Effect of seasonal variation in seawater dissolved mercury concentrations on mercury accumulation in the muscle of red sea bream (Pagrus major) held in Minamata Bay, Japan

Japanese stingfish (Sebastiscus marmoratus) and Bambooleaf wrasse (Pseudolabrus japonicas) are monitored annually for mercury pollution in Minamata Bay, Japan. The average total mercury concentration in the muscle of these two species in Minamata Bay was 0.36 mg?kg^?1 wet weight and 0.20 kg^?1 wet weigh, respectively, between 2008 and 2010. This is higher than levels elsewhere in Japan (0.125 mg?kg^?1 wet weight and 0.038 mg?kg^?1 wet weight, respectively). The FDA (2001) and EPA (2004) suggested that a proportion of mercury accumulated in fish is derived from seawater. We reared young red sea bream (Pagrus major) over a 2-year period in Minamata Bay and Nagashima (control) to evaluate the uptake of mercury from seawater and dietary sources. Fish were fed a synthesized diet that did not contain mercury. There was no difference in mercury accumulation in the muscle of red sea bream between Minamata Bay and Nagashima. Thus, our results suggest that the majority of mercury accumulated in fish muscle is not from seawater.     

Re-emission of heavy water vapour from soil to the atmosphere

The re-emission process of tritiated water (HTO) deposited on a soil surface is an important process to assess tritium doses to the general public around nuclear fusion facilities in future. A field experiment using heavy water (HDO) as a substitute for HTO was carried out in the summertime to investigate the re-emission process of HTO from soil to the atmosphere. In the experiment, the time variations of depth profiles of HDO concentrations in soil exposed to HDO vapour and soil mixed with HDO were measured during the re-emission process on the field. The HDO concentrations in soil water in top soil layers of both the exposed and mixed soil rapidly decreased with time during the re-emission. However, the decrease of exposed soil was much greater than that of mixed soil. The re-emission process was analysed using a model including the evaporation of HDO from soil, the exchange between soil HDO and air H2O, and the diffusion of HDO in soil. It was found that the model is applicable to calculating the time variations of detailed depth profiles of HDO concentration in soil water in surface soil layers, using an estimated exchange velocity.     

Effect of density-driven flow on the through-diffusion experiment

Diffusion is one of the main mechanisms of solute transport in pore water of geologic media. The effective diffusion coefficient of a solute in a rock is usually measured by the through-diffusion experiment. However, in this experiment, the effect of advection, induced by density difference between dense aqueous solution and pure water, has not been considered. To evaluate the effect of density-driven flow, a through-diffusion experiment using Fontainebleau sandstone was conducted for KCl and KI aqueous solutions with various densities. The measured effective diffusion coefficients were positively correlated with the density difference; the effective diffusion coefficient of a 1 M KI solution (density difference, 0.119 g/cm³) was one order of magnitude larger than that of a 0.1 M KCl solution (density difference, 0.005 g/cm³). The result is explained by a theoretical model using a diffusion–advection equation including Darcy's law. Based on the theory, a diagram to evaluate the condition at which the measured effective diffusion coefficient does not include the effect of advection is presented.     

Cytochrome p450 induction and gonadal status alteration in common carp (Cyprinus carpio) associated with the discharge of dioxin contaminated effluent to the Hikiji River,Kanagawa Prefecture,Japan

