Amelioration effect of humic acid extracted from solubilized excess sludge on saline-alkali soil

In this study, the main characteristics and soil amendment effects on the saline–alkali soil of humic acid extracted from solubilized excess sludge (SS-HA) were investigated. The excess sludge was solubilized prior to extraction to improve the humic acid recovery rate. The structural features of SS-HA were characterized by an elemental analysis, Fourier transform infrared spectroscopy, and ¹H-nuclear magnetic resonance spectroscopy, and compared with those of HA extracted from non-solubilized excess sludge (ES-HA). The results showed that extraction efficiency of humic acid was enhanced by using solubilization, although structural properties of humic acid extracted from solubilized excess sludge were almost the same as those of ES-HA. To study a utilization method of SS-HA, the soil amendment effects on saline–alkali soil by mixture of SS-HA were investigated with a model soil-column experiment. SS-HA reduced the pH of the saline–alkali soil, and the effect was immediately observed or faster than the case in which only peat is added. Moreover, the cation exchangeable capacity of the saline–alkali soil was enhanced by addition of SS-HA.     

A spatially explicit empirical model of structural development processes in natural forests based on climate and topography

Stand structure develops with stand age. Old-growth forests with well-developed stand structure support many species. However, development rates of stand structure likely vary with climate and topography. We modeled structural development of 4 key stand variables and a composite old-growth index as functions of climatic and topographic covariates. We used a hierarchical Bayesian method for analysis of extensive snap-shot National Forest Inventory (NFI) data in Japan (n = 9244) to account for differences in stand age. Development rates of structural variables and the old-growth index exhibited curvilinear responses to environmental covariates. Flat sites were characterized by high rates of structural development. Approximately 150 years were generally required to attain high values (approximately 0.8) of the old-growth index. However, the predicted age to achieve specific values varied depending on environmental conditions. Spatial predictions highlighted regional variation in potential structural development rates. For example, sometimes there were differences of >100 years among sites, even in the same catchment, in attainment of a medium index value (0.5) after timber harvesting. The NFI data suggested that natural forests, especially old natural forests (>150 years), remain generally on unproductive ridges, steep slopes, or areas with low temperature and deep snow, where many structural variables show slow development rates. We suggest that maintenance and restoration of old natural forests on flat sites should be prioritized for conservation due to the likely rapid development of stand structure, although remaining natural forests on low-productivity sites are still important and should be protected.     

Effects of environmental conditions,low-level potassium,ethylenediaminetetraacetic acid,or combination treatment on radiocesium-137 decontamination in Napier grass

Environmental Science and Pollution Research - Phytoextraction is widely used to remove environmental pollutants such as heavy metals or radionuclides from soil. It is important to understand how...     

Polybrominated diphenyl ethers (PBDEs) and organochlorines in melon-headed whales, Peponocephala electra, mass stranded along the Japanese coasts: maternal transfer and temporal trend

Polybrominated diphenyl ethers (PBDEs) and organochlorine compounds (OCs) were determined in the blubber of 55 melon-headed whales (Peponocephala electra) mass stranded along the Japanese coasts since 1982. DDTs and PCBs were predominant in all the specimens investigated. In whales that died during the latest event in 2006, concentrations of PBDEs (190–510 ng/g lipid wt) were approximately two orders of magnitude lower than DDTs and PCBs, but comparable with HCHs and HCB. Maternal transfer of PBDEs to offspring through the whole reproductive process was estimated to be 85% of the mother's body burden, while that occurring during gestation was much lower (2.6–3.5%). Concentrations of PCBs, DDTs, and HCB were lower in melon-headed whales stranded after the year 2000 than those stranded in 1982, whereas PBDE and CHL levels showed a temporal increase during the past 20 years, suggesting that the peak of their usage and contamination occurred after the year 1982.     

Organotin compounds and polychlorinated biphenyls of livers in squid collected from coastal waters and open oceans

The current status of global marine pollution by TBT (tributyltin), TPT (triphenyltin) and polychlorinated biphenyls (PCBs) was examined by determining their concentrations in squid livers. TBT and TPT concentrations in squid livers were higher in coastal waters than in open oceans. The highest values of TBT and TPT of 279 and 519 ng g(-1), respectively, were detected off Japan. TBT concentrations were higher in the northern hemisphere than those of the southern hemisphere organisms. TPT was not detected in squid livers collected in the southern hemisphere. The variation in TBT and TPT concentrations between the northern and the southern hemisphere was greater than those recognized for PCBs distribution in the world oceans. This global distribution pattern of TBT, TPT and PCB seemed to reflect their usage (amount, period and manner of utilization). Approximate TBT concentrations in seawater estimated from bioaccumulation factor in the squid liver were 0.1-5.8 ng litre(-1) in waters around Japan, tr-0.8 ng litre(-1) in oceanic waters in the northern hemisphere, and tr-0.4 ng litre(-1) in the southern hemisphere oceans.     

Elevated water temperature reduces the acute toxicity of the widely used herbicide diuron to a green alga, Pseudokirchneriella subcapitata

In the actual environment, temperatures fluctuate drastically through season or global warming and are thought to affects risk of pollutants for aquatic biota; however, there is no report about the effect of water temperature on toxicity of widely used herbicide diuron to fresh water microalgae. The present research investigated inhibitory effect of diuron on growth and photosynthetic activity of a green alga Pseudokirchneriella subcapitata at five different temperatures (10, 15, 20, 25, and 30 °C) for 144 h of exposure. As a result, effective diuron concentrations at which a 50 % decrease in algal growth occurred was increased with increasing water temperature ranging from 9.2 to 20.1 μg L^–1 for 72 h and 9.4–28.5 μg L^–1 for 144 h. The photochemical efficiency of photosystem II (F _v/F _m ratio) was significantly reduced at all temperatures by diuron exposure at 32 μg L^–1 after 72 h. Inhibition rates was significantly increased with decreased water temperature (P?<?0.01). Intracellular H₂O₂ levels as an indicator of oxidative stress were also decreased with increasing temperature in both control and diuron treatment groups and were about 2.5 times higher in diuron treatment groups than that of controls (P?<?0.01). Our results suggest water temperatures may affect the toxicokinetics of diuron in freshwater and should therefore be considered in environmental risk assessment.     

