Arifin Abdu

Phytoremediation of heavy metals: A green technology

The environment has been contaminated with organic and inorganic pollutants. Organic pollutants are largely anthropogenic and are introduced to the environment in many ways. Soil contamination with toxic metals, such as Cd, Pb, Cr, Zn, Ni and Cu, as a result of worldwide industrialization has increased noticeably within the past few years. There are some conventional remediation technologies to clean polluted areas, specifically soils contaminated with metals. In spite of being efficient, these methods are expensive, time consuming, and environmentally devastating. Recently, phytoremediation as a cost effective and environmentally friendly technology has been developed by scientists and engineers in which biomass/microorganisms or live plants are used to remediate the polluted areas. It can be categorized into various applications, including phytofiltration, phytostabilization, phytoextraction, and phytodegradation. A brief review of phytoremediation of soils contaminated with heavy metals has been complied to provide an extensive applicability of this green technology. Key words: Phytoremediation, heavy metals, soil pollution, toxicity.

Heavy metal uptake and translocation by Justicia gendarussa Burm F. from textile sludge contaminated soil

Abstract Heavy metals are dangerous environmental pollutants that can be transferred and accumulated in human and animal bodies causing deoxyribonucleic acid (DNA) damage and carcinogenic effects. A glass house experiment was conducted to evaluate the potential of Justicia gendarussa Burm F. to absorb heavy metals from textile industry sludge. Justicia gendarussa seedlings were planted on six different growth media (soil+sludge) comprising: 100% soil, 100% sludge, 80% sludge+20% soil, 60% sludge+40% soil, 40% sludge+60% soil and 20% sludge+80% soil. The maximum height increment and number of leaves were found in 20% sludge+80% soil while the highest basal diameter increment was recorded in the 100% sludge. Copper and iron were highly concentrated in the roots, zinc in the leaves, while aluminium was concentrated in both leaves and stems. Justicia gendarussa seems to have a high potential to absorb high amounts of Al and Fe in the leaves and roots. This species showed high translocation (TF) and low bioconcentration factor (BCF) in the contaminated soil. Justicia gendarussa was able to tolerate and accumulate a high concentration of heavy metals. Therefore, this species can be considered as a potential phytoremediator.

Assessment of heavy metal uptake and translocation in Dyera costulata for phytoremediation of cadmium contaminated soil

Abstract Heavy metal pollution is a widespread global problem causing serious environmental concern. Cadmium, one of the heavy metals, is water soluble and can be transferred from soil to plants and enter into the food chain. It is detrimental to human health because it accumulates in the body and can cause renal tubular dysfunction, pulmonary emphysema and osteoporosis. This heavy metal needs to be cleaned up for a clean and safe environment. An experiment was conducted to evaluate the potential of Dyera costulata as a phytoremediator to absorb cadmium from contaminated soils. Dyera costulata seedlings were planted on six different growth media (soil + different levels of cadmium): Control, 25 ppm Cd, 50 ppm Cd, 75 ppm Cd, 100 ppm Cd and 150 ppm Cd. The highest growth performance mainly height, basal diameter and number of leaves were in the control, 50 ppm Cd and 25 ppm Cd treatments, respectively. The highest accumulation of cadmium (52.9 ppm) was in the 75 ppm Cd treatment. Among the plant parts, leaves showed the highest concentration of cadmium. Dyera costulata showed high translocation factor and low bioconcentration factor values in soil at high cadmium concentrations and was also able to tolerate and accumulate high concentrations of cadmium. The roots of Dyera costulata were found to be suitable for the absorption of cadmium in contaminated soils. This species can be an efficient phytoremediator for soils contaminated with cadmium.

Influence of agricultural activity on soil morphological and physicochemical properties on sandy beach ridges along the east coast of Peninsular Malaysia

ABSTRACT Along the east coast of Peninsular Malaysia, beach ridges are formed with interspersed swales, which are referred to locally as beach ridges interspersed with swales (BRIS). Although BRIS soils are regarded as problematic lowland soils for agriculture because of their very sandy texture and concomitant infertility, agricultural activities in such soils have been recently increasing. This study was conducted to characterize the BRIS soils and to evaluate the influence of agricultural activities on soil characteristics and fertility. Three 1-km transects from the shoreline running inland were established; two transects passed through the experimental farm of Cherating Station of the Malaysian Agriculture Research Development Institute while the other transect passed through an adjacent remnant forest. The soils located close to the shoreline and that further inland were classified as Typic Quartzipsamments and Typic Haplohumods, respectively. The soils had a very high sand content, occasionally exceeding 95%, were acidic and had low cation exchange capacity (CEC) values. While soil organic matter was the determining factor for cation exchange capacity, the regression slope of CEC against soil carbon in the Bhs horizon of the Spodosols was different from that in the other horizons. Because the effective CEC value was much lower than the CEC value, the development of the negative charges on variable-charge surfaces seemed to be largely restricted under acidic conditions. For the Spodosols, the levels of aluminum (Al) and iron (Fe) oxides extracted with acid ammonium oxalate and those oxides with dithionite-citrate-sodium bicarbonate were negligible in the A to E horizons, but they showed sharp peaks in the Bhs horizons. Agricultural activities affected the soil in three ways. First, the A horizon of the farm soil had lower amounts of total carbon (C) and nitrogen (N) compared with the forest, suggesting insufficient input of plant litter to sustain original levels of soil organic matter. Second, although the levels of pH, and exchangeable calcium (Ca) and magnesium (Mg), were higher in the farm soil than the forest, exchangeable potassium (K) was occasionally not detected despite fertilizer application. This finding might be due to the preferential adsorption of divalent cations over monovalent K on the variable negative charges on soil organic matter surfaces as well as limited development of the charge sites in the sandy soil. Finally, the Spodosols under agricultural land use had the highest peak of available phosphorus (P) in the Bhs horizon despite its low level in the overlying A and E horizons. While phosphate is known to be immobile relative to other anions, our finding suggest the downward translocation of mineral P from fertilizer and its retention in the Bhs horizon. Based on the findings, soil organic matter was very important in BRIS soil. Increasing organic matter levels of the soils can improve soil fertility through enhancing cation exchange capacity and the resulting increase in basic cations.

Soil morphological and chemical properties in homegardens on sandy beach ridges along the east coast of Peninsular Malaysia

ABSTRACT The morphological and chemical properties of homegardens in the beach ridges with interspersed swales (BRIS) soils were evaluated in order to find a clue for developing sustainable agricultural management. Field survey and soil sampling were conducted at the homegardens and secondary forests in Sungai Ular Village and in the experimental farm of Malaysian Agriculture Research Institute (MARDI), Cherating Station. Chemical fertilizers including ash, charcoal waste and plant litter were applied to the homegardens in both the inland-ward area (HG-I) and in the shoreline area (HG-S). Manure was applied in HG-I and seafood waste from fish processing was buried in the soils in HG-S. High correlation was found between total carbon (T-C) and cation exchange capacity (CEC), indicating soil organic matter was the determinant factor for CEC in the very sandy BRIS soils. The levels of T-C, total nitrogen (T-N), and CEC at 0–10 cm in HG-I in parallel with increasing ages of homegardens. The soils in 0–10 cm and 20–30 cm showed higher levels of T-C and T-N with higher C/N ratios in HG-I than in HG-S and the MARDI farm. The high levels of exchangeable Ca, Mg, and K in HG-I compared with the MARDI farm, suggesting that improved CEC with increasing soil organic matter in HG-I heighten the retention of basic cations supplied as chemical fertilizer, ash, and manure. The level of available P was higher in HG-S than HG-I, attributed by the seafood waste application in the shoreline area. Thus, on the BRIS, the levels of soil organic matter and nutrients can be sustained by the homegarden management although it cannot be regarded as a closed system compared with those in the other tropical regions because chemical fertilizer was used and a certain amounts of nutrients seemed to leach down beyond plant rooting depth.