Jilin City Research Articles

First report of Mycoplasma hyopneumoniae seroprevalence in farmed wild boars in China

Porcine enzootic pneumonia caused by Mycoplasma hyopneumoniae affects the global pig industry with significant economic losses. It is yet to know whether wild boars in China were infected with M. hyopneumoniae. The present study was conducted to examine the seroprevalence and to evaluate risk factors of M. hyopneumoniae infection in farmed wild boars in China. A total of 882 serum samples were collected from farmed wild boars in Jilin City, Siping City and Baishan City in Jilin Province, northeastern China from April 2015 to February 2016, and were examined by the double sandwich enzyme-linked immunosorbent assay (ELISA). Seventy-eight out of 882 (8.8%) serum samples were M. hyopneumoniae-seropositive. Among region groups, wild boars from Jilin city (11.7%, 33/281) had the highest seropositivity, followed by Siping city (11%, 29/263) and Baishan city (4.7%, 16/338), and the difference was statistically significant (P = 0.0031). The M. hyopneumoniae seroprevalence in the female wild boars (9.0%, 75/831) was higher than that in the male wild boars (5.9%, 3/51) (P = 0.4429). The results of this investigation showed that farmed wild boars were susceptible to M. hyopneumoniae. Logistic regression analysis showed that there is a significant correlation between the geographical area and M. hyopneumoniae infection, which may be related to the regional environment. This is the first report of M. hyopneumoniae seroprevalence in farmed wild boars in China, which provided baseline information for further studies and control of M. hyopneumoniae infection in wild boars in China.

Comprehensive assessment of groundwater pollution risk based on HVF model: A case study in Jilin City of northeast China

A comprehensive model for groundwater risk assessment was proposed by combining the hazard of contaminated sources (H), groundwater intrinsic vulnerability (V) and groundwater function value (F), and verified in Jilin City of northeast China. This model is characterized by integrating groundwater resource, ecology, and geological environment under the impact of climate change and human activities. The hazard of potential polluted sources was assessed by quantifying the properties and the potential infiltrating load of contaminants. The groundwater intrinsic vulnerability was evaluated by the DRASTIC model. The groundwater function value was assessed by multiplying seventeen indexes with their corresponding weightings. The groundwater pollution risk mapping of Jilin City was generated based on ArcGIS and validated by the level difference method between the risk classification and the pollution classification. The results showed that groundwater has a relatively low possibility of pollution because the area with less than, or equal to, the medium classification of risk accounted for 67.61% of the study area. The hazard harmfulness from the different contaminant sources played the most important role in determining the high groundwater pollution risk areas. Different influencing factors lead to relatively high pollution risk in specific areas. According to the validation of the level difference method, areas correctly identified by groundwater pollution risk mapping accounted for 95.81% of the study area, which is nearly twice as high as that of specific vulnerability mapping. The HVF model proved to be suitable for assessing groundwater pollution risk in Jilin City of northeast China. The groundwater pollution risk mapping can be applied for the effective protection and sustainable supply of groundwater.

Spatial and temporal distribution of forest fire frequency and forest area burnt in Jilin Province, Northeast China

Forest fires caused by natural forces or human activities are one of the major natural risks in Northeast China. The incidence and spatial distribution of these fires vary over time and across the forested areas in Jilin Province, Northeast China. In this study, the incidence and distribution of 6519 forest fires from 1969 to 2013 in the province were investigated. The results indicated that the spatiotemporal distribution of the burnt forest area and the fire frequency varied significantly by month, year, and region. Fire occurrence displayed notable temporal patterns in the years after forest fire prevention measures were strictly implemented by the provincial government. Generally, forest fires in Jilin occurred in months when stubble and straw were burned and human activities were intense during traditional Chinese festivals. Baishan city, Jilin city, and Yanbian were defined as fire-prone regions for their high fire frequency. Yanbian had the highest frequency, and the fires tended to be large with the highest burned area per fire. Yanbian should thus be listed as the key target area by the fire management agency in Jilin Province for better fire prevention.

