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Sun X.,Akesu Regional Environment Monitoring Center | Gan W.,Akesu Regional Environment Monitoring Center | Lin Y.,Zhejiang Environmental Monitoring Association | Zhang Z.,Akesu Regional Environment Monitoring Center | And 4 more authors.
Huanjing Kexue Xuebao/Acta Scientiae Circumstantiae | Year: 2015

The present study aimed to analyze the algorithm of MODIS C006 3 km satellite aerosol product by using atmospheric concentrations of airborne particulates (PM10) and meteorological data (e.g. visibility and relative humidity) collected from a metrological monitoring station (1a) at Akesu of Xinjiang. The precision and stability of this aerosol product was compared with the observed data of AERONET. The results revealed that there was a close and positive correlation between the data from MODIS C006 3 km product and those from the ground station AOD (Issyk-Kul) (r=0.8836). Although the observed precision of MODIS was within the acceptable range, it overestimated the PM10 concentration. AOD and PM10 followed similar variation trends and the correlation between PM10 concentrations at the two meteorological stations in Akesu city was 0.55, which was significant and better than those reported in similar studies. When AOD was corrected against vertical aerosol heights and relative humidity, the correlation was improved but not significantly with reduced standard errors and covariance. There was a significant seasonal variation in MODIS 3 km AOD, with the highest in the spring above 1.5 and only 0.6~0.7 in the summer and autumn. However, within the city area of Akesu, the average AOD remained >1.0 even in the summer and autumn, probably due to the high density of population, transport and industrial activities. In summary, the quality of MODIS C006 3 km AOD product was stable, with improved spatial coverage based on monthly and seasonal mean values. It can satisfactorily meet the requirements of long-term monitoring and regional-scale assessment. ©, 2015, Science Press. All right reserved.

Huang C.,Zhejiang University of Technology | Ye X.,Kent State University | Deng C.,Binghamton University State University of New York | Zhang Z.,Zhejiang Environment Monitoring Center | Wan Z.,Zhejiang Institute of Hydraulics and Estuary
Remote Sensing | Year: 2016

Wetlands are important ecosystems as they are known as the "kidney of the earth". Particularly, urban wetlands play an important role in providing both natural and social beneficial services. However, urban wetlands are suffering from various human impacts, such as excessive land use conversion, air and water pollution, especially those in developing countries undergoing rapid industrialization and urbanization. Therefore, it is of great necessity to derive timely biomass information for optimal design, management and protection of urban wetlands. In this paper, we develop a set of models for estimating above ground biomass (AGB) in Xixi National Wetland Park in Hangzhou, China by using optical images and Synthetic Aperture Radar (SAR) images. A series of vegetation indices (VIs) derived from optical data is introduced along with spectral data. The modeling methods consist of (1) curve estimation; (2) linear regression for multivariable model; (3) Back Propagation Neural Network (BPNN) modeling. Curve estimation is a combination of linear and nonlinear regressions. It is applied to generate AGB models from a single variable including Normalized Difference Vegetation Index (NDVI) and radar backscatter coefficient. The models are then compared via three accuracy metrics. According to the results, SAR models generally show better accuracy than optical models and BPNN models show the greatest accuracy among all the models. The BPNN model from the combination of Terra Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) and European Remote-Sensing Satellite-2 (ERS-2) SAR (Synthetic Aperture Radar) image has the least root mean square (RMSE, 0.396 kg/m2), least mean absolute error (MAE, 0.256 kg/m2) and the greatest correlation coefficient (0.974). The results indicate that AGB can be estimated by integrating optical and SAR imagery. Four maps of AGB are derived to illustrate the distribution of AGB in the study area. The total AGB in the study area is estimated to be between 165,000 and 210,000 kg/m2. © 2016 by the authors.

