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This study was designed to investigate organophosphorus pesticides (OPs) concentrations in fresh vegetables and estimate potential health risks to inhabitants. A total of 214 samples of seven types of vegetables were collected from Changchun, the capital of Jilin province, one of the most important vegetable production areas. The eleven OPs were analyzed by gas chromatography coupled with flame photometric detector (GC-FPD). Results showed that 23.4% of samples contained OPs above maximum residue limit (MRL), 68.7% of samples below MRL and only 7.9% of samples were found free of OPs. Detection rates of OPs decreased in the following order: diazinon (82.2%) > phorate (45.8%) > dimethoate (29.4%) > parathion-methyl (27.6%) > omethoate (23.8%) > dichlorvos (22.9%) > fenitrothion (21%) > fenthion (18.7%) > parathion (18.2%) > methamidophos (17.3%) > malathion (12.1%). The OPs levels were higher for leafy than for non-leafy vegetables. The percentages of OPs above MRL: welsh onion (82.5%) > radish (37.5%) > pepper (17.2%) > Chinese cabbage (14.3%) > cucumber (3.2%) > eggplant (2.9%) > tomato (0%). 49.5% samples contained two or more OPs. The average target hazard quotients (ave THQ) were all less than one and the average Hazard Index (ave HI) for adults and children were 0.448 and 0.343, respectively. It is concluded that inhabitants who are exposed to average OPs levels may not be endangered by health risk.

The aim of this study was to investigate organophosphorus pesticides (OPs) concentrations in rice grains and estimate potential health risk to inhabitants. A total of 102 rice samples were collected from the Irrigated Area of Songhua River, located in Jilin province, one of the most important rice production areas and a key agricultural area in China. The twelve OPs were determined by gas chromatography coupled with flame photometric detector. Results showed that OPs concentrations in rice grains did not exceed maximum residue limit. The mean concentrations obtained for the detected twelve OPs in µg kg−1 were as follows: omethoate (0.60), diazinon (0.56), parathion-methyl (0.54), dimethoate (0.38), isocarbophos (0.38), phorate (0.31), fenitrothion (0.24), parathion (0.23), fenthion (0.23), malathion (0.13), dichlorvos (0.13), and methamidophos (0.08). Diazinon (39.2%), omethoate (31.4%), and parathion-methyl (25.5%) had the highest frequency in the detected twelve OPs. 69.6% of samples contained m...

Due to rapid industrialization and urbanization during the last two decades, contamination of urban agricultural soils by heavy metals is on an increase all over China. In this study, fifty soil samples were collected from urban vegetable fields in a chemical industrial area and non chemical industrial area in Jilin City to investigate the heavy metal pollution level. The mean Pb, Cr, Cu, Ni, Zn, and Cd contents (30.84, 65.65, 26.41, 23.07, 135.14, and 0.1434 mg kg−1 dry weight, respectively) in the urban vegetable soils were higher than their corresponding natural background values. The principal component analysis (PCA) was performed to identify the possible sources of metal contamination in the study area. The results indicated that Cu and Zn were mainly from industrial activities, while Pb and Cd were derived from traffic activities and agricultural activities, and Cr and Ni tended to be from parent material. The distribution of comprehensive pollution index values showed that Pb, Cr, Cu, Ni, ...

Labile soil organic carbon pools are widely regarded as valuable indicators of changes in soil C sequestration pools and dynamics induced by different soil management practices. The objective of this study was to evaluate how a new conservational agricultural management (NCAM), which has been proved to be an effective pattern to increase corn yield, affects soil organic C (SOC) and labile SOC pools after a 9-year experiment in Northeast China. Narrow-wide row (1.70 m wide row and 0.30 m narrow row, corn is sowed in the narrow row with two lines), no-till, residue retention, change of ridge direction, and fallow are adopted for NCAM. Soil under conventional agricultural management (CAM) was also studied to be as a comparison. Soil samples were taken from 0–20 to 20–40 cm depths. The results showed that no significant difference was found for SOC between the two managements for both depths, indicating that SOC is a too gross measurement. Soil labile organic C fractions: microbial biomass C, hot-water extractable organic C and permanganate oxidizable C (KMnO 4 –C) contents were significantly higher under NCAM compared to CAM for both depths, reflecting the build-up of labile C pools under NCAM. In addition, of the three C fractions, KMnO 4 –C was the most sensitive indicator of changes in SOC induced by different agricultural management regimes. Our results implied that the application of NCAM is important to soil C sequestration and improving soil quality.

Given the importance in soil C cycling, changes in the composition of hot-water extractable organic matter (HWEOM) due to the land use conversion are less known. The purposes of this study were to elucidate the structural characteristics of HWEOM from soils collected from a native wetland and five croplands which originated from the wetlands by conversions for 3, 8, 16, 22, and 24 years, and to relate the structural characteristics to soil enzyme properties. We examined the structural characteristics of HWEOM by UV absorption and fluorescence. The values of specific absorption at 254 nm, humification index and fluorescence efficiency index of HWEOM showed a tendency to increase initially compared to the values of wetland (the highest value was found in the cropland with cultivation-time of 16 years), and then the values tended to decline with time. Soil β-glucosidase and N -acetyl-β-glucosaminidase activities were negatively affected by the structural characteristics of soil HWEOM. Our results indicate that the HWEOM from the croplands contained more highly condensed aromatic compounds, and were less mobile than that from the native wetland. Furthermore, the stabilities of HWEOM in the croplands with short/long cultivated-time were different.

Three primary marsh types including Calamagrostis angustifolia marsh, Carex lasiocarpa marsh and Carex meyeriana marsh and the arables land reclaimed in different years were selected as studying objects, and the total sulfur in these soils were analyzed. The results indicated that the mean total sulfur was 622.4 mg.kg-1 in Calamagrostis angustifolia marsh soils, 820.5 mg.kg-1 in Carex meyerianan marsh soils, and 1,022.4 mg.kg-1 in Carex lasiocarpa marsh soils. Naoli River, Bielahong River, Yalu River and Nongjiang River are the four typical rivers in Sanjiang Plain. The mean total sulfur was 925 mg.kg-1 in Naoli Valley soils, 708.6 mg.kg-1 in Bielahong Valley soils, 841.8 mg.kg-1 in Yalu Valley, and 636.5 mg.kg-1 in Nongjiang Valley. The total sulfur in both marshes and arable soils presented distinct regularity, namely it gradually decreased from surface soil to botteom. The average total sulfur in the arable land reclaimed between 1980 and 2000 was 180.5 mg.kg-1, and it was 735.8 mg.kg-1 in natural marsh soils. So the total sulfur in arable land was remarkably lower than that in the marshes, and the reclamation could result in sulfur loss.