The concentrations of Cd, Cu, Pb, and Zn in sediments, water, and different plant organs of six aquatic vascular plant species, Ceratophyllum demersum L. Echinochloa pyramidalis (Lam.) Hitchc. & Chase; Eichhornia crassipes (Mart.) Solms-Laub; Myriophyllum spicatum L.; Phragmites australis (Cav.) Trin. ex Steud; and Typha domingensis (Pers.) Poir. ex Steud, growing naturally in the Nile system (Sohag Governorate), were investigated. The aim was to define which species and which plant organs exhibit the greatest accumulation and evaluate whether these species could be usefully employed in biomonitoring and phytoremediation programs. The recorded metals in water samples were above the standard levels of both US Environmental Protection Agency and Egyptian Environmental Affairs Agency except for Pb. The concentrations of heavy metals in water, sediments, and plants possess the same trend: Zn > Cu > Pb > Cd which reflects the biomonitoring potentialities of the investigated plant species. Generally, the variation of heavy element concentrations in water and sediments in relation to site and season, as assessed by two-way repeated measured ANOVA, was significant (p < 0.05). However, insignificant variations were observed in the concentrations of Pb and Cd in sediments in relation to season and of Cu and Zn in relation to site. Results also showed that the selectivity of the heavy elements for the investigated plants varied significantly (p < 0.05) with species variation. The accumulation capability of the investigated species could be arranged according to this pattern: C. demersum > E. crassipes > M. spicatum > E. pyramidalis > T. domingensis > P. australis. On the basis of the element concentrations, roots of all the studied species contain higher concentrations of Cu and Zn than shoots while leaves usually acquire the highest concentrations of Pb. Cd concentrations among different plant organs are comparable except in M. spicatum where the highest Cd concentrations were recorded in the leaves. Our results also demonstrated that all the studied species can accumulate more than 1,450-fold the concentration of the investigated heavy elements in water rendering them of interest for use in phytoremediation studies of polluted waters. Given the absence of systematic water quality monitoring, heavy elements in plants, rather than sediments, provide a cost-effective means for assessing heavy element accumulation in aquatic systems during plant organ lifespan.

In view of their potential bioaccumulation of heavy metals, Ceratophyllum demersum and Myriophyllum spicatum was studied under hydroponic cultures enriched by different Pb concentrations (25, 50, 75 mg/l) for 1-7 days. Both species exerted remarkable capabilities to concentrate Pb in their tissues as compared to control. The highest accumulation value of Pb (164.26 mg/g x dw) was recorded in C. demersum and the most of metal (91.72 mg/g dw) accumulated after 1 d. Significant reduction in photosynthetic pigments and appearance of morphological symptoms such as chlorosis and fragmentation of leaves were evident after 7d at 75 mg/l. The activity of POX and APX, carotenoids and proline showed induction at lower concentration and duration followed by decline. Major re-shuffle in protein patterns appeared as a tolerant mechanism, which both species developed under Pb toxicity. Results suggest that both species responded positively to Pb concentration and accumulated high amount of metal. Due to metal accumulation coupled with detoxification potential, both species appear to have potential for use as phytoremediators and the developed responses can be used as reliable biomarkers for Pb water pollution.

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Green remediation is a known technology that uses different types of plants to extract contaminants from the environment. This study aims to remove heavy metals from treated wastewater by using natural growing plants on River Nile banks in Egypt. Secondary treated effluent was collected from West Gerga wastewater treatment plant located in Sohag city, Egypt. Experiments using two types of aquatic plants were carried out. They were planted individually and in combination with different densities on the secondary treated wastewater surface for 10 days retention time to remove cadmium (Cd), nickel (Ni) and lead (Pb). It was concluded that both plants have high capabilities to remove heavy metals directly from treated wastewater. The removal efficiency of Cd and Pb was higher when they are planted together than that of individually planted. A positive relationship was observed between detention time and heavy metals removal. The removal efficiency of heavy metals increased with the increase of plants density for both plants types. Also the availability of aquatic plants and their free cost makes their use an economically attractive alternative. In addition, the removal of these plants from River Nile improves the performance of water distribution networks in Egypt.

