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1.
High nitrogen (N) loading rates received by coastal bays can have deleterious effects on aquatic ecosystems. Salt marshes
can intercept land-based N through seasonal plant uptake, denitrification, and burial. Salt marshes fringing Delaware’s Inland
Bays are characterized by different plant species occurring in close proximity. To evaluate N pool retention and loss for
the dominant plant species, we measured seasonal N concentration and pool size, N resorption efficiency, loss during decomposition,
and soil N. Seasonal variation in N pools and fluxes differed among species. Seasonal differences in the total N pools of
the herbaceous species were largely influenced by belowground fine root and dead macro-organic matter fluxes. N production
rate estimates ranged from 18 g N m−2 year−1 aboveground for the high marsh shrub to 40.8 g N m−2 year−1 above- and belowground for the high marsh rush illustrating the importance of incorporating species-specific dynamics into
ecosystem N budgets. 相似文献
2.
Xu Naizheng Zhang Taolin Wang Xingxiang Liu Hongying 《Environmental Earth Sciences》2011,63(5):1021-1028
Soil carbon sequestration plays an essential role in mitigating CO2 increases and the global greenhouse effect. This paper calculates soil organic carbon (SOC) storage changes during the course
of industrialization and urbanization in Yangtze Delta region, China, based on the data of the second national soil survey
(1982–1985) and the regional geochemical survey (2002–2005), with the help of remote sensing images acquired in periods of
1980, 2000, 2005. The results show that soils in the top 0–20 and 0–100 cm depth in this region demonstrate the carbon sink
effect from the early 1980s to the early 2000s. The SOC storage in 0–20 cm depth has resulted in increase from 213.70 to 238.65 Tg,
which corresponds to the SOC density increase from 2.94 ± 1.08 to 3.28 ± 0.92 kg m−2, and mean carbon sequestration storage and rate are 1.25 Tg a−1, 17.14 g m−2 a−1, respectively. The SOC storage in 0–100 cm depth has resulted in increase from 690.26 to 792.65 Tg, which corresponds to
the SOC density increase from 9.48 ± 4.22 to 10.89 ± 3.42 kg m−2, and mean carbon sequestration storage and rate are 5.12 Tg a−1, 70.32 g m−2 a−1, respectively. Urban area in Yangtze Delta region, China, increased more than 3,000 km2 and the urban growth patterns circled the central city region in the past 20 years. The SOC densities in 0–20 cm depth decrease
gradually along urban–suburban–countryside and the urban topsoil is slightly enriched with SOC. Compared to the data of the
second national soil survey in the early 1980s, the mean SOC density in urban area increased by 0.76 kg m2, or up 25.85% in the past 20 years. With the characteristics of SOC storage changes offered, land-use changes, farming system
transition and ecological city construction are mainly attributed to SOC storage increases. Because of lower SOC content in
this region, it is assumed that the carbon sink effect will go on in the future through improved soil management. 相似文献
3.
This paper estimates CO2 fluxes in a municipal site for final disposal of solid waste, located in Gualeguaychu, Argentina. Estimations were made using
the accumulation chamber methods, which had been calibrated previously in laboratory. CO2 fluxes ranged from 31 to 331 g m−2 day−1. Three different populations were identified: background soil gases averaging 46 g m−2 day−1, intermediate anomalous values averaging 110 g m−2 day−1 and high anomalous values averaging 270 g m−2 day−1. Gas samples to a depth of 20 cm were also taken. Gas fractions, XCO2 < 0.1, XCH4 < 0.01, XN2 ~0.71 and XO2 ~0.21, δ13C of CO2 (−34 to −18‰), as well as age of waste emplacement, suggest that the study site may be at the final stage of aerobic biodegradation.
In a first approach, and following the downstream direction of groundwater flow, alkalinity and δ13C of dissolved inorganic carbon (−15 to 4‰) were observed to increase when groundwater passed through the disposal site. This
suggests that the CO2 generated by waste biodegradation dissolves or that dissolved organic matter appears as a result of leachate degradation. 相似文献
4.
