In a reconnaisance soil geochemical and plant survey undertaken to study the heavy metal uptake by major food crops in Malaysia, 241 soils were analysed for cation exchange capacity (CEC), organic carbon (C), pH, electrical conductivity (EC) and available phosphorus (P) using appropriate procedures. These soils were also analysed for arsenic (As), cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), mercury (Hg), nickel (Ni), lead (Pb) and zinc (Zn) using aqua regia digestion, together with 180 plant samples using nitric acid digestion. Regression analysis between the edible plant part and aqua regia soluble soil As, Cd, Cr, Cu, Hg, Ni, Pb and Zn concentrations sampled throughout Peninsular Malaysia, indicated a positive relationship for Pb in all the plants sampled in the survey (R2 = 0.195, p < 0.001), for Ni in corn (R2 = 0.649, p < 0.005), for Cu in chili (R2 = 0.344, p < 0.010) and for Zn in chili (R2 = 0.501, p < 0.001). Principal component analysis of the soil data suggested that concentrations of Co, Ni, Pb and Zn were strongly correlated with concentrations of Al and Fe, which is suggestive of evidence of background variations due to changes in soil mineralogy. Thus the evidence for widespread contamination of soils by these elements through agricultural activities is not strong. Chromium was correlated with soil pH and EC, Na, S, and Ca while Hg was not correlated with any of these components, suggesting diffuse pollution by aerial deposition. However As, Cd, Cu were strongly associated with organic matter and available and aqua regia soluble soil P, which we attribute to inputs in agricultural fertilisers and soil organic amendments (e.g. manures, composts).

Magnetic and non-magnetic fractions of coal fly ashes from SE US electric power plants were characterized with special emphasis on the potential environmental consequences of their terrestrial disposal. Quartz and mullite were the crystalline minerals dominating the non-magnetic fractions. Magnetic fractions contained magnetite, hematite, and, to a lesser extent, quartz and mullite. Chemical analyses revealed that magnetic fractions had about 10 times higher concentrations of Fe, and 2-4 times higher concentrations of Co, Ni, and Mn. Non-magnetic fractions were enriched in K, Al and Ca. Iron content within fly ash particles was negatively correlated with elements associated with aluminosilicate matrix (Si, Al, K, Na). Solubility of most elements was higher in the non-magnetic than in the magnetic fractions of alkaline fly ashes at comparable pH. Calcium was associated with the non-magnetic fraction of the alkaline fly ashes which resulted in a higher pH buffering capacity of this fraction.

The disposal of industrial paper mill sludge waste is a big issue and has a great importance all over the world. A study was conducted to determine the chemical properties of recycled paper mill sludge (RPMS) and assess its possibilities for land application. RPMS samples were collected from six different paper mills in Malaysia and analyzed for physical and chemical properties, heavy metals, polycyclic aromatic hydrocarbons, 13C-NMR spectra and for the presence of dioxins/furans. The RPMS was dewatered, sticky with a strong odour, an average moisture of 65.08%, pH 7.09, cation exchange capacity (CEC) 14.43 cmol (+) kg–1, N 1.45, P 0.18, K 0.12, Ca 0.82, Mg 0.73, Na 0.76 and Al, 1.38%. The polycyclic aromatic hydrocarbons (PAHs) and heavy metals levels were below the standard Class 2 limits. The dioxin and furan were in below the standard concentration of Class 1. The most prominent peak in the 13C-NMR spectra of RPMS was centered at 31 ppm, proving the presence of methylene (-CH2) groups in long aliphatic chains, with lipids and proteins. The signal at 89 ppm and highly shielded shoulder at 83 ppm were due to presence of cellulose carbon C-4, and the peak at 63 and 65 ppm was due to the cellulose carbon spectrum. The RPMS therefore contains significant amount of nutrients with safe levels of heavy metals and PAHs for environment and can be used as a fertilizer and soil amendment for land application.

The decomposition and nutrient release temporal patterns of three oil palm residues used as soil mulch were studied. Empty fruit bunches (EFB; 1000 kg plot−1), Eco-mat (processed EFB carpet; 30 kg plot−1), and pruned palm fronds (180 kg plot−1) were left to decompose (and sampled monthly) on the soil surface for 8 months. The frond's leaflets had the highest initial concentration for most nutrients, and the frond's rachis and Eco-mat the lowest. The order of residue quality and rate of residue mass loss were: leaflets > fronds > EFB > Ecomat > rachis. EFB however had a higher mass loss rate than the fronds. Residue mass loss and nutrient release rates were faster at the beginning than at the end of the decomposition period. Leaflets released the highest total amount of nutrients (except for K), and rachis the lowest. The fronds released either significantly higher (for N and Ca) or not significantly different (for P and Mg) total amount of nutrients than EFB. Converting EFB into Eco-mat had resulted in nutrient losses (e.g. N, K and Mg) and a residue quality reduction in Eco-mat. This study's results would aid in better soil and oil palm fertilisation management.