Zhang Z.,Zhejiang Environment Monitoring Center | Yu H.,Zhejiang Environment Monitoring Center | Hu Z.,Zhejiang Environment Monitoring Center | Zhou B.,Zhejiang Environment Monitoring Center | And 2 more authors.
2nd International Conference on Information Science and Engineering, ICISE2010 - Proceedings | Year: 2010

Atmospheric aerosol, which is an important parameter required for climate change studies, local air quality monitoring, global aerosol transport modeling, atmospheric correction and global aerosol characterization, decreases seriously regional air quality and may have a negative impact on public human health. Because aerosols had complex sources and the short lifetime, it is difficult to study the particles directly. Remote sensing satellites provided the best ways to characterize spatial field and regional characterization of aerosol particles. The study presents a prototype method for extracting high resolution aerosol optical depth (AOD) in eastern China using remote sensing satellites data. An AOD derivation experiment by HJ-1 CCD data was carried out in Zhejiang province, China, in April 22th, 2010. NASA's aerosol retrieval algorithm was introduced in the study which was developed Robert C. Levy and Lorraine A. Remer based on the Dark Dense Vegetation(DDV) algorithm of Kaufman. The Look-up Table was computed from the 6S RT model. The results had been validated by MODIS atmospheric aerosols production suggesting that the HJ-1 data works well for atmosphere particles detection under complex land characteristic of eastern China, especially in Zhejiang province. Such investigations are expanding satellites for AOD detection, as well as exploring the potential capability for air quality monitoring for HJ-1 data. A very large potential for HJ-1 as an efficient satellite data to retrieve aerosol products was also demonstrated in the study. © 2010 IEEE.

Zhang Y.,Nanjing Agricultural University | Liu S.,Nanjing Agricultural University | Yu H.,Zhejiang Environment Monitoring Center | Liu D.,Nanjing Agricultural University | Wang B.,Nanjing Agricultural University
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2012

Benthic macroinvertebrates are common, long-lived, sensitive to disturbance, and cost-effective to sample, which make them ideal biological indicators of aquatic system degradation, and they are used in stream biomonitoring worldwide. As biological indicators, macroinvertebrates can provide insight into the current and past conditions of waterbodies and they integrate the effects of cumulative stressors. However, patterns in stream macroinvertebrate assemblages are the result of a combination of processes acting at different spatial scales. Understanding the relative influence of environmental variables at different spatial scales can increase our ability to detect anthropogenic influences on stream integrity, as well as to assess and manage aquatic resources. In this study, we used Qiantang River basin as an example of a human disturbed watershed. Based on environmental and biotic data of 60 sites located in the middle section of Qiantang River basin, the specific aims of our study were: (1) to analyze the stream macroinvertebrate assemblages; (2) to identify the key environmental factors that are linked to variation in macroinvertebrate assemblages; and (3) to partition the additive effects of watershed-scale and reach-scale variables, as well as their interaction, on macroinvertebrate community composition. Environmental variables mainly included land use (urban, agriculture, forest, and the total impervious area), geographical location, elevation, slope, stream order, and the area of sub-basin at the watershed scale, physical habitat conditions and water chemistry at the reach scale. Macroinvertebrate responses were characterized by the relative abundance of 262 taxa. Principal components analysis was used to explore the major environmental gradients, and canonical correspondence analysis was adopted to determine the relationships between environmental variables and macroinvertebrate composition. Variation partitioning was performed using partial canonical correspondence analysis (pCCA) to understand the relative importance of different scale factors in macroinvertebrate variation. Assessment of the main environmental gradients suggested that degradation of the macroinvertebrate communities was mainly due to the increase of anthropogenic land cover, followed by elevated nutrient concentrations, and habitat destruction. At the watershed scale, the most important variables structuring macroinvertebrate assemblages were latitude, altitude, sub-basin area, percentage of forest; at the reach scale, they were total N, total P, the concentrations of Ca2+ and SiO2, and the mean substrate score. The total explained variation was 26. 4%. Of this, the results of the pCCA indicated that the relative proportions of explained variation attributed to watershed-scale and reach-scale environmental variables were 50% and 31%, respectively. The results of the pCCA suggested that watershed-scale variables play a more important role in stream macroinvertebrates of this study region than reach-scale variables, which could be important for biodiversity conservation and restoration, land management, and environmental monitoring and assessment.