Zongqiang Chang Qi Feng Jianhua Si Yonghong Su Haiyang Xi Jianlin Li 《Environmental Geology》2009,58(3):483-490
Field experiments on the CO2 flux of alpine meadow soil in the Qilian Mountain were conducted along the elevation gradient during the growing season of
2004 and 2005. The soil CO2 flux was measured using the Li-6400-09 soil respiration chamber attached to the Li-6400 portable photosynthesis system. The
effects of water and heat and roots on the soil CO2 flux were statistically analyzed. The results show that soil CO2 flux along the elevation gradient gradually decreases. The soil CO2 flux was low at night, with lowest value occurring between 0200 and 0600 hours, started to rise rapidly during 0700–0830
hours, and then descend during 1600–1830 hours. The peak CO2 efflux appears during 1100–1600 hours. The diurnal average of soil CO2 efflux was between 0.56 ± 0.32 and 2.53 ± 0.76 μmol m−2 s−1. Seasonally, soil CO2 fluxes are relatively high in summer and autumn and low in spring and winter. The soil CO2 efflux, from the highest to the lowest in the ranking order, occurred in July and August (4.736 μmol m−2 s−1), June and September, and May and October, respectively. The soil CO2 efflux during the growing season is positively correlated with soil temperature, root biomass and soil water content. 相似文献
5.
Ana Carolina Ruiz-Fernández José Luis Marrugo-Negrete Roberth Paternina-Uribe Libia Hascibe Pérez-Bernal 《Estuaries and Coasts》2011,34(6):1117-1128
With the aim of evaluating temporal changes in sedimentation and organic carbon (Corg) supplied over the last ~100 years, a sediment core was collected at Soledad Lagoon, a costal ecosystem surrounded by mangroves,
located in the Cispatá Estuary (Caribbean coast of Colombia). The core sediments were characterized by low concentrations
of calcium carbonate (0.2–2.9%), organic matter (3–8%), total nitrogen (0.11–0.38%), and total phosphorus (0.19–0.65 mg g−1). Fe and Al concentrations ranged from 4% to 5%, and Mn from 356 to 1,047 μg g−1. The 210Pb-derived sediment and mass accumulation rates were 1.54 ± 0.18 mm year−1 and 0.08 ± 0.01 g cm−2 year−1, respectively. The sediment core did not provide evidence of human impact, such as enhancement of primary production or nutrient
enrichment, which may result from recent land uses changes or climate change. The Corg fluxes estimated for Soledad Lagoon core lay in the higher side of carbon fluxes to coastal ecosystems (314–409 g m−2 year−1) and the relatively high Corg preservation observed (~45%) indicate that these lagoon sediments has been a net and efficient sink of Corg during the last century, which corroborate the importance of mangrove areas as important sites for carbon burial and therefore,
long-term sequestration of Corg. 相似文献
6.
Eva Pacioni Marco Petitta Ezio Burri Maria Fanelli Piero Mazzeo Fabrizio Ruggieri 《Environmental Earth Sciences》2010,61(1):201-216
This paper analyses flow and transport of pesticides from the unsaturated zone to groundwater so as to predict concentration
of those contaminants in the Fucino Plain’s groundwater, by site investigations and numerical simulations. Pesticides were
detected in surface water (peaks of 13 μg L−1) and groundwater (peaks of 0.37 μg L−1). Modelling tools made it possible to identify that pattern of precipitation, organic matter content, and root thickness
are the key factors involved in vertical seepage of pesticides. Numerical simulations indicated that a significant fraction
of contaminants is leached from the most surficial soil layers through runoff, while only a secondary fraction is mobilised
towards groundwater. Likelihood of contaminating deep groundwater is fairly low, whereas surface waters show higher susceptibility.
Results of the proposed conceptual hydrogeological model show that pesticides are more likely to be entrained by mixing of
stream water with shallow groundwater in periods of high water exploitation from shallow wells. 相似文献
7.
Phytoplankton Biomass and Production in Subtropical Hong Kong Waters: Influence of the Pearl River Outflow 总被引:1,自引:0,他引:1
Alvin Y. T. Ho Jie Xu Kedong Yin Yuelu Jiang Xiangcheng Yuan Lei He Donald M. Anderson Joseph H. W. Lee Paul J. Harrison 《Estuaries and Coasts》2010,33(1):170-181
The size-fractionated phytoplankton biomass and primary production were investigated in four contrasting areas of Hong Kong
waters in 2006. Phytoplankton biomass and production varied seasonally in response to the influence of the Pearl River discharge.
In the dry season, the phytoplankton biomass and production were low (<42 mg chl m−2 and <1.8 g C m−2 day−1) in all four areas, due to low temperatures and dilution and reduced light availability due to strong vertical mixing. In
contrast, in the wet season, in the river-impacted western areas, the phytoplankton biomass and production increased greater
than five-fold compared to the dry season, especially in summer. In summer, algal biomass was 15-fold higher than in winter,
and the mean integrated primary productivity (IPP) was 9 g C m−2 day−1 in southern waters due to strong stratification, high temperatures, light availability, and nutrient input from the Pearl
River estuary. However, in the highly flushed western waters, chl a and IPP were lower (<30 mg m−2 and 4 g C m−2 day−1, respectively) due to dilution. The maximal algal biomass and primary production occurred in southern waters with strong
stratification and less flushing. Spring blooms (>10 μg chl a L−1) rarely occurred despite the high chl-specific photosynthetic rate (mostly >10 μg C μg chl a
−1 day−1) as the accumulation of algal biomass was restricted by active physical processes (e.g., strong vertical mixing and freshwater
dilution). Phytoplankton biomass and production were mostly dominated by the >5-μm size fraction all year except in eastern
waters during spring and mostly composed of fast-growing chain-forming diatoms. In the stratified southern waters in summer,
the largest algal blooms occurred in part due to high nutrient inputs from the Pearl River estuary. 相似文献
8.
Jenifer E. Dugan David M. Hubbard Henry M. Page Joshua P. Schimel 《Estuaries and Coasts》2011,34(4):839-850
We investigated the role of sandy beaches in nearshore nutrient cycling by quantifying macrophyte wrack inputs and examining
relationships between wrack accumulation and pore water nutrients during the summer dry season. Macrophyte inputs, primarily
giant kelp Macrocystis pyrifera, exceeded 2.3 kg m−1 day−1. Mean wrack biomass varied 100-fold among beaches (range = 0.41 to 46.43 kg m−1). Mean concentrations of dissolved inorganic nitrogen (DIN), primarily NOx−-N, and dissolved organic nitrogen (DON) in intertidal pore water varied significantly among beaches (ranges = 1 to 6,553 μM
and 7 to 2,006 μM, respectively). Intertidal DIN and DON concentrations were significantly correlated with wrack biomass.
Surf zone concentrations of DIN were also strongly correlated with wrack biomass and with intertidal DIN, suggesting export
of nutrients from re-mineralized wrack. Our results suggest beach ecosystems can process and re-mineralize substantial organic
inputs and accumulate dissolved nutrients, which are subsequently available to nearshore waters and primary producers. 相似文献
9.
Leonard Boszke Artur Kowalski Aleksander Astel Andrzej Barański Barbara Gworek Jerzy Siepak 《Environmental Geology》2008,55(5):1075-1087
The mobility and bioavailability of mercury in the soil from the area near a plant using elemental mercury for manufacturing
thermometers, areometers, glass energy switches and other articles made of technical glass has been evaluated. Mercury has
been determined by sequential extraction method and with additional thermo desorption stage to determine elemental mercury.
The procedure of sequential extraction involves five subsequent stages performed with the solutions of chloroform, deionized
water, 0.5 M HCl, 0.2 M NaOH and aqua regia. The mean concentration of total mercury in soil was 147 ± 107 μg g−1 dry mass (range 62–393), and the fractionation revealed that mercury was mainly bound to sulfides 56 ± 8% (range 45–66),
one of the most biounavailable and immobile species of mercury in the environment. The fractions that brought lower contribution
to the total mercury content were semi-mobile humic matter 22 ± 9% (range 11–34) and elemental mercury 17 ± 5% (range 8–23).
The contributions brought by the highly mobile and toxic organomercury compounds were still lower 2.3 ± 2.7% (range 0.01–6.5).
