Effects of biochar and the earthworm Eisenia fetida on the bioavailability of polycyclic aromatic hydrocarbons and potentially toxic elements

Polycyclic aromatic hydrocarbons (PAHs) and potentially toxic elements (PTEs) were monitored over 56 days in calcareous contaminated-soil amended with either or both biochar and Eisenia fetida. Biochar reduced total (449 to 306 mg kg⁻¹) and bioavailable (cyclodextrin extractable) (276 to 182 mg kg⁻¹) PAHs, PAH concentrations in E. fetida (up to 45%) but also earthworm weight. Earthworms increased PAH bioavailability by >40%. Combined treatment results were similar to the biochar-only treatment. Earthworms increased water soluble Co (3.4 to 29.2 mg kg⁻¹), Cu (60.0 to 120.1 mg kg⁻¹) and Ni (31.7 to 83.0 mg kg⁻¹) but not As, Cd, Pb or Zn; biochar reduced water soluble Cu (60 to 37 mg kg⁻¹). Combined treatment results were similar to the biochar-only treatment but gave a greater reduction in As and Cd mobility. Biochar has contaminated land remediation potential, but its long-term impact on contaminants and soil biota needs to be assessed.     

Spatial trends of organochlorinated pesticides,polychlorinated biphenyls,and polybrominated diphenyl ethers in Atlantic Anguillid eels

The bioaccumulation of lipophilic contaminants such as polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), and polybrominated diphenyl ethers (PBDEs) can result in a reduction in fitness and spawner quality in eels and may be a factor in Anguillid sp. population declines. Contaminant concentrations in eels have been studied extensively in Europe, but data for American eels are severely lacking. Concentrations of PCBs, OCPs, and PBDEs were determined in American eel from eastern Canada and New York, USA, along with European eel from Belgium. Principal component analysis revealed that eels captured in the St. Lawrence estuary were a mixture of upstream migrants from the St. Lawrence River watershed, and fish captured in local tributaries. Contaminant concentrations were dependent on origin, related to the local environment, and were lower than historic values. In Canada, concentrations of OCPs and PCBs in eel tissues were below the Canadian human consumption guidelines for contaminants in fish, indicating that the current risk to consumers is low. However, concentrations of PCBs, total DDT, and mirex in eels from L. Ontario and the upper St. Lawrence R. were above Great Lakes guidelines for the protection of piscivorous predators. Concentrations of penta-BDE homologs exceeded the Canadian guideline for environmental quality in over half of the eels in this study, but concentrations of the other homolog groups were below the guideline.     

Effect of time and mode of depuration on tissue copper concentrations of the earthworms Eisenia andrei, Lumbricus rubellus and Lumbricus terrestris

Eisenia andrei, Lumbricus rubellus and Lumbricus terrestris were exposed to 250, 250 and 350mgkg(-1) Cu respectively in Cu(NO(3))(2(aq)) amended soil for 28 d. Earthworms were then depurated for 24 to 72h, digested and analysed for Cu and Ti or, subsequent to depuration were dissected to remove any remaining soil particles from the alimentary canal and then digested and analysed. This latter treatment proved impossible for E. andrei due to its small size. Regardless of depuration time, soil particles were retained in the alimentary canal of L. rubellus and L. terrestris. Tissue concentration determinations indicate that E. andrei should be depurated for 24h, L. rubellus for 48h and L. terrestris should be dissected. Ti was bioaccumulated and therefore could not be used as an inert tracer to determine mass of retained soil. Calculations indicate that after 28 d earthworms were still absorbing Cu from soil.     

Identification of phase II in vivo metabolites of alkyl-anthracenes in rainbow trout (Oncorhynchus mykiss)

Metabolism of xenobiotics is a two-step process that increases the polarity of compounds to facilitate their excretion. In previous work, the major in vitro phase I metabolites of alkyl-anthracenes by rainbow trout (Oncorhynchus mykiss) CYP enzymes were shown to be predominantly ring hydroxylated metabolites. Here, we present the first report on the identification of in vivo phase II metabolites of alkyl-anthracenes in juvenile rainbow trout. Bile was collected from trout injected with individual alkyl-anthracenes with, in some cases, a co-injection of β-naphthoflavone (BNF). Some samples were digested with the β-glucuronidase enzyme to confirm the presence of glucuronide conjugates. The metabolites were separated using a water-acetonitrile gradient on a HPLC system equipped with a C₁₈ column and a UV-diode array detector. Trout with endogenous and BNF-induced enzymes produced the same metabolites, but higher concentrations of metabolites were detected after enzyme induction. Alkyl-anthracenes were metabolized predominantly on the rings as evidenced by the UV spectral analysis. Likewise, mass spectrometry and UV spectral analysis confirmed a predominance of glucuronide conjugates for all systems investigated.     

