Fadong Li

Tracing nitrate pollution sources and transformation in surface- and ground-waters using environmental isotopes

Water pollution in the form of nitrate nitrogen (NO3(-)-N) contamination is a major concern in most agricultural areas in the world. Concentrations and nitrogen and oxygen isotopic compositions of nitrate, as well as oxygen and deuterium isotopic compositions of surface and groundwater from a typical irrigated region in the North China Plain (NCP) collected from May to October in 2012 were analyzed to examine the major nitrate sources and transformations. Concentrations of NO3(-)-N ranged from 0.2 to 29.6 mg/L (mean of 11.2 mg/L) in surface water, and from 0.1 to 19.4 mg/L (mean of 2.8 mg/L) in groundwater. Approximately 46.7% of the surface water samples and 10% of the groundwater samples exceeded the World Health Organization (WHO) drinking water standard for NO3(-)-N. Surface water samples that exceeded the standard were collected mainly in the dry season (May and October), while groundwater samples that exceeded the standard were collected in the wet season (June). Overall, the highest nitrate levels were observed in surface water in May and in groundwater in June, indicating that fertilizer application, precipitation, and irrigation strongly influence the NO3(-)-N concentrations. Analyses of isotopic compositions suggest that the main sources of nitrate are nitrification of fertilizer and sewage in surface water, in contrast, mineralization of soil organic N and sewage is the groundwater sources during the dry season. When fertilizers are applied, nitrate will be transported by precipitation through the soil layers to the groundwater in the wet season (June). Denitrification only occurred in surface water in the wet season. Attempts should be made to minimize overuse of nitrogen fertilizers and to improve nitrogen use efficiency in irrigated agricultural regions.

Behavior and fate of alkylphenols in surface water of the Jialu River, Henan Province, China

The behavior and fate of alkylphenols (APs) were studied in surface water from the Jialu River, Henan Province, China. Located at its upper stream, Zhengzhou city is regarded as the major discharge source to this river with its annual effluents containing 726 kg for nonylphenol (NP) and 30.2 kg for octylphenol (OP). The concentrations of NP and OP in surface water ranged from 75.2 to 1520 ngL(-1) and from 20.9 to 63.2 ngL(-1), respectively. To assess the behavior of APs along the river, a mass balance equation based on chloride was adopted, due to its relative conservation. The results showed that dilution effect was prevailing in determining the APs concentrations in surface water along the river. The effect of potential biodegradation was also estimated with an assumption of the optimized biodegradation. The contributions of dilution and biodegradation to the decline of APs concentrations were 38.8%, 23.7% for NP and 57.8%, 24.3% for OP, respectively. The other contribution to the decline of APs concentrations along the river was considered as an integrated effect of adsorption and air-water exchange with the values of 37.5% for NP and 17.9% for OP. The decay half-lives of NP and OP from surface water bodies were 1.6 and 2.4d, respectively. About 70.2% of total NP and 24.1% of total OP were finally eliminated from water phase to surrounding matrix in the downstream. The results suggested that the downstream river channel served as the net sink of APs in the study area.

Trace metal in surface water and groundwater and its transfer in a Yellow River alluvial fan: Evidence from isotopes and hydrochemistry

Metals are ubiquitous in the environment. The aim of sustainable management of the agro-ecosystem includes ensuring that water continues to fulfill its function in agricultural production, cycling of elements, and as a habitat of numerous organisms. There is no doubt that the influence of large-scale irrigation projects has impacted the regional surface-groundwater interactions in the North China Plain (NCP). Given these concerns, the aim of this study is to evaluate the pollution, identify the sources of trace metals, analyze the influence of surface-groundwater interactions on trace metal distribution, and to propose urgent management strategies for trace metals in the agriculture area in China. Trace metals, hydrochemical indicators (EC, pH, concentrations of Na(+), K(+), Mg(2+), Ca(2+), Cl(-), SO4(2-), and HCO3(-)) and stable isotopic composition (δ(18)O and δ(2)H) were determined for surface water (SW) and groundwater (GW) samples. Trace metals were detected in all samples. Concentrations of Fe, Se, B, Mn, and Zn in SW exceeded drinking water standards by 14.8%, 29.6%, 25.9%, 11.1%, and 14.8% higher, respectively, and by 3.8%, 23.1%, 11.5%, 11.5%, and 7.7% in GW. The pollution of trace metals in surface water was more serious than that in groundwater, and was also higher than in common irrigation areas in NCP. Trace metals were found to have a combined origin of geogenic and agriculture and industrial activities. Their distribution varied greatly and exhibited a certain relationship with the water flow direction, with the exception of a number of singular sites. Hydrochemical and environmental isotopic evidence indicates surface-groundwater interactions influence the spatial distribution of trace metal in the study area. Facing the ongoing serious pollution, management practices for source control, improved control technologies, and the construction of a monitoring net to warn of increased risk are urgently needed.

Distribution and Contamination Risk Assessment of Dissolved Trace Metals in Surface Waters in the Yellow River Delta

ABSTRACT This study investigated the dissolved trace metal contamination levels of Zn, Sr, B, Al, Ba, Fe, Mn, Li, V, Be, Cd, Cr, Cu, Mo, Ni, Se, and Pb in 23 surface waters of the Yellow River Delta (YRD) in China. Coefficients of variation with 66–260% reflected large spatial variations of concentrations of metals. Compared to drinking water guidelines established by the World Health Organization and the U.S. Environmental Protection Agency, the primary trace metal pollution components (Al, B, V, and Zn) were above drinking water standard levels by 82.6%, 47.8%, 52.2%, and 52.2%, respectively. Preliminary risk assessments were determined via the Hazard Quotient (HQ) to evaluate the human health risk of these metals. HQingestion of V indicated potential deleterious health effects for residents. Hierarchical cluster results revealed that clusters 1, 2, and 3 were primarily affected by pollution from industrial and domestic activities, natural and agriculture activities, and oil fields, respectively. Principal component analysis results indicated Fe, Mn, Al, and Ba were controlled by natural sources, whereas anthropogenic activities led to high pollution levels of Al, B, V, Zn, and Sr.

Status of POPs accumulation in the Yellow River Delta: From distribution to risk assessment.

The Yellow River Delta (YRD) is a large region of China with complex pollution sources and a long history of environmental deterioration. Despite this, relatively little data exists on the status of important contaminants of concern in this region. Here, we review the literature on the status of key persistent organic pollutants (POPs) of concern including organochlorine pesticides (OCPs), polycyclic aromatic hydrocarbons (PAHs), and polychlorinated biphenyls (PCBs) in the YRD. Sources, source identification methods, and spatial distribution patterns are presented. Additionally, POPs contamination levels reported in the literature were evaluated against popular regulatory limits worldwide to form a basis for overall environmental health. Our review determined that OCPs in the YRD originated mainly from current pesticide use and past agricultural pesticide application. Sources of PAHs included petrochemical inputs, coal fired plants, and wood combustion. PCB levels were impacted by the petrochemical industry as well as waste disposal of PCB containing equipment. OCPs exhibited a spatial distribution pattern that increased along the urban-rural gradient, while the opposite was seen for PAHs and PCBs. Comparisons of POPs contamination levels in the YRD with popular regulatory limits suggest that the extent of PCB contamination all mediums (sediment, soil, water, and biota) exceeded that of PAHs and OCPs. Overall pollution levels in the YRD seem to be in control; however, levels from heavily polluted point sources raise numerous concerns about the ecological health of the region and require more attention from regulatory authorities.

Sources, concentrations and risk factors of organochlorine pesticides in soil, water and sediment in the Yellow River estuary

The environmental occurrence, sources and risk factors of organochlorine pesticides (HCHs and DDTs) and their isomers or metabolites were studied using comprehensive surveys (including soil, surface water, groundwater and sediment sampling) conducted in the Yellow River Delta (YRD). HCHs and DDTs were all detected in multi environmental media. Compared with reported organochlorine pesticide values in China and abroad and with related environmental quality standards, the concentrations of HCHs and DDTs were generally at low levels in the YRD. Composition of OCPs (DDT metabolites and HCH isomers) showed that DDTs in the multiple environments of the YRD not only came from residues of dicofol but also from atmospheric deposition, while HCH pollution results from the historical usage of a mixture of technical HCH and lindane. Furthermore, the sum of Excess Lifetime Cancer Risk (∑ELCR) exposure to HCHs exceeded the generally acceptable risk level of 1.0E-06 recommended by the USEPA for carcinogenic chemicals.

Assessment of the Influences of Different Potential Evapotranspiration Inputs on the Performance of Monthly Hydrological Models under Different Climatic Conditions

AbstractPotential evapotranspiration (PET), which determines the upper limit of actual evapotranspiration (AET), is a necessary input in monthly hydrological models. In this study, the sensitivities of monthly hydrological models to different PET inputs are investigated in 37 catchments under different climatic conditions. Four types of PET estimation methods (i.e., Penman–Monteith, Hargreaves–Samani, Jensen–Haise, and Hamon) give significantly different PET values in the 37 catchments. However, similar runoff simulations are produced based on different PET inputs in both nonhumid and humid regions. It is found that parameter calibration of the hydrological model can eliminate the influences of different PET inputs on runoff simulations in both nonhumid and humid regions. However, the influences of parameter calibration on the simulated water balance components, including AET and water storage change (WSC), are different in nonhumid and humid regions. In nonhumid regions, simulated runoff, AET, and WSC ar...

Impacts of Yellow River Irrigation Practices on Trace Metals in Surface Water: A Case Study of the Henan-Liaocheng Irrigation Area, China

ABSTRACT Large-scale irrigation practices may disturb local hydrologic cycles and distribute trace metals throughout the environment. Reported here is the spatial pattern of trace metals and associated health risks in an agricultural area of China, which has a long history of irrigation with water from the Yellow River. Multivariate statistical analyses and a risk-assessment model were employed to interpret the environmental data. It indicated that Zn, Se, B, Ba, Fe, Mn, Mo, Ni, V, Al, Li, Sr, Be, Cd, Cr, Cu, and Pb were all detected in the surface waters. Compared to drinking water guidelines, the primary trace metal pollution components (Al, Fe, Se, B, Mn, and Zn) exceeded drinking water standards by 40.7%, 14.8%, 29.6%, 25.9%, 11.1%, and 14.8%, respectively. Except for one site that exhibited anomalous metal concentrations, landscape features of trace metals identified a uniform distribution of trace metals for all sample sites. The calculated mean value of Hazard Quotients (HQs) exceeded the USEPAs recommendations by a factor of 2.9 times the threshold value. Primary sources of trace metals were associated with natural deposition, industrial and agrochemical processes, and a mixed source of both geogenic and anthropogenic origins.

Spatial Distribution, Potential Sources, and Risk Assessment of Trace Metals of Groundwater in the North China Plain

ABSTRACT Diversion of water for irrigation from the Yellow River has impacted groundwater quality in the North China Plain (NCP). In this study, by using geochemical and isotope methods, groundwater origin, the spatial distribution of trace metals, pollution sources, and health risks were evaluated. Groundwater is recharged from surface water. The primary pollution components in surface water were B, Al, Se, Zn, Mn, and Ni—with concentrations exceeding standards by 100%, 84.4%, 64.4%, 31.1%, 20%, and 2.2%, respectively. In groundwater, exceeding standard rates for those elements were 100%, 100%, 61%, 25.7%, 39%, and 4.9%, respectively. The spatial distribution of polluted metals in surface water and groundwater was correlated, indicating an irrigation-influenced spatial distribution of trace metals in the groundwater. The trace metals were introduced via anthropogenic and geogenic activities. Zinc poses the most serious non-carcinogenic hazard for local residents. The ingestion pathway is much more likely to lead to zinc toxicity than the dermal absorption pathway. The carcinogenic Cd and Pb could result in an increased cancer risk for individuals exposed to the water. Non-carcinogenic hazard and carcinogenic risk attributable to groundwater is serious in the regions traversed by the rivers in the study area.

Polycyclic aromatic hydrocarbons in the Yellow River estuary: Levels, sources and toxic potency assessment

This paper presents a systematic but preliminary study on the levels, sources and risk of exposure to polycyclic aromatic hydrocarbons (PAHs) in the Yellow River estuary by examining 16 priority PAHs listed by the U.S. EPA in four main environmental media (soil, surface water, groundwater and sediment). The concentration of individual PAHs in each medium in the study area was compared with the reported PAH values in China and abroad and to related environmental quality standards. The pollution levels of PAHs were found to be moderate in the soil and sediment, and low in the surface water and groundwater. Wood, coal combustion and petroleum inputs are the main PAH sources in soil and sediment, while petroleum inputs and petroleum combustion are the main PAH sources in surface water and groundwater. This indicates that PAH input caused by the high-speed inflow of external water over a long time has made a definite contribution to the occurrence of PAHs in surface water and groundwater in the study area. Furthermore, the mean value of the sum of the Excess Lifetime Cancer Risk (∑ELCR) exposure to PAHs in all media exceeded the generally acceptable risk level of 1.0E-06 recommended by the USEPA for carcinogenic chemicals, and the relative proportion contributed by DBA to the ∑ELCR was the greatest.