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1.
Pensacola Bay, Florida, was in the strong northeast quadrant of Hurricane Ivan when it made landfall on September 16, 2004
as a category 3 hurricane on the Saffir-Simpson scale. We present data describing the timeline and maximum height of the storm
surge, the extent of flooding of coastal land, and the magnitude of the freshwater inflow pulse that followed the storm. We
computed the magnitude of tidal flushing associated with the surge using a tidal prism model. We also evaluated hurricane
effects on water quality using water quality surveys conducted 20 and 50 d after the storm, which we compared with a survey
14 d before landfall. We evaluated the scale of hurricane effects relative to normal variability using a 5-yr monthly record.
Ivan's 3.5 m storm surge inundated 165 km2 of land, increasing the surface area of Pensacola Bay by 50% and its volume by 230%. The model suggests that 60% of the Bay's
volume was flushed, initially increasing the average salinity of Bay waters from 23 to 30 and lowering nutrient and chlorophylla concentrations. Additional computations suggest that wind forcing was sufficient to completely mix the water column during
the storm. Freshwater discharge from the largest river increased twentyfold during the subsequent 4 d, stimulating a modest
phytoplankton bloom (chlorophyll up to 18 μg l−1) and maintaining hypoxia for several months. Although the immediate physical perturbation was extreme, the water quality
effects that persisted beyond the first several days were within the normal range of variability for this system. In terms
of water quality and phytoplankton productivity effects, this ecosystem appears to be quite resilient in the face of a severe
hurricane effect. 相似文献
2.
Anita R. Schiller 《Natural Hazards》2011,56(1):331-346
This paper examines the possible storm surge damage from a major hurricane to hit the Houston Metropolitan Statistical Area
(MSA.) Using storm surge analysis on a unique data set compiled from the Texas Workforce Commission (QCEW), the paper estimates
the expected industry-level damage for each county in the Houston MSA. The advantages of using GIS to analyze the expected
storm surge damage estimation is that it provides an accurate estimation of the number of affected employees and probable
wages losses, by industry and county, based on QCEW data. The results indicate that the ‘Basic Chemical Manufacturing’ and
‘Oil and Gas Extraction’ industries incur the highest employee and payroll losses while the ‘Restaurants and Eateries’ has
the largest establishment damage if a major hurricane were to hit the Houston MSA. 相似文献
3.
Normalized Difference Vegetation Index (NDVI) data were used to investigate vegetation changes after Hurricane Katrina (2005)
for the Weeks Bay Reserve and surrounding area of coastal AL. Landsat 5 satellite images were acquired before landfall (March
24, 2005), after landfall (September 16, 2005), and 8 months after landfall (April 28, 2006). The March 2005 to September
2005 image comparison showed that average NDVI values decreased by 49% after landfall. Continuing into the next year, average
NDVI values were −44% lower in April 2006 than they were in March 2005. Among habitat types, the estuarine emergent wetland
experienced the largest average NDVI value decrease (−64%). The estuarine emergent wetland NDVI values continued to decrease
by −27% from September 2005 to April 2006, whereas other habitats increased in NDVI. This continued suppression of NDVI values
was attributed to increased salinity from the storm surge and to regional drought conditions that occurred after landfall.
These results provide insight into the sensitivity of coastal vegetation from the interactions of both tropical cyclones and
long-term environmental conditions. 相似文献
4.
Ocean surges onto coastal lowlands caused by tropical and extra tropical storms, tsunamis, and sea level rise affect all coastal
lowlands and present a threat to drinking water resources of many coastal residents. In 2005, two such storms, Hurricanes
Katrina and Rita struck the Gulf Coast of the US. Since September 2005, water samples have been collected from water wells
impacted by the hurricanes’ storm surges along the north shore of Lake Pontchartrain in southeastern Louisiana. The private
and public water wells tested were submerged by 0.6–4.5 m of surging saltwater for several hours. The wells’ casing and/or
the associated plumbing were severely damaged. Water samples were collected to determine if storm surge water inundated the
well casing and, if so, its effect on water quality within the shallow aquifers of the Southern Hills Aquifer System. In addition,
the samples were used to determine if the impact on water quality may have long-term implication for public health. Laboratory
testing for several indicator parameters (Ca/Mg, Cl/Si, chloride, boron, specific conductance and bacteria) indicates that
surge water entered water wells’ casing and the screened aquifer. Analysis of the groundwater shows a decrease in the Ca/Mg
ratio right after the storm and then a return toward pre-Katrina values. Chloride concentrations were elevated right after
Katrina and Rita, and then decreased downward toward pre-Katrina values. From September 2005 to June 2006, the wells showed
improvement in all the saltwater intrusion indicators. 相似文献
5.
