Mercury Contamination and Dynamics in the Sediment of the Second Songhua River,China

The Second Songhua River (SSR) was subjected to a large amount of mercury discharge from petrochemical industries in Jilin City from the 1960s to 1980s. The objectives of this study were to investigate the spatial and temporal change of mercury concentration in the sediments of the river and to assess Hg pollution in sediment employing enrichment ratio. Bottom sediments sampled in 2005 were digested with various acids followed by analysis by atomic fluorescence spectrometry for Hg, ICP-MS for Cd, Pb and Sc, and ICP-OES for Co, Cr, Cu, Zn, Mn, Ni, P, Pb, Sb, Ti, V, Al, Fe, Mg, Ca, Na, and K, in order to measure the total concentrations of these elements in the sediments. Results indicated that mercury concentrations in the sediments were strongly related with distance from the historic industrial point source, decreasing at an exponential rate from 1.27 mg kg^?1 at Jilin City to 0.01 mg kg^?1 at downstream Haerbin City. In addition, mercury concentration decreased from 16.8 mg kg^{? 1} y^?1 in 1974 to 0.09 mg kg^?1 y^?1 in 2005 in the sediments at effluent discharge site, and from 0.006 mg kg^?1 y^?1in 1974 to 0.004 mg kg^?1 y^?1 in 2005 at Songyuan City 257 km downstream. In the sedimentary sections of the river, deeper sediments contained higher concentrations of mercury as compared to the surface sediments, suggesting discharges of higher levels of mercury in the past and its subsequent burial over the years by less polluted sediments. Background concentrations of mercury in the surface sediments, reconstructed by tracer Sc, were 0.011 to 0.018 mg kg^?1. Enrichment ratios of Hg in the sediments of SSR was 5 to 75, indicating moderate to extreme pollution, while the sediment of Songhua River is less contaminated, with enrichment ratios of 0.9 to 1.5. At present, the previously accumulated and buried mercury in sediments may not significantly affect water quality of the SSR, but might pose a potential ecological risk to aquatic and amphibian animals. Natural attenuation seems to be an economic remedial choice for these sediments.     

A Rhizosphere-Associated Symbiont,Photobacterium spp. Strain MELD1, and Its Targeted Synergistic Activity for Phytoprotection against Mercury

Though heavy metal such as mercury is toxic to plants and microorganisms, the synergistic activity between them may offer benefit for surviving. In this study, a mercury-reducing bacterium, Photobacterium spp. strain MELD1, with an MIC of 33 mg . kg^-1 mercury was isolated from a severely mercury and dioxin contaminated rhizosphere soil of reed (Phragmites australis). While the whole genome sequencing of MELD1 confirmed the presence of a mer operon, the mercury reductase MerA gene showed 99% sequence identity to Vibrio shilloni AK1 and implicates its route resulted from the event of horizontal gene transfer. The efficiency of MELD1 to vaporize mercury (25 mg . kg^-1, 24 h) and its tolerance to toxic metals and xenobiotics such as lead, cadmium, pentachlorophenol, pentachloroethylene, 3-chlorobenzoic acid, 2,3,7,8-tetrachlorodibenzo-p-dioxin and 1,2,3,7,8,9-hexachlorodibenzo-p-dioxin is promising. Combination of a long yard bean (Vigna unguiculata ssp. Sesquipedalis) and strain MELD1 proved beneficial in the phytoprotection of mercury in vivo. The effect of mercury (Hg) on growth, distribution and tolerance was examined in root, shoot, leaves and pod of yard long bean with and without the inoculation of strain MELD1. The model plant inoculated with MELD1 had significant increases in biomass, root length, seed number, and increased mercury uptake limited to roots. Biolog plate assay were used to assess the sole-carbon source utilization pattern of the isolate and Indole-3-acetic acid (IAA) productivity was analyzed to examine if the strain could contribute to plant growth. The results of this study suggest that, as a rhizosphere-associated symbiont, the synergistic activity between the plant and MELD1 can improve the efficiency for phytoprotection, phytostabilization and phytoremediation of mercury.     

Fractionation,mobility and multivariate statistical evaluation of metals in marine sediments of Cape Town Harbour,South Africa

Abstract

Distribution of possible chemical forms of Al, Si, Sn, Pb, Zn, Fe, Hg, Cd and Cu in marine sediments of Cape Town harbour was investigated using a modified Tessier’s sequential extraction procedure and ICP-MS and ICP-AES for heavy metals determination. The mean fractions for all metals at all locations were: 1.5–7196 mg kg^-1 for Si, 7.79–7266 mg kg^-1 for Al, 161-639 mg kg^-1 for Cu, 19–41978 mg kg^-1 for Fe, 2.83–5864 mg kg^-1 for Zn, 1.45–13.26 mg kg^-1for Cd, 9.87–223 mg kg^-1 for Sn, 11.98-979 mg kg^-1 for Pb and 0.13–5.93 mg kg^-1 for Hg. Si, Al and Zn were mostly associated with Fe–Mn oxides, whereas Sn and Hg were mainly bound to residual and organic matter. Pb existed mainly in the residual and iron/manganese oxide phases while Cd was evenly distributed in all the five phases. The loading plots of heavy metals bound to the various chemical forms, as well as Pearson correlation coefficients, enabled the determination binding relationship. Pb, Sn and Hg exhibited similar binding behaviour which indicated an anthropogenic point source from wastes from the ship maintenance workshop, and the presence of Sn in the organic phase can be identified with the use of anti-fouling paints at the harbour, whereas Al, Fe, Si, Cu and Zn would probably be of natural origin. Lastly Cd probably came from a diffuse pollution sources in the harbour due to its unique binding characteristic. The mobility of heavy metals varied depending on location and the heavy metal type. The mobility of metals followed the order: Si > Zn > Fe > Cu> Al> Cd> Pb > Sn > Hg. The high percentage of Cd and Pb in the bioavailable forms suggested the need to keep close surveillance on these metals because of their high toxicity.     

Recent evolution of sedimentary heavy metals in a coastal lagoon contaminated by industrial wastewaters (Pialassa Baiona,Ravenna, Italy)

From 2000 to 2002, sediment contamination by Cd, Cu, Hg, Pb and Zn was analysed in the Pialassa Baiona salt marsh, which receives petrochemical wastewaters from the industrial district of Ravenna (Italy). The recent contamination levels were compared with data of previous studies carried out in 1982, in order to assess whether environmental policies and remedial measures reduced sediment pollution. Sedimentary profiles of Cu and Pb were homogeneous along the uppermost 0–10 cm horizon, which corresponded to the sedimentation in the last 30 years. Concentrations of Zn attained a peak (up to 800 mg kg⁻¹ dry weight) in the 0–4 cm sediment horizon, which was assumed to correspond to the last 10–15 years. A wide-spread contamination by Hg was detected in the salt marsh as well as in the main channel with peaks up to 20–40 mg kg⁻¹ dry weight. Nonetheless, recent sediments resulted less contaminated, since Hg discharge from industrial plants ceased about 20 years ago. Contamination levels by Hg values were two orders of magnitude higher than the international sediment quality standards. Cadmium, which was analysed for the first time in 2000–2002, attained a peak in the surface layers (1–2.5 mg kg⁻¹ d.w.), with a progressive decline along the sediment column. Through comparison with pre-industrial values detected in the deeper sediment horizons (before 1920), Hg showed the highest enrichment factor, up to 300 times. Cd and Zn concentrations in recent sediments were from 2 to 10 times higher than background values. In terms of possible adverse effects, Hg posed the highest risk, and Cd and Zn were frequently above the recommended thresholds.     

