Abstract. Al-Abbawy DAH, Al-Thahaibawi BMH, Al-Mayaly IKA, Younis KH. 2021. Assessment of some heavy metals in various aquatic plants of Al-Hawizeh Marsh, southern of Iraq. Biodiversitas 22: 338-345. In order to describe the degree of contamination of aquatic environments in Iraq, heavy metals analysis (Fe, Ni, Cr, Cd, Pb, and Zn) was conducted for six aquatic macrophytes from different locations of Al-Hawizeh Marsh in southern Iraq. The six species were Azolla filiculoides (floating plant), Ceratophyllum demersum, Potamogeton pectinatus, Najas marina (submerged plants), Phragmites australis, and Typha domingensis (emergent plants). The results indicate that cadmium, chromium, and iron concentrations in aquatic plants were above the World Health Organization (WHO). In contrast, zinc, copper, and lead were within the allowable limits. C. demersum and N. marina showed higher concentrations of heavy metal accumulation than the other aquatic plants. The concentration of heavy metals in plant tissues during the summer months was higher than in the different seasons. C. demersum and N. marina showed higher concentrations of heavy metal accumulation than the other aquatic plants. Heavy metal bioconcentration (BCF) was calculated to assess heavy metals bioaccumulation in the aquatic plants.

Aquatic macrophyte communities and environmental factors were studied at four Al-Hawizeh marsh sites from December 2017 until November 2018. Quantitative data from thirty species of aquatic plants were collected to investigate density, vegetation cover, biomass and their relationship to the environmental factors. For emerging plants, relative abundance reached the highest values (36%) than submerged and wet species, while free-floating plants produced the lowest value (17%).Physical and chemical properties have been studied including water temperature ranging from 11.3 ° C in January to 31.4 ° C in August, dissolved oxygen (DO)ranging from 1.88 mg/L in September to 10.5 mg / L in April, pH varied from 7.2 in June to 8.4 in December, electrical conductivity (EC μ.S/cm) differs from 2257 μ.S/cm in November to 6859 μ.S/cm in April. The results identified the highest percentages of vegetation cover reported during the summer, the lowest percentages revealed during the winter for all plant groups. The highest annual vegetation cover rates for submergent species achieved 52.54% by C.demersum, for free-floating plants 66.67% of S. polyrrhiza, for emergent plants 85.5% of P. australis, 41.62% of P. paspaloide for wet plants. Total mean biomass of plant groups showed the highest value of 844.02 (gm dry weight/m2) reported by emerging plants, the lowest value of 47.25 (gm dry weight / m2) by the wet plants. Thus, biomass values were correlated with the vegetation cover values for all plants.

Increasing the demand for potable water, followed by the high quantity of discharged effluents linked with the water scarcity problems has necessitated giving more attention to improving wastewater treatment processes and operations. The constructed wetland has proven to be an excellent green sustainable technique for purification. This study aimed to examine the performance of four experimental free water surface constructed wetlands (FWSCWs) for the depuration of sewage effluents as a secondary treatment stage during winter season conditions. The objectives were to assess the raw and treated wastewater concentrations, evaluate the removal efficiency of chemical oxygen demand (COD), biological oxygen demand (BOD), nutrients, and total suspended solids (TSS) of each treatment line, and compare the impact of plastic rings (biofilm carriers) and Lemna minor L. with the presence of gravel bed on the treatment efficiency and bacterial growth, as well as assess the plant's adaption and growth. The results showed that all treatment systems improved the water characteristics, and adding biofilm carriers enhanced the efficiency of water purification, especially BOD reduction. The combination of the plants, biofilm carriers, and gravel in the wetland filter significantly enhanced (ρ < 0.05) the treatment efficiency in terms of TSS, COD, BOD, Ammonia (NH 3 ), Nitrates (NO 3 ), and Orthophosphate (PO 4 ) compared to the control treatment system (gravel bed). Plant growth was restricted in the presence of carriers in the system. Further study for examining the system performance under summer conditions, which may improve the nutrient reduction rates by biofilm carriers, is underway.

The current study aims to improve the quality of wastewater collected from the secondary sedimentation tank of Hamdan sewage water treatment plant, Basrah, Iraq, using C. demersum L. for phytoremediation potential in the laboratory experiment. The experiments were also designed to establish some toxicological effects of wastewater on plant physiology as a response to wastewater stresses. The selected physio-chemical parameters of wastewater were conducted. Plant analyses were also measured before and after 21st day of exposure. The results showed the efficiency of the plant in improving the water quality in a different ratio. The dilution 1:3 (T3) was the most efficient with a significant difference (p<0.05) between treatment and control for most of the measured parameters. The result showed the efficiency of Ceratophyllum demersum in removing the Total hardness, Ca+2, Mg+2, BOD5, COD, NO3-2, PO4-2, Na+ and Cl- in 1:3 dilution (55.88, 13.27, 89.55, 90, 47.37, 50.65, 48.51, 16.28 and 40.24)% compared with (17.65, 5.42, 27.31, 50, 15.79, 16.30, 13.86, 6.73 and 15.77 )% in control respectively. The Ceratophyllum demersum plant has proven to be effective in improving the quality of wastewater, and therefore it can be considered an effective candidate in phytoremediation technology.

This study was carried out to determine the heavy metal accumulation of Juncus rigidus Desfontaines, 1798 from three different regions of the Basrah Province in Southern of Iraq. Specifically, the concentrations of lead, nickel, and cadmium were determined in the roots, culms and leaves of the plant. The results indicated that the highest accumulation of the heavy metal was recorded in lead (Pb) 12.50± 3.58 mg kg-1 and then in nickel (< 0.30). The lowest value was recorded for cadmium (< 0.05). As well, lead concentrations in J. rigidus varied in different locations and parts of the plant from undetectable in control to 12.66, 19.33, and 9.80 mg kg-1 in leaves, culm, and roots respectively from Station 2, and 10.76, 12.66, and 9.50 mg kg-1 in Station 3. The values of translocation factor (TF), bioconcentration factor (BCF), and Biological Accumulation Coefficient (BAC) were greater than>1 used to the ability of J. rigidus for both phytoextraction and phytostabilization. The anatomical analysis showed that heavy metal accumulation in plant tissues led to a reduction in root and culm thickness; in polluted area it has been found that cortex and intercellular spaces in aerenchyma layers were deceased in size, whereas high pollution levels were observed in vascular bundles, which were smaller, and had increased sclerenchyma, as well as appeared more black or dark color compared to the specimens grown in the control area.