The lowest contributions brought the acid-soluble mercury 1.5 ± 1.3% (range 0.1–3.5) and water-soluble mercury 1.0 ± 0.3%
(range 0.6–1.7). The surface layer of soil (0–20 cm) was characterized by higher mercury concentrations than that of the subsurface
soil (60–80 cm), but the fractional contributions were comparable. The comparison of mercury fractionation results obtained
in this study for highly polluted soils with results of fractionation of uncontaminated or moderately contaminated samples
of soil and sediments had not shown significant statistical differences; however, in the last samples elemental mercury is
usually present at very low concentrations. On the basis of obtained correlation coefficients it seems that elemental mercury
soils from “Areometer” plant are contaminated; the main transformation is its vaporization to atmosphere and oxidation to
divalent mercury, probably mainly mediated by organic matter, and next bound to humic matter and sulfides. 相似文献
10.
The production of organic matter and calcium carbonate by a dense population of the brittle star Acrocnida brachiata (Echinodermata) was calculated using demographic structure, population density, and relations between the size (disk diameter)
and the ash-free dry weight (AFDW) or the calcimass. During a 2-year survey in the Bay of Seine (Eastern English Channel,
France), organic production varied from 29 to 50 gAFDW m−2 year−1 and CaCO3 production from 69 to 104 gCaCO3 m−2 year−1. Respiration was estimated between 1.7 and 2.0 molCO2 m−2 year−1. Using the molar ratio (ψ) of CO2 released: CaCO3 precipitated, this biogenic precipitation of calcium carbonate would result in an additional release between 0.5 and 0.7 molCO2 m−2 year−1 that represented 23% and 26% of total CO2 fluxes (sum of calcification and respiration). The results of the present study suggest that calcification in temperate shallow
environments should be considered as a significant source of CO2 to seawater and thus a potential source of CO2 to the atmosphere, emphasizing the important role of the biomineralization (estimated here) and dissolution (endoskeletons
of dead individuals) in the carbon budget of temperate coastal ecosystems. 相似文献
11.
Forests play a primary role in the cycling and storage of mercury (Hg) in terrestrial ecosystems. This study aimed to assess differences in Hg cycling and storage resulting from different vegetation at two adjacent forest stands - beech and spruce. The study site Načetín in the Czech Republic's Black Triangle received high atmospheric loadings of Hg from coal combustion in the second half of the 20th century as documented by peat accumulation rates reaching 100 μg m−2 y−1. In 2004, the annual litterfall Hg flux was 22.5 μg m−2 y−1 in the beech stand and 14.5 μg m−2 y−1 in the spruce stand. Soil concentrations and pools of Hg had a strong positive relation to soil organic matter and concentrations of soil sulfur (S) and nitrogen (N). O-horizon Hg concentrations ranged from 245 to 495 μg kg−1 and were greater in the spruce stand soil, probably as a result of greater dry Hg deposition. Mineral soil Hg concentrations ranged from 51 to 163 μg kg−1 and were greater in the beech stand soil due to its greater capacity to store organic carbon (C). The Hg/C ratio increased with depth from 0.3 in the O-horizon to 3.8 μg g−1 in the C horizon of spruce soil and from 0.7 to 2.7 μg g−1 in beech soil. The Hg/C ratio was greater at all mineral soil depths in the spruce stand. The organic soil Hg pools in beech and spruce stands (6.4 and 5.7 mg m−2, respectively) were considerably lower than corresponding mineral soil Hg pools (39.1 and 25.8 mg m−2). Despite the important role of S in Hg cycling, differences in soil Hg distribution at both stands could not be attributed to differences in soil sulfur speciation. 相似文献
12.