Arsenic and Mercury in the Soils of an Industrial City in the Donets Basin,Ukraine

Soil and house dust collected in and around Hg mines and a processing facility in Horlivka, a mid-sized city in the Donets Basin of southeastern Ukraine, have elevated As and Hg levels. Surface soils collected at a former Hg-processing facility had up to 1300 mg kg^?1 As and 8800 mg kg^?1 Hg; 1M HCl extractions showed 74–93% of the total As, and 1–13% of the total Hg to be solubilized, suggesting differential environmental mobility between these elements. In general, lower extractability of As and Hg was seen in soil samples up to 12 km from the Hg-processing facility, and the extractable (1M HCl, synthetic precipitation, deionized water) fractions of As are greater than those for Hg, indicating that Hg is present in a more resistant form than As. The means (standard deviation) of total As and Hg in grab samples collected from playgrounds and public spaces within 12 km of the industrial facility were 64 (±38) mg kg^?1 As and 12 (±9.4) mg kg^?1 Hg; all concentrations are elevated compared to regional soils. The mean concentrations of As and Hg in dust from homes in Horlivka were 5–15 times higher than dust from homes in a control city. Estimates of possible exposure to As and Hg through inadvertent soil ingestion are provided.     

Effects of Cadmium,Copper, Lead,and Zinc Contamination on Metal Accumulation by Safflower and Wheat

Accumulation of heavy metals (HMs) in cultivated soils is a continuing environmental problem in many parts of the world. An increase in HM concentration can enhance uptake of toxic metals by crops and enter the human food chain. In this study, the uptake behavior of wheat and safflower was evaluated in a calcareous soil by using 12 undisturbed columns in which half were artificially contaminated. Heavy metals in the form of CdCl₂ (15 mg Cd kg^{? 1}), CuSO₄ (585 mg Cu kg^{? 1}), Pb(NO₃)₂ (117 mg Pb kg^{? 1}), and ZnCl₂ (1094 mg Zn kg^{? 1}) were sprayed on the soil surface and completely mixed in the top 10 cm. The background total concentrations of Cd, Cu, Pb and Zn were 1.6, 29.5, 17.5 and 61.2 mg kg^{? 1}, respectively. After metal application, half of the columns (3 contaminated and 3 uncontaminated) were sown with wheat (Triticum aestivum) and the other half with safflower (Carthamus tinctorious) and grown for 74 days until maturity. After harvesting, soil columns were cut into 10-cm sections and analyzed for HNO₃- and DTPA-extractable metal concentrations. Metal concentrations were also measured in different plant tissues. The results showed that artificial contamination of topsoil decreased the transpiration rate of wheat by 12% and that of safflower by 6%. In contaminated columns, Cd, Cu, Pb, and Zn accumulation in wheat shoot was greater by 8.0-, 1.9-, 3.0-, and 2.1-fold than the control, respectively. Accordingly, these numbers were 46.0-, 1.3-, 1.7-, and 1.6-fold in safflower shoot. Soil contamination with HMs resulted in a 55% decrease in shoot dry matter yield of wheat while it had no significant effect on shoot dry matter of safflower. The normalized water consumption for safflower was therefore not affected by metal contamination (≈ 13 mm H₂O g^{? 1} of dry weight for all safflower and uncontaminated wheat treatments), while contaminated wheat was much less water efficient at about 27 mm H₂O g^{? 1} dry weight. It was concluded that although artificial contamination had a negative effect on wheat growth, it did not affect safflower's normal growth and water efficiency.     

Assessment of Soil Arsenic,Chromium, Mercury,and Lead at an Agricultural Landscape Scale

Knowledge of arsenic and heavy metal concentrations and distributions is essential in the design of environmental regulatory strategies. The present study was undertaken as a preliminary survey on soil contamination in a representative agricultural area of southwestern China. The objectives were: (1) to characterize the variability of As, Cr, Hg, and Pb; (2) to assess the effect of land use (vegetable land and paddy fields) on these elements; and (3) to identify their natural or artificial origins. Samples from 119 sites were collected and analyzed in 2006. Land use map units were delineated at a scale of 1:2000 from field survey. Analysis of variance, correlation analysis, factor analysis, and a geographic information system were adopted to investigate the spatial distributions and sources of the elements. The average concentrations of the elements were 6.26 mg As kg^?1, 52.90 mg Cr kg^?1, 0.066 mg Hg kg^?1, and 33.13 mg Pb kg^?1. Mean contents of Hg and Pb were markedly higher than their background levels indicating the risk of mercury and lead pollution (p < 0.05). Mean concentration of Pb was significantly higher in paddy fields than vegetable land (p < 0.05). The variability of Cr was associated with topography, while Hg was controlled by human activities and atmospheric deposition. The high heterogeneities of As and Pb were mainly ascribed to land use and the consequent agricultural management practices. The results of the study will assist planners and policymakers in developing effective policies to protect soils from long-term arsenic and heavy metal accumulation.     

Boletus roseoflavus,a new species of Boletus in section Appendiculati from China

Boletus roseoflavus is described as a new species based on morphological and molecular studies of the type collection and additional materials. Boletus roseoflavus is morphologically distinct from other related species (B. regius, B. appendiculatus, and B. speciosus) by its light pink, pink, or rosy pileus, lemon yellow or golden yellow context, and lemon yellow or light yellow, enlarged download stipe with yellow reticulation. Phylogenetic analyses based on ribosomal DNA internal transcribed spacer regions and nuclear large subunit ribosomal RNA indicate that B. roseoflavus belongs to Boletus section Appendiculati.     

The amount of food ingested in a single meal by rainbow trout offered chopped herring, dry and wet diets

Two-year-old 1·5-kg rainbow trout were held in cages and conditioned by feeding either on low-fat chopped herring (H trout) or dry pellets (P trout) for 15 weeks. Their satiation amounts were then determined under standard conditions. On a wet weight basis H trout ate 2·5-3·5 times more food than P trout; this was sufficient to compensate for the high water content of herring and thereby maintain the dry matter intake. When P trout were offered herring (PH trout) they consumed more food than when offered dry pellets but not as much as H trout. Stomach capacity restricted the intake and their dry matter intake was reduced by c. 40%. When H trout were offered dry pellets (HP trout) they adjusted their intake immediately close to the level of P trout although their larger stomachs could have accommodated more than twice this volume of dry food. The return of appetite after a satiation meal was almost linear with time. Appetite increased at c. 556 mg g^-1 body weight h^-1 for H trout and at 142 mg g^-1 bw h^-1 for P trout. The return of appetite in PH trout was significantly slower (c. 370 mg g^-1 bw h^-1) than in H trout; the previous dietary history of the PH trout limited their capacity to process larger volumes of wet food in a single meal. Fish offered dry diet (P and HP trout) had similar rates of appetite return despite their previous feeding history suggesting that the property of the dry feed itself might limit meal size. The total gastric emptying time of diets of similar dry matter content (with and without large amounts of water) was similar, but the delay time before gastric emptying starts tended to be longer for dry diets. Dry pellets appear to impose a demand for water that prolongs the gastric delay. This water demand is met partly by drinking since the trout fed on dry pellets drank significantly more (436 ± 189 mg kg^-1 h^-1) than unfed and herring-fed trout which drank little or not at all (65 ± 113 and 70 ± 66 mg kg^-1 h^-1 respectively). Dietary water facilitated food processing and increased daily dry matter intake of trout when fed four times a day. When only one satiation meal per day was allowed, dietary water had no effect. It is concluded from this work that, in addition to gastric volume, a short-term limitation on the size of satiation meals in the rainbow trout is the availability of water to moisturize the food and thus to promote gastric digestion and emptying.     

