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排序方式: 共有101条查询结果,搜索用时 78 毫秒
61.
对聊古一井数字化氡观测资料进行分析研究的结果显示,科学合理的气水分离装置对于获得真实可靠的观测结果具有重要作用;保障仪器的正常工作状态。是数字化氡观测的重要环节之一。聊古一井数字化氡的变化特征主要受气温,气压和井压的影响。分析和排除这些因素的影响是数字化观测资料分析应用的基础。 相似文献
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耿杰 《地震地磁观测与研究》2005,26(5):76-80
2003年5月初至2003年10月下旬,聊古一井气体总量现明显的低值异常过程,在对上述异常变化进行现场分析落实的基础上,结合对聊古一井水化学测项投测以来地震异常特征和聊古一井水化学测项前兆意义的分析结果,认为聊古一井气体总量的异常变化属场兆异常,可作为该井周围不同地震构造带上发生5级以上地震的一种判据。聊古一井气体总量异常过程较好地对应了2003年11月25日山西洪洞发生的5.0级地震。 相似文献
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Concentrations of polychlorinated dibenzo-p-dioxins (dioxins)(PCDDs) and polychlorinated dibenzofurans (PCDFs)(furans) in sediments from Port Jackson ranged from 32 to 4352 pg WHO-TEQ DF g(-1)dw with a mean of 712 pg g(-1)dw. Maximum total dioxins plus furans concentrations in this sediment was 6,290,000 pg g(-1)dw, which is the highest recorded in Australia and among the highest reported for sediment globally. Permanent bans were placed on fin fishing and prawn trawling in February, 2006 for the whole estuary, based on dioxin tissue burdens. A distinct congener profile corresponded to chemicals known to have been produced by industry on the shores of Homebush Bay in the upper estuary. These chemicals are being dispersed extensively and exceed pre-anthropogenic concentrations in even distant, less developed parts of the harbour. Remediation of sediments is currently being undertaken, with the intention of containing dispersion of dioxins and reducing body burdens in fin fish and prawn populations. 相似文献
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Trace organic contamination in biota collected from the Pearl River Estuary, China: a preliminary risk assessment 总被引:5,自引:0,他引:5
Wei S Lau RK Fung CN Zheng GJ Lam JC Connell DW Fang Z Richardson BJ Lam PK 《Marine pollution bulletin》2006,52(12):1682-1694
The marine ecosystem of the Pearl River Delta, located on the southern coast of China, has been heavily exploited following the rapid economic growth that has occurred since the 1980s. This investigation aimed to elucidate trace organic contamination in marine biota inhabiting the Pearl River Delta area. Biota samples, including green-lipped mussels (Perna viridis), oysters (Crassostrea rivularis) and shrimp (Penaeus orientalis) were sampled from 16 stations fringing the Estuary. Elevated concentrations (on a dry weight basis) of polycyclic aromatic hydrocarbons (27.8–1041.0 ng/g), petroleum hydrocarbons (1.7–2345.4 μg/g), polychlorinated biphenyls (2.1–108.8 ng/g), DDTs (1.9–79.0 ng/g), and hexachlorocyclohexanes (n.d.–38.4 ng/g) were recorded. A human health risk assessment was conducted to estimate the risk to local residents associated with the consumption of biota collected from the Pearl River Estuary. The results indicated that PCBs were at levels that may cause deleterious health effects in populations that consume large amounts of seafood. However, it would be instructive to establish health criteria for trace organic contaminants that are specific to the local populations, in order to derive a more accurate and relevant health risk assessment. 相似文献
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Baussant T Ortiz-Zarragoitia M Cajaraville MP Bechmann RK Taban IC Sanni S 《Marine pollution bulletin》2011,62(7):1437-1445
Mussels (Mytilus edulis) were continuously exposed to dispersed crude oil (0.015-0.25 mg/l) for 7 months covering the whole gamete development cycle. After 1 month exposure to 0.25 mg oil/l, the level of alkali-labile phosphates (ALP) and the volume density of atretic oocytes in female gonads were higher than those in the gonads of control females, indicating that oil affected the level of vitellogenin-like proteins and gamete development. Spawning of mussels was induced after 7 months oil exposure. Parental oil exposure did not affect subsequent fertilization success in clean seawater but this was reduced in 0.25 mg oil/l. Parental exposure to 0.25 mg oil/l caused both slow development and a higher percentage of abnormalities in D-shell larvae 2 days post-fertilization; reduced growth 7 days post-fertilization. These effects were greatly enhanced when larval stages were maintained at 0.25 mg oil/l. Similar studies are warranted for risk assessment prognosis. 相似文献
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Coral species composition of drilled cores from emergent bank reefs, and coral cover of the surface of old and living reefs located along the coast of the state of Bahia, Eastern Brazil, revealed that there is a marked change in the occurrence of the major building coral species in different time intervals of the reef structure, as well as in the living surface of reefs located in two different geographical sites. Holocene core sections from two reef areas (12 degrees 40'S-38 degrees 00'W and 18 degrees 00'S-39 degrees 00'W) have as major reef builders, on its topmost core interval (3 to 4 ky old), the endemic coral Mussismilia braziliensis Verrill, 1868, which also dominate on the 2.5-3.5 ky old surfaces of truncated reef tops. At the base of the cores (the 2m lower interval, older than 4 ky BP), another endemic coral Mussismilia harttii Verrill, 1868 is the dominant reef component. The relative abundance of M. braziliensis on the living surfaces of shallow reefs from both areas, shows that in the southern area, it is up to 98% on reefs located 60 km off the coast, in depths between 3 and 4m, but do not exceed 1.3% on the surface of the northern reefs located 1-2 km off the coast in depths 4-5m. The Holocene falling sea level that occurred along the coast of Brazil since 5.1 ky BP, causes an increasing runoff into the area of coastal reefs. This phenomenon may have affected the nearshore reef building fauna, replacing a more susceptive coral fauna with one better adapted to low light levels and higher sediment influx. The high turbidity associated with early Holocene shelf flooding, should also be responsible for the absence of M. braziliensis during the initial stages of reef buildup in Brazil. At the present time, the rapidly increasing human pressure, due to changes in land uses of the coastal zone (increasing sedimentation rate, nutrification of coastal waters, industrial pollution) and underwater practices, such as overfishing and an intense tourism, is aggravating the recovery capacity of this already naturally threatened coral community. If this situation coupled with increasing sea surface temperature persists, modern coral reef growth, in Brazil cannot be maintained and the major reef building coral species of the reefs in Bahia, a remnant endemic coral fauna will very soon appear in the list of endangered species. 相似文献