From January 1987 to February 1988 the annual biomass cycle and demography of the seagrass Zostera marina were assessed in San Quintin Bay, a shallow coastal lagoon on the Pacific coast of Baja California, Mexico. Shoot density and aboveground biomass were sampled monthly along two intertidal transects parallel to the shore. Belowground biomass was sampled every 2 mo. Shoot density differed between transects, ranging from 929±71 (SE) in July to 279 ±80 shoots m−2 in December, at the deeper transect (I). At the shallow transect (II) there was not a significant difference through time, and a mean of 737 shoots m−2 was calculated. Lateral shoots were present year round and represented between 1% and 30% of total density at transect I and between 3% and 25% at transect II. Reproductive shoots were present from March to September at both transects, with a density range of 77±28 shoots m−2 (March) to 9±3 shoots m−2 (September), and represented 5% of total shoot density. Neither aboveground biomass nor LAI (Leaf Area Index) differed between transects, with values ranging between 77±14.5 g dry wt m−2 (October 1987) and 13±2.4 g dry wt m−2 (February 1988) for aboveground biomass, and between 0.6±0.2 m2 leves m−2 substrate (January) and 2.7±0.3 m2 leaves m−2 substrate (September) for LAI. Neither root biomass nor rhizome biomass differed between transects, or as a function of time; the mean value for roots was 17 g dry wt m−2 and for rhizomes 29 g dry wt m−2. Belowground biomass represented 54% of total biomass. We found a significant correlation between aboveground biomass and LAI (r=0.949 for transect I, and 0.926 for transect II) as well as between total biomass (aboveground and belowground) and LAI (r=0.814), which allows us to consider using LAI as a predictor of these variables. Biomass changes were related to changes in shoot weight (r=0.676 at transect I; 0.582 at transect II), more than to changes in shoot number. Water temperature was found to be the driver of biomass changes in the aboveground compartment. 相似文献
13.
Michael J. Durako Piotr Kowalczuk Michael A. Mallin William J. Cooper Jason J. Souza David H. Wells 《Estuaries and Coasts》2010,33(6):1430-1441
Surface water optical characteristics, nutrients, and planktonic chlorophyll a concentrations were analyzed in the Cape Fear River (CFR) plume over a 2-year period. CFR discharge during the dry year (109 ± 105 m3s−1) was only 25% of the wet year discharge (429 ± 337 m3s−1). Partitioning the contributions of phytoplankton pigments, non-pigmented particles, and colored dissolved organic matter
(CDOM) to the absorption of photosynthetically active radiation (PAR) indicated that CDOM was the dominant contributor to
PAR absorption. Particulate absorption was relatively greater during the dry year. Pigment absorption was minor and varied
little among stations or between years. Chlorophyll a concentrations were reduced at the most plume-influenced stations during the wet year, despite lower turbidity and higher
nitrate concentrations. Ammonium and orthophosphate concentrations were not different between years. CDOM absorption [a
CDOM
(412)] ranged from 0.05 to 8.25 m−1 with highest values occurring near the CFR mouth. Our results suggest that for coastal ecosystems with significant blackwater
river inputs, CDOM may exert a major limiting influence over near-shore primary production. 相似文献
14.
S. K. Mandal N. Majumder C. Chowdhury D. Ganguly M. Dey T. K. Jana 《Environmental Earth Sciences》2012,65(7):2027-2036
Elevated concentrations of arsenic in the sediment and pore water in the Sundarban wetlands pose an environmental risk. Adsorption
and desorption are hypothesized to be the major processes controlling arsenic retention in surface sediment under oxic/suboxic
condition. This study aims to investigate sorption kinetics of As(III & V) and its feedback to arsenic mobilization in the
mangrove sediment. It ranges from sand to silty clay loam and shows the adsorption of As(III & V) following the Langmuir relation.
Estimates of the maximum adsorption capacity are 59.11 ± 13.26 μg g−1 for As(III) and 58.45 ± 8.75 μg g−1 at 30°C for As(V) in the pH range 4 to 8 and salinity 15–30 psu. Extent of adsorption decreases with increasing pH from 4
to 8 and desorption is the rate-limiting step in the reaction of arsenic with sediment. Arsenic in the sediment could be from
a Himalayan supply and co-deposited organic matter drives its release from the sediment. Arsenic concentration in the sediment
is well below its maximum absorption capacity, suggesting the release of sorbed arsenic in pore water by the microbial oxidation
of organic matter in the sediment with less feedback of adsorption. 相似文献
15.
In the past several decades, the techniques used to discern the different sedimentary fractions of P have been refined. This
has allowed for a better understanding of P burial of the different P fractions and diagenetic reactions and, ultimately,
the constraining of P residence time in the oceans. P sequential extraction was performed on eight sediment cores (between
16 and 24 cm deep) collected along a salinity gradient from the Ojo de Liebre Lagoon and the salt evaporation saltern of Guerrero
Negro, Baja California Sur, Mexico in order to determine, under purely diagenetic conditions (in the absence of anthropogenic
activities and biogenic sediment reworking), the fractionation and flux of P to the sediments. The majority of P was found
in the authigenic fraction (37 ± 5.4% to 53 ± 8.9%), with P associated to organic matter comprising the overall smallest percentage
(0.25 ± 0.43% to 21 ± 6.0%) relative to total P. The average flux of total P to the sediments for all the sites was found
to be (451 ± 127) × 10−4 mol m−2 year−1, up to several orders of magnitude greater than those found in other studies. It is concluded that P is most likely transformed
from P associated to organic matter to the authigenic mineral phase and that P was retained in the sediments in its mineral
form rather than in reactive forms. This particular study area has the ability to retain large quantities of P in the sediments. 相似文献
16.