Bioaccumulation of Trace Mercury in Trophic Levels of Benthic, Benthopelagic, Pelagic Fish Species, and Sea Birds from Arvand River, Iran

In this study, concentration of mercury was determined in the trophic levels of benthic, benthopelagic, pelagic fish species, and river birds from Arvand River, located in the Khuzestan province in the lowlands of southwestern Iran at the head of the Persian Gulf. The order of mercury concentrations in tissues of the fish species was as follows: liver>gill>muscle and in tissues of the kingfisher species was as follows: feather>liver>kidney>muscle. Therefore, liver in fish and feather in kingfisher exhibited higher mercury concentration than the other tissues. There was a positive correlation between mercury concentrations in fish and kingfisher species with size of its food items. We expected to see higher mercury levels in tissues of female species because they are larger and can eat larger food items. The results of this study show that the highest mean mercury level were found in the kingfisher (Anas crecca), followed by benthic (Epinephelus diacanthus), benthopelagic (Chanos chanos), and pelagic fish (Strongylura strongylura). Mean value of mercury in fish species, S. strongylura were (0.61 μg g^?1 dry weight), C. chanos (0.45 μg g^?1 dry weight), E. diacanthus (0.87 μg g^?1 dry weight), and in kingfisher species A. crecca was (2.64 μg g^?1 dry weight). Significant correlation between mercury concentration in fish and kingfisher may be related to high variability of mercury in the fish.     

Mercury in the marine food chain in the Southern Ocean at Macquarie Island: an analysis of a top predator,Patagonian toothfish (<Emphasis Type="Italic">Dissostichus eleginoides</Emphasis>) and a mid-trophic species,the warty squid (<Emphasis Type="Italic">Moroteuthis ingens</Emphasis>)

The characteristics and habitat of the Patagonian toothfish (Dissostichus eleginoides) are typical of fish that accumulate high concentrations of mercury. In this study, mercury determinations were made on samples of muscle tissue from Macquarie Island toothfish and the Southern Ocean deepwater warty squid (Moroteuthis ingens). The analysis of mercury in the biological tissues was made by cold vapour-atomic absorption spectrometry following acid digestion. Performance of the analytical procedure was assessed by analysis of certified reference material (DORM-2, dogfish muscle). Mercury concentrations of 16 Macquarie Island toothfish ranged from 0.12 mg kg^–1 (550 g, 381 mm TL) to 0.59 mg kg^–1 (6,100 g, 823 mm TL), with a mean concentration of 0.33±0.12 mg kg^–1. A significant correlation was found between mercury and either toothfish weight or total length. The fish analysed were juveniles, which suggests that larger individuals would have higher mercury concentrations well exceeding food standard code limits for mercury in fish (typically 0.5 mg kg^–1). Warty squid, also from around Macquarie Island, had a low mean mercury concentration of 0.086 mg kg^–1 in mantle tissue; no significant correlation existed between mercury concentration and either squid mantle length or total weight. It is postulated that the squid have a mechanism, possibly involving the digestive gland, that prevents bioaccumulation of mercury in the mantle, and presumably other body tissues.     

Brassica juncea tested on urban soils moderately contaminated by lead: Origin of contamination and effect of chelates

Urban garden soils are a potential repository of heavy metal pollution, resulting from either anthropogenic or geogenic origin. The efficiency of phytoextraction was compared on two garden soils with the same texture and topsoil Pb concentration (170 mg kg^?1) but not the same origin: one geogenic, the other anthropogenic. Two varieties of Brassica juncea were tested with citric acid (25 mmol kg^?1) or ethylenediaminetetraacetic acid (EDTA, 2.5 mmol kg^?1). Geogenic Pb was shown to be two times less available than anthropogenic Pb, as a result of which the phytoextraction efficiency was reduced by 59%. Pb mobility in the soil was solely enhanced with EDTA, which increased the Pb concentration in shoots of B. juncea by between 14 and 26 times in comparison with the control. The highest Pb concentration in shoots still remained low, however (i.e., 45 mg kg^?1 dry weight). Regardless of the chelates introduced, B. juncea 426308 accumulated roughly twice as much lead as B. juncea 211000, but only for the anthropogenic contaminated soil. Under these conditions, the amount of Pb accumulated by B. juncea (even when assisted by EDTA) was not high enough to envision achieving soil clean-up within a reasonable time frame.     

Uptake of arsenic by mushrooms from soil

ABSTRACT

Graphite furnace atomic absorption spectrometry (standard addition method) was used to determine the total arsenic in wild-growing mushrooms after digestion with nitric acid, then with perchloric acid and in associated soils after digestion with mixtures of nitric and hydrofluoric acids in a microwave system. Among 83 species of mushrooms the highest concentrations of arsenic on a dry mass basis were found in Laccaria amethystea (26–125 mg kg^?1), Laccaria laccata (11–33 mg kg^?1), Thelephora terrestris (38 mg kg^?1), Boletus cavipes (11.6 mg kg^?1) and Ramaria botrytis (10 mg kg^?1). Mushroom caps of L. laccata, L. amethystea, and B. cavipes had approximately double the arsenic concentrations found in stems. The arsenic concentrations in caps of L. amethystea and L. laccata were directly proportional to the concentrations in the soils. The concentrations of arsenic in the soils were in the range 6.5–65 mg kg^?1. Among the 19 mushroom caps with arsenic concentrations above the method detection limit of 0.2 mg As/kg dry mass, only L. amethystea and L. laccata had arsenic concentration ratios ‘cap/soil’ higher than 1 (between 1.1 and 1.9). Thelephora terrestris had a ratio of 2.37.     

Modeling and Mapping of Atmospheric Mercury Deposition in Adirondack Park,New York

The Adirondacks of New York State, USA is a region that is sensitive to atmospheric mercury (Hg) deposition. In this study, we estimated atmospheric Hg deposition to the Adirondacks using a new scheme that combined numerical modeling and limited experimental data. The majority of the land cover in the Adirondacks is forested with 47% of the total area deciduous, 20% coniferous and 10% mixed. We used litterfall plus throughfall deposition as the total atmospheric Hg deposition to coniferous and deciduous forests during the leaf-on period, and wet Hg deposition plus modeled atmospheric dry Hg deposition as the total Hg deposition to the deciduous forest during the leaf-off period and for the non-forested areas year-around. To estimate atmospheric dry Hg deposition we used the Big Leaf model. The average atmospheric Hg deposition to the Adirondacks was estimated as 17.4 g m yr with a range of −3.7–46.0 g m yr. Atmospheric Hg dry deposition (370 kg yr) was found to be more important than wet deposition (210 kg yr) to the entire Adirondacks (2.4 million ha). The spatial pattern showed a large variation in atmospheric Hg deposition with scattered areas in the eastern Adirondacks having total Hg deposition greater than 30 μg m⁻² yr⁻¹, while the southwestern and the northern areas received Hg deposition ranging from 25–30 μg m⁻² yr⁻¹.     

Effects of Dietary Pantothenic Acid on Growth,Intestinal Function,Anti-Oxidative Status and Fatty Acids Synthesis of Juvenile Blunt Snout Bream Megalobrama amblycephala