A laboratory experiment was led to examine the lead bioaccumulation capacity of Ludwigia stolonifera (Guill. & Perr.) exposed to various Pb concentrations (0, 10, 25, 50, and 100 mg/L) for 1, 3, 5, and 7 days. The lead accumulation increased as the metal concentrations in the solution increased and over time, to an extreme accretion of 6840 mg/kg DW(dry weight) at 100 mg/L of lead on the 10 days exposure. The proportion removal efficiency, translocation factor, and bioconcentration factor of the plant were assessed. The maximum bioconcentration factor values (1981.13) indicate that the plant was a Pb hyperaccumulator, and translocation factor values (1.85), which are >1, indicate fit of L. stolonifera for eliminating Pb in Pb-contaminated water. Photosynthetic pigments were decreased with increase of Pb concentration and time exposure. Total chlorophyll content and Chl a/b ratio lowered to between 46 and 62% at 100 mg/L Pb after 10 days exposure. Protein content and soluble carbohydrate indicated a similar trend, which showed the highest decrease (7.26 and 36.2 mg/g FW(fresh weight), respectively) at 100 mg/L of Pb after 10 days. The activity of the antioxidant enzymes superoxide dismutase, ascorbate, and peroxidase was increased significantly in comparison to the control. The results indicate that L. stolonifera is a newly recognized Pb hyperaccumulator (6840 mg/kg DW), but physiological status indicates that the plant is not tolerant to high Pb concentrations.

The aquatic species Ceratophyllum demersum and Myriophyllum spicatum were grown in a hydroponic system to analyze the activity of antioxidant enzymes and protein response under different cadmium concentrations. The behavior of the studied antioxidant enzymes (APX and POD) was affected by Cd-exposure and exhibited to some extent different activity. In comparison with control, the activity of APX and POD varied significantly (P<0.01) among Cd-treatments, where the increase in Cd-concentration coupled with an initial increase in the activity of both antioxidant enzymes and subsequent Cd-treatments caused a decline in the activity. Generally, the activity of APX found to be more pronounced in M. spicatum (4-8 fold of control) in comparison to C. demersum. The treated plants exhibited different protein patterns depending on the plant species, Cd-concentration and time of exposure. Protein synthesis appears to be more sensitive to cadmium in C. demersum, than other plants where, appearance of high molecular weight (138, 127, 112, 109 and 100 kDa) protein at 25mg/L-Cd, disappearance of 38 kDa proteins was recorded in all sets of experiment.

Long-term use of inorganic fertilizers can increase soil acidity, be harmful to the environment, and leaving bad effects on human health. Organic fertilizer application is one of the safer alternatives with numerous benefits, such as supplying nutrients for plant growth. Sunflower is one of the most important grown oilseed crops in the world. Sunflower plants need a supply of essential nutrients for their optimal growth. As a result, the aim of this research is to explore the effect and mechanism of two organic fertilizers from different sources (sugarcane bagasse ash (SBA), compost coupled with biofertilizer (CCB)) and NPK inorganic fertilizer as a control on enzyme activity, physiological traits, and the uptake of mineral contents and heavy metals in sunflower plant (Helianthus annuus L.). Fresh or dry mass (FM, DM), osmolytes and secondary metabolites, photosynthesis pigments, and enzymatic and non-enzymatic antioxidant molecules were all determined. Both sugarcane bagasse ash and compost coupled with biofertilizer resulted in a high value of fresh and dry mass, plant height, and chlorophyll content. The results revealed that the use of sugarcane bagasse ash (SBA) and compost coupled with biofertilizer increased osmolyte contents (soluble proteins and soluble sugars), antioxidants system enzyme/molecule (catalase, superoxide dismutase, peroxidase, and TGS) and secondary metabolites. However, the highest value of proline, total free amino acids, and phenolic compounds in sunflower plants was determined after NPK fertilizer application. On the contrary, it lowered Na, Na/K ratio, and Cd content. Data showed that organic fertilizers enhanced the accumulation of Cl, PO4, and SO4 content in sunflower plants. Generally, CCB and SBA treatments increased Cu, Zn, and Pb accumulation in sunflower plants. Using organic fertilizers with chemical NPK fertilizer can improve the chemical, physical, and biological soil properties.