Mulching materials from oil palm residues such as pruned palm fronds (OPF), empty fruit bunches (EFB), and Eco-mat (ECO; a compressed EFB mat) are often the recommended soil and water conservation practices (CP) for oil palm plantations on hill slopes. Another recommended CP is the construction of silt pits or trenches (SIL) across the hill slope to capture runoff and then return the water and nutrients into the surrounding soil. Although these four CP are recommended practices, their relative effects on improving soil physical properties and on increasing the soil water content have never been compared with one another. Consequently, the objective of this study was to fill in this knowledge gap. A threeyear field experiment was conducted in a non-terraced oil palm plantation, and soil samples from 0 to 0.15, 0.15 to 0.30, and 0.30 to 0.45 m depths were collected every three months and analyzed for their soil physical properties. Soil water content up to 0.75 m depth was also measured daily. EFB released the highest amount of organic matter and nutrients into the soil compared to OPF, ECO, and SIL. Hence, EFB was most effective to increase soil aggregation, aggregate stability, soil water retention at field capacity, available soil water content, and the relative proportion of soil mesopores. Due to these improved soil physical properties, EFB also gave the highest soil water content. Unlike ECO that concentrated more water in the upper soil layers, EFB distributed the soil water more uniformly throughout the whole soil profile, but SIL concentrated more soil water in the lower soil layers (>0.30 m) because the water levels in the pits were often below 0.30 m from the soil surface. The large opening area of the silt pits could have also caused large evaporative water losses from the pits. EFB mulching is recommended as the best CP, particularly for oil palm plantations on hill slopes.

The feasibility of durian tree sawdust (DTS), coconut coir (CC) and oil palm empty fruit bunch (EFB) as low-cost biosorbents for the removal of Cu(II), Pb(II) and Zn(II) ions from aqueous solutions was investigated. The effects of solution pH and initial metal concentration on adsorption capacity were examined in batch experiments. The affinity and the adsorption capacity of DTS, CC and EFB were evaluated. The adsorption behaviour of Cu(II), Pb(II) and Zn(II) ions onto DTS, CC and EFB was described using Freundlich and Langmuir isotherm models. The separation factor (RL) analysis suggests that the removal of metal ions onto three agricultural wastes studied was favourable. The maximum adsorption capacities (Q) estimated from the Langmuir isotherm model for Cu(II), Pb(II) and Zn(II) were 18.42, 20.37 and 22.78 mg/g for DTS, 18.38, 37.04 and 24.39 mg/g for CC, and 26.95, 37.59 and 21.19 mg/g for EFB, respectively. The characterisation studies were carried out using Scanning Electron Microscope (SEM), Energy Dispersive X-ray Spectrometer (EDX) and Fourier Transform Infrared Spectrometer (FTIR). The surface morphology of the biosorbents changed significantly following interaction with metal ions. The primary adsorption mechanism was complexation between metal ions and binding sites of biosorbents. Both hydroxyl and amine groups are the main binding sites in DTS, CC and EFB.

Lettuce varieties Bombilasta BBL and Italian 167 were treated with different concentrations of cadmium (0, 3, 6, 9, and 12 mg/L) in a nutrient film technique (NFT) system to study its toxicity on phytochemicals and nutrient elements. Antioxidants analysis which employed DPPH and FRAP, flavonoids, phenolic, vitamin C, malondialdehyde (MDA), and proline indicated significant effects of Cd treatment on the varieties tested. Different concentration levels of Cd lead to positive interactions in FRAP, phenolic, and MDA but no significant effect in flavonoids, vitamin C, and proline. Contents of macro-and microelements in the varieties were significantly affected with increase in the toxicity levels of Cd in all nutrient elements tested with interactions exhibited for iron, manganese, and zinc.

In Malaysia, four soil conservation practices are oft en recommended for non-terraced oil palm (Elaeis guineensis Jacq.) plantations. Th ese practices are oil palm empty fruit bunches (EFB), Ecomat (a compressed EFB mat; ECO), and pruned oil palm fronds. Th ese three oil palm residues are used as organic mulching materials. Th e fourth method is silt pits (SIL) which are soil trenches to collect nutrients from runoff water and later redistribute them back into the soil. Nonetheless, the relative eff ectiveness of these four methods in improving soil and oil palm properties have never been studied. A 3-yr fi eld experiment was consequently conducted to determine their relative eff ects on increasing soil chemical properties (pH, cation exchange capacity, organic C, total N, available P, and exchangeable K, Ca, and Mg) and oil palm nutrition levels (N, P, K, Ca, and Mg). Biomass decomposition rate and nutrients release rate in the fi eld by the three mulching materials were also determined. Results showed that EFB mulching was signifi cantly better than the other three soil conservation practices in improving nearly all of the measured soil and plant parameters. Empty fruit bunches was most eff ective partly because of the combined eff ects of higher amounts of dry matter added and the higher nutrient concentrations in the EFB than in other mulching materials. Silt pitting was found not to be as eff ective as EFB because SIL could only trap and return nutrients back into the soil, whereas EFB could do both: trap nutrients and release additional nutrients into the soil as it decomposes.