A. G. Langdon

Bioaccumulation of heavy metals in fishes from Taihu Lake, China

The Cr, Zn, Cu, Cd, Pb contents were determined in Cyprinus carpio Linnaeus, Carassius auratus Linnaeus, Hypophthalmichthys molitrix and Aristichthys nobilis, which were caught from Meiliang Bay, Taihu Lake, a large, shallow and eutrophic lake of China. The results showed that: (1) the Cr, Cu, Pb, Cd contents in the edible parts of the four fish species were much lower than Chinese Food Health Criterion (1994), but the Zn contents were higher than the Criterion; (2) Cd contents were the highest in the liver of fish, Pb contents were almost the same in all organs of fish, Cr contents mainly enriched in the skin and gonads, Zn contents were the highest in the gonad (female), and Cu contents were the highest in the liver; (3) the total metal accumulation was the greatest in the liver and the lowest in the muscle. The total metal accumulation was the highest in C. auratus L. This investigation indicated that fish products in Taihu Lake were still safe for human consumption, but the amount consumed should be controlled under the Chinese Food Health Criterion to avoid excessive intake of Zn.

Analytical methodology for the determination of freely available bleached kraft mill effluent-derived organic constituents in recipient sediments

Methodology for the extraction, identification, and quantification of the freely available bleached kraft mill effluent constituents present in sediments is reported. A single Soxhlet Dean-Stark (SDS) extraction is followed by extract fractionation and quantification of the chlorophenolic constituents, resin acids, and base neutral resin-sourced cyclic hydrocarbons by gas chromatography mass spectrometry (GC/MS). The extractable organic halide (EDX) content is also determined. The methodology was evaluated for the recovery and reproducibility of selected target compounds, surrogate standards, and some isotopically carbon-13 and deuterium labeled compounds. The recoveries of resin acids, resin-sourced hydrocarbons, chlorophenols and chloroguaiacols were typically of the order 80-95%, while replicate analyses resulted in relative standard deviations of the order 5-15%. Application of the methodology to some recipient sediments adjacent to a NewZealand bleached kraft mill resulted in the detection of elevated concentrations of abietan-18-oic acid, retene, and dehydroabietin

The fate of resin acids-1. The biotransformation and degradation of deuterium labelled dehydroabietic acid in anaerobic sediments

A lake sediment was collected downstream from the discharge from a bleached kraft pulp and paper mill, spiked with 6-d2-dehydroabietic acid and anaerobically incubated for 264 days. The concentrations of the deuterium label, 6-d2-dehydroabietic acid and resulting biotransformation products were monitored periodically. The 6-d2-dehydroabietic acid transformed to d-tetrahydroretene (62 % conversion), and 6-d2-dehydroabietin (1 % conversion). Towards the end of the study, minor quantities of d-retene and methyl d-tetrahydrophenanthrene were observed. Based on the appearance and disappearance of these and other compounds and mass balances for labelled and unlabelled components, a pathway for the conversion of dehydroabietic acid to several derived base neutrals was proposed. This is the first conclusive study indicating that in resin acid enriched sediments, anaerobic processes form resin acid derived base neutral compounds.

The fate of resin acids-2. The fate of resin acids and resin acid derived neutral compounds in anaerobic sediments

A sediment, sampled from a hydroelectric lake receiving a bleached kraft mill effluent discharge, was incubated anaerobically for 264 days. Both recipient and sterilised control sediments were periodically sampled and analysed to monitor the changes in resin acid composition with time. Over 264 days of incubation, the concentration of total resin derived compounds decreased by 50%. The total resin acid concentration was reduced by 50% whereas the concentration of resin derived neutrals decreased by 54%. Relative to an incubated sterile control sediment, the pimaranic acid concentration remained constant, 8-pimarenic and 8-isopimarenic acid concentrations slightly increased and pimaric, isopimaric, abietanic and secodehydroabietic acid concentrations decreased. Dehydroabietic acid was transformed to tetrahydroretene simultaneously with the transformation of labelled dehydroabietic acid to a variety of labelled products. Throughout the incubation period, the concentration of fichtelite remained constant. The concentration of retene slightly increased until the final 50 days of incubation, during which time dehydroabietin and tetrahydroretene concentrations decreased. This is the first study reporting the degradation of a variety of resin acids and derived neutrals in an anaerobic sediment.

The structure characterization of cellulose xanthogenate derived from the straw of Eichhornia crassipes

Alkali-treated straw and cellulose xanthogenate were derived from shoot and root biomass of Eichhornia crassipes by treatment with NaOH and CS(2), respectively. The structures of the raw and modified plant materials were characterized by XRD, TGA/DTA, and FTIR. Alkali treatment increased the crystallinity of raw plant material, while the subsequent CS(2) treatment had the reverse effect. The thermal stability of the plant material was diminished by alkali treatment but was restored by subsequent CS(2) treatment. Alkali treatment removed most of the lignin and hemicellulose from the raw plant material, whereas the formation of cellulose xanthogenate introduced new C=S and O-CS-S functional groups.