Cold Wave Climate Characteristics and Risk Zoning in Jilin Province

Using the meteorological data of 50 stations in Jilin Province from 1961 to 2016, the demographic and economic data, and geographical information of all counties and cities aims to conduct the risk zoning of cold wave disasters in Jilin Province. The results show that, since 1961, the average number of cold wave occurrences per year in Jilin Province is 8.3 days, of which the highest number of occurrences occurred in February, followed by December and January, and the spring cold wave occurred mostly in March. From the map of cold-sea disaster risk zoning in Jilin Province, due to factors such as topography and land use distribution, the west and east of Jilin Province have a certain resilience to the disasters caused by cold waves, and the risk of disasters is low. The distribution of agricultural facilities and large areas of farmland in the central region are extremely sensitive to cold wave disasters and have a high risk of disasters. Areas with high risk of cold wave are mainly concentrated in Siping City, Changchun City, Liaoyuan City, Jilin City, northern Tonghua City and most of Baishan City. Areas with low cold wave risk are mainly concentrated in most of Baicheng City, most of Songyuan City and Yanbian Prefecture. And other places are moderately risky areas of cold waves.

Spatial differences of Chinese material medicine resources species in Jilin province

The differences in the spatial distribution of regional Chinese material medicine resources between regions are determined by differences in natural conditions and social resources among different regions. Spatiotemporal evolution of the distribution of Chinese material medicine resources is a manifestation of the development process of Chinese medicine industry in time and space. The spatiotemporal evolution of the distribution of regional Chinese material medicine resources can reveal the regularity of spatial distribution of Chinese material medicine resources. County as the basic unit of the national material medicine resources census, the difference of resource endowment is of great significance to the rational development of Chinese material medicine resources policy and the coordinated development of regional resources and environment. Based on the results of the pilot project of Jilin province, this study selected 51 counties that had completed the census of Chinese material medicine resources. According to the species of Chinese material medicine resources, we explored the diversity of Chinese material medicine resources in Jilin province by using statistical data analysis (ESDA), trend surface analysis and spatial variability function to analyze the spatial differences of Chinese material medicine resources. Chinese material medicine resources are distributed in the eastern and southeastern part of Jilin province, mostly in the Changbai Mountains. The species of Chinese material medicine resources tend to be low-value spatial aggregation; the overall cold spots are located in Changchun and Jilin city, near the administrative center, mostly urban built-up area. The rich areas of Chinese material medicine resources are rich in hot spots, mainly in broad-leaved forest. The low-abundance of Chinese material medicine resources is dominated by cultivated vegetation.

An Investigation on the Current Situation of Sexual Education in Urban Junior High School Students in Jilin City

This study is to understand the status quo of sexual physiology, sexual psychology, sexual attitudes and acceptability of sexual education of urban junior high school students in Jilin City, and to analyze the potential causes, so as to provide references for juvenile sexual health education. A random stratified cluster sampling method was used to extract 500 students in four middle schools. A questionnaire survey was conducted, and analyzed by SDS scale. It is relatively late to acquire sex knowledge; the level of sexual knowledge is relatively low; the way of sexual knowledge acquisition is based on the network media; self-protection consciousness is strong; awareness of adverse effect of puppy love is not enough; sexual concept is more open. The urban junior middle school students in Jilin City have a certain degree of sexual knowledge, but the degree of sexual education is low, the timming to accept sexual education is late, sexual attitude is relatively open, sexual education is less popular, and lack of professional education personnel and way.

