Characteristics of haze weather in Chongqing, China and its determinants analysis based on automatic monitoring stations

Statistical analyses were carried out on the characteristics of haze weather and their relation with air quality and meteorological factors using data recorded by the national air quality and meteorological monitoring network of Chongqing, China in 2013. The results showed that the hourly occurrence rate of haze in Chongqing was 81.3% and that 67.2% of the total number of haze hours was at the level of mild to light haze. Haze was more likely to occur in autumn and winter (67.2% of the total number of hours; occurrence rate 97.5%) and was more likely to occur between 22: 00 and 10: 00. Haze mainly occurred when the wind speed was <1.2 m s(-1) and the relative humidity was >50%. Haze rarely occurred when the wind speed was >3.0 m s(-1) and the relative humidity was <30%. There was a positive correlation between temperature and visibility. The occurrence rate was higher with positive variations in the 24-h temperature records. The main factor affecting haze was the level of PM2.5 pollution. Haze mainly occurred when rho(PM2.5) was between 35 and 250 mu g m(-3), accounting for 86.4% of the total number of hours of haze. When r(PM2.5) was >75 mu g m(-3), the occurrence rate of haze was 100.0%. The mean value of r(PM2.5)/rho(PM10) during the hours of haze was 72.9%, 17.7% higher than that at other times. The number of hours with air pollution accounted for 48.8% of the total number of hours, far less than the occurrence of haze. When the ambient air quality was excellent or good, haze was present in 65.4% of hours. We suggest that there are differences between the assessment of air quality and the definition of haze used in China. The relationship between haze and air quality would be better matched if we used the World Meteorological Organization's definition of haze (visibility < 5.0 km). Copyright (C) 2016 Turkish National Committee for Air Pollution Research and Control. Production and hosting by Elsevier B.V. All rights reserved

Accuracy assessment of approaches to spatially explicit reconstruction of historical cropland in Songnen Plain, Northeast China

To understand historical human-induced land use/cover change (LUCC) and its climatic effects, it is essential to reconstruct historical land use/cover changes with explicit spatial information. In this study, based on the historically documented cropland area at county level, we reconstructed the spatially explicit cropland distribution at a cell size of 1 km x 1 km for the Songnen Plain in the late Qing Dynasty (1908 AD). The reconstructions were carried out using two methods. One method (hereafter, referred to as method I) allocated the cropland to cells ordered from a high agricultural suitability index (ASI) to a low ASI, but they were all within the domain of potential cropland area. The potential cropland area was created by excluding natural woodland, swamp, water bodies, and mountains from the study area. The other method (hereafter, method II) allocated the cropland to cells in the order from high ASI to low ASI within the domain of cropland area in 1959. This method was based on the hypothesis that the cropland area domain in 1959 resulted from enlargement of the cropland area domain in 1908. We then compared these two reconstructions. We found that the cropland distributions reconstructed by the two methods exhibit a similar spatial distribution pattern. Both reconstructions show that the cropland was mostly found in the southern and eastern parts of the Songnen Plain. The two reconstructions matched each other for about 68% of the total cropland area. By spatially comparing the unmatched cropland cells of the two reconstructions with the settlements for each county, we found that unmatched cropland cells from method I are closer to settlements than those from method II. This finding suggests that reconstruction using method I may have less bias than reconstruction with method II

东北地区创新资源与产业协同发展研究

采用探索性空间数据分析和象限图法,以县区为基本研究单元,从空间和行业2个视角,探讨东北地区创新资源和产业发展的集聚性和协同性。通过研究发现:东北地区创新资源和产业发展均表现出明显的空间集聚性,主要集中在沈阳、大连、长春和哈尔滨等城市市辖区,但在市辖区内部集聚区存在较大差异,导致创新资源和产业发展协调性在四大城市市辖区及其周边县区呈严重偏离特征,尤其是汽车制造业和通用设备制造业,而医药制造业和专用设备制造业空间协同性较好;从行业分析,通用设备制造业、化学原料和化学制品制造业、医药制造业和专用设备制造业集聚了东北地区55%的发明专利,而43.3%的工业总产值集中在农副食品加工业、汽车制造业,黑色金属冶炼和压延加工业,非金属矿物制品业,石油加工、炼焦和核燃料加工业等5大行业,导致各行业创新资源和产业发展的协同性相对较低,且仅非金属制造业的协同性高于所有行业平均水平

Response of a salt-sensitive plant to processes of soil reclamation in two saline-sodic, coastal soils using drip irrigation with saline water

