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Mg Dry Weight (mg + dry_weight)
Selected AbstractsThe regional variation of aboveground live biomass in old-growth Amazonian forestsGLOBAL CHANGE BIOLOGY, Issue 7 2006YADVINDER MALHI Abstract The biomass of tropical forests plays an important role in the global carbon cycle, both as a dynamic reservoir of carbon, and as a source of carbon dioxide to the atmosphere in areas undergoing deforestation. However, the absolute magnitude and environmental determinants of tropical forest biomass are still poorly understood. Here, we present a new synthesis and interpolation of the basal area and aboveground live biomass of old-growth lowland tropical forests across South America, based on data from 227 forest plots, many previously unpublished. Forest biomass was analyzed in terms of two uncorrelated factors: basal area and mean wood density. Basal area is strongly affected by local landscape factors, but is relatively invariant at regional scale in moist tropical forests, and declines significantly at the dry periphery of the forest zone. Mean wood density is inversely correlated with forest dynamics, being lower in the dynamic forests of western Amazonia and high in the slow-growing forests of eastern Amazonia. The combination of these two factors results in biomass being highest in the moderately seasonal, slow growing forests of central Amazonia and the Guyanas (up to 350 Mg dry weight ha,1) and declining to 200,250 Mg dry weight ha,1 at the western, southern and eastern margins. Overall, we estimate the total aboveground live biomass of intact Amazonian rainforests (area 5.76 × 106 km2 in 2000) to be 93±23 Pg C, taking into account lianas and small trees. Including dead biomass and belowground biomass would increase this value by approximately 10% and 21%, respectively, but the spatial variation of these additional terms still needs to be quantified. [source] Leaching of heavy metals and nutrients from calcareous sandy-loam soil receiving municipal solid sewage sludgeJOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 3 2010Mohsen Jalali Abstract Leaching column experiments were conducted to determine the degree of mobility of heavy metals (HMs) and nutrients after the addition of municipal solid sewage sludge (MSS) in a sandy-loam soil. Treatments were (1) soil application of low metal content MSS, (2) soil application of metal-enriched municipal solid sewage sludge (EMSS), and (3) control. The MSS application represented a dose of 200 Mg dry weight (dw) ha,1. Soil columns were incubated at room temperature for 15 d and were irrigated daily with distilled water to make a total of 557,mm. Leachates were collected and analyzed for HMs and nutrients. The Ni and Pb added to soil via MSS and EMSS were found to be leached through the 20,cm columns of calcareous sandy soil although Ni and Pb concentrations in the percolate were small relative to the total amounts of metals applied. Losses of K+ from the EMSS, MSS, and control were 92.5, 82.0, and 52.5,kg ha,1, respectively. Losses of Mg2+ were in the range from 104.4 (control treatment) to 295.2,kg ha,1 (EMSS), while the loss of Ca2+ was in the range from 265.0 (control treatment) to 568.2,kg ha,1 (EMSS). The results showed that the amounts of P leached from EMSS (3.02,kg ha,1) and MSS (2.97,kg,1 ha,1) were significantly larger than those from the control treatment (1.54,kg ha,1). The geochemical code Visual MINTEQ was used to calculate saturation indices. Leaching of P in different treatments was controlled by rate-limited dissolution of hydroxyapatite, ,-tri-Ca phosphate, and octa-Ca phosphate. The results indicate that application of MSS to a sandy soil, at the loading rate used in this study, may pose a risk in terms of groundwater contamination with Ni, Pb, and the studied nutrients. [source] Activation of gelatinolytic/collagenolytic activity in dentin by self-etching adhesivesEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 2 2006Yoshihiro Nishitani Mild acids are known to activate dentin matrix metalloproteinase (MMPs). All self-etching dental adhesives are acidic (pH 1.5,2.7) and may activate dentin MMPs. The