Effects of dam reconstruction on thermal-ice regime of Fengman Reservoir

A laterally-averaged 2D water temperature model coupled with an ice cover module was used to investigate the influences of the Fengman Dam reconstruction on its thermal regime. Variations of the thermal-ice regime and outflow temperature under typical hydro-metrological conditions were simulated and validated with field data. Due to the partial dismantling of the old dam after the reconstruction, the intake water is primarily taken from the surface layer of the reservoir. As a result, the total heat storage of the reservoir throughout the year and the outflow temperature from January to March will decrease. Furthermore, the low outflow temperature in the winter will result in a decline of the downstream water temperature and negatively impact the rime scenery near Jilin City. In order to increase the outflow temperature in winter, an operation scheme that combined the new intake with the old intake of the III-phase project of old dam was discussed. The results indicated that this scheme could increase the outflow temperature to ensure a 70km open channel in the downstream river in a typical winter, and eliminated the negative effects on the rime scenery.

Plants Selection for Domestic Sewage Treatment in Jilin City

This experiment studied the removal efficiency of domestic sewage by testing 19 species of wetland plants along the Songhua River in Jilin City. It is shown that plants can purify domestic sewage, and the ability of removal efficiency is varied on different species. Rumex patientia var.callosus is the best in removal efficiency of TN(29.14%);Coleus blumei Benth. could effectively reduce output of TP and COD,the best removal efficiencies for TP is 58.04%, COD is 95.18%; Oenanthe javanica(Blume) DC. has better efficiency to increase DO in´sewage, and the maximum increase is 262.22%;Rumex.patientia var.callosus,Alisma orientale(Sam.)Juz.,Oenanthe javanica(Blume) DC.,Erigeron annuus (L. ) Pers. may be used as plants for the construction of sewage treatment landscape, because these plants have better comprehensive capacity for domestic sewage treatment.
 Water pollution has become a general and worldwide problem today. The application of wetland plants for waste water treatment features low cost,easiness to manage, high efficiency and etc.(Han Xiaoyuan etc.,2005;Li linfeng etc.,2006;Zhang Honggang,Hong Jianming,2006).Wetland plants can not only absorb nitrogen and phosphorus directly but also remove the heavy metals and organics in the waste water. (Xu Weiwei etc.,2005;Cheng Wei etc.,2005;C.C.Tanner,2001;Tang Shirong,2006;SAMAKEMoussa,2003;L.K.Mitchell,A.D Karathanasis,1995).According to current research reports,Phragmitas communis Trin, Juncus effuses Linn, Rush, and Iris japonica Thunb, Buttery Swordflag can efficiently remove nitrogen and phosphorus from the sewage (Deng Futang etc.,2005;Yuan Donghai etc.,2004;A. Fey,G. Benckiser,J.C.G. Ottow,1999).The constructed wetlands consisting of varied plants,such as Phragmitas communis Trin,Canna indica Linn. or Acorus gramineus Soland,Grassleaved Sweetflag,are effective in eliminating chemical oxygen demand(“COD”) in the waste water(Zhao Jiangang etc.,2006;Zhong Yushu etc.,2006;Yuan Donghai etc.,2004).Therefore wetlands can be used to reduce water pollution(Weng Meiya etc.,2005;Liu Zilian etc.,2005;Robert M. Seams,1995).So far most current studies have been developed in the South China with few in the Northeast area of China. 19 kinds of wetland plants growing along the Songhua River is selected in Jinlin City. We analyze and decide which plants are suitable for plant landscape application due to their better urban sewage treatment functions.

Study of atmospheric CO2 and CH4 at Longfengshan WMO/GAW regional station: The variations, trends, influence of local sources/sinks, and transport