Stanley A. Changnon 《Natural Hazards》2011,59(2):1175-1187
High winds are one of the nation’s leading damage-producing storm conditions. They do not include winds from tornadoes, winter
storms, nor hurricanes, but are strong winds generated by deep low pressure centers, by thunderstorms, or by air flow over
mountain ranges. The annual average property and crop losses in the United States from windstorms are $379 million and windstorms
during 1959–1997 caused an average of 11 deaths each year. Windstorms range in size from a few hundred to hundreds of thousands
square kilometers, being largest in the western United States where 40% of all storms exceed 135,000 km2. In the eastern United States, windstorms occur at a given location, on average, 1.4 times a year, whereas in the western
US point averages are 1.9. Midwestern states average between 15 and 20 wind storms annually; states in the east average between
10 and 25 storms per year; and West Coast states average 27–30 storms annually. Storms causing insured property losses >$379 million and windstorms
during 1959–1997 caused an average of 11 deaths each year. Windstorms range in size from a few hundred to hundreds of thousands
square kilometers, being largest in the western United States where 40% of all storms exceed 135,000 km2. In the eastern United States, windstorms occur at a given location, on average, 1.4 times a year, whereas in the western
US point averages are 1.9. Midwestern states average between 15 and 20 wind storms annually; states in the east average between
10 and 25 storms per year; and West Coast states average 27–30 storms annually. Storms causing insured property losses >1
million, labeled catastrophes, during 1952–2006 totaled 176, an annual average of 3.2. Catastrophic windstorm losses were
highest in the West and Northwest climate regions, the only form of severe weather in the United States with maximum losses
on the West Coast. Most western storms occurred in the winter, a result of Pacific lows, and California has had 31 windstorm
catastrophes, more than any other state. The national temporal distribution of catastrophic windstorms during 1952–2006 has
a flat trend, but their losses display a distinct upward trend with time, peaking during 1996–2006. 相似文献
6.
Nan D. Walker 《Estuaries and Coasts》2001,24(4):498-508
Changes in circulation, water level, salinity, suspended sediments, and sediment flux resulted from Tropical Storm Frances and Hurricane Georges in the Vermilion-Atchafalaya Bay region during September 1998. Tropical Storm Frances made landfall near Port Aransas, Texas, 400 km west of the study area, and yet the strong and long-lived southeasterly winds resulted in the highest water levels and salinity values of the year at one station in West Cote Blanche Bay. Water levels were abnormally high across this coastal bay system, although salinity impacts varied spatially. Over 24 h, salinity increased from 5 to 20 psu at Site 1 on the east side of West Cote Blanche Bay. Abnormally high salinities were recorded in Atchafalaya Bay but not at stations in Vermilion Bay. On September 28, 1998, Hurricane Georges made landfall near Biloxi, Mississippi, 240 km east of the study area. On the west side of the storm, wind stress was from the north and maximum winds locally reached 14 m s−1. The wind forcing and physical responses of the bay system were analogous to those experienced during a winter cold-front passage. During the strong, north wind stress period, coastal water levels fell, salinity decreased, and sediment-laden bay water was transported onto the inner shelf. As the north wind stress subsided, a pulse of relatively saline water entered Vermilion Bay through Southwest Pass increasing salinity from 5 to 20 psu over a 24-h period. National Oceanic and Atmospheric Administration (NOAA)-14 reflectance imagery revealed the regional impacts of wind-wave resuspension and the bay-shelf exchange of waters. During both storm events, suspended solid concentrations increased by an order of magnitude from 75 to over 750 mg l−1. The measurements demonstrated that even remote storm systems can have marked impacts on the physical processes that affect ecological processes in shallow coastal bay systems. 相似文献
7.
Joseph Palis 《GeoJournal》2009,74(3):227-234
My paper aims to ask what space characterizes the various constructs of orientalism and othering in the early short films
of Thomas Edison. Using Lefebvre’s concept that social space “subsumes things produced, and encompasses their interrelationships
in their coexistence and simultaneity” in these early shorts, I will look at three Biograph actualities found at the Library
of Congress-American Memory page to show how space is manifested and negotiated onscreen. I will examine Edison’s “Filipinos
Retreat From Trenches”, “Capture of Trenches at Candaba” and “U.S. Troops and Red Cross in the Trenches Before Caloocan” which
were all released in 1899. These reenacted short films were shot during the tumultuous years of the Spanish-American War.
In the Biograph shorts, the privileged positions of both Spanish and American forces in relation to the annexation of a foreign
land in world history books is indicative of the tendency to de-emphasize the contribution of the native population in the
war. Manthia Diawara has said that “space is related to power and powerlessness, insofar as those who occupy the center of
the screen are usually more powerful than those in the background or completely absent from the screen.” The spatial hierarchies
and spatially situated images in Edison’s short films show how historically configured power relations encrypted oppression
to its external “others” through the cinematic apparatus.
相似文献
Joseph PalisEmail: |
8.
The speeds of historical cool-season extratropical cyclones along the U.S. east coast, hereafter East Coast Winter Storms
(ECWS), occurring during the period from 1951 to 2006 were computed. Average storm speed was 13.8 ms−1 with stronger storms generally moving faster than weaker storms and faster storms forming during the midwinter months (December–March).
There was no clear trend in ECWS speed during the time period, although considerable season-to-season variability was present.
The monthly and seasonal variations in storm speed could not be attributed to the El Ni?o-Southern Oscillation or North Atlantic
Oscillation (NAO) alone. However, the speed of ECWS was considerably slower when both El Ni?o and the negative phase of NAO
occurred simultaneously. Characteristic patterns in the upper levels of the atmosphere, specifically 300 hPa zonal winds and
500 hPa geopotential heights, were present during periods when ECWS speeds were among the slowest (and separately fastest).
For slow storm speed, these patterns also prevailed during months in which El Ni?o and negative NAO phase occurred. These
patterns were also present during months with extended runs of high oceanic storm surge. This provides a qualitative link
between the atmospheric conditions associated with slow storms and potentially high coastal storm surge impacts. Among the
prime consequences of ECWS speed are extended periods of high storm surge, mainly due to slow-moving storms. The sustained
high tidal levels often lead to substantial damage caused by coastal flooding, overwash, and beach erosion. 相似文献
9.
L. Caballero J. L. Macías A. García-Palomo G. R. Saucedo L. Borselli D. Sarocchi J. M. Sánchez 《Natural Hazards》2006,39(1):103-126
In September 1998 tropical storm “Earl” swept southern Mexico, producing intense rainfall in the states of Oaxaca and Chiapas.
Among the most devastated cities was Motozintla, located in the drainage basin of the Allende, La Mina and Xelajú Grande Rivers.
