Jingshuang Liu

Health risk assessment of heavy metal exposure to street dust in the zinc smelting district, Northeast of China

Heavy metal contamination in the street dust due to metal smelting in the industrial district of Huludao city was investigated. Spatial distribution of Hg, Pb, Cd, Zn and Cu in the street dust was elucidated. Meanwhile, noncancer effect and cancer effect of children and adults due to exposure to the street dust were estimated. The maximum Hg, Pb, Cd, Zn and Cu contents in the street dust are 5.212, 3903, 726.2, 79,869, and 1532 mg kg(-1), and respectively 141, 181, 6724, 1257 and 77.4 times as high as the background values in soil. The trends for Hg, Pb, Cd, Zn and Cu are similar with higher concentrations trending Huludao zinc plant (HZP). The exponential equation fits quite well for the variations of Pb, Cd, Zn and Cu contents with distance from the pollution sources, but not for Hg. The biggest contribution to street dust is atmospheric deposition due to metal smelting, but traffic density makes slight contribution to heavy metal contamination. According to the calculation on Hazard Index (HI), in the case of noncancer effect, the ingestion of dust particles of children and adults in Huludao city appears to be the route of exposure to street dust that results in a higher risk for heavy metals, followed by dermal contact. The inhalation of resuspended particles through the mouth and nose is almost negligible. The inhalation of Hg vapour as the fourth exposure pathway to street dust is accounting for the main exposure. Children are experiencing the potential health risk due to HI for Pb larger than safe level (1) and Cd close to 1. Besides, cancer risk of Cd due to inhalation exposure is low.

Multivariate and geostatistical analyses of the spatial distribution and sources of heavy metals in agricultural soil in Dehui, Northeast China

The characterization of the content and source of heavy metals in soils are necessary to establish quality standards on a regional level and to assess the potential threat of metals to food safety and human health. The surface horizons of 114 agricultural soils in Dehui, a representative agricultural area in the black soil region, Northeast China, were collected and the concentrations of Cr, Ni, Cu, Zn, and Pb were analyzed. The mean values of the heavy metals were 49.7 ± 7.04, 20.8 ± 3.06, 18.9 ± 8.51, 58.9 ± 7.16, and 35.4 ± 9.18 mg kg(-1) for Cr, Ni, Cu, Zn, and Pb, respectively. Anthropic activities caused an enrichment of Cu and Pb in soils. However, metal concentrations in all samples did not exceed the guideline values of Chinese Environmental Quality Standard for Soils. Multivariate and geostatistical analyses suggested that soil Cr, Ni, and Zn had a lithogenic origin. Whereas, the elevated Cu concentrations in the study area were associated with industrial and agronomic practices, and the main sources of Pb were industrial fume, coal burning exhausts, and domestic waste. Source identification of heavy metals in agricultural soil is a basis for undertaking appropriate action to reduce metal inputs.

Optimal strategies for determination of free/extractable and total microcystins in lake sediment

The optimization of analytical procedures for the quantification of free and total microcystins (MCs) in natural sediments was systematically examined based on solvent extraction and Lemieux oxidation. In this optimized analytical procedure, a sequential solvent extraction using 50% (v/v) methanol and EDTA-sodium pyrophosphate was selected as the optimal extraction solvent for free MCs analysis, after which the purified extracts and sediment residuals were applied to the optimized Lemieux oxidation for determination of total MCs in lake sediments. The optimized procedures were shown to be efficient and reliable for the routine analysis of both free and total MCs in lake sediment samples, as indicated by the minimal adverse impact of sediment organic matter on the recovery of free MCs and yield of MMPB (2-methyl-3-methoxy-4-phenylbutyric acid). Finally, the developed procedures were applied to field sediment samples collected from Lake Dianchi during a bloom season and seven of thirty samples showed positive results.

Effects of Wetland Reclamation on Soil Nutrient Losses and Reserves in Sanjiang Plain, Northeast China

The carbon (C), nitrogen (N) and phosphorus (P) variations of a temperate wetland soil under continuous cultivation for 40 yr were determined and evaluated in the Sanjiang Plain, Northeast China. The results showed that the soil organic carbon (SOC) and total nitrogen (TN) contents in each soil layer decreased sharply after cultivation for 2-3 yr, and exhibited minor differences after cultivation for 11 yr, which showed an exponential decline curve with the increase of cultivation years. The reduction rates of carbon and nitrogen reserves were 14.79% and 28.53% yr−1 at the initial reclamation stages of 2-3 yr and then decreased to 2.02-3.08% yr−1 and 1.98-2.93% yr−1 after cultivation for 20 yr, respectively. Soil total phosphorus (TP) reserves decreased within cultivation for 5 yr, and then gradually restored to the initial level after cultivation for 17 yr. Both SOC and TN could be restored slightly when the farmland was left fallow for 8 yr after reclamation for 11 yr, whereas TP had no significant difference. These results demonstrated that wetland cultivation was one of the most important factors influencing on the nutrient fate and reserves in soil, which could lead to the rapid nutrient release and slow restoration through abandon cultivation, therefore protective cultivation techniques preventing nutrients from loss should be immediately established after wetland reclamation.

