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1.
Wenjun Z 《Environmental monitoring and assessment》2007,125(1-3):301-312
Our world is largely dependent upon the forestry productions. Through the exploitation of forest reserves, we manufacture
various industrial products, furniture, and obtain fuel and energy. Forestry productions should be conducted without large-scale
deforestation and environmental degradation. In present study we perform a review and forecast analysis on forestry productions
worldwide, with the objectives of providing an insight into the trend for several types of forestry productions in the future,
and providing referential data for sustainable forestry productions and environmental management. Polynomial functions are
used to fit trajectories of forestry productions since 1961 and forecasts during the coming 20 years are given in detail.
If the past pattern continues, world fibreboard production would dramatically grow and reach 224,300,000 ± 44,400,000 m3 by the year 2020, an increase up to 240.7 to 408.9% as compared to the present level. Roundwood production of the world would
change by −55.5 to 70.4% and reach 3,526,600,000 ± 2,066,800,000 m3 by 2020. In 2020 world production of sawlogs and veneer logs would change by −100 to 164.6% and reach 1,212,900,000 ± 1,242,600,000 m3. Global wood fuel production would change by −68.9 to 1.4% and reach 1,130,900,000 ± 600,800,000 m3 by 2020. Forestry productions in developed countries would largely surpass productions in developing countries in the near
future. World forestry production grew since 1961 excluding wood fuel. Roundwood and wood fuel account for the critical proportions
in the forestry productions. Wood fuel production has being declined and rapid growing of roundwood production has slowed
in recent years. Widespread use of regenerative wood substitutes and worldwide afforestation against deforestation will be
among the most effective ways to reduce deforestation and environment degradation associated with forestry productions. 相似文献
2.
The main objective of this research was to estimate the total mass of nitrogen discharged from various sources in Korea using
the mass balance approach. Three different nitrogen mass balances were presented: (1) agricultural activities including raising
crops and animal husbandry; (2) domestic activities, and (3) activities in forest and urban areas. These nitrogen balances
were combined to estimate riverine discharge of nitrogen to the ocean in national scale. Nitrogen inputs include atmospheric
deposition, biological nitrogen fixation, application of inorganic fertilizers/manures, animal feed/imported foodstuffs, and
meat/fish. Nitrogen outputs include ammonia volatilization, denitrification, human/animal waste generation, crop/meat production,
and riverine discharge to the ocean. The estimated total nitrogen input in Korea was 1,194.5 × 103 tons N/year. Nitrogen discharged into rivers was estimated as 408–422 × 103 tons N/year, of which 66–71% was diffuse in origin. The estimated diffuse discharges for land uses were estimated as 82 × 103 tons N/year from agricultural areas, 7 × 103 tons N/year from forestry and 75 × 103 tons N/year from urban and industrial areas. 相似文献
3.
Water quality assessment: surface water sources used for drinking and irrigation in Zaria,Nigeria are a public health hazard 总被引:1,自引:0,他引:1
Chigor VN Umoh VJ Okuofu CA Ameh JB Igbinosa EO Okoh AI 《Environmental monitoring and assessment》2012,184(5):3389-3400
We assessed the quality and pollution status of source surface waters in Zaria, Nigeria by monitoring the nature, cause and
extent of pollution in Samaru stream, Kubanni River and Kubanni dam over a period of 10 months, between March and December
2002. A total of 228 water samples was collected from 12 sites and analysed for a total of ten physicochemical and one bacteriological
quality indicators, using standard methods. Aesthetic water quality impairment parameters were also observed. The mean values
of most water quality parameters were significantly higher (P < 0.05) in both the stream and river than in the dam. There was no significant correlation between faecal coliform counts
(FCC) and water temperature (in the range 15–33°C); pH (5.77–7.32); and turbidity (1.4–567 NTU). The high FCC ranged from
2.0 × 101 to 1.6 × 106 MPN/100 ml and exceeded the WHO standards for drinking water and water used for fresh-produce irrigation, and correlated
positively (P < 0.05) with conductivity (in the range 68–1,029 μS/cm); TDS (10.0–70.0 mg/l); TSS (10.0–70.0 mg/l); Cl (7.5–181 mg/l); PO4−P (0.01–0.41 mg/l); NO3−N (0.6–3.8 mg/l) and BOD5 (0.1–14.9 mg/l). The main pollution sources were municipal wastewater, stormwater runoffs, the ABU sewage treatment plant,
abattoir effluents and irrigation farms treated with chemical fertilisers. We conclude that these water bodies are potentially
hazardous to public health and that proper sewage treatment and river quality monitoring are needed to warn against hazards
to public health. 相似文献
4.
Reddy KJ Kumar JR Ramachandraiah C Reddy SA Reddy AV 《Environmental monitoring and assessment》2008,136(1-3):337-346
N-Ethyl-3-cabazolecarboxaldehydethiosemicarbazone (ECCT) is proposed as a new, sensitive and selective complexing reagent
for the separation and extractive spectrophotometric determination of palladium(II) at pH: 4.0 to form a yellowish orange
colored 1:1 chelate complex, which is very well extracted in to n-butanol. The absorbance was measured at a maximum wavelength,
410 nm. This method obeys Beer’s law in the concentration range 0.0–6.6 μg mL−1 and the correlation coefficient of Pd(II)-ECCT complex is 0.998, which indicates an excellent linearity between the two variables
with good molar absorptivity and Sandell’s sensitivity, 1.647 × 104 l mol−1cm−1, 6.49 × 10−3 μg cm−2, respectively. The instability constant of complex calculated from Edmond’s method, 2.724 × 10−5 was in good agreement with the value calculated from Asmus’ method 2.624 × 10−5, at room temperature. The precision and accuracy of the method is checked with calculation of relative standard deviation
(n = 5), 0.839. Edmond’s method was observed to be a more selective method in the presence of EDTA, oxalate and phosphate ions.
The method was successfully applied for the determination of Pd(II) in water samples, synthetic mixtures and hydrogenation
catalysts, employing an atomic absorption spectrometer for comparing these results. 相似文献
5.
The contribution of fugitive dust from traffic to air pollution can no longer be ignored in China. In order to obtain the
road dust loadings and to understand the chemical characteristics of PM10 and PM2.5 from typical road dust, different paved roads in eight districts of Beijing were selected for dust collection during the
four seasons of 2005. Ninety-eight samples from 28 roads were obtained. The samples were resuspended using equipment assembled
to simulate the rising process of road dust caused by the wind or wheels in order to obtain the PM10 and PM2.5 filter samples. The average road dust loading was 3.82 g m − 2, with the highest of 24.22 g m − 2 being in Hutongs in the rural–urban continuum during winter. The road dust loadings on higher-grade roads were lower than
those on lower-grade roads. Attention should be paid to the pollution in the rural–urban continuum areas. The sums of element
abundances measured were 16.17% and 18.50% for PM10 and PM2.5 in road dust. The average abundances of OC and EC in PM10 and PM2.5 in road dust were 11.52%, 2.01% and 12.50%, 2.06%, respectively. The abundance of elements, water-soluble ions, and OC, EC
in PM10 and PM2.5 resuspended from road dust did not change greatly with seasons and road types. The soil dust, construction dust, dust emitted
from burning coal, vehicle exhaust, and deposition of particles in the air were the main sources of road dust in Beijing.
Affected by the application of snow-melting agents in Beijing during winter, the amount of Cl − and Na + was much higher during that time than in the other seasons. This will have a certain influence on roads, bridges, vegetations,
and groundwater. 相似文献
6.
Heavy metal pollution of water resources can be apprehended in East Singhbhum region which is a highly mineralised zone with
extensive mining of copper, uranium and other minerals. Ten groundwater samples were collected from each site and the heavy
metal analysis was done by atomic absorption spectrophotometer. Analysis of the results of the study reveals that the concentration
of iron, manganese, zinc, lead, copper and nickel in groundwater of Bagjata mining area ranged 0.06–5.3 mg l − 1, 0.01–1.3 mg l − 1, 0.02–8.2 mg l − 1, 1.4–28.4 μg l − 1, 0.78–20.0 μg l − 1 and 1.05–20.1 μg l − 1, respectively. In case of Banduhurang mining area, the range was 0.04–2.93 mg l − 1, 0.02–1.1 mg l − 1, 0.01–4.68 mg l − 1, 1.04–33.21 μg l − 1, 1.24–18.7 μg l − 1 and 1.06–14.58 μg l − 1, respectively. The heavy metals were found to be below the drinking water standards (IS:10500 1993) except iron (0.3 mg l − 1) and manganese (0.1 mg l − 1). The hazard quotients of the heavy metals for drinking water were below 1 posing no threat due to intake of water to the
people for both the areas. 相似文献
7.
A sensitive spectrophotometric method has been developed for determination of ametryn in agricultural samples. The proposed
method was based on reaction with pyridine and further coupling with sulfanilic acid to form a colored product. The absorbance
was measured at 400 nm with a molar absorptivity of 2.1 × 105 L mol−1 cm−1. The method shows a linear range from 0.2–20 μg mL−1 with limit of detection and limit of quantification 0.16 and 0.54 μg mL−1, respectively. The method has been successfully applied to the determination of ametryn in sugarcane juice and commercial
formulations after separation of ametryn from triazine herbicides based on solvent extraction. Recovery values were found
to be in the range of 96.0 ± 0.2% to 98.4 ± 0.1%. 相似文献
8.
Al-Tayar NG Nagaraja P Vasantha RA Shresta AK 《Environmental monitoring and assessment》2012,184(1):181-191
A simple, rapid, and sensitive method involving the interaction of 2,4-dinitrophenylhydrazine with imipramine hydrochloride
in presence of vanadium (V) in sulfuric acid medium has been proposed for the determination of vanadium. The purple-colored
product developed showed an absorption maximum at 560 nm and was stable for 24 h. The working curve was linear over the concentration
range of 0.1–2.8 μg ml − 1, with sensitivity of detection of 0.0124 μg ml − 1. Molar absorptivity and Sandell’s sensitivity were found to be 2.6 × 104 l/mol cm and 0.0039 μg cm − 1, respectively. The accuracy of the proposed method was assessed by Student’s t test and variance ratio F test, and the results were on par with the reported method. The method was successfully used in the determination of V in
water, human urine, soil, and plant samples, and it was free from interference by various concomitant ions. 相似文献
9.
Nagpur City located in semiarid area of central India is a fast-growing industrial centre. In recent years, rapid development
has created an increased demand for drinking water, which is increasingly being fulfilled by groundwater abstraction. The
present study was undertaken to assess major ion chemistry of shallow groundwater to understand geochemical evolution of groundwater
and water quality for promoting sustainable development and effective management of groundwater resources. A total of 47 water
samples were collected from shallow aquifer of selected parts of the city and the water chemistry of various ions viz. Ca2 + , Mg2 + , Na + , K + , CO3 2-_{3}^{\ \, 2-}, HCO3 -_{3}^{\ \, -}, Cl − , SO4 2-_{4}^{\ \,2-} and NO3 -_{3}^{\ \,-} are carried out. The chemical relationships in Piper diagram identify Ca–HCO3–Cl and mixed Ca–Na–HCO3–Cl as most prevalent water types. Alkaline earth exceeds alkalis and weak acids exceed strong acids. Ionic ratios and Gibb’s
diagram suggest that silicate rock weathering and anthropogenic activities are the main processes that determine the ionic
composition in the study area. The nitrate appeared as a major problem of safe drinking water in this region. We recorded
highest nitrate concentration, i.e., 411 mg/l in one of the dug well. A comparison of groundwater quality in relation to drinking
water quality standards revealed that about half of the shallow aquifer samples are not suitable for drinking. 相似文献
10.
Bondareva L 《Environmental monitoring and assessment》2012,184(6):3831-3847
Discharges from the Mining-and-Chemical Combine (MCC) of Rosatom, downstream from Krasnoyarsk, resulted in radioactive contamination
of sediments of the River Yenisei. The concentration of artificial gamma-emitting radionuclides (137Cs, 60Co, 152Eu, and 241Am) was determined with the objective to analyze the migration processes leading to the transport of these radionuclides.
The content of artificial radionuclides in the surface layers of the study area varied in wide ranges: 137Cs—318–1,800 Bq/kg, 60Co—87–720 Bq/kg, 152Eu—12–287 Bq/kg and 241Am—6–76 Bq/kg. There was a sequence of migration of radionuclides investigated in the surface layer of sediments that were
collected in the near zone of influence of the MCC: 241Am ≈ 152Eu > 60Co > 137Cs. Radionuclide species have been found to be directly related to sediment structure and composition. 相似文献
11.
Academic, government, and industrial field researchers have generated a significant database of field studies of the volatility
of soil applied fumigants. However, limited work exists in validating physical models against field volatility data sets and
fully exploring the volatility parametric response surface. Field studies quantifying atmospheric flux for soil fumigants
1,3-dichloropropene and chloropicrin are validated against the United States Department of Agriculture (USDA Salinity Laboratory)
soil physics model CHAIN_2D that was modified specifically for agronomic uses of soil fumigants. Comparison between model
predictions and field observations for six unique field trials in five different states indicate that CHAIN_2D effectively
captures the magnitude and duration of fumigant emission from soil observed experimentally with r
2
∼ 0.14–0.96 (avg. 0.66) for peak emission, and r
2
∼ 0.76–1.0 (avg. 0.91) for cumulative emissions (r equals the Pearson moment correlation coefficient). Correct prediction magnitudes suggest that CHAIN_2D is a useful tool
for extrapolating flux predictions to diverse scenarios not addressed by field trials. Examples of mitigation strategies such
as the use of agricultural films (tarps), increased soil injection depth, and management of soil water content, under near
semi-infinite parameter combinations of soil, meteorological, and agronomic properties are discussed. 相似文献
12.
Bhatia A Pathak H Jain N Singh PK Tomer R 《Environmental monitoring and assessment》2012,184(5):3095-3107
Conventional blanket application of nitrogen (N) fertilizer results in more loss of N from soil system and emission of nitrous
oxide, a greenhouse gas (GHG). The leaf color chart (LCC) can be used for real-time N management and synchronizing N application
with crop demand to reduce GHG emission. A 1-year study was carried out to evaluate the impact of conventional and LCC-based
urea application on emission of nitrous oxide, methane, and carbon dioxide in a rice–wheat system of the Indo-Gangetic Plains
of India. Treatments consisted of LCC scores of ≤4 and 5 for rice and wheat and were compared with conventional fixed-time
N splitting schedule. The LCC-based urea application reduced nitrous oxide emission in rice and wheat. Application of 120 kg
N per hectare at LCC ≤ 4 decreased nitrous oxide emission by 16% and methane by 11% over the conventional split application
of urea in rice. However, application of N at LCC ≤ 5 increased nitrous oxide emission by 11% over the LCC ≤ 4 treatment in
rice. Wheat reduction of nitrous oxide at LCC ≤ 4 was 18% as compared to the conventional method. Application of LCC-based
N did not affect carbon dioxide emission from soil in rice and wheat. The global warming potential (GWP) were 12,395 and 13,692 kg CO2 ha−1 in LCC ≤ 4 and conventional urea application, respectively. Total carbon fixed in conventional urea application in rice–wheat
system was 4.89 Mg C ha−1 and it increased to 5.54 Mg C ha−1 in LCC-based urea application (LCC ≤ 4). The study showed that LCC-based urea application can reduce GWP of a rice–wheat
system by 10.5%. 相似文献
13.
Removal of hexavalent chromium from contaminated ground water using zero-valent iron nanoparticles 总被引:1,自引:0,他引:1
Ritu Singh Virendra Misra Rana Pratap Singh 《Environmental monitoring and assessment》2012,184(6):3643-3651
Batch experiments were conducted on ground water samples collected from a site contaminated with Cr(VI) to evaluate the redox
potential of zero-valent iron (Fe0) nanoparticles for remediation of Cr(VI)-contaminated ground water. For this, various samples of contaminated ground water
were allowed to react with various loadings of Fe0 nanoparticles for a reaction period of 60 min. Data showed 100% reduction of Cr(VI) in all the contaminated ground water
samples after treatment with 0.20 gL−1 of Fe0 nanoparticles. An increase in the reduction of Cr(VI) from 45% to 100% was noticed with the increase in the loading of Fe0 nanoparticles from 0.05 to 0.20 gL−1. Reaction kinetics of Cr(VI) reduction showed pseudo first-order kinetics with rate constant in the range of 1.1 × 10−3 to 3.9 × 10−3 min−1. This work demonstrates the potential utility of Fe0 nanoparticles in treatment and remediation of Cr(VI)-contaminated water source. 相似文献
14.
Freshwater cladocera such as Daphnia magna and Ceriodaphnia dubia have been used extensively for freshwater toxicity test worldwide. However, these species may not be indigenous in certain
geographical regions, which restrict the utility of these organisms as test species. In the present study, we investigated
optimal culture and test conditions for an indigenous freshwater macroinvertebrate of Korea, Moina macrocopa. The culture conditions that were evaluated included water temperature (20°C and 25°C), rearing media (moderately hard water
or MHW, with or without selenium supplementation, or Elendt M4), and food density (2.5 × 107 and 5 × 107 cells/mL of Selenastrum capricornutum), and their effects on the life history characteristics of M. macrocopa were determined. Population growth rate of M. macrocopa was maximized at 25°C with 5 × 107 cells/mL of algal food density in MHW. A series of chronic three brood reference toxicant tests were conducted under the
ideal culture conditions that were identified here, and the results of the tests indicated reliable reproducibility of the
test protocol. Optimal culture and test conditions that were identified for M. macrocopa in the present study are suggested for evaluation of chronic toxicity of chemicals and industrial or municipal discharge. 相似文献
15.
Sharma KK Kalpana Sharma V Gupta P Jaya M Kumar A Singh B 《Environmental monitoring and assessment》2008,137(1-3):179-184
Fipronil termiticide belongs to phenyl-pyrazole class of chemical compounds. It has broad-spectrum activity particularly against
house hold pests such as cockroaches, mosquitoes, locusts, ticks, and fleas at both larval and adult stages. At high dosage
it can be used to control subterranean termites in building foundations. To evaluate long term efficacy against termites the
persistence and vertical distribution of fipronil was studied under natural weather conditions of Dehradun, India. Fipronil
was applied at four concentrations i.e. 0.05, 0.1, 0.25 and 0.5% a.i ha−1 by drenching 17 × 17 in.2 plot prepared as per modified ground board test. Soil samples were collected after 22, 38 and 56 months of treatment up to
the depth of 75 cm. The soil core was cut into five distinct sections i.e. 0–15, 15–30, 30–45, 45–60 and 60–75 cm depth. The
residues were extracted by shaking 20 g soil sample with acetone. The acetone extract was concentrated and cleaned-up over
florisil column. Fipronil residues were estimated on GLC at 220, 260, and 300°C oven, injector and detector temperature respectively.
Fipronil was found to persist beyond 56 months after application. Two metabolites viz. desulfinyl and sulfide-fipronil were
detected in sampling after 22 months of application that also dissipated with time. Fipronil residues were found up to 60 cm
depth. The residues in deeper layers dissipate slowly with time and after 56 months of treatment residues were detected only
up to 30 cm depth. 相似文献
16.
Different multivariate statistical analysis such as, cluster analysis, principal component analysis, and multidimensional
scale plot were employed to evaluate the trophic status of water quality for four monitoring stations. The present study was
carried out to determine the physicochemical parameters of water and sediment characteristics of Pondicherry mangroves—southeast
coast of India, during September 2008–December 2010. Seasonal variations of different parameters investigated were as follows:
salinity (10.26–35.20 psu), dissolved oxygen (3.71–5.33 mg/L), pH (7.05–8.36), electrical conductivity (26.41–41.33 ms−1), sulfide (1.98–40.43 mg/L), sediment texture sand (39.54–87.31%), silt (9.89–32.97%), clay (3.06–31.20%), and organic matter
(0.94–4.64%). pH, temperature, salinity, sand, silt, clay, and organic matter indicated a correlation at P < 0.01. CA grouped the four seasons in to four groups (pre-monsoon, monsoon, post-monsoon, summer) and the sampling sites
in to three groups. PCA identified the spatial and temporal characteristics of trophic stations and showed that the water
quality was worse in stations 3 and 4 in the Pondicherry mangroves. 相似文献
17.
In a comprehensive program of environmental radioactivity survey in South Caspian region,137Cs inventories in soil has been measured at more than 50 sites in the Iranian northern province of Guilan. This has been the
first wide-range survey of soil radionuclide inventories in the narrow band sensitive ecosystem of south Caspian shore. Radioactivity
measurements were carried out using HPGe gamma-spectrometry system. The activity concentration of 137Cs in surface soil exhibits a mean value of 17.6 ± 9.4 Bq kg−1, with a range of 2.3–41.7 Bq kg−1. In many sites, split-level sampling method has been applied down to a depth of 20 cm. There were found generally two profiles.
Most profiles exhibit a negative exponential distribution, while others revealed a clear subsurface peak in 5–10-cm layer.
Cesium deposition in the study area has been estimated to be in the range of 0.38–2.9 kBq m−2 with a mean value of 1.7 kBq m−2. Distribution patterns of 137Cs concentration levels and deposition values have been estimated using Kriging interpolation method. Observed hotspots in
deposition pattern coincide with areas of higher precipitation. 相似文献
18.
Podlaski R 《Environmental monitoring and assessment》2007,135(1-3):339-351
Tree damage, gauged by the amount of defoliation, is one of the basic criteria used to determine treatments for protected
and economic forests. Monitoring should include an assessment of the degree of tree damage in different spatial scales. Therefore,
in addition to the commonly applied large-area methods, small-area methods should be used. The aim of the paper is to present
the results of the accuracy assessment of a small-area method, proposed by Podlaski (2005) [Podlaski, R. (2005). Inventory of the degree of tree defoliation in small areas. Forest Ecology and Management, 215, 361–377], for monitoring the degree of tree damage. The degree of tree damage was shown in sub-blocks P3 of the system of information on natural environment (SINUS). To estimate the spatial distribution of the degree of tree defoliation,
survey sampling, based on simple random sampling with replacement (SRSWR), was used. The degree of damage to fir (Abies alba Mill.) and beech (Fagus sylvatica L.) was analysed in the Święty Krzyż forest section in the Świętokrzyski National Park. The maximum total estimation errors
for the proportion of trees with a degree zero of damage, and with second and third degrees of damage together (for α = 0.05) were at most 30.8% for fir and 24.3% for beech trees. For standard, small-area evaluations, these are satisfactory
values. In the Święty Krzyż forest section, the number of P3 sub-blocks with 0.00–5.00% of undamaged trees and with 80.01–100.00% of moderately- or severely-damaged trees was significantly
greater for fir than for beech. These results indicate that the fir population was unhealthier than the beech group in the
study area. P3 sub-blocks of the SINUS system, in which the proportion of the healthiest trees was highest, were situated at the forest
margin, bordering on meadows and arable fields (in the case of fir) and forming dense patches consisting of several sub-blocks,
or occurring singly in the whole study area (in the case of beech). The results show the significant differentiation of forest
tree health in small areas. 相似文献
19.
Eutrophication and Sedimentation Patterns in Complete Exploitation of Water Resources Scenarios: An Example from Northwestern Semi-arid Mexico 总被引:1,自引:0,他引:1
Sánchez-Carrillo S Alatorre LC Sánchez-Andrés R Garatuza-Payán J 《Environmental monitoring and assessment》2007,132(1-3):377-393
Water requirements to supply human needs lead water stakeholders to store more water during surplus periods to fulfil the
demand during – not only – scarcity periods. At the reservoirs, mostly those in semi-arid regions, water level then fluctuates
extremely between rises and downward during one single year. Besides of water management implications, changes on physical,
chemical and biological dynamics of these drawdown and refilling are little known yet. This paper shows the results, throughout
a year, on solids, nutrients (N and P), chlorophyll-a, and sedimentation changes on the dynamics, when the former policy was applied in a reservoir from the semi-arid Northwestern
Mexico. Water level sinusoidal trend impinged changes on thermal stratification and mixing, modifying nutrient cycling and
primary producer responses. According to nitrogen and phosphorus concentration as well as chlorophyll-a, reservoir was mesotrophic, becoming hypertrophic during drawdown. Nutrient concentrations were high (1.22 ± 0.70 and 0.14 ± 0.12 mg
P l−1), increasing phosphorus and lowering N:P significantly throughout the study period, although no intensive agricultural, no
urban development, neither industrial activities take place in the watershed. This suggests nutrient recycling complex mechanisms,
including nutrient release from the sediment–water interface as the main nutrient pathway when shallowness, at the same time
as mineralization, increases. Outflows controlled nitrogen and phosphorus availability on the ecosystem while organic matter
depended on river inflows. As on other subtropical aquatic ecosystems, nitrogen limited primary productivity (Spearman correlation
R = 0.75) but chlorophyll-a seasonal pattern showed an irregular trend, prompting other no-nutrient related limitants. Shallowness induced a homogeneous
temporal pattern on water quality. This observed temporal variability was mainly explained statistically by changes on solids
(mineral and organic), chlorophyll-a and flows (62.3%). Annual sedimentation rates of total solids ranged from 11.73 to 16.29 kg m−2 year−1 with organic matter comprising around 30%. N:P ratio on sedimentation rates were as high as could be expected in a resuspension
dominated ecosystem, and spatially inverse related with N:P ratio on bottom sediments. Distance from river inlet into the
reservoir reveals a marked spatial heterogeneity on solid and nitrogen sedimentation, showing the system dependence on river
inflows and supporting resuspension as the main phosphorus pathway. Accretion rates (2.19 ± 0.40 cm year−1) were not related to hydrological variability but decreased with the distance to the river input. Total sediment accumulation
(9,895 tons km−2 year−1) denotes siltation as other serious environmental problem in reservoirs but possibly not related with operational procedures. 相似文献
20.
Atmospheric surface aerosol radiative forcing (SARF) ΔF, forcing efficiency ΔFe and fractional forcing efficiency ΔFFe evaluated from cloud-screened narrowband spectral and thermal-offset-corrected radiometric observations during the Asia dust
outbreak episodes in Gwangju, Republic of Korea are reported in this study. Columnar aerosol optical properties (aerosol optical
depth (AOD), τ
aλ, Angstrom exponent α, mass concentration of fine and coarse mode particles) were also reported for the station between January
2000 and May 2001 consisting of 211cloud-free days. Results indicate that majority of the AOD were within the range 0.25–0.45
while some high aerosol events in which AODs ≥ 0.6 were observed during the severe dust episodes. For example, AOD increases
from annual average value of 0.34 ± 0.13 at 501 nm to values >0.60 during the major dust events of March 27–30 and April 7–9,
2000, respectively. The α
501–870 nm which is often used as a qualitative indicator of aerosol particle size had values ranging from 0.01 to 1.77. The diurnal
forcing efficiency ΔDFe at Gwangju was estimated to be −81.10 ± 5.14 W m −2/τ
501 nm and −47.09 ± 2.20 W m −2/τ
501 nm for the total solar broadband and visible band pass, respectively while the fractional diurnal forcing efficiency ΔFDFe were −15.8 ± 0.64%/τ
501 nm and −22.87 ± 1.13%/τ
501 nm for the same band passes. Analyses of the 5-day air-mass back trajectories were further developed for Gwangju in order to
classify the air-mass and types of aerosol reaching the site during the Asia dust episodes. 相似文献