Han M.,Nanjing Agricultural University | Yu H.,Zhejiang Environment Monitoring Center | Zhou B.,Zhejiang Environment Monitoring Center | Zhang Y.,Nanjing Agricultural University | Wang B.,Nanjing Agricultural University
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2012

Study of the degradation of urban stream ecosystems has been an important focus of urban ecology. During urbanization, infrastructure such as dams and other water projects can have a significant impact on the stream ecosystem. Dams create barriers, upstream and downstream, which hinder the migration of benthic invertebrates, change their living environment and affect their reproductive success, negatively affecting the macroinvertebrate community and its structure. This destroys the integrity of the stream ecosystem. To date, there has been no published research on this topic in China. Therefore, we surveyed the macroinvertebrate assemblages of nine sites (six in urban streams with run-of stream dams [2- 3m] and three in reference forest streams) in August, in Xitiao River catchment, Anji County, Zhejiang Province. Using the data collected, we explored the biological degradation of urban streams and the impact of run-of stream dams on the structure and composition of the macroinvertebrate community as well as on a range of biochemical parameters. Multiple comparison and non-parametric tests were used to compare the biochemical parameters of the different stream types, performed using SPSS 18. 0 statistical software. Non-metric multidimensional scaling (NMDS) analysis was used to compare the community composition, performed using Primer 6. 0 software. Our results showed that the main substrate components of the reference sites were boulders (35. 92%) and cobbles (33. 66%), while the substrate of the urban streams was mostly gravel (57. 97%). Water temperature, conductivity, and concentrations of total nitrogen and total phosphorous were all significantly (P < 0. 05) higher in urban streams than in reference streams, whereas total taxa richness and EPT (Ephemeroptera, Plecoptera and Trichoptera) taxa richness were significantly (P<0. 05) lower in the urban streams than in the reference streams. Differences in velocity (P =0. 273) and depth/ width (P =3. 92) between sites above and below the dams were not significant. Dissolved oxygen, pH, total nitrogen concentration, water temperature and conductivity were also very similar between sites above and below the dams. An exception to this was that total phosphorus concentration was greater below the dams than above the dams. Moreover, total taxa richness, EPT taxa richness, Shannon diversity index and evenness index of the sites above and below the dams were similar. However, the biotic index was higher below dams than above dams. In addition, the ratio of sensitive taxa to tolerant taxa was lower at sites below dams, and the ratio of predators to collector-gatherers was higher at the sites below dams. Furthermore, NMDS analysis demonstrated that the macroinvertebrate community composition greatly varied between the sites above and below the dams in these urban streams. These results suggested that the sediment composition, water quality and benthic community structure had been significantly degraded in urban streams, particularly downstream of the dams. These observations are preliminary since they are based on a survey conducted in August only, and therefore do not allow comprehensive assessment of the ecological effects of dam constructions. However, our findings indicate that there may be negative impacts and support the need for regular and long- term observations of the macroinvertebrate community in urban streams with dams.

Xu H.Y.,Zhejiang Environment Monitoring Center | Yu H.Y.,Zhejiang Environment Monitoring Center | Han M.C.,Zhejiang Environment Monitoring Center | Huang P.S.,Zhejiang Wanli University | Li G.G.,Zhejiang Wanli University
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2015

This study aimed to understand the characteristics of zooplankton community structure and their association with environmental factors in different sources of drinking water. A seasonal investigation was conducted on zooplankton from two drinking water sources (8 rivers and 8 reservoirs) in Zhejiang Province, China, from January 2010 to October 2011. A total of 21 dominant species (genus) of zooplankton (8 Rotifera, 5 Cladocera, 5 Cyclopoida, and 3 Calanoida) were recorded. The primary dominant species in each group of zooplankton were Polyarthra trigla, Bosmina longirostris, Thermocyclops dybowskii, and Sinocalanus dorrii, respectively. Nine of the dominant species (genera) were at the same time indicator species of water trophic state. The more frequently that indicator species of trophic state occurred, the more comprehensive the trophic level index (TLIc) (P < 0.01) of the rivers was. Over the 2-year study period, the average density of zooplankton in the rivers and reservoirs was 345.2 L-1 and 199.4 L-1, respectively, while the biomass was 0.667 mg/L and 0.421 mg/L, respectively. Rotifer and copepod nauplii dominated both the rivers and reservoirs, representing 87.9% and 88.3% density, respectively. Crustaceans were mainly Cyclopoida, which had 2 times the biomass of Calanoida in the rivers, whereas Calanoida had 2 times the biomass of Cyclopoida in the reservoirs. The river community density (biomass) coefficient of variation ranged between 158.2% and 325.5%, while that of reservoirs ranged between 107.8% and 345.2%. The results of the stepwise regression analysis showed that the correlative coefficient between the density (biomass) of the zooplankton community and the water quality factors was much higher in the rivers (P < 0.01) than in the reservoirs (P < 0.05). Total phosphorus (TP) and ammonia nitrogen primarily occurred in the rivers and the reservoirs in all effective regression equations, respectively. Path and decision coefficient analysis showed that TP and chlorophyll a (Chl.a) content in the rivers had a positive effect on the population dynamics of the zooplankton community (rotifers, copepod nauplii, and Cyclops), whereas dissolved oxygen content had a negative effect. TP was the most important factor affecting population dynamics of rotifers, copepod nauplii, and Cyclops in the rivers, whereas Chl.a was the most important factor limiting the communities growth. The reservoir fishery resources aquaculture might cause zooplankton abundance to decline, the Calanoida community to gradually disappear, and the water trophic state to transform from nitrogen limitation conditions to phosphorus limitation conditions. The river community (rotifers, copepod nauplii, and Cyclops) density (biomass) had a significant linear regression relationship with the water trophic index TLIcDensity(TLIcBiomass) (P < 0.001). Copepod nauplii density constituted a limiting factor for TLIcDensity, due to its maximum average coefficient of variation (261.8%). Rotifer biomass constituted a limiting factor for TLIcBiomass, due to its maximum average coefficient of variation (257.9%). The average variation coefficient of Cyclops density (biomass) was moderate, with small fluctuations; thus, this group represented the most important and stable water quality indicator. The study results provide an important reference for selecting specific expansion indicators of the zooplankton community in water quality monitoring. None of the zooplankton community density (biomass) groups in the reservoirs had any significant linear regression relationships with the water TLIc (P > 0.05). © 2015, Ecological Society of China. All rights reserved.