Effect of long-term cultivation on soil organic carbon fractions and metal distribution in humic and fulvic acid in black soil, Northeast China

Cultivation affects soil organic matter and its fractions. Fulvic acid (FA) and humic acid (HA) make up an important part of soil organic matter, and their binding capacity influences heavy metal behaviour in soil. This research studied changes in soil organic components and the distribution of copper (Cu), lead (Pb), and zinc (Zn) in HA and FA affected by long-term cultivation in black soils. Uncultivated sites and their adjacent cultivated sites (18, 50, and >200 years) were selected. Alkaline sodium hydroxide/pyrophosphate extraction of humic substances and precipitation of HA by acidification were used to separate the HA and FA fractions. Concentrations of Cu, Pb, and Zn in HA and FA were determined. The content of soil organic carbon (C) had decreased by 30% after 200 years of cultivation. Cultivation led to a moderate decrease (38%) in HA and a minor decrease (7%) in FA. The CHA/CFA ratio, which is a humification parameter, decreased from 2.05 in the uncultivated soil to 1.38 in the soil cultivated for 200 years, indicating a lower degree of humification of organic matter in cultivated soils. Of the Na4P2O7 + NaOH-extracted Pb and Zn, 47–60% and 63–76%, respectively, was associated with FA, showing that FA has a high affinity for Pb and Zn. Of the Na4P2O7 + NaOH-extracted Cu, 55% was in the HA fraction. The share of Cu and Zn in the HA fraction decreased with cultivation time, but cultivation did not bring about a systematic change in Pb distribution in humic substances. The results show that cultivation can decrease the humified C content and metals bound to the HA fraction, and suggest that cultivation may potentially increase the mobility of heavy metals.

Exploring the anthropogenic driving forces of China's provincial environmental impacts

Human activities can have dramatic effects on the environment so that evaluating the anthropogenic driving forces is an important issue in the consideration of how humans impact the world. In this paper, ecological footprint (EF) was used as an aggregate index of total human impacts in 31 provinces in mainland China during 2010. The STIRPAT model was employed to analyze the major anthropogenic drivers of EF. The empirical results demonstrate that great disparities of EF exist at the spatial scale. Provinces with the largest total EF are mostly distributed in the populated east coast of China, whereas provinces with the lowest total EF are mostly found in west China. Similar to EF, ecological deficit (ED) is a dominant characteristic of most municipal areas in China. The results of STIRPAT show that population has the largest potential effect on the Chinese environment at the provincial scale, followed by EF intensity, affluence, percentage of gross domestic product (GDP) from the industrial sector, age structure, and per capita land area. Urbanization has negative effects on EF disparities, but it is not an inevitable factor in this case. This study is helpful to recognizing the human effects on environment and helps to facilitate the management of sustainable development across China.

Effects of elevated CO2 concentration and nitrogen supply on biomass and active carbon of freshwater marsh after two growing seasons in Sanjiang Plain, Northeast China.

An experiments were carried out with treatments differing in nitrogen supply (0, 5 and 15 g N/m2) and CO2 levels (350 and 700 micromol/mol) using OTC (open top chamber) equipment to investigate the biomass of Calamagrostis angustifolia and soil active carbon contents after two years. The results showed that elevated CO2 concentration increased the biomass of C. angustifolia and the magnitude of response varied with each growth period. Elevated CO2 concentration has increased aboveground biomass by 16.7% and 17.6% during the jointing and heading periods and only 3.5% and 9.4% during dough and maturity periods. The increases in belowground biomass due to CO2 elevation was 26.5%, 34.0% and 28.7% during the heading, dough and maturity periods, respectively. The responses of biomass to enhanced CO2 concentrations are differed in N levels. Both the increase of aboveground biomass and belowground biomass were greater under high level of N supply (15 g N/m2). Elevated CO2 concentration also increased the allocation of biomass and carbon in root. Under elevated CO2 concentration, the average values of active carbon tended to increase. The increases of soil active soil contents followed the sequence of microbial biomass carbon (10.6%) > dissolved organic carbon (7.5%) > labile oxidable carbon (6.6%) > carbohydrate carbon (4.1%). Stepwise regressions indicated there were significant correlations between the soil active carbon contents and plant biomass. Particularly, microbial biomass carbon, labile oxidable carbon and carbohydrate carbon were found to be correlated with belowground biomass, while dissolved organic carbon has correlation with aboveground biomass. Therefore, increased biomass was regarded as the main driving force for the increase in soil active organic carbon under elevated CO2 concentration.

Seasonal characteristics of Carex lasiocarpa biomass and nutrient accumulation in the typical wetland of Sanjiang Plain, China

Seasonal dynamics of above- and belowground biomass and nutrient characteristics (nitrogen, carbon, and phosphorus) of Carex lasiocarpa were investigated in the typical wetland of Sanjiang Plain, China from May 2007 to September 2008. The results show that the changes of aboveground biomass during the growing season are best described by the twice function curve model, whereas the changes of belowground biomass follow the exponential increase curve model. Both the organic carbon contents in the above- and belowground plant parts show significant positive linear correlations with the growing time, and the coefficients R2 are 0.983 and 0.746, respectively. The carbon accumulations of the above- and belowground plant parts during the growing season show the same dynamics as those of the biomass. However, the nitrogen contents and accumulation in C. lasiocarpa aboveground and belowground parts show exponential increase during the growing season. The dynamics of C. lasiocarpa phosphorus contents follows the twice function curve model, whereas the accumulation of phosphorus shows the linear increase. The ratios of C/N in different parts of C. lasiocarpa fit the negative linear relations with total nitrogen content in the growing season. Moreover, the ratios of C/P in C. lasiocarpa plant also fit the negative linear relations with total phosphorus content. The results show that nitrogen is the primary limiting nutrient for C. lasiocarpa growth as compared with carbon and phosphorus.

Experimental soil-warming effects on carbon processes of typical meadow Calamagrostis angustifolia wetland ecosystem in the Sanjiang Plain, northeast China.

Abstract To examine the effects of soil warming on carbon-accumulation and -release processes in the wetland ecosystem, a field-warming experiment was conducted under flooded and unflooded water conditions in the typical meadow Calamagrostis angustifolia (C. angustifolia) (TMC) wetland in the Sanjiang Plain, northeast China. Warming cables were used to simulate soil warming. Warming caused significant increases in aboveground biomass compared with belowground biomass during the growing season, and the enhancement of aboveground biomass increased with plant growth while belowground biomass showed an opposite effect. Significant positive correlation was found between aboveground biomass and 10–20-cm soil content whereas belowground biomass was more significantly correlated with 0–10-cm soil content. Positive linear correlations were found between CO2 and CH4 fluxes and warming-induced changes in liable carbon (LBC) and carbohydrate carbon (CHC) contents. Flooded water conditions tended to increase the accumulation of belowground biomass, content and CH4 fluxes under warming treatment. Soil warming could not only stimulate the carbon-accumulation and -release processes in the TMC wetland ecosystem directly, but also indirectly through the enhancement of nitrogen availability and active carbon contents. The contents of and active carbon could be sensitive indicators for the carbon-process changes in wetland ecosystems under soil warming.

Pollution assessment of organochlorine pesticides in urban agricultural soils of Jilin City, China

ABSTRACT The content, source, and pollution level of organochlorine pesticides (OCPs) in soils are necessary to assess potential risks to eco-environment and human health, and to target environment-friendly policies. A total of 50 surface soil samples were collected from urban vegetable fields of Jilin City and thirteen OCPs were analyzed. The concentrations were in the ranges of 3.16–48.35 ng·g−1 for Dichloro-Diphenyl-Tricgloroethanes (DDTs, sum of o, p′-DDT, p, p′-DDT, p, p′-DDD, and p, p′-DDE), 4.37–44.77 ng·g−1 for Hexachlorocyclohexanes (HCHs, sum of α-HCH, β-HCH, γ-HCH, and δ-HCH), 1.19–13.17 ng·g−1 for Chlordanes (sum of heptachlor, t-chlordane, and c-chlordane), 0.24–2.60 ng·g−1 for aldrin, and nd–3.43 ng·g−1 for dieldrin, respectively. The different compositions indicated that the residues of DDTs and HCHs originated mainly from the historical application, while chlordanes were mostly from recent input. On the basis of soil quality standards of China and the Netherlands, DDTs and chlordanes in this study were categorized as light pollution, and HCHs were classified as no pollution for the majority of soil samples. There are a variety of OCPs residues in urban vegetable soils of Jilin City, but it is still safe and suitable for agricultural production.