The aim of this study was to evaluate the impact of soil types and properties on coastal saline soil reclamation and the response of plant growth to the reclamation processes in two soils. Two very heavy coastal saline soils were reclaimed in a three-year trial using drip irrigation with saline water. Chinese roses (Rosa chinensis) were planted, and soil indexes, growth characters, ion absorption and dry matter production were determined. Our results showed that significant salt leaching occurred in both soils, and the effect during the early period of reclamation was better in sandy loam than silt soil. There were higher emergence and survival rates of plants in sandy loam soil due to the rapid reclamation process, while plant growth and dry mass were greater in silt soil due to good fertilizer and water conservation. Most roots were present in the 0-20-cm profile in both soils, but the fine root length value in silt soil was relatively high. These results indicate that water and nutrient management differed in the two soils. During soil reclamation, more attention should be paid to nutrient supply and maintaining soil moisture in sandy loam and to rapidly establishing suitable soil root-zone environments for plant emergence in silt soil. (C) 2015 Elsevier B.V. All rights reserved

Estimation of effective hydraulic parameters in heterogeneous soils at field scale

Determination of soil hydraulic parameters at field scale is of great importance for modeling soil water dynamics and for agricultural water management practice. The parameter regionalization has been a hot topic for many decades in soil science and hydropedology. Based on the statistical description and spatial structure of the soil physical and hydraulic properties measured via soil sampling in the field, three inverse modeling approaches had been proposed to obtain the effective hydraulic parameters. The validity and effectiveness of the three approaches had been discussed by designing four simulation scenarios (a 'fine scale solution' plus the three upscaling approaches). For each inverse modeling, the soil water distribution along the profiles and their dynamics during seven growing seasons (from the year of 2000 to 2006) in the study area had been simulated through the combined use of HYDRUS-1D and PEST. Results demonstrated that the effective soil hydraulic parameters derived from all the three approaches were comparable and fairly close to the 'fine scale solution'. Although, statistics of the hydraulic parameters indicated that the median of K-s of first soil layer, as compared to that of other layers, was most closest to the effective K-s values that were obtained through the three upscaling approaches; while the median of theta(s) values for the top three layers was close to the effective theta(s) values in scenario 2 and scenario 3, but fairly smaller than that in scenario 4. The soil water dynamics were not sensitive to the residual soil water content (theta(r)), even though the theta(r) showed quite different distribution pattern from that of K-s and theta(s). In conclusion, the practice of combining the PEST with the HYDRUS-1D provided an effective and reasonable method to inversely determine the effective hydraulic parameters of the equivalent soil profile in the field. (C) 2015 Elsevier B.V. All rights reserved

Influence of ginseng cultivation under larch plantations on plant diversity and soil properties in Liaoning Province, Northeast China

Currently, transforming the mode of forest management and developing multiple forest management practices are actively encouraged in China. As one forest management type, ginseng cultivation under larch plantations has been developed significantly in the east of Liaoning Province. However, research on the influence of the ecological environment for this mode of production is still deficient. Based on this, our study compares the plant diversity and soil properties in the ginseng cultivation under larch plantations (LG) with larch plantations (LP) and natural secondary forests (SF). First, we randomly selected three plots for each of the three stand types which have similar stand characteristics; then, we carried out a plant diversity survey and soil sampling in each of the nine plots. The results show that no significant difference was found in plant diversity between LG and LP, but the evenness of herbs was significantly lower in LG than LP. No obvious changes in soil physical properties were found in LG, but a significant decrease in most of the soil nutrient content was presented in LG. Furthermore, we found a correlation between plant diversity (H') and soil properties in the three kinds of stand types, especially between herbaceous plant diversity and soil properties. We conclude that ginseng cultivation under larch plantations has no obvious effect on plant diversity, except the herbaceous evenness. Soil fertility can be depleted significantly in LG, but physical structures are not affected. Moreover, maintaining the diversity of herbaceous plants and controlling the density of ginseng cultivation in LG by farmers are important for the ecological environment. Based on this study and its good comprehensive benefits and with the support of policy, we think this forest management type should be promoted moderately in the region

Characteristics of Soil and Organic Carbon Loss Induced by Water Erosion on the Loess Plateau in China