Edward Castañeda-Moya Robert R. Twilley Victor H. Rivera-Monroy Keqi Zhang Stephen E. DavisIII Michael Ross 《Estuaries and Coasts》2010,33(1):45-58
The distribution of mangrove biomass and forest structure along Shark River estuary in the Florida Coastal Everglades (FCE)
has been correlated with elevated total phosphorus concentration in soils thought to be associated with storm events. The
passage of Hurricane Wilma across Shark River estuary in 2005 allowed us to quantify sediment deposition and nutrient inputs
in FCE mangrove forests associated with this storm event and to evaluate whether these pulsing events are sufficient to regulate
nutrient biogeochemistry in mangrove forests of south Florida. We sampled the spatial pattern of sediment deposits and their
chemical properties in mangrove forests along FCE sites in December 2005 and October 2006. The thickness (0.5 to 4.5 cm) of
hurricane sediment deposits decreased with distance inland at each site. Bulk density, organic matter content, total nitrogen
(N) and phosphorus (P) concentrations, and inorganic and organic P pools of hurricane sediment deposits differed from surface
(0–10 cm) mangrove soils at each site. Vertical accretion resulting from this hurricane event was eight to 17 times greater
than the annual accretion rate (0.30 ± 0.03 cm year−1) averaged over the last 50 years. Total P inputs from storm-derived sediments were equivalent to twice the average surface
soil nutrient P density (0.19 mg cm−3). In contrast, total N inputs contributed 0.8 times the average soil nutrient N density (2.8 mg cm−3). Allochthonous mineral inputs from Hurricane Wilma represent a significant source of sediment to soil vertical accretion
rates and nutrient resources in mangroves of southwestern Everglades. The gradient in total P deposition to mangrove soils
from west to east direction across the FCE associated with this storm event is particularly significant to forest development
due to the P-limited condition of this carbonate ecosystem. This source of P may be an important adaptation of mangrove forests
in the Caribbean region to projected impacts of sea-level rise. 相似文献
17.
Zhemin Shen Jianda Zhang Liya Qu Zeqin Dong Shenshen Zheng Wenhua Wang 《Environmental Geology》2009,57(6):1399-1407
Wanshan mercury mine is the largest cinnabar deposit in Guizhou, China. Few effective methods had been achieved to remedy
Hg heavily contaminated field soils. In this paper, a modified EK method with approaching cathodes (AC-EK) and an I−/I2 lixiviant was described to remedy mercury-contaminated field soils near Wanshan mercury mine. Paddy Soil I and Paddy Soil
II were sampled and contained 576.73 ± 45.50 and 491.35 ± 4.73 mg/kg Hg, respectively. Although they contained 6.9 and 9.4%
organic matter respectively, more than 92 and 89% Hg were removed by AC-EK within 5 days. Removal ratio increased by 0.21
and 0.68 times using EK process with ACs over that with one single cathode (SC-EK). AC-EK method saved nearly 26.4–28.1% electric
power as compared to SC-EK method. As an I−/I2 lixiviant solution was used to solubilize HgS(HgO) during EK process, the bonding of Hg to organic functional S groups should
be less important than the binding to inner sites of organic matter in soil. The relationship between EK remediation effect
and soil organic matter content was fitted to a linear model. It turned out that when soil OM increased by 1.0%, EK removal
ratio (%) of Hg would decrease by 2.63%. 相似文献
18.