purpose of this study was to compare the ability of several all-in-one adhesives to activate gelatinolytic and collagenolytic activities in powdered mineralized dentin. Powdered dentin made from human teeth was mixed with all-in-one adhesives (Clearfil Tri-S Bond, G-Bond, Adper Prompt L-Pop) or a self-etching primer (Clearfil SE Bond primer) for varying times and then the reaction was stopped by extracting the adhesives using acetone. Fresh untreated mineralized dentin powder had a gelatinolytic activity of 3.31 ± 0.39 relative fluorescent units (RFU) per mg dry weight (24 h) that increased, over storage time, to 87.5 RFU mg,1 (24 h) after 6,8 wk. When fresh powder was treated with acidic Tri-S Bond, the gelatinolytic activity increased from 3.24 ± 0.70 RFU mg,1 to >,112.5 RFU mg,1 (24 h) after 20 min and then remained unchanged. Monomers with lower pH values produced less activity. There was a significant, direct correlation between gelatinolytic activity and pH, with Tri-S giving the highest activity. Coating dentin powder with Tri-S resin prevented fluorescent substrates from gaining access to the enzyme, even though it activated the enzyme. In conclusion, self-etch adhesives may activate latent MMP and increase the activity to near-maximum levels and contribute to the degradation of resin,dentin bonds over time. [source] A comparison among differently enriched rotifers (Brachionus plicatilis) and their effect on Atlantic cod (Gadus morhua) larvae early growth, survival and lipid compositionAQUACULTURE NUTRITION, Issue 1 2008A.S. GARCIA Abstract We evaluated the effect of differently enriched rotifers on the early growth, survival and lipid composition of Atlantic cod larvae (Gadus morhua). The enrichments tested were: (i) AlgaMac 2000®; (ii) AquaGrow® Advantage; and (iii) a combination of Pavlova sp. paste and AlgaMac 2000®. Larvae from treatment 3 [1.50 ± 0.11 mg dry weight (dw) and 7.10 ± 0.14 dw specific growth rate (SGR)] were heavier (P = 0.006) and grew faster (P = 0.004) than larvae from treatment 2 (1.03 ± 0.04 mg dw and 6.29 ± 0.04 dw SGR). No significant differences were found in the final weight and SGR among larvae from treatment 1 (1.21 ± 0.07 mg dw and 6.58 ± 0.20 dw SGR) and larvae from treatments 2 and 3. The treatment 3 also resulted in the best survival at the end of the experimental period, estimated to be 3 on a scale from 1 to 5, whereas the survival estimates for the two other groups were 1,2. Larvae from the treatment 3 reached 37 days posthatch with levels of ,6DPA 32-fold higher than newly hatched larvae. Differences in the larval enrichment of ,6DPA may explain the differences in growth and survival of the Atlantic cod larvae. [source] Complete and partial replacement of Artemia nauplii by Moina micrura during early postlarval culture of white shrimp (Litopenaeus schmitti)AQUACULTURE NUTRITION, Issue 2 2006L. MARTÍN Abstract Growth rate, soluble protein content, osmotic stress and digestive enzyme activity were studied in early Litopenaeus schmitti postlarvae under different feeding regimens, by partially or completely replacing Artemia nauplii with Moina micrura. Growth was significantly higher in the postlarvae fed with a mixture of M. micrura, Artemia nauplii and algae (0.030 mg dry weight (dw) larva,1 day,1, 17.4 ± 2.1% day,1), together with the postlarvae fed on Artemia nauplii and algae (0.027 mg dw larva,1 day,1, 18.3 ± 1.9% day,1). Complete replacement of Artemia nauplii by M. micrura produced the lowest growth rate (0.018 mg dw larva,1 day,1, 14.3 ± 1.6% day,1) and induced the highest protease and , -amylase activities and lower soluble protein contents. No significant difference among the treatments could be detected in postlarval resistance to osmotic stress. Based on the growth results, soluble protein content, enzymatic activity and osmotic stress resistance, we determined that the partial replacement of Artemia nauplii by M. micrura did not affect the growth, the soluble protein content and the nutritional state in the postlarvae of L. schmitti. To our knowledge, this is the first reported use of M.micrura as feed for early postlarvae of L. schmitti. [source] | ||||||||||