Accumulations of polychlorinated dibenzo-p-dioxins, dibenzofurans and coplanar polychlorinated biphenyls were analyzed in common carp (Cyprinus carpio) collected in the Hikiji River, Kanagawa Prefecture, Japan in which dioxin contaminated effluent was released during the period starting from November 1992 to March 2000. Higher levels of 2,3,7,8-tetrachlorinated dibenzo-p-dioxin toxic equivalents were observed in carps collected downstream to the dioxin release site (contaminated site) than the reference site. Modulations of cytochrome p450 (CYP) enzyme in liver, serum estrogen concentration and gonadal somatic index (GSI) were also measured as biomarkers for the contaminants. Total CYP content in livers was markedly higher in male and female carps from the contaminated site relative to the reference site fish. The expression level of the cytochrome p450 1A and Ethoxyresorufin O-deethylase activity were significantly higher in female carps from the contaminated site than from the reference site. A lower level of plasma estrogen was observed in carps from the contaminated site. The GSI in female carps from the contaminated site was smaller than that recorded at the reference site. The present study indicates that dioxins released to the Hikiji River might induce the CYP enzyme and inhibit the reproductive functions in common carps dwelling downstream from the release site.     

Environmental impact evaluation of feeds prepared from food residues using life cycle assessment

There is increasing concern about feeds prepared from food residues (FFR) from an environmental viewpoint; however, various forms of energy are consumed in the production of FFR. Environmental impacts of three scenarios were therefore investigated and compared using life cycle assessment (LCA): production of liquid FFR by sterilization with heat (LQ), production of dehydrated FFR by dehydration (DH), and disposal of food residues by incineration (IC). The functional unit was defined as 1 kg dry matter of produced feed standardized to a fixed energy content. The system boundaries included collection of food residues and production of feed from food residues. In IC, food residues are incinerated as waste, and thus the impacts of production and transportation of commercial concentrate feeds equivalent to the FFR in the other scenarios are included in the analysis. Our results suggested that the average amounts of greenhouse gas (GHG) emissions from LQ, DH, and IC were 268, 1073, and 1066 g of CO(2) equivalent, respectively. The amount of GHG emissions from LQ was remarkably small, indicating that LQ was effective for reducing the environmental impact of animal production. Although the average amount of GHG emissions from DH was nearly equal to that from IC, a large variation of GHG emissions was observed among the DH units. The energy consumption of the three scenarios followed a pattern similar to that of GHG emissions. The water consumption of the FFR-producing units was remarkably smaller than that of IC due to the large volumes of water consumed in forage crop production.     

Unique aluminosilicate-based natural nanoparticles in the volcanogenic Goshiki-numa pond

We report here the occurrence of uniquely shaped nanoparticles newly discovered in natural ponds. Nanoparticles originate from the Goshiki-numa pond community in Japan, where volcanic activity facilitated the formation of four specific ponds. We built a steric three-dimensional image of nanoparticles by integrating 120 transmission-electron-microscope image fragments obtained from various angle ranges. The thick-walled, cylindrically shaped particle has an outer diameter that measures approximately 40 nm and a length that measures 70 nm. A 10-nm-thick wall surrounds a 30 nm hole located in the particle centre. Particles are composed of an aluminium silicate-based material with an Al₂O₃:SiO₂ ratio of 2:1. They also exhibit an amorphous X-ray diffraction pattern. Although the water solubility characteristics and the infrared spectrum of these newly discovered particles resembles imogolite, these two materials do not have identical structural characteristics.     

Dynamics of microcystins-LR and -RR in the phytoplanktivorous silver carp in a sub-chronic toxicity experiment

A sub-chronic toxicity experiment was conducted to examine tissue distribution and depuration of two microcystins (microcystin-LR and microcystin -RR) in the phytoplanktivorous filter-feeding silver carp during a course of 80 days. Two large tanks (A, B) were used, and in Tank A, the fish were fed naturally with fresh Microcystis viridis cells (collected from a eutrophic pond) throughout the experiment, while in Tank B, the food of the fish were M. viridis cells for the first 40 days and then changed to artificial carp feed. High Performance Liquid Chromatography (HPLC) was used to measure MC-LR and MC-RR in the M. viridis cells, the seston, and the intestine, blood, liver and muscle tissue of silver carp at an interval of 20 days. MC-RR and MC-LR in the collected Microcystis cells varied between 268-580 and 110-292 microg g(-1) DW, respectively. In Tank A, MC-RR and MC-LR varied between 41.5-99.5 and 6.9-15.8 microg g(-1) DW in the seston, respectively. The maximum MC-RR in the blood, liver and muscle of the fish was 49.7, 17.8 and 1.77 microg g(-1) DW, respectively. No MC-LR was detectable in the muscle and blood samples of the silver carp in spite of the abundant presence of this toxin in the intestines (for the liver, there was only one case when a relatively minor quantity was detected). These findings contrast with previous experimental results on rainbow trout. Perhaps silver carp has a mechanism to degrade MC-LR actively and to inhibit MC-LR transportation across the intestines. The depuration of MC-RR concentrations occurred slowly than uptakes in blood, liver and muscle, and the depuration rate was in the order of blood>liver>muscle. The grazing ability of silver carp on toxic cyanobacteria suggests an applicability of using phytoplanktivorous fish to counteract cyanotoxin contamination in eutrophic waters.     

