Probabilistic human health-risk assessment and influencing factors of aromatic hydrocarbon in groundwater near urban industrial complexes in Northeast China.

Organic pollutants are common in the environment, very difficult to remove, and pose a serious threat to human health. Probabilistic risk assessment advances conservative single-point estimation and brings a new perspective to risk assessment. From 2009 to 2019, we monitored the distribution of major pollutants in an industrial park in Northeastern China. The result showed the maximum concentration of benzene reached 73,680 µg/L in 2009, benzo[a]pyrene reached 36.80 ng/L in 2016. These concentrations are significantly above the levels set by Chinese regulatory agencies. The single-factor index increases year by year, and pollutants gradually spread from the pollution leakage source to surrounding areas. A new method was used to quantify the human health risk from groundwater organic pollution accurately, based on the triangular fuzzy numbers coupled with the Monte Carlo simulation. The Monte Carlo simulation was used to simulate the triangular fuzzy numbers. This simplified the operation between the triangular fuzzy numbers and their function successfully and obtained the risk as a set of values. The results indicated that non-carcinogenic risk was negligible in all age groups (children, adolescents, and adults). Conversely, when it comes to carcinogenic risks, adults were about 50-270 times the tolerable level of risk due to long exposure years and wide skin contact areas. Oral ingestion played an essential role in total exposure (>90%) compared to dermal contact. Control of exposure duration and intake should be prioritized when making decisions to reduce risk uncertainty. Monte Carlo simulation-triangular fuzzy numbers can effectively reduce the risk of uncertainty and reflect the complex conditions of the groundwater environment for small amounts of data or inaccurate data.

Hydrochemical appraisal of groundwater quality and pollution source analysis of oil field area: a case study in Daqing City, China.

Serious groundwater pollution not only affects the development of enterprises but also threatens the life and health of residents. To explore the utilization potential of shallow groundwater and the status of water quality pollution in Daqing city, factor analysis and Kriging spatial interpolation methods were applied to analyze the spatial distribution characteristics of pollution sources. The results showed that the HCO3-Ca + Mg type water with a maximum salinity of 1.5 g/L was the main chemical type of shallow groundwater in this area. Based on the Fe pollution index, the shallow underground water quality in the northeast of Daqing city can be used for drinking. Due to higher salinity, the locations of the availability of groundwater for irrigation only were in the west. Multivariate statistical analysis was carried out using a factor analysis method, and eight main impact factors were extracted in the study. The pollution sources of human activity impact factors were mainly found to be the direct discharge of organic matter from industrial wastewater in petrochemical enterprises and domestic sewage and the inappropriate or excessive application of agricultural fertilizers. The primary geological environment factors were mainly affected by the hydrogeological and runoff conditions in the study area. Pollution factors were mainly distributed in the northeast of the study area where the pollution was a serious problem, while those in the south-central area were fewer and the pollution was light. This study provides a scientific decision basis for the application of groundwater and the management of groundwater resources in this area.

Health risk assessment of groundwater nitrogen pollution in Songnen Plain.

Access to safe drinking water is one of the fundamental human rights and an important part of healthy living. This study considered various land use methods, used geostatistical analysis, and triangular random model to explore nitrogen pollution and estimate its potential risk to human health for local populations in Songnen Plain of Northeast China and recognize parameter uncertainties. Nitrate concentrations in groundwater ranged from 0.01 to 523.45 mg/L, more than 72.35% of the samples exceeded Grade III threshold (20 mg/L of N) as per China's standard, and nitrate nitrogen content is greater than 20 mg/L accounted for around 60% of the research area, mainly distributed in the eastern and central high plain area. The nitrate-nitrogen content of groundwater in the town land was significantly higher than that of agricultural land, and the ammonia nitrogen content was conversely. The townland's risk value was two times that of agricultural land, considering different land use methods would avoid overestimating or underestimating regional risk value. Non-carcinogenic risks (HI) of two land use were above the safety level (i.e., HI > 1), suggesting that groundwater nitrate would have significant health effects on the age groups, and further threaten children. There was a wide range of fluctuations in the uncertainty of nitrogen concentration and model evaluation parameters; triangular random model was more sensitive to data changes, which could reduce the uncertainty. The contribution rate of nitrate-nitrogen concentration to risk was above 90%, which explained the need for random sampling to improve the evaluation results reliability. The findings in this paper will provide new insight for solving uncertainties in water safety management.

Assessment and validation of groundwater vulnerability to nitrate in porous aquifers based on a DRASTIC method modified by projection pursuit dynamic clustering model.

The groundwater vulnerability assessment has been identified as an important tool of groundwater pollution prevention. In this study, the DRASTIC method was modified to estimate the groundwater vulnerability of porous aquifers to nitrate. The parameter system was optimized by replacing the original parameters of aquifer media, soil media, impact of the vadose zone and hydraulic conductivity with quantitative parameters of aquifer thickness, nitrate attenuation intensity, hydraulic resistance and groundwater velocity and adding pollutant input intensity to develop the DRANTHVP method. In addition, the rating scale of the DRASTIC method was revised, and the weight and influence degree of each parameter were determined using the projection pursuit dynamic clustering (PPDC) model. The DRANTHVP method was applied to the plain area of western Jilin Province, and the vulnerability index map of groundwater to nitrate pollution was established. The DRANTHVP method improved the correlation coefficient between vulnerability index and nitrate concentration to 0.720, which was more than three times that of the original DRASTIC method. And the high variance of the (ANOVA) F statistic indicated that there was less overlap between the nitrate values in different vulnerability classes. Furthermore, the DRANTHVP method produced a more uniform distribution of vulnerability classes. In short, the DRANTHVP method using the PPDC model was suitable to assess the groundwater vulnerability of porous aquifers to nitrate in the study area. Hence, the mapping of groundwater vulnerability to nitrate can provide a scientific and reasonable basis for the formulation of groundwater resource protection plan.

Hydrochemical characteristics and quality assessment of groundwater for irrigation use in central and eastern Songnen Plain, Northeast China.

The hydrochemical characteristics of groundwater in Songnen Plain's agricultural area were analyzed based on aquifer types and topography classification to evaluate irrigation suitability and factors influencing groundwater quality. Samples of different groundwater types and topographical conditions within the research area were collected and chemical indices, such as sodium adsorption ratio, %Na+, residual sodium carbonate, and magnesium hazard values, were calculated to assess the groundwater suitability for irrigation. The results indicated that groundwater was generally neutral, with low total dissolved solids and slightly high hardness; the dominant anion in groundwater was HCO3-, while Ca2+ was the relatively stable primary cation found in water samples from the high plain and river valley plain. The nitrate in groundwater significantly exceeded WHO drinking water standards, especially in the unconfined water of the high plain, which was due to the large-scale agricultural production activities in the eastern regions. The main reactions in the groundwater system were weathering and dissolution of carbonates and sulfates and ion-exchange reactions. Horizontal zoning in water chemical characteristics was prominent; from the high plain to river valley plain and low plain, the hydrochemistry gradually transitioned from HCO3-Ca-Na to HCO3-Na-Ca and HCO3-Na. Based on the chemical indices, the majority of samples were suitable for agricultural irrigation except for some in the western area with high salinity and sodium hazards. Treatment measures to groundwater and soil should be taken to reduce the possibility of soil salinization and promote crop growth in these latter regions.