Four groups of juvenile Megalobrama amblycephala were fed three times daily with six semi-purified diets containing 3.39 (PA unsupplied diet), 10.54, 19.28, 31.04, 48.38 and 59.72 mg kg^-1 calcium D-pantothenate. The results showed that survival rate, final weight, specific growth rate, protein efficiency ratio and nitrogen retention efficiency all increased significantly (P<0.01) as dietary PA levels increased from 3.39 to 19.28 mg kg^-1, whereas the opposite was true for feed conversion ratio. Whole-body crude protein increased as dietary PA levels increased, while the opposite pattern was found for the crude lipid content. Intestinal α-amylase, lipase, protease, Na⁺-K⁺-ATPase, alkaline phosphatase and gamma-glutamyl transferase activities were all elevated in fish fed PA-supplemented diets. Hepatic catalase activities improved with increases in dietary PA, while the opposite was true for malondialdehyde contents. The liver PA concentration and coenzyme A content rose significantly (P<0.01), up to 31.04 mg kg^-1, with increasing dietary PA levels and then plateaued. The percentage of hepatic saturated fatty acids increased significantly (P<0.01) as dietary PA levels increased, while the percentages of monounsaturated fatty acids and polyunsaturated fatty acid (PUFA) decreased as dietary PA increased. Fish fed diets containing 19.28 and 31.04 mg kg^-1 PA exhibited higher (P<0.01) docosahexaenoic acid and PUFA percentages in muscle than those fed with other diets. The expression of the gene encoding pantothenate kinase was significantly up-regulated (P<0.01) in fish fed PA-supplemented diets. Hepatic Acetyl-CoA carboxylase α, fatty acid synthetase, stearoyl regulatory element-binding protein 1 and X receptor α genes all increased significantly (P<0.01) as dietary PA levels increased from 3.39 to 31.04 mg kg^-1. Based on broken-line regression analyses of weight gain, liver CoA concentrations and PA contents against dietary PA levels, the optimal dietary PA requirements of juvenile blunt snout bream were estimated to be 24.08 mg kg^-1.     

Nutritive value of deep stacked and ensiled broiler litter for sheep

Broiler litter was deep stacked and ensiled with water to achieved 40% moisture before being added, with or without 5% sugarcane molasses or with rumen contents, to a basal diet. The influence of stacking and ensiling of broiler litter on the numbers of Salmonella, Shigella, Proteus and total number of colony forming units (CFU) was investigated. Nutritive value of broiler litter processed by deep stacking and ensiling was evaluated in a digestibility trial. The experiment was conducted with 30 wethers allotted to five diets. A basal diet (20% corn grain, 23% wheat bran, 37% cotton seed cake, 18% wheat straw and 2% dicalcium phosphate) was given alone (1) or with broiler litter processed by deep stacking (2), ensiling (3), ensiling with 5% added molasses (4), or ensiling with rumen contents (1:1, wet basis) (5). For Diets 2–5, the ratio of basal diet to silage was 1:1, dry basis. For the digestion trial, diets were given at 20 g dry matter (DM) kg⁻¹ body weight per day. Initial samples of broiler litter showed 2.5 × 10⁸ CFU and Salmonella, Shigella and Proteus were present. The processes of deep stacking and ensiling were equally effective in achieving a complete elimination of all the pathogens. Apparent digestibilities of organic matter (OM) and crude protein (CP) (559.1 g kg⁻¹ and 608.7 g kg⁻¹ DM) were lower (P < 0.05) for diet 2 (deep stacked litter) than for the other waste-containing diets (OM: 578.7 g kg⁻¹, 582.9 g kg⁻¹, 594.1 g kg⁻¹; CP: 688.6 g kg⁻¹, 675.8 g kg⁻¹, 709.0 g kg⁻¹ DM, for Diets 3, 4 and 5, respectively). Among the waste-containing diets, cellulose digestibility (398.7 g kg⁻¹ DM) was higher (P < 0.05) for Diet 5 (ensiled litter-rumen contents). The results indicate that deep stacking and ensiling are equally feasible and effective for eliminating the pathogens and processed broiler litter can be incorporated in the diet of ruminants at levels of up to 50% without any adverse effect on the health of the animals.     

Mercury distribution in sediment profiles from lakes of the high pantanal,Mato Grosso State,Brazil

Sediment cores from lakes located in the Pantanal Swamp, Central Brazil were analysed for the distribution of mercury released by the local gold mining. Atmospheric transport is the only pathway of mercury contamination of these remote lakes. Mercury concentrations were higher at the surface of sediments (62 to 80 ug.kg^–1) decreasing to values of 20 to 30 ug.kg^–1 in deeper layers. Mercury deposition rate was estimated as 90 to 120 ug Hg.m^–2yr^–1 Although mercury concentrations were much lower than in industrialized areas, mercury deposition rate for these Pantanal lakes is of the same order of magnitude of deposition rates measured in lakes in industrialized areas     

The localization of mercury and metallothionein in the cerebellum of rats experimentally exposed to methylmercury

Summary Rats were dosed with methylmercuric chloride, either by gastric gavage (5 × 10 mg kg^-1 body weight over a 15-day period), or in their drinking water (20 mg methylmercuric chloride l^–1 for 14 or 42 days). Localization of mercury within the cerebellum was performed with a silver physical development technique, and metallothionein with dinitrophenyl hapten-sandwich immunohistochemistry. Mercury was detected in structurally undamaged Purkinje neurones and adjacent Bergmann glial cells; no mercury was detected in granule cells even though these small cells nearest the Purkinje layer had a high incidence of pyknotic nuclei. In general, metallothionein was detected mainly in Bergmann glial cells, Purkinje cells, astrocytes and glial cells of white matter; no metallothionein was detected in granule cells. We hypothesized that the resistance of Purkinje cells to methylmercuric chloride reflects their ability to transform organic mercurials to inorganic mercury that, in turn, induces the synthesis of radical-scavenging metallothionein molecules.     

Assessment of Total and Organic Mercury Levels in Blue Sharks (Prionace glauca) from the South and Southeastern Brazilian Coast

Mercury occurrence was evaluated in samples of edible muscle tissue of 27 blue sharks (Prionace glauca) caught in the Atlantic Ocean, adjacent to the south and southeastern Brazilian coast, indicating a slight increase in comparison with previous data obtained for the same studied area and being higher than those fish caught at different sites of the Atlantic Ocean. Total Hg concentrations ranged from 0.46 to 2.40 mg kg^?1 with the organic Hg fraction ranging between 0.44 and 2.37 mg kg^?1. A negative correlation between total Hg concentration in muscle tissue and blue shark size was obtained, and 40 % of samples analyzed had Hg concentrations higher than 1.0 mg kg^?1 Hg, the maximum concentration permitted in Brazilian predator fish. Data obtained showed that total Hg can be used as a reliable predictor of organic Hg in blue shark muscle because 95 to 98 % of the total Hg measured was found to be organic mercury. The wide range of Hg concentrations obtained for our set of samples can be explained by the heterogeneity of sampled population and the large size of the studied area. Given the adverse toxicological effects of Hg on animals and humans, a regular monitoring program of Hg contamination in Brazilian marine ecosystem can be recommended.     

Methods of improving the utilization of cereal straw by ruminants. II. Further studies on dried grass as a supplement for lambs

Sixteen growing castrated lambs (37.0 ± 3.31 kg) were used in two 5 × 5 and one 6 × 6 Latin squares to measure the intake and digestibility of: (1) urea—molasses-treated straw, or mixtures containing (2) 25; (3) 50; or (4) 75% dried grass; and (5) grass alone. The dry matter intake was 40, 50, 69, 84 and 90 g day^?1 per kg of metabolic live weight (P<0.001), and digestibility was 470, 489, 591, 671 and 735 g kg^?1, respectively, for the above treatments. The dry matter intake of lambs offered diets 2, 3 and 4 as complete diets was 47, 56 and 66 g day^?1 kg of metabolic live weight, and digestibility was 513, 621 and 673 g kg^?1, respectively. When the feeds were offered separately, dry matter intake was 54, 63 and 78 g day^?1 per kg of metabolic live weight and digestibility was 541, 582 and 662 g kg^?1, respectively. Dry matter intake for mixed diets was higher (P<0.01) than for feeds given separately.