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151.
Water resources and land use are closely linked with each other and with regional climate, assembling a very complex system. The understanding of the interconnecting relations involved in this system is an essential step for elaborating public policies that can effectively lead to the sustainable use of water resources. In this study, an integrated modelling framework was assembled in order to investigate potential impacts of agricultural expansion and climate changes on Irrigation Water Requirements (IWR) in the Taita Hills, Kenya. The framework comprised a land use change simulation model, a reference evapotranspiration model and synthetic precipitation datasets generated through a Monte Carlo simulation. In order to generate plausible climate change scenarios, outputs from General Climate Models were used as reference to perturbing the Monte Carlo simulations. The results indicate that throughout the next 20 years the low availability of arable lands in the hills will drive agricultural expansion to areas with higher IWR in the foothills. If current trends persist, agricultural areas will occupy roughly 60% of the study area by 2030. This expansion will increase by approximately 40% the annual water volume necessary for irrigation. Climate change may slightly decrease crops' IWR in April and November by 2030, while in May a small increase will likely be observed. The integrated assessment of these environmental changes allowed a clear identification of priority regions for land use allocation policies and water resources management. 相似文献
152.
Mst. Shamsun Nahar Jing Zhang Akira Ueda Fujishiro Yoshihisa 《Environmental geochemistry and health》2014,36(6):1079-1094
The present study evaluated water supply geochemistry in Dhaka City, Bangladesh, to provide detailed trace level (subppb) water quality data that include major ions, low dissolved oxygen (DO) and toxic trace metals for sustainable development. Dhaka Groundwater, which almost uniformly meets the World Health Organization guideline, has become the preferred source. Due to groundwater depletion and an ever-increasing need to meet water demands by city residents, Dhaka water supply and sewerage authority has initiated the treatment of river water, despite the fact that very little is known about the geochemical structure, and trace metal content in the Dhaka water supply. Major ion composition of water samples was determined, and the results used to generate Stiff diagrams. The diagrams served to visually compare water from different sources based on units of mass/volume. Hydrochemical facies analysis showed supply ground and surface waters are comprised predominately of Ca–Na–Mg–HCO3 and Ca–Na–Mg–HCO3–Cl types. Spatial distribution of ions, and Na/Cl and Na/SiO2 molar ratio indicated that silicate weathering is the dominant geochemical process. Chemical data revealed that toxic Cr metal mobilization is associated with chemical hazards from the leather industry. The vulnerability of deep wells to contamination by As is governed by the geometry of induced groundwater flow paths and the geochemical conditions encountered between the shallow and deep regions of the aquifer. Quantifying total arsenic (As) and As from interlocking geochemical cycles (Fe, Mn) may assist in interpreting As dynamics in Dhaka well water. The surface source water was hypoxic to anoxic low DO associated with very high concentrations of biological oxygen demands, and electrical conductivity compared to industrial and non-industrial urban processes and standard activity guidelines. The results of this study should be applied to future research focused on the potential to improve water quality in urban and surrounding areas. 相似文献
153.
Detection of Dechlorane Plus and brominated flame retardants in marketed fish in Japan 总被引:3,自引:0,他引:3
Kakimoto K Nagayoshi H Yoshida J Akutsu K Konishi Y Toriba A Hayakawa K 《Chemosphere》2012,89(4):416-419
Fish samples purchased from Japanese markets were analyzed for Dechlorane Plus (DP)(syn-, anti-), polybrominated diphenyl ether (PBDE), and hexabromocyclododecane (HBCD)(α, γ). Twenty fish were analyzed using gas chromatography-mass spectrometry for DP and PBDE, and using liquid chromatography-tandem mass spectrometry for HBCD. DP was detected in 18 samples and ∑DP concentrations were <0.2-14.2 pg g−1 wet wt. Among the DP isomers, anti-DP was the dominant residue observed in this study. PBDE was detected in all samples. Concentrations of ∑PBDE ranged from 2.2 to 878 pg g−1 wet wt. HBCD was detected in 18 samples, and ∑HBCD concentrations were <0.02-21.9 ng g−1 wet wt. In fish landed near the East China Sea and the Sea of Japan, we detected relatively high concentrations of DP, PBDE, and HBCD. These results indicate that the seawaters around East Asia are contaminated with flame retardants. This study demonstrates the presence of DP in fish marketed in Japan for the first time. 相似文献
154.
Katsuhisa Baba Akira Miyazono Keiji Matsuyama Shoui Kohno Shin Kubota 《Marine Biology》2007,151(5):1977-1987
In November 2003, we first observed prevalent occurrence of a hydroid, Eutima japonica, on soft body tissues of age zero Japanese scallop (Mizuhopecten yessoensis) juveniles cultured in large areas of Funka Bay, Hokkaido. The occurrence coincided with massive death of juvenile scallops.
A major objective was to clarify ecological relationships between the symbionts, and to infer the relationship between symbiosis
and the massive mortality. To do this, we investigated distributions of association rates of hydroids with juvenile scallops
at 15–34 sites over 3 years (2003–2005), with age one adult scallops at 24 sites in 2003, and with mussels at 13 sites in
2004. We studied seasonal changes in association rates with juvenile scallops, and numbers of polyps per juvenile scallop
at three sites from November 2003 to June 2004. We also quantified the hydroid impacts on juvenile scallop shell length growth
and triglyceride accumulation in the digestive gland. The association rate of E. japonica polyps with juvenile scallops was high in large areas of Funka Bay in 2003, and overlapped the distribution of mussels bearing
polyps. Association rates with age one adult scallops were very low in November 2003, even at the sites where polyps were
very common on juvenile scallops. Levels of hydroid occurrence in juvenile scallops varies by year. We found that hydroids
presence in juvenile scallops declined drastically in 2004 and 2005. The association rates with juvenile scallops, and numbers
of polyps per juvenile scallop declined during winter, until they disappeared completely in the following June. Since polyps
were rare in adult scallops, we believe that infection of juvenile scallops was probably initiated from the planulae produced
by medusae released from polyps growing on Mytilus spp., especially M. galloprovincialis. Subsequently, the inhabitation spread intraspecifically and interspecifically. In juvenile scallops, inhabitation of polyps
reduced shell length growth by 43%, and triglyceride accumulation in digestive glands by 24–47%. Inhabitation of E. japonica on juvenile scallop is best regarded as parasitism, rather than inquilinism or commensalism. Occurrence of polyps was probably
not a direct lethal factor for juvenile scallops, because there were some sites where association rates were high, but mortalities
were low. Massive mortalities in 2003 may have resulted from simultaneous impacts of heavy polyp load and stresses caused
by the way in which the animals were handled (transferred from cages for pre-intermediate culture to cages for intermediate
culture), because the massive mortality occurred within a month of the transfer. The presence of polyps in juvenile scallops
does not affect the quality of the product in Funka Bay, because market size scallops are hydroid-free. 相似文献
155.
Wong Tuk-Yee Miho Nakatani Tomiyuki Maeda 《Environmental monitoring and assessment》1991,19(1-3):27-33
It is well known that in the analysis of low temperature vaporized metal elements such as cadmium and lead, a high ashing temperature causes a loss of the target atoms at the ashing stage, while low ashing temperature causes incomplete decomposition of organic components in the sample. In order to solve these problems, the effect of oxygen addition on determination of cadmium and lead in blood and foods was studied. Oxygen was introduced into the atmosphere in the graphite furnace at the beginning of ashing stage for 20 seconds at 0.5 l/min. Relation between ashing temperature and sensitivity was examined, and the oxygen addition minimized signal depression by the sample matrix. It can be concluded that the addition of oxygen at the ashing stage not only reduces the background absorption, but also suppress the volatilization of target atoms at the ashing stage by the formation of their oxides. 相似文献