Sarah E. Rothenberg Matthew E. Kirby Broxton W. Bird Margie B. DeRose Chu-Ching Lin Xinbin Feng Richard F. Ambrose Jennifer A. Jay 《Environmental Earth Sciences》2010,60(5):993-1005
In southern California, USA, wildfires may be an important source of mercury (Hg) to local watersheds. Hg levels and Hg accumulation
rates were investigated in dated sediment cores from two southern California lakes, Big Bear Lake and Crystal Lake, located
approximately 40-km apart. Between 1895 and 2006, fires were routinely minimized or suppressed around Big Bear Lake, while
fires regularly subsumed the forest surrounding Crystal Lake. Mean Hg concentrations and mean Hg accumulation rates were significantly
higher in Crystal Lake sediments compared to Big Bear Lake sediments (Hg levels: Crystal Lake 220 ± 93 ng g−1, Big Bear Lake 92 ± 26 ng g−1; Hg accumulation: Crystal Lake 790 ± 1,200 μg m−2 year−1, Big Bear 240 ± 54 μg m−2 year−1). In Crystal Lake, the ratio between post-1965 and pre-1865 Hg concentrations was 1.1, and several spikes in Hg levels occurred
between 1910 and 1985. Given the remote location of the lake, the proximity of fires, and the lack of point sources within
the region, these results suggested wildfires (rather than industrial sources) were a continuous source of Hg to Crystal Lake
over the last 150 years. 相似文献
19.
R. E. Masto L. C. Ram P. R. Shandilya S. Sinha J. George V. A. Selvi 《Environmental Earth Sciences》2011,64(4):1107-1115
Coal handling, crushing, washing, and other processes of coal beneficiation liberate coal particulate matter, which would
ultimately contaminate the nearby soils. In this study, an attempt was made to determine the status of soil bio-indicators
in the surroundings of a coal beneficiation plant, (in relation to a control site). The coal beneficiation plant is located
at Sudamudih, and the control site is 5 km away from the contaminated site, which is located in the colony of Central Institute
of Mining and Fuel Research Institute, Digwadih, Dhanbad. In order to estimate the impact of coal deposition on soil biochemical
characteristics and to identify the most sensitive indicator, soil samples were taken from the contaminated and the control
sites, and analyzed for soil organic carbon (SOC), soil N, soil basal respiration (BSR), substrate-induced respiration (SIR),
and soil enzymes like dehydrogenase (DHA), catalase (CAT), phenol oxidase (PHE), and peroxidase (PER). Coal deposition on
soils improved the SOC from 10.65 to 50.17 g kg−1, CAT from 418.1 to 804.11 μg H2O2 g−1 h−1, BSR from 8.5 to 36.15 mg CO2–C kg−1 day−1, and SIR from 24.3 to 117.14 mg CO2–C kg−1 day−1. Soils receiving coal particles exhibited significant decrease in DHA (36.6 to 4.22 μg TPF g−1 h−1), PHE (0.031 to 0.017 μM g−1 h−1), PER (0.153 to 0.006 μM g−1 h−1), and soil N (55.82 to 26.18 kg ha−1). Coal depositions significantly (P < 0.01) decreased the DHA to 8.8 times, PHE to 1.8 times, and PER to 25.5 times, but increased the SOC to 4.71 times, CAT
to 1.9 times, SIR to 4.82 times, and BSR to 4.22 times. Based on principal component analysis and sensitivity test, soil peroxidase
(an enzyme that plays a vital role in the degradation of the aromatic organic compounds) is found to be the most important
indicator that could be considered as biomarkers for coal-contaminated soils. 相似文献
20.
Feasibility of electrolyte conditioning with strong alkaline solution on electrokinetic remediation of fluorine-contaminated
field soil was investigated in the laboratory. The initial concentration of fluorine, pH and organic matter content in the
soil were 1,058 mg kg−1, 8.17 and 20.51 g kg−1, respectively. Electrokinetic experiments were conducted under two different concentrations of alkaline solution and three
different voltage gradients. The removal of fluorine increased with the concentration of the alkaline solution and applied
voltage and fluorine removed up to 73% within 10 days. Anolyte enhanced electrokinetic process could promote effectively the
migration of fluoride in soil. The electromigration was the main transport mechanism and the electroosmotic flow had an effect
on the migration of fluoride in soil. Appropriate anolyte enhanced electrokinetic method could be applied to remediate fluorine
from contaminated field soil and has significant potential for removing other anionic pollutants such as arsenate and chromate
from soil. 相似文献