Soil erosion has been a common environmental problem in the Loess Plateau in China. This study aims to better understand the losses of soil organic carbon (SOC) induced by water erosion. Laboratory-simulated rainfall experiments were conducted to investigate the characteristics of SOC loss induced by water erosion. The applied treatments included two rainfall intensities (90 and 120 mm h(-1)), four slope gradients (10 degrees, 15 degrees, 20 degrees, and 25 degrees), and two typical soil types-silty clay loam and silty loam. Results showed that the sediment OC enrichment ratios (ERoc) in all the events were relative stable with values ranged from 0.85 to 1.21 and 0.64 to 1.52 and mean values of 0.98 and 1.01 for silty clay loam and silty loam, respectively. Similar to the ERoc, the proportions of different sized particles in sediment showed tiny variations during erosion processes. No significant correlation was observed between ERoc values and the proportions of sediment particles. Slope, rainfall intensity and soil type almost had no impact on ERoc. These results indicate that the transportation of SOC during erosion processes was nonselective. While the mean SOC loss rates for the events of silty clay loam and silty loam were 0.30 and 0.08 g m(-2) min(-1), respectively. Greater differences in SOC loss rates were found in events among different soil types. Meanwhile, significant correlations between SOC loss and soil loss for all the events were observed. These results indicated that the amount of SOC loss was influenced primarily by soil loss and the SOC content of the original soil. Erosion pattern and original SOC content are two main factors by which different soils can influence SOC loss. It seems that soil type has a greater impact on SOC loss than rainfall characteristics on the Loess Plateau of China. However, more kinds of soils should be further studied due to the special formation processes in the Loess Plateau

Relationship between organic matter humification and bioavailability of sludge-borne copper and cadmium during long-term sludge amendment to soil

Recycling of sludge as soil amendment poses certain risk of heavy metals contamination. This study investigated the relationship between organic matter in composted sludge and its heavy metals bioavailability over 7 years. Periodic monitoring indicated a gradual increase in organic matter degradation, accompanied by changing degrees of polymerization, i.e., ratio of humic acid (HA)/fulvic acid (FA) coupled with incremental exchangeable fraction of copper (Cu) in sludge, with a growing rate of 74.7%, rather than that in soil. However, cadmium (Cd) in composted sludge exhibited an independent manner. Linear-regression analysis revealed that the total proportion of the Cu active fraction (exchangeable plus carbonate bound) was better correlated with the degree of polymerization (DP) and humification ratio (HR) than the degradation ratio of organic matter. Overall, amount of uptaken Cu was more dependent on the humification degree of organic matter, especially the proportion of HA in humus. (C) 2016 Elsevier B.V. All rights reserved

Influence of drip irrigation by reclaimed water on the dynamic change of the nitrogen element in soil and tomato yield and quality

This paper carries out an analysis of the influence of the dynamic change pattern of soil in every crop growth period and irrigation by reclaimed water on yield and quality of fruit and vegetables comparative to drip irrigation by groundwater under the condition of drip irrigation by reclaimed water based on a. field experiment. The results show the variation of peak value of concentration of NH4+-N in topsoil is: drip irrigation by reclaimed water > drip irrigation by 50% reclaimed water > drip irrigation by groundwater, the concentration of NH4+-N is higher at the depth of 0-40 cm with almost no accumulation of NH4+-N below the depth of 40 cm NO3-N presence in soil slightly increases across the entire growth period with irrigation by reclaimed water. Irrigation by reclaimed water increases tomato yield and irrigation water use efficiency, and has an improved taste index indicated by an improved soluble sugar and titratable acidity content of the fruit without any obvious adverse influence on the nutritive indexes such as Vc soluble solid. The shortening of the irrigation period and increase in buried depth of drip irrigation tape are to promote an increase in tomato yield and irrigation water use efficiency to carry out drip irrigation by reclaimed water under the condition of having a shorter irrigation period and a greater depth of drip irrigation tape and to yield a higher rate of water conservation. (C) 2016 Elsevier Ltd. All rights reserved

Assessing methods of identifying open water bodies using Landsat 8 OLI imagery

Remote sensing is an effective technology for monitoring water resources. However, many methods in remote sensing imagery used to identify open bodies of water have often been shown to produce varying water body classification results for the same bodies of water. Therefore, it is necessary to have measures to assess these methods. In this study, we used datasets collected in the field to assess methods for identifying open water bodies using images from the Landsat 8 Operational Land Imager. From this, we clarified the difference in the performance between the use of spectral reflectance images and that of digital number (DN) value images for the classification of water bodies. The results showed that the normalized difference water index (NDWI), calculated using green and near-infrared bands (NDWIGreen/NIR) with reflectance, captured correct control points with an accuracy of greater than 95 % and was therefore the superior method. The result of a comparison in performance in terms of the NDWI between reflectance images and DN value images was consistent with their initial definitions. The NDWI indices calculated by the initial definitions yielded more reasonable results in the classification of water bodies. The optimized threshold, calibrated and validated by 737 field control points, generated water classification results with a higher confidence in this study. We think that it might be better to set the optimized threshold of NDWIGreen/NIR to -0.05 instead of the value of zero used in many studies. However, more optimized thresholds for other regions need to be calibrated and confirmed if data are available. Our results indicated that NDWI methods are more suitable for water body classification than single-band methods when the frequency histogram method is used