Zhang Z.,Zhejiang Environment Monitoring Center | Yu H.,Zhejiang Environment Monitoring Center | Hu Z.,Zhejiang Environment Monitoring Center | Zhou B.,Zhejiang Environment Monitoring Center | Han M.,Zhejiang Environment Monitoring Center
Applied Mechanics and Materials | Year: 2012

By taking advantage of temporal and spatial remote sensing, the present paper was to map, identify and characterize urban heat island in rapid urbanization area of east China. For research areas including six metropolitan cities around Hangzhou bay in east China, urban heat island measurements were monitored from surface temperature maps at 1km resolution derived from MOD11A2 both day and night acquired in the year of 2005 and 2009. LST normalization with NDSTI was applied in order to quantify UHI spatial changes at four seasons. The result showed that urban heat island phenomenon expanded contiguously in the study area. Day change of UHI seems to be more chaos than night change due to day UHI influenced by both solar and human being activities. There was some kind of urban cool island phenomenon in winter when urban surface temperatures were to be-1 - 0°C lower than the ambient LST. Except for winter, other seasons' UHI during daytime changed from 0.5°C to 2.5 °C and nighttime strongly changed from 0.5°C to 5 °C in 2009. During the night, six cites' UHI roughly coincides and UHI in winter was the smallest and in autumn was the biggest one. The study provided causation and environmental awareness of urbanization to urban planners in future urban development.

Zhang Z.,Zhejiang Environment Monitoring Center | Yu H.,Zhejiang Environment Monitoring Center | Hu Z.,Zhejiang Environment Monitoring Center | Zhou B.,Zhejiang Environment Monitoring Center | Han M.,Zhejiang Environment Monitoring Center
2010 4th International Conference on Bioinformatics and Biomedical Engineering, iCBBE 2010 | Year: 2010

Random agricultural burning such as crop straw fire, especial during the harvest seasons of summer and autumn, is a very common phenomenon in rural or suburban cities in China. However, several pollutions may caused by this kind of biomass burning including climate-destructive aerosols and carbon fluxes which decrease seriously regional air quality and may have an negative impact on public human health leading to respiratory illness. Using remote sensing is an available method to detect and monitor agricultural burning arbitrarily with its better time and spatial effectiveness. As a part of EOS mission, MODIS was suitable for fire detection as some high-temperature-sensitive bands of the sensor had been improved. A hybrid algorithm presented by the paper had archived two major advancements on adjusting the potential thresholds to suit lower temperature of crop straw burning than forest fires and introducing latest land cover data to exclude fake agriculture burning Are points which not located in croplands. The results had been validated by FIRMS's active Are production suggesting that the modified algorithm works well for agriculture burning under complex land characteristic of eastern China, especially in Zhejiang province. A very large potential for satellite data as an efficient method to detect agriculture burning was also demonstrated in the study. © 2010 IEEE.

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