Environmental factors in debromination activity of polybrominated diphenyl ethers by hepatic microsomes of freshwater fish

Although the debromination of polybrominated diphenyl ethers (PBDEs) in fish species has been studied, environmental factors, such as chemical contamination and habitat temperature, have not been well understood. This study compared debromination of BDE209 by hepatic microsomes of wild and cultured fish. PBDE concentrations in muscle tissue were lower in cultured fish than in wild fish. Debromination activity was high in wild common carp, followed by cultured common carp, moderate in cultured ayu sweetfish, and low in two cultured fish (rainbow trout and cherry salmon) and wild Japanese sea bass. Although common carps have been known as the species which have higher debromination ability, there were differences between wild and cultured common carps. First, wild common carp debrominated much more BDE209 than cultured common carp. Second was debromination of BDE209 lasted 96 h in wild carp but only 24 h in cultured carp. Wild carp were collected from warm wastewater effluent with consistently high concentrations of micropollutants. Cultured carp were collected from colder clean waters. Therefore, environmental factors in debromination include contamination or ambient temperature. To investigate the effects of habitat environment on debromination of PBDEs, we collected wild carp in summer and winter at two different locations with similar PBDE contamination levels. Carp collected from the natural river in winter had the highest BDE99 debromination activity. Although the results indicated seasonal difference of debromination of BDE209, we could not confirm whether habitat temperature or physiological cycle of carp affected to debromination ability. Thus, further investigation such as in vivo experiment is required.

     

Radiographic and genetic diagnosis of sporadic hypochondroplasia early in the neonatal period

Hypochondroplasia is an autosomal dominant skeletal dysplasia expressing postnatal onset of short stature with mild rhizomelic shortening of the limbs. This manifestation leads to restricted prenatal diagnosis of the disorder. We report here on a sporadic case of a hypochondroplastic baby, whose prenatal sonographic measurements were serially recorded from 19 weeks of gestation. Mild shortening of the limbs became manifest after 26 weeks of gestation. Biparietal diameter was within the normal range throughout gestation. Both parents were of average stature. A tentative diagnosis of a nonlethal short-limb skeletal dysplasia was made. At birth, the clinical manifestations of the neonate were not characteristic, but the radiographic features raised the possibility of hypochondroplasia. Molecular analyses revealed a C to G mutation at nucleotide 1659 of the fibroblast growth factor receptor 3 (FGFR3) gene, a common mutation in hypochondroplasia. Copyright © 2004 John Wiley & Sons, Ltd.     

240Pu/239Pu atom ratios in seawater from Sagami Bay, western Northwest Pacific Ocean: sources and scavenging

Seawater samples were collected in Sagami Bay, western Northwest Pacific Ocean, and their (239+240)Pu activities and (240)Pu/(239)Pu atom ratios were determined by alpha-spectrometry and sector field high-resolution ICP-MS. A few samples also were analyzed for (137)Cs activities. The (239+240)Pu inventory of 41.1 Bq m(-2) was equivalent to the expected cumulative deposition density of atmospheric global fallout at the same latitude and this inventory was considerably lower than inventories in the underlying sediment columns. This result indicated that a significant amount of (239+240)Pu has been removed into the underlying sediments through enhanced scavenging from the water column by the high fluxes of particles in this region. The atom ratio of (240)Pu/(239)Pu showed no notable variation from the surface to the bottom; the average value was 0.234+/-0.004. This atom ratio was significantly higher than the mean global fallout ratio of 0.18, proving the existence of close-in fallout plutonium originating from the Pacific Proving Grounds (PPG). The relative contributions of the global stratospheric fallout and the PPG close-in fallout were evaluated by using the two end-member mixing model. The contribution of the PPG close-in fallout was estimated to be 15.2 Bq m(-2), which corresponded to 37% of the (239+240)Pu inventory in the water column. Thus (239)Pu and (240)Pu from the two sources of global fallout and close-in fallout have been homogenized in the water masses in the western Northwest Pacific margin during the past three decades.     

Phosphate removal and recovery with a synthetic hydrotalcite as an adsorbent

Phosphate removal is important to control eutrophication and an ion exchange process is one of several treatment processes for this purpose. Hydrotalcite compounds (HTALs) are useful as adsorbents for phosphate removal because of their ion exchange properties. In this study, the adsorption properties of a granular synthetic HTAL for phosphate and the method of regeneration of the granular HTAL were examined. The adsorption isotherm of the granular HTAL was approximated by a modified Langmuir type, and the maximum adsorption capacity was 47.3 mg P g(-1), which corresponded to the content of HTAL in the granular one. Phosphate adsorbed on the HTAL was effectively desorbed with alkaline NaCl solutions and the HTAL was regenerated with 25 w/v% MgCl(2) solution. The regenerated HTAL could be reused repeatedly for the phosphate removal. Phosphate in the exhausted desorption solution was recovered as a precipitate of calcium phosphate by addition of CaCl(2), and the residual exhausted desorption solution could be also reused after supplying NaOH. The results suggest the possibility of an effective system for phosphate removal and recovery, which includes the following processes: adsorption, desorption, recovery of phosphate, and regeneration of the HTAL and the desorption solution.