The rainfall from the tropical storm totaled 175 mm on September 8 and 130 mm on September 9, duplicating in two days the
average monthly precipitation in the region. Numerous landslides occurred in the vicinity of Motozintla, depositing large
volumes of material into the Xelajú Grande stream. Much of this sediment was subsequently remobilized, yielding debris flows,
hyperconcentrated flows, and sediment-laden flows that inundated most sections of Motozintla city. The flows covered an approximate
area of 3.15 km2 with a minimum volume of 4.4 × 106 m3 of sediment. Communication of Motozintla with the rest of the Chiapas State was interrupted for about a month, as was the
supply of potable water, food, electricity, and fuel. The geologic record around Motozintla indicates that the Xelajú Grande
River has been a pathway for similar large floods during the last 6000 years. The oldest deposit yielded a radiocarbon age
of 5320 ± 100 14C years. B.P. At least two historic floods have occurred during the last 100 years, a time period defined by a stratigraphically
distinct tephra of 1902. Frequency analysis of the historical record of daily rainfall in the Motozintla area suggests that
events like that of September, 1998, have a recurrence interval of about 25 years. After the catastrophic flows of 1998, the
mitigation measures by Municipal Authorities were made without regard to geological and environmental factors, or to taking
into consideration the flow magnitude and appropriate hazard-mitigation techniques, with the result that Motozintla remains
at serious risk for future floods. Unfortunately, prior to the publication of this study, in early October 2005, Motozintla
was seriously damaged again by intense rain provoked by Hurricane Stan. 相似文献
10.
The giant Mercosul aquifer system consists of Triassic-Jurassic eolian-fluvio-lacustrine sandstones confined by Cretaceous
basalt flows, and it covers about 1,195,500 km2 (461,583 miles2) in South America. The aquifer system encompasses all of the Paraná Basin and part of the Chaco-Paraná Basin and is one of
the world's largest. The eolian Botucatu Sandstone and its equivalents form an important part of this system. Maps of structure,
thickness of overlying rocks, and water temperature, and a potentiometric map, all based on 322 wells, define hydrogeologic
characteristics and provide the basis for establishing guidelines for the long-term equilibrium use of this important multinational
aquifer system. The Mercosul aquifer system is divided into two domains – the larger and better understood Paraná Basin and
the smaller and less well understood Chaco-Paraná Basin. Most of the northern part of the Paraná Basin has axially-directed
groundwater flow, whereas the southern part of the aquifer discharges mostly to the southwest into the Corrientes Province
of Argentina, with negligible discharge into the Atlantic Ocean. The Mercosul aquifer system is conservatively estimated to
have been flushed at least 180 times since deposition. Various factors are responsible for this flushing, including appreciable
rainfall since the end of the Cretaceous Period, probable uplift of the basins' borders in Late Cretaceous time, simple basin
geometry, long-term riverine and groundwater flow to the southwest (ancestral and present Paraná River Systems), and stable
cratonic setting.
Key hydraulic properties of the Mercosul aquifer system are compared to those of the eolian Jurassic Navajo-Nugget System
of the western United States. The results demonstrate the importance of tectonics and climate on the evolution of sub-continental
aquifer systems.
Received, September 1997 / Revised, December 1998 / Accepted, January 1999 相似文献
11.
Characteristics of winter mass balance of Glacier No.1 at the headwaters of the Urumqi River,Tianshan Mountains 总被引:1,自引:1,他引:0
This study analyzes the response of glacier to climate change during the past 49 years in Urumqi River source region, the
Tianshan Mountains of China. The temporal and spatial variations of winter mass balance (bn-w) at different time scales were
analyzed to identify their response to climate change during 1988–2006 (The observation of winter mass balance observation
began in 1988) on the Glacier No.1 at the headwaters of the Urumqi River, Tianshan Mountains, China. The winter accumulation
shows a significantly decreasing trend. The results show that the cumulative values on Glacier No.1 is 2,202 mm water equivalent
during 1988–2006 and the mean values is 116 mm a−1. Furthermore, the trend analysis of the winter mass balance indicates a rapid decrease since 1990, and the mean mass balance
is only 79 mm a−1 during 1997–2006. Winter mass balance correlates well negatively with the total evaporation from September to April (r = −0.68, α = 0.01), and positively with the total precipitation from September to April (r = 0.74, α = 0.01). However, winter mass balance shows a weak correlation with mean minimum air temperature during September
to April (r = −0.35), and runoff on September (r = −0.13). 相似文献
12.
Y. A. Moustafa J. Pätzold Y. Loya G. Wefer 《International Journal of Earth Sciences》2000,88(4):742-751
We present a study based on X-ray chronologies and the stable isotopic composition of fossil Porites spp. corals from the northern Gulf of Aqaba (Red Sea) covering the mid-Holocene period from 5750 to 4450 14C years BP (before present). The stable oxygen and carbon isotopic compositions of five specimens reveal regular annual periodicities.
Compared with modern Porites spp. from the same environment, the average seasonal δ
18O amplitude of the fossil corals is higher (by ca. 0.35–0.60‰), whereas annual growth rates are lower (by ca. 3.5 to 2 mm/year).
This suggests stronger seasonality of sea surface temperatures and increased variability of the oxygen isotopic composition
of the sea water due to changes in the precipitation and evaporation regime during the mid-Holocene. Most likely, summer monsoon
rains reached the northern end of the Red Sea at that time. Average annual coral growth rates are diminished probably due
to an increased input and resuspension of terrestrial debris to the shallow marine environment during more humid conditions.
Our results corroborate published reports of paleodata and model simulations suggesting a northward migration of the African
monsoon giving rise to increased seasonalities during the mid-Holocene over northeastern Africa and Arabia.
Received: 4 January 1999 / Accepted: 13 September 1999 相似文献
13.
Formation and failure of the Tsatichhu landslide dam, Bhutan 总被引:1,自引:1,他引:1
At 00:30 (local time) on the 10th September 2003 a joint and foliation defined wedge of material with an estimated volume of 7–12×106 m3 slid into the narrow Tsatichhu River Valley, in Jarrey Geog, Lhuentse, eastern Bhutan. The Tsatichhu River, a north–easterly flowing tributary of the Kurichuu River, was completely blocked by the landslide. During its movement, the landslide transitioned into a rock avalanche that travelled 580 m across the valley before colliding with the opposite valley wall. The flow then moved down valley, travelling a total distance of some 700 m. The rock avalanche was accompanied by an intense wind blast that caused substantial damage to the heavily forested valley slopes. The resulting geomorphologically-typical rock-avalanche dam deposit created a dam that impounded a water volume of 4–7×106 m3 at lake full level. This lake was released by catastrophic collapse of the landslide, which occurred at 16:20 (local time) on 10th July 2004, after reported smaller failures of the saturated downstream face. The dam failure released a flood wave that had a peak discharge of 5900 m3 s−1 at the Kurichhu Hydropower Plant 35 km downstream. 相似文献
14.
Marine contamination of groundwater may be caused by seawater intrusion and by salt spray. The role of both processes was
studied in the Cyclades archipelago on four small islands (45–195 km2) whose aquifers consist essentially of fractured, weathered metamorphic rocks. Annual rainfall ranges from 400 to 650 mm
and precipitation has high total dissolved solids contents of 45–223 mg l–1. The chemical characteristics of the groundwater, whose salinity is from 0.4 to 22 g l–1, are strongly influenced by seawater intrusion. However, the effect of atmospheric input is shown in certain water sampling
locations on high ground elevation where the dissolved chloride contents may attain 200 mg l–1.
Received: 14 November 1995 · Accepted: 9 September 1996 相似文献
15.
Mingrui Qiang Fahu Chen Jiawu Zhang Ruiping Zu Ming Jin Aifeng Zhou Shun Xiao 《Environmental Geology》2007,51(7):1229-1238
Samples of surface deposits in the Lake Sugan catchment, as well as surface lake sediments, eolian materials occulted in the
lake ice cover, and airborne dust were collected for grain-size analysis. The results show that the coarse fraction of the
lake sediments could be transported by ambient winds and to a lesser extent by river flow in the study area. Sediment cores
were retrieved from Lake Sugan in December 2000, and 210Pb and 137Cs dating and grain-size analyses were performed on these samples. 210Pb ages and the volume percentage of the fraction of lake sediments >63 μm were used to reconstruct the dust storm history
from 1957 to 2000. Observational data for dust storm events collected at a local meteorological station largely agrees with
the reconstructed trend for the past 44 years, suggesting that lake sediments can be employed to trace the dust storm history
of the northern Qinghai–Tibetan Plateau. 相似文献
16.
Rainfall-induced landslide event of May 2010 in the eastern part of the Czech Republic 总被引:3,自引:2,他引:1
Tom��? P��nek Rudolf Br��zdil Jan Klime? Veronika Smolkov�� Jan Hradecky Pavel Zahradn��?ek 《Landslides》2011,8(4):507-516
More than 150 landslides originated in the eastern part of the Czech Republic (region of the Flysch Outer Western Carpathians—hereinafter,
OWC) due to soil saturation caused by antecedent precipitation and long lasting and intensive rainfalls on 16–18 May 2010
(>300 mm as measured by some stations). As a consequence, a multitude of small failures originated 88% of which was smaller
than 104 m2. Most landslides are characterised as shallow (<10 m) or middle–deep (10–30 m) incipient (rather short travel) landslides,
debris slides and soil slips spatially clustered to a geological domain underlain by rather weak thin-bedded flysch and unconsolidated
Quaternary deposits. An exception to this is represented by a kilometre-long rockslide (∼2–3 mil m3) affecting tectonically weakened and weathered claystone/mudstone-dominated flysch on the southern slope of Mt. Girová (the
Beskydy Mountains). The rockslide is one of the largest long runout landslides in the territory of the Czech Republic activated
over the past few decades as it reaches the dimensions of the largest documented Holocene long runout landslides in the Czech
part of the OWC. A majority of the May 2010 landslide events developed inside older (Holocene or historic) landslide terrains,
which points to their spatial persistency and recurrent nature. In spite of the fact that the May 2010 landslide event was
not as destructive as some previous landslide activisation in the OWC region (e.g. July 1997 event), it left many slope failures
at the initial stage of their potential future reactivation. 相似文献
17.
Asbury H. Sallenger Hilary F. Stockdon Laura Fauver Mark Hansen David Thompson C. Wayne Wright Jeff Lillycrop 《Estuaries and Coasts》2006,29(6):880-888
Four hurricanes battered the state of Florida during 2004, the most affecting any state since Texas endured four in 1884.
Each of the storms changed the coast differently. Average shoreline change within the right front quadrant of hurricane force
winds varied from 1 m of shoreline advance to 20 m of retreat, whereas average sand volume change varied from 11 to 66 m3 m−1 of net loss (erosion). These changes did not scale simply with hurricane intensity as described by the Saffir-Simpson Hurricane
Scale. The strongest storm of the season, category 4 Hurricane Charley, had the least shoreline retreat. This was likely because
of other factors like the storm's rapid forward speed and small size that generated a lower storm surge than expected. Two
of the storms, Hurricanes Frances and Jeanne, affected nearly the same area on the Florida east coast just 3 wk apart. The
first storm, Frances, although weaker than the second, caused greater shoreline retreat and sand volume erosion. As a consequence,
Hurricane Frances may have stripped away protective beach and exposed dunes to direct wave attack during Jeanne, although
there was significant dune erosion during both storms. The maximum shoreline change for all four hurricanes occurred during
Ivan on the coasts of eastern Alabama and the Florida Panhandle. The net volume change across a barrier island within the
Ivan impact zone approached zero because of massive overwash that approximately balanced erosion of the beach. These data
from the 2004 hurricane season will prove useful in developing new ways to scale and predict coastal-change effects during
hurricanes. 相似文献
18.
Geochemical modeling of coal mine drainage, Summit County, Ohio 总被引:4,自引:1,他引:4
A. Foos 《Environmental Geology》1997,31(3-4):205-210
Geochemical modeling was used to investigate downstream changes in coal mine drainage at Silver Creek Metro-park, Summit
County, Ohio. A simple mixing model identified the components that are undergoing conservative transport (Cl–, PO4
3–, Ca2+, K+, Mg2+ and Na+) and those undergoing reactive transport (DO, HCO3
–, SO4
2–, Fe2+, Mn2+ and Si). Fe2+ is removed by precipitation of amorphous iron-hydroxide. Mn2+ are removed along with Fe2+ by adsorption onto surfaces of iron-hydroxides. DO increases downstream due to absorption from the atmosphere. The HCO3
– concentration increases downstream as a result of oxidation of organic material. The rate of Fe2+ removal from the mine drainage was estimated from the linear relationship between Fe+2 concentration and downstream distance to be 0.126 mg/s. Results of this study can be used to improve the design of aerobic
wetlands used to treat acid mine drainage.
Received: 4 June 1996 · Accepted: 17 September 1996 相似文献
19.
Zdzisław M. Migaszewski Agnieszka Gałuszka Stanisław Hałas Józef Dąbek Sabina Dołęgowska Irena Budzyk Ewa Starnawska Artur Michalik 《Environmental Geology》2009,57(1):29-40
In 2005 and 2006, hydrogeochemical study was carried out in the bipartite Wiśniówka Mała pit lake of the Holy Cross Mountains
(south-central Poland). This is the largest acidic water body in Poland. This report presents the element concentrations in
the water and sediment, stable sulfur and oxygen isotope ratios in the soluble sulfates, and stable oxygen isotope ratio in
the water. The scope of the investigation also encompassed mineralogical examinations (scanning electron microscope, X-ray
diffraction) of the sediment. The results of this study show that there is a spatial and temporal variability in concentrations
of most elements and sulfur isotope ratios in the examined pit lake. The water of the western pond displayed a lower pH with
a mean of 3.73 and higher conductivity (390 μS cm−1) as well as higher concentrations of sulfates (156 mg L−1) and most of the cations and anions. The concentrations of Fe2+ and Fe3+ averaged 0.8 and 0.4 mg·L−1. In contrast, the eastern pond water revealed a higher pH (mean of 4.36), lower conductivity (293 μS cm−1) and lower sulfate (90 mg L−1) and trace metal levels. Similar variations were recorded in the stable sulfur isotope ratios. The δ34SV-CDT(SO4
2−) values in the water of the western pit pond were in the range of −6.7 to −4.6‰ (mean of −5.6‰), whereas that in the eastern
pit pond ranged from −2.2 to −0.9‰ (−1.6‰). The alkalinity of the entire lake water was below 0.1 mg·L−1 CaCO3. No distinct difference in the δ18OV-SMOW(SO4
2−) was noted between the western and eastern pit ponds. Compared to the Purple Pond in the Sudetes (Poland) and similar sites
throughout the world, the examined pit lake is highlighted by distinctly low concentrations of sulfates, iron and other trace
metals. Based on this and other studies performed in the Holy Cross Mountains, a conclusion can be drawn that the SO4
2− in the Wiśniówka Mała pit lake water is a mixture of SO4
2− derived from the following sources: (1) pyrite oxidation (especially in the western pond water), (2) leaching of soluble
sulfates from soils and waste material, as well as (3) subordinate deposition of airborne sulfate precipitation. 相似文献
20.
Wentao Ma 《Natural Hazards》2012,62(1):141-148
Dongjing reservoir with storage capacity of 955 million m3 and 150 m dam height had been set up in Guizhou province, southeastern China on May in 2005. After filling with water in
August 20, 2009, the reservoir-induced earthquake in 20 km took place first in September 2009 at the 440 m water level. When
the water level changes, the number of earthquakes is increased rapidly. On January 17, 2010, the largest M 4.4 earthquake
with depth of 7 km has happen and month frequency achieved 21 events at the highest water level. M 4.4 earthquake caused rock
collapse with the disaster of killed six people and nine injure. After our investigation and study, the reason of higher epicentral
intensity of earthquake was the surface effect of near-field elastic wave transmission. The disaster of rock falls certainly
depended on the very very shallow earthquake, the height of valley and fault. Comparing as same magnitude of natural earthquake,
very shallow earthquake increased 1–2° of epicentral intensity I0, more than twice amplitude of S-wave at 200 m height of valley and the largest displacement on fault. The superposition of
three factors has increased the epicentral intensity of earthquake and directly caused rock collapse with the disaster of
killed six people and nine injure. 相似文献