Quantification of free and esterified long-chain fatty acids without extraction by high-performance liquid chromatography in anaerobic digestion sludge

Journal of Material Cycles and Waste Management - During anaerobic digestion, the concentrations of long-chain fatty acids (LCFAs) need to be monitored to achieve good performance due to their...     

Identification of sources of lead in the atmosphere by chemical speciation using X-ray absorption near-edge structure (XANES) spectroscopy

Sources of Pb pollution in the local atmosphere together with Pb species, major ions, and heavy metal concentrations in a size-fractionated aerosol sample from Higashi-Hiroshima(Japan) have been determined by X-ray absorption near-edge structure(XANES) spectroscopy, ion chromatography, and ICP-MS/AES, respectively. About 80% of total Pb was concentrated in fine aerosol particles. Lead species in the coarse aerosol particles were PbC2O4, 2PbCO3·Pb(OH)2, and Pb(NO3)2, whereas Pb species in the fine aerosol particles were PbC2O4, PbSO4, and Pb(NO3)2. Chemical speciation and abundance data suggested that the source of Pb in the fine aerosol particles was different from that of the coarse ones. The dominant sources of Pb in the fine aerosol particles were judged to be fly ash from a municipal solid waste incinerator and heavy oil combustion. For the coarse aerosol particles, road dust was considered to be the main Pb source. In addition to Pb species, elemental concentrations in the aerosols were also determined. The results suggested that Pb species in size-fractionated aerosols can be used to identify the origin of aerosol particles in the atmosphere as an alternative to Pb isotope ratio measurement.     

Toxicity of ozonated animal manure to the house fly, Musca domestica

Swine manure slurries were ozonated at a dosage of 1 g/L and tested for their toxicity to the house fly (Musca domestica). The observed toxicity of ozonated swine manure was consistent and independent of origin of the swine manure. A dose (dilution) response curve was performed. A 50% dilution in the ozonated swine manure slurry resulted in 90% reduction in toxicity. Neither the synthetic nor ozonated synthetic swine manure, both of which contained higher concentrations of formaldehyde and three other unidentified carbonyl compounds than the ozonated swine manure, were toxic to the flies. Ozonated swine manure slurry was centrifuged and passed through a 0.45-microm filter. The liquid phase was as toxic as the unfiltered slurry; as such, the toxicant appears to be present in liquid phase. Neither ammonia, hydrogen sulfide, formaldehyde, nor other simple aldehydes appeared to be the toxic agent. The toxic agent appears to be a polar chemical compound and is concentrated in the urine. Several possible compounds have been identified. The toxicity of untreated and ozonated manure slurries from different livestock was compared. Six animal manure slurries (beef and dairy cattle, horse, poultry, sheep, and swine) were ozonated (dosage of 1 g/L) and tested for toxicity to the house fly. Ozonated dairy cattle manure slurry showed 78% mortality after 72 h, whereas ozonated swine manure slurry achieved a 100% mortality rate in 48 h. Neither the unozonated dairy nor swine manure slurries, nor any of the other raw or ozonated manure slurries, were toxic to the flies.