  nonspecific mechanisms.  However, the increase in plant resistance was not very significant. Therefore, it is more expedient to obtain plants that are resistant to copper.

Conserving water resources and protecting them from pollution are of high account in the natural cycle of our life. This study has tried to determine the refining potential and capacity of water hyacinth (Eichhornia crassipes) in order to remove the cadmium from water, studying the influence of factors such as initial concentration of cadmium, contact time, absorbent mass, and pH. Results have shown that the best efficiency of cadmium, more than 99%, was obtained in the optimum conditions (i.e. retention time of 30 hours, adsorbent dose of three plants (12 stems), and pH=6.6). By increasing the initial concentration of cadmium from 0.28 to 8.28 mg/L, the elimination efficiency did not change; moreover, by increasing the absorbent mass, the elimination efficiency increased from 98.4 to 99.8 and the lowest retention time was obtained for the balance. All experiments have been repeated three times, showing in the end that water hyacinth is able to absorb cadmium up to 8.28 mg/L. This process follows Freundlich isotherm (R2=0.98). Results of this study indicate that this plant can grow well at high levels of cadmium and the growth of water hyacinth is better in the presence of cadmium than control conditions (city water). Finally, it can be concluded that it is necessary to provide a reliable, cheap, and fast method to eliminate pollution. Eichhornia crassipes, a promising plant with great functionality, can be used as a refiner in order to eliminate the heavy metals in wastewater (sewage) effluents, particularly industrial sewage.

Activated carbon is known an as appropriate adsorbent due to its high adsorption capacity for most pollutants, especially heavy metals. In the present study, activated carbon was synthesized from orange wood by employing the chemical activation method. Additionally, cysteine amino acid was used to modify the activated carbon surface, leading to an enhancement in adsorption ability because of having a nitrogen group. Based on the results, the adsorption capacity of the modified activated carbon was obtained at 120 mg g-1 adsorbent. The parameters affecting adsorption such as the amount of used adsorbent, as well as solution pH, primary concentration, and contact time were optimized, followed by performing the adsorption process under optimal conditions. The optimal adsorption conditions included the pH of 6, contact time of 60 min, adsorbent amount of 50 mg, and primary cadmium concentration of 80 ppm. Further, kinetic and thermodynamic parameters were assessed and optimized. The results of which represented the best fit between adsorption with Langmuir isotherm and the pseudo-second-order kinetic model. The results represented that the quasi-second-order model with a higher regression coefficient (R2 = 0.97) described the experimental data better than the quasi-first-order one (R2 = 0.83). The adherence of adsorption kinetics to the pseudo-second-order model suggested a chemical interaction as the rate-determining step. Regarding adsorption thermodynamics, the effect of temperature was examined on adsorption by using Van't Hoff's equations, which reflect the endothermicity of the process.