Atmospheric CO2 and CH4 have been continuously measured since 2009 at Longfengshan WMO/GAW station (LFS) in China. Variations of the mole fractions, influence of long-distance transport, effects of local sources/sinks and the characteristics of synoptic scale variations have been studied based on the records from 2009 to 2013. Both the CO2 and CH4 mole fractions display increasing trends in the last five years, with growth rates of 3.1±0.02 ppm yr‒1 for CO2 and 8±0.04 ppb yr‒1 (standard error, 1-σ) for CH4. In summer, the regional CO2 mole fractions are apparently lower than the Marine Boundary Layer reference, with the lowest value of‒13.6±0.7 ppm in July, while the CH4 values are higher than the MBL reference, with the maximum of 139±6 ppb. From 9 to 17 (Local time, LT) in summer, the atmospheric CO2 mole fractions at 10 m a.g.l. are always lower than at 80 m, with a mean difference of‒1.1±0.2 ppm, indicating that the flask sampling approach deployed may underestimate the background mole fractions in summer. In winter, anthropogenic emissions dominate the regional CO2 and CH4 mole fractions. Cluster analysis of backward trajectories shows that atmospheric CO2 and CH4 at LFS are influenced by anthropogenic emissions from the southwest (Changchun and Jilin city) all year. The synoptic scale variations indicate that the northeastern China plain acts as an important source of atmospheric CO2 and CH4 in winter.

Toxoplasma gondii Infection in Farmed Wild Boars (Sus scrofa) in Three Cities of Northeast China.

The apicomplexan protozoan parasite Toxoplasma gondii is a widely distributed etiological agent of foodborne illness. This parasite can cause production losses in livestock and serious disease in humans through consumption of contaminated meat. Pig meat is the most likely source of human infection, and wild boars may play a role in the transmission of T. gondii by serving as a reservoir host. This study aimed to investigate the seroprevalence of antibodies to T. gondii among farmed wild boars in China. In an 11-month survey, a total of 882 serum samples were obtained from farmed wild boars from three cities (Jilin City, Siping City, and Baishan City) in Jilin province, Northeast China and were tested for antibodies specific for T. gondii. Using modified agglutination test and a cutoff titer of 1:25, the prevalence of T. gondii infection in the examined samples was 10.0% (88 of 882). The highest seroprevalence was observed in animals from Jilin city (15.3%, 43/281) and followed by Siping (11.4%, 30/263) and Baishan (4.4%, 15/338). Logistic regression analysis revealed a significant correlation between the investigated geographic region and T. gondii infection. In addition, prevalence was higher in females compared to males, and the highest prevalence was detected in piglets. These findings indicate that farmed wild boars may become a source of foodborne toxoplasmosis, posing a food safety threat to the public health in the investigated areas. Implementation of effective measures to control T. gondii infection in farmed wild boars in China may be warranted.

Groundwater depth predictions by GSM, RBF, and ANFIS models: a comparative assessment

The potential of grey self-memory model (GSM), radial basis function network (RBF), and adaptive neuro fuzzy inference system (ANFIS) models in forecasting groundwater depths over an unconfined aquifer was compared. GSM, RBF, and ANFIS modeling was carried out at five sites in Jilin City, northeastern China, considering the influential lags of monthly groundwater depth as the inputs. The performance of the models was evaluated using criteria standards (R, RMSE, MARE, NS) and graphical indicators. Results indicate that the performance of all models was satisfactory in the region which lack of hydro-meteorological data. Comparison of the goodness-of-fit statistics in the research indicated that ANFIS was the better technique than the other two at all the sites except for J21, and GSM(1,1) was the worst model at all the sites. However, considering the practical advantages of GSM(1,1) technique, it was recommended as an alternative and cost-effective groundwater modeling tool. Meanwhile, it was found that the modeling prediction for the well with the stable and evenly distributed data series has more accurate fitting results, generally.

PCDD/Fs distribution characteristics and health risk assessment in fly ash discharged from MSWIs in China

This study provided distribution and health risk information of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in fly ash from 4 municipal solid waste incinerators (MSWIs) in four seasons from four sites, including Zhengzhou City in Henan Province, Chuzhou City in Anhui Province, Jilin City in Jilin Province and Zibo City in Shandong Province. The toxic equivalent concentration (I-TEQ) values of PCDD/Fs ranged from 0.0707 to 0.7742ng I-TEQ/g, and no identical sequence occurred during four seasons in different sampling sites. The stabilization process might efficiently reduce the content and toxicology of PCDD/Fs in fly ash. The value of PCDD/PCDF in fly ash ranged from 0.145 to 0.787 after solidification. The characteristic index (DCI) of 2,3,4,7,8-P5CDF was 0.803 with 6.6% under 95% probability for fly ash samples discharged from MSWIs. The 95th percentile carcinogenic risks (CRs) for onsite workers were lower than the threshold value (10−5), suggesting that the cancer risk levels of PCDD/Fs in fly ash for onsite workers were acceptable. The 95th percentile non-carcinogenic risks (non-CRs) for onsite workers were lower than 1, suggesting no obvious non-carcinogenic effect was developed for onsite workers. This paper provide an overview information on the distribution of PCDD/Fs in fly ash during four seasons, and it could be used as an important fingerprint to distinguish the fly ash sources. Thus, the research could provide basic information for fly ash management in environment.

Feasibility study of in-situ bioremediation for nitrobenzene-contaminated groundwater

Although many studies have simulated in-situ bioremediation of contaminated groundwater, most of them have not considered hydrochemical conditions and indigenous microorganisms, thus potentially rendering results inapplicable to actual in-situ groundwater bioremediation projects. This study focused on a nitrobenzene-contaminated groundwater site located in Jilin City, China. The actual nitrobenzene-contaminated groundwater was taken from Jilin City to simulate in-situ groundwater bioremediation in the laboratory. The feasibility of in-situ bioremediation for nitrobenzene-contaminated groundwater was studied according to actual site conditions and characteristics of nitrobenzene-degrading microorganisms in groundwater. The results showed that nitrobenzene-degrading bacterium strain NB1 was the dominant species that could effectively and rapidly degrade nitrobenzene by a partial reductive pathway. No negative factors on the growth or degrading function of this strain in groundwater could be detected. During a laboratory simulation experiment, combined in-situ bioremediation technologies, namely air sparging and bioaugmentation, could readily remove approximately 89.56% of nitrobenzene from groundwater without adding nutrients; oxygen was found to be the important growth factor for strain NB1. As the substrate of nitroreductase, encoded by the nitrobenzene nitroreductase (nbzA) gene, nitrobenzene was likely to significantly affect the expression of this gene. In conclusion, in-situ bioremediation is a feasible way to solve the problem of nitrobenzene-contaminated groundwater in Jilin City as long as sufficient oxygen and biomass of strain NB1 is ensured.

A study on the relationship between medical students' social adaptability and their family education

Objective To understand the situation of medical students' social adaptability and analyze its relationship with their family upbringing style. Methods A cross-sectional study was adopted, and the random sampling method was used to selected medical students as targeted population in a medical university in Jilin City. Parenting Style Assessment Scale and Social Adaptation Diagnostic Scale were applied to know the family rearing styles and social adaptability status of medical college students. Results Among the 198 responders, the proportion of good and strong social adaptability among medical college studies accounted for only 8.1% (16) and 2.0% (4); The social adaptation ability of the urban students and the only child students was higher than that of the rural and non only child students (P<0.05); In parental rearing patterns, regardless of sex, whether students were the only child and where their census register was, emotional warmth and understanding were all positively correlated with medical students' social adaptation ability(P<0.05), while refusal and denial were negatively correlated with medical students' social adaptation ability (P<0.05); In addition, the severe over protection and other parenting styles also showed a certain degree of negative correlation with social adaptability(P<0.05). Conclusion The social adaptability of medical students is poor, and their parenting styles was correlated with their social adaptation ability. Parents should give their children warmth and understanding, rather than rejection, denial, punishment, and overprotection, which will help to improve medical students' social adaptability. Key words: Medical students; Family rearing patterns; Social adaptability

Profiles of lead in urban dust and the effect of the distance to multi-industry in an old heavy industry city in China

Lead (Pb) concentration in urban dust is often higher than background concentrations and can result in a wide range of health risks to local communities. To understand Pb distribution in urban dust and how multi-industrial activity affects Pb concentration, 21 sampling sites within the heavy industry city of Jilin, China, were analyzed for Pb concentration. Pb concentrations of all 21 urban dust samples from the Jilin City Center were higher than the background concentration for soil in Jilin Province. The analyses show that distance to industry is an important parameter determining health risks associated with Pb in urban dust. The Pb concentration showed an exponential decrease, with increasing distance from industry. Both maximum likelihood estimation and Bayesian analysis were used to estimate the exponential relationship between Pb concentration and distance to multi-industry areas. We found that Bayesian analysis was a better method with less uncertainty for estimating Pb dust concentrations based on their distance to multi-industry, and this approach is recommended for further study.

Treatment of necrotizing acute pancreatitis with peritoneal lavage and dialysis by a new simplified technique insert catheters: One retrospective study.

Peritoneal lavage and dialysis is an approach to treat necrotizing acute pancreatitis as it removes dialyzable toxins and reduces severe metabolic disturbances. Successful catheter implantation is important for delivering adequate peritoneal lavage and dialysis. The aim of the present study was to describe a new modified percutaneous technique for the placement of peritoneal dialysis catheters and assess the effectiveness and safety of peritoneal lavage and dialysis used for treatment of necrotizing acute pancreatitis. We conducted a retrospective data review of 35 patients of necrotizing acute pancreatitis from January 2010 to December 2014 in Jilin City Central Hospital and The First Affiliated Hospital of ZheJiang University. In total, 18 patients underwent peritoneal lavage and dialysis after inserting catheters by our new technique (group A), whereas 17 patients underwent ultrasound-guided percutaneous catheter drainage (group B). By analyzing the patients’ data, the drainage days and mean number of hours between the debut of the symptoms and the hospital admission were lower in group A (P < 0.05, P < 0.05, respectively). The complication rate of 5.6 and 17.6%, respectively (P = 0.261), and a mortality rate of 16.7 and 5.9% for each group, respectively (P = 0.316). Likewise, hospitalization time was similar for the group A: 31 ± 25.3 days compared with 42.8 ± 29.4 days in the group B (P = 0.211). Peritoneal lavage and dialysis can be used in necrotizing acute pancreatitis, and our new modified percutaneous technique offers the same complication and mortality rate as ultrasound-guided drainage but with a shorter drainage days.

Hydrogeochemistry characteristics of groundwater and its suitability for water supply and irrigation in Jilin City, China

Groundwater is the most important water resources in modern water supply, and its quality is the determining factor, especially for the groundwater supply under extreme events. Groundwater quality survey has been carried out in Jilin City, which is a famous industrial city in northeast China. The results show that (1) the distribution of major ions in the groundwater is as follows: Ca2+ > Mg2+ > Na+ > K+ and HCO3− > SO4 2− > Cl− > NO3−; the Piper’s, Gibbs’s, and Langelier–Ludwig’s diagrams suggest that groundwater was evolved due to the water–rock interaction; (2) geochemical relations (Ca/Mg ratio, Ca + Mg versus HCO3 + SO4, Na versus Cl) suggest that the dissolution of carbonate minerals gypsum and halite is the significant mechanism dominating the groundwater chemistry, the relations also suggest that the ion exchange is the secondary processes for higher concentrations of Ca2+ and Mg2+ ions; (3) the influences of agricultural fertilizers and irrigation practice are the other reasons for increasing NO3 − ions in the groundwater; according to the drinking water quality standards, the groundwater is not suitable for drinking with reference to the concentrations of total hardness, Ca2+, Mg2+, NO3 −, F−, and Fe in many locations; (4) based on the parameters mentioned (sodium adsorption ratio, Kelly’s ratio, sodium percent, permeability index, and magnesium hazard), the groundwater quality is assessed and the overall irrigation qualities of wells are demarcated as suitable for irrigation.