Using deuterated PAH amendments to validate chemical extraction methods to predict PAH bioavailability in soils

Validating chemical methods to predict bioavailable fractions of polycyclic aromatic hydrocarbons (PAHs) by comparison with accumulation bioassays is problematic. Concentrations accumulated in soil organisms not only depend on the bioavailable fraction but also on contaminant properties. A historically contaminated soil was freshly spiked with deuterated PAHs (dPAHs). dPAHs have a similar fate to their respective undeuterated analogues, so chemical methods that give good indications of bioavailability should extract the fresh more readily available dPAHs and historic more recalcitrant PAHs in similar proportions to those in which they are accumulated in the tissues of test organisms. Cyclodextrin and butanol extractions predicted the bioavailable fraction for earthworms (Eisenia fetida) and plants (Lolium multiflorum) better than the exhaustive extraction. The PAHs accumulated by earthworms had a larger dPAH:PAH ratio than that predicted by chemical methods. The isotope ratio method described here provides an effective way of evaluating other chemical methods to predict bioavailability.     

A review of studies performed to assess metal uptake by earthworms

Earthworms perform a number of essential functions in soil; the impacts of metals on earthworms are often investigated. In this review we consider the range of earthworm species, types of soil and forms of metal for which metal uptake and accumulation have been studied, the design of these experiments and the quantitative relationships that have been derived to predict earthworm metal body burden. We conclude that there is a need for more studies on earthworm species other than Eisenia fetida in order to apply the large existing database on this earthworm to other, soil dwelling species. To aid comparisons between studies agreement is needed on standard protocols that define exposure and depuration periods and the parameters, such as soil solution composition, soil chemical and physical properties to be measured. It is recommended that more field or terrestrial model ecosystem studies using real contaminated soil rather than metal-amended artificial soils are performed.     

Is the OECD acute worm toxicity test environmentally relevant? The effect of mineral form on calculated lead toxicity

In a series of experiments the toxicity of lead to worms in soil was determined following the draft OECD earthworm reproduction toxicity protocol except that lead was added as solid lead nitrate, carbonate and sulphide rather than as lead nitrate solution as would normally be the case. The compounds were added to the test soil to give lead concentrations of 625-12 500 microg Pb g(-1) of soil. Calculated toxicities of the lead decreased in the order nitrate> carbonate> sulphide, the same order as the decrease in the solubility of the metal compounds used. The 7-day LC50 (lethal concentration when 50% of the population is killed) for the nitrate was 5321+/-275 microg Pb g(-1) of soil and this did not change with time. The LC50 values for carbonate and sulphide could not be determined at the concentration ranges used. The only parameter sensitive enough to distinguish the toxicities of the three compounds was cocoon (egg) production. The EC50s for cocoon production (the concentration to produce a 50% reduction in cocoon production) were 993, 8604 and 10246 pg Pb g(-1) of soil for lead nitrate, carbonate and sulphide, respectively. Standard toxicity tests need to take into account the form in which the contaminant is present in the soil to be of environmental relevance.     

Relative proportions of polycyclic aromatic hydrocarbons differ between accumulation bioassays and chemical methods to predict bioavailability

Chemical methods to predict the bioavailable fraction of organic contaminants are usually validated in the literature by comparison with established bioassays. A soil spiked with polycyclic aromatic hydrocarbons (PAHs) was aged over six months and subjected to butanol, cyclodextrin and tenax extractions as well as an exhaustive extraction to determine total PAH concentrations at several time points. Earthworm (Eisenia fetida) and rye grass root (Lolium multiflorum) accumulation bioassays were conducted in parallel. Butanol extractions gave the best relationship with earthworm accumulation (r² ≤ 0.54, p ≤ 0.01); cyclodextrin, butanol and acetone-hexane extractions all gave good predictions of accumulation in rye grass roots (r² ≤ 0.86, p ≤ 0.01). However, the profile of the PAHs extracted by the different chemical methods was significantly different (p < 0.01) to that accumulated in the organisms. Biota accumulated a higher proportion of the heavier 4-ringed PAHs. It is concluded that bioaccumulation is a complex process that cannot be predicted by measuring the bioavailable fraction alone.     

Investigation of the toxicity of the products of decoloration of Amaranth by Trametes versicolor

Trametes versicolor decolorized 2000 mg L(-1) of the mono-azo substituted naphthalenic dye Amaranth with no dye sorption observed visually. The changes in the toxicity were assessed over a period of 30 d for the dye-treated viable culture, control (no dye added), and a boiled culture treated with dye, using the Microtox Acute Toxicity assay. Before dye addition, the culture filtrate had some toxicity, which increased after the dye addition. The toxicity of the dye-treated culture decreased during the treatment. The loss of toxicity occurred at the same time, with the loss of color suggesting that detoxification is associated with decoloration. The change in pH was due to natural metabolic processes and had a small effect on detoxification. Because the toxicity of the treatment was similar to that of the control at the end of the treatment, the effluent seems to be safe for release into the environment, potentially rendering this treatment suitable for industrial application.     

A Cu tolerant population of the earthworm Dendrodrilus rubidus (Savigny, 1862) at Coniston Copper Mines, Cumbria, UK

Dendrodrilus rubidus were sampled from a mine spoil soil at Coniston Copper Mine, an abandoned Cu mine in Cumbria, UK and a Cu-free control site. Earthworms were maintained for 14d in both Kettering loam and a Moorland soil amended with Cu nitrate. Mortality, condition index, weight change and tissue concentration were determined. In both soils D. rubidus native to the mine site were able to tolerate significantly higher soil Cu concentrations (MWRT, p相似文献