Metal adsorption by quasi cellulose xanthogenates derived from aquatic and terrestrial plant materials

The FTIR spectra, SEM-EDXA and copper adsorption capacities of the raw plant materials, alkali-treated straws and cellulose xanthogenate derivatives of Eichhornia crassipes shoot, rape straw and corn stalk were investigated. FTIR spectra indicated that of the three plant materials, the aquatic biomass of E. crassipes shoot contained more OH and CO groups which accounted for the higher Cu(2+) adsorption capacities of the raw and alkali treated plant material. SEM-EDXA indicated the incorporation of sulphur and magnesium in the cellulose xanthogenate. The Cu(2+) adsorption capacities of the xanthogenates increased with their magnesium and sulphur contents. However more copper was adsorbed than that can be explained by exchange of copper with magnesium. Precipitation may contribute to the enhanced uptake of copper by the cellulose xanthogenate.

Effect of chemical and biological degumming on the adsorption of heavy metal by cellulose xanthogenates prepared from Eichhornia crassipes

Cellulose xanthogenates, derived from the straw of Eichhornia crassipes, were prepared as adsorbents for heavy metals by CS(2) sulfonation and magnesium substitution after degumming with alkali, self-isolated A(1) strain and pectase, respectively. The effects of three degumming treatments were compared by functional groups analysis, surface morphology and surface element composition and heavy metal (Pb(2+)) adsorption studies. The results demonstrate that bio-degumming treatments by A(1) strain and pectase have weaker degumming effects than alkali treatment. However, the surface characteristics of the bio-degumming products, especially the pectase degumming product, are more beneficial to heavy metal adsorption. In comparison to that of the raw plant materials, the Pb(2+) adsorption performances of the three xanthogenates improved significantly, although no obvious differences being observed among themselves. From an environmental point of view, the two bio-degumming treatments, especially the pectase degumming treatment, are more beneficial to prepare heavy metal adsorbents than the alkali degumming treatment.

Bile analyses of goldfish (Crassius auratus) resident in a New Zealand hydrolake receiving a bleached kraft mill discharge

Bile was collected from goldfish (Crassius auratus) sampled from five sites on a river receiving the biologically treated discharge from a New Zealand bleached kraft mill. The bile was subjected to an alkaline hydrolysis, extracted with dichloromethane and analysed for resin acids and chlorophenolic compounds by GC/MS. The bioaccumulation and persistence in the bile of both saturated and unsaturated resin acids and chlorophenolic compounds was found for sites downstream of the mills discharge. Abietanic, 13-abietenic and seco-dehydroabietic acids were the major bile bioaccumulated resin acids and 2,4,6 trichlorophenol was the predominant chlorophenolic compound detected. Elevated levels up to 507 μg/g(dw bile) per resin acid and 61 μg/g(dw bile) per chlorophenol were found adjacent to the mills discharge point. Attenuated levels of these compounds were identified at a site 2.4 km downstream where the effluent was partially mixed, while levels at a well mixed site subject to a natural fifty fold dilution, 9.1 km downstream, were only marginally greater than those identified at an upstream (control) site.

Organochlorine contaminants in sediments of the Tauranga Harbour, New Zealand

Abstract DDT, DDE, and DDD (up to 0.5 ng g‐1per compound) and traces of dieldrin (< 0.1 ng g‐1), were detected in surficial sediments collected from four sites in the greater Tauranga Harbour. An elevated level of PCBs (19.9 ng g‐1) was identified in a Waikareao Estuary sample. PCB and DDT levels of up to 24.1 ng g‐1 and 5.38 ng g‐1,respectively, were subsequently detected in other eastern shore Waikareao Estuary sediment samples. Higher levels of PCBs (68.6 and 73.8 ng g‐1) and DDTs (total 7.52 and 19.2 ng g‐1) were detected in sediments from two eastern shore stormwater drains identified as the likely sources of the PCB and DDT burden entering the Waikareao Estuary. Black, carbonaceous, coal‐ and asphalt‐like, paniculate material (98% loss of organic carbon on ignition), isolated by sieving a representative sediment sample, exhibited DDT and PCB levels which were respectively 85 and 6 times higher than was the case for other sieved fractions.

Preparation of volatile fatty acid (VFA) calcium salts by anaerobic digestion of glucose

Many potentially useful intermediates such as hydrogen and volatile fatty acids (VFAs) are formed during the complex anaerobic digestion processes that produce methane from biomass. This study recovers VFAs from an anaerobic digester by a combination of gas stripping and absorption with calcium carbonate slurry. Glucose was used as the model substrate because it is readily available, inexpensive, and easily digested. Sludge from a meatworks anaerobic digester produced methane and carbon dioxide (and sometimes a small amount of hydrogen) when batch‐fed with glucose. Conditioning the neutral anaerobic sludge to an acidic pH (below 4.8) was achieved using repeated 1 g L−1 doses of glucose. After conditioning, mainly VFAs and hydrogen were produced. The intermediate VFAs could be stripped using headspace gas. In subsequent fed‐batch digestion/stripping cycles, the pH decreased when glucose was added and then increased when the VFA was gas stripped. The predominant acids formed at low pH values were lactic, butyric, and acetic acids. Lactic acid was converted to VFAs during stripping. The VFA calcium salts recovered were 80% butyrate and 20% acetate with minor quantities of propionate and valerate.