Spatio-temporal variation of groundwater contamination using IEA-UEF in urban areas of Jilin City, North-eastern China

Groundwater monitoring wells located in urban areas of Jilin City were sampled from 1980 to 2009 for eight groundwater quality parameters: pH, SO42−, Cl−, NO3−-N, NO2− -N, NH4+-N, F−, and total hardness (TH). The data were analysed by a universal exponential formula based on an immune evolutionary algorithm, and later mapped with the Kriging interpolation method. The primary objectives were to assess the main parameters that influenced groundwater quality and the spatio-temporal variability of groundwater contamination over several years. The results showed that NO3−, NH4+, and TH were the main parameters that influenced groundwater quality. Spatially, groundwater was polluted in all urban areas to varying degrees, and the Jiangbei district was the most heavily polluted location. Temporally, the groundwater contamination status could generally be classified into four stages and showed the following pattern during 1980–2009: heavy – light – heavy – light.

Sedimentary record of polycyclic aromatic hydrocarbons in Songhua River, China

Concentrations of polycyclic aromatic hydrocarbons (PAHs) were determined in surface sediments and one dated sediment core from the Songhua River, Northeast China. The total concentration of 15 PAHs (16 priority pollutants designed by the United States Environmental Protection Agency minus naphthalene) in the surface sediments ranged from 16 to 421 ng/g dry weight. An evaluation of PAH sources based on diagnostic ratios suggested that PAHs in the most surface sediments were mainly derived from biomass and coal combustion, with the exception of those from Jilin City, where both petroleum contamination and combustion were possible sources of PAHs. A historical record of PAH contamination was reconstructed using a 210Pb and 137Cs dated sediment core from a backwater zone of the river. The characteristic changes in concentrations, fluxes and patterns of 15 PAHs over the past 75 years were captured in detail. Two increases in PAH fluxes were observed during the period from the early 1930s to the mid 1960s, and from the mid 1970s and the mid 1990s. The increases were attributed to the several wars (1937–1953) and reconstruction of new China (1949–1965) and the implementation of the Reform and Open Policy since 1978. Two declines in PAH fluxes were also observed from the mid 1960s to the mid 1970s and from the mid 1990s to the present. The decreases were attributed to the Great Cultural Revolution (1966–1976) and the implementation of some pollution reduction measures since the 1990s. This study is the first attempt to provide information on the sedimentary record of PAHs in the Songhua River.

Quantitative evaluation of specific vulnerability to nitrate for groundwater resource protection based on process-based simulation model

It has been proved that groundwater vulnerability assessment is an effective tool for groundwater protection. Nowadays, quantitative assessment methods for specific vulnerability are scarce due to limited cognition of complicated contaminant fate and transport processes in the groundwater system. In this paper, process-based simulation model for specific vulnerability to nitrate using 1D flow and solute transport model in the unsaturated vadose zone is presented for groundwater resource protection. For this case study in Jilin City of northeast China, rate constants of denitrification and nitrification as well as adsorption constants of ammonium and nitrate in the vadose zone were acquired by laboratory experiments. The transfer time at the groundwater table t50 was taken as the specific vulnerability indicator. Finally, overall vulnerability was assessed by establishing the relationship between groundwater net recharge, layer thickness and t50. The results suggested that the most vulnerable regions of Jilin City were mainly distributed in the floodplain of Songhua River and Mangniu River. The least vulnerable areas mostly appear in the second terrace and back of the first terrace. The overall area of low, relatively low and moderate vulnerability accounted for 76% of the study area, suggesting the relatively low possibility of suffering nitrate contamination. In addition, the sensitivity analysis showed that the most sensitive factors of specific vulnerability in the vadose zone included the groundwater net recharge rate, physical properties of soil medium and rate constants of nitrate denitrification. By validating the suitability of the process-based simulation model for specific vulnerability and comparing with index-based method by a group of integrated indicators, more realistic and accurate specific vulnerability mapping could be acquired by the process-based simulation model acquiring. In addition, the advantages, disadvantages, constraint conditions and applying prospects of the quantitative approach for specific vulnerability assessment were discussed.