Huiwang Gao

Ecological risk assessment of nonylphenol in coastal waters of China based on species sensitivity distribution model

Nonylphenol (NP) is an endocrine disruptor and causes feminization and carcinogenesis in various organisms. Consequently, the environmental distribution and ecological risks of NP have received wide concern. China accounts for approximately 10% of the total NP usage in the world, but the water quality criteria of NP have not been established in China and the ecological risks of this pollutant cannot be properly assessed. This study thus aims to determine the predicted no effect concentration (PNEC) of NP and to assess the ecological risks of NP in coastal waters of China with the PNEC as water quality criteria. To obtain the HC5 (hazardous concentration for 5% of biological species) and PNEC estimates, the species sensitivity distributions (SSDs) models were built with chronic toxicity data of NP on aquatic organisms screened from the US Environmental Protection Agency (USEPA) ECOTOX database. The results showed that the PNEC for NP in freshwater and seawater was 0.48 μg L(-1) and 0.28 μg L(-1), respectively. The RQ (risk quotient) values of NP in coastal waters of China ranged from 0.01 to 69.7. About 60% of the reported areas showed a high ecological risk with an RQ value ≥ 1.00. NP therefore exists ubiquitously in coastal waters of China and it poses various risks to aquatic ecosystems in the country. This study demonstrates that the SSD methodology can provide a feasible tool for the establishment of water quality criteria for emergent new pollutants when sufficient toxicity data is available.

Air pollution–aerosol interactions produce more bioavailable iron for ocean ecosystems

Acidic air pollutants dissolve iron in aerosols and fertilize the ocean. It has long been hypothesized that acids formed from anthropogenic pollutants and natural emissions dissolve iron (Fe) in airborne particles, enhancing the supply of bioavailable Fe to the oceans. However, field observations have yet to provide indisputable evidence to confirm this hypothesis. Single-particle chemical analysis for hundreds of individual atmospheric particles collected over the East China Sea shows that Fe-rich particles from coal combustion and steel industries were coated with thick layers of sulfate after 1 to 2 days of atmospheric residence. The Fe in aged particles was present as a “hotspot” of (insoluble) iron oxides and throughout the acidic sulfate coating in the form of (soluble) Fe sulfate, which increases with degree of aging (thickness of coating). This provides the “smoking gun” for acid iron dissolution, because iron sulfate was not detected in the freshly emitted particles and there is no other source or mechanism of iron sulfate formation in the atmosphere.

Regional precipitation variability in East Asia related to climate and environmental factors during 1979-2012

This paper studies the inter-annual precipitation variations in different regions of East Asia from oceans to interior areas in China during 1979 – 2012. The results computed by Empirical Orthogonal Functions (EOF) demonstrate that the annual precipitation changes are mainly related to the El Niño-Southern Oscillation, East Asian summer monsoon and aerosols. We also found that the increased Sea surface temperature (SST) could explain the precipitation changes over the Northwest Pacific in the dry season (Oct. – May) and the East China Sea and the South China Sea in the rainy season (Jun. – Sep.). The precipitation changes over the ocean unexplained by SST were likely due to the water vapor transport dominated by dynamic factors. With the increased SST, the moisture transported from oceans to interior land was likely redistributed and caused the complicated regional variability of precipitation. Moreover, the impacts of aerosols on cloud and precipitation varied with different pollution levels and different seasons.

Removal capacity and pathways of phenolic endocrine disruptors in an estuarine wetland of natural reed bed

Phenolic compounds are partly known as endocrine disruptors with various harmful effects including feminization and carcinogenesis at very low concentrations. Consequently, the pathways and removal of these compounds in natural and artificial sewage treatment systems such as wetlands have received wide concern. In this paper, a natural reed bed wetland with an area of 695ha located in the Liaohe River estuary in Northeast China was employed as a demonstration site to study the retention and removal efficiency of phenolic compounds including 4-nonylphenol (4-NP), bisphenol A (BPA), 4-t-octylphenol (4-t-OP), and 2,4-dichlorophenol (DCP), and to evaluate their purification capacity via water and mass balance analyses during an irrigation period from May 9 to September 8, 2009. The results showed that the phenolic compounds could be retained in the wetland system and removed through various processes. On average, 27.5% of phenolic compounds could be retained by the wetland substrate during the initial three-day irrigation period with a retention capacity order of 4-t-OP>4-NP>BPA>DCP. During the following 120d irrigation period, the phenolic compounds could be efficiently removed with an average percentage of 91.6%. It is estimated that 1.76kgd(-1) of phenolic compounds could be removed by the Liaohe River estuarine wetland (∼8×10(4)ha). The reed bed wetland system therefore provides a feasible mitigation option for phenolic pollutants in sewage and wastewater.

Variability in the Correlation between Asian Dust Storms and Chlorophyll a Concentration from the North to Equatorial Pacific

A long-term record of Asian dust storms showed seven high-occurrence-frequency centers in China. The intrusion of Asian dust into the downwind seas, including the China seas, the Sea of Japan, the subarctic North Pacific, the North Pacific subtropical gyre, and the western and eastern Equatorial Pacific, has been shown to add nutrients to ocean ecosystems and enhance their biological activities. To explore the relationship between the transported dust from various sources to the six seas and oceanic biological activities with different nutrient conditions, the correlation between monthly chlorophyll a concentration in each sea and monthly dust storm occurrence frequencies reaching the sea during 1997–2007 was examined in this study. No correlations were observed between dust and chlorophyll a concentration in the <50 m China seas because atmospheric deposition is commonly believed to exert less impact on coastal seas. Significant correlations existed between dust sources and many sea areas, suggesting a link between dust and chlorophyll a concentration in those seas. However, the correlation coefficients were highly variable. In general, the correlation coefficients (0.54–0.63) for the Sea of Japan were highest, except for that between the subarctic Pacific and the Taklimakan Desert, where it was as high as 0.7. For the >50 m China seas and the North Pacific subtropical gyre, the correlation coefficients were in the range 0.32–0.57. The correlation coefficients for the western and eastern Equatorial Pacific were relatively low (<0.36). These correlation coefficients were further interpreted in terms of the geographical distributions of dust sources, the transport pathways, the dust deposition, the nutrient conditions of oceans, and the probability of dust storms reaching the seas.

Ecosystem-Based Assessment Indices of Restoration for Daya Bay near a Nuclear Power Plant in South China

China has adopted nuclear power generation as one of the strategic energy sources to resolve the dilemma between its ever-growing energy demand and the associated environmental issues. To achieve the latter, a systematic assessment of the state of the ecosystem near nuclear power plants and its restoration via ongoing recovery actions would be highly desirable and much needed. Current assessment methods are mostly based on the individual components of the ecosystem and the methods are therefore not integrated. In this paper, we report a set of system-based assessment indices to study the restoration of Daya Bay in Guangdong, China where a nuclear power plant has been in operation for 15 years. The results show that decades of intensive exploitation by the various coastal activities have pushed Daya Bays ecosystem away from its baseline and its structure and functions are impaired; ecosystem restoration does not make up for the weakening of the ecological carrying capacity due to anthropogenic sea-use, nonetheless, the potential for recovery still exists. The case study suggests that the system-based indices can provide integrated information for ecosystem restoration assessment and management.

Ecosystem health assessment in the pearl river estuary of China by considering ecosystem coordination.

Marine ecosystem is a complex nonlinear system. However, ecosystem health assessment conventionally builds on a linear superposition of changes in ecosystem components and probably fails to evaluate nonlinear interactions among various components. To better reflect the intrinsic interactions and their impacts on ecosystem health, an ecosystem coordination index, defined as the matching level of ecosystem structure/services, is proposed and incorporated into the ecosystem health index for a systematic diagnosis in the Pearl River Estuary, China. The analysis results show that the ecosystem health index over the last three decades decreased from 0.91 to 0.50, indicating deteriorating from healthy to unhealthy status. The health index is 3–16% lower than that calculated using the common method without considering ecosystem coordination. Ecosystem health degradation in the Pearl River Estuary manifested as significant decreases in structure/services and somewhat mismatching among them. Overall, the introduction of coordination in ecosystem health assessment could improve the understanding of the mechanism of marine ecosystem change and facilitate effective restoration of ecosystem health.

Identification of Major Sources of Atmospheric NH3 in an Urban Environment in Northern China During Wintertime

To assess the relative contributions of traffic emission and other potential sources to high levels of atmospheric ammonia (NH3) in urban areas in the wintertime, atmospheric NH3 and related pollutants were measured at an urban site, ∼300 m from a major traffic road, in northern China in November and December 2015. Hourly average NH3 varied from 0.3 to 10.8 ppb with an average of 2.4 ppb during the campaign. Contrary to the common perspective in literature, traffic emission was demonstrated to be a negligible contributor to atmospheric NH3. Atmospheric NH3 correlated well with ambient water vapor during many time periods lasting from tens of hours to several days, implying NH3 released from water evaporation is an important source. Emissions from local green space inside the urban areas were identified to significantly contribute to the observed atmospheric NH3 during ∼60% of the sampling times. Evaporation of predeposited NHx through wet precipitation combined with emissions from local green space likely caused the spikes of atmospheric NH3 mostly occurring 1-4 h after morning rush hours or after and during slight shower events. There are still ∼30% of the data samples with appreciable NH3 level for which major contributors are yet to be identified.

Concentration, Size Distribution, and Formation of Trimethylaminium and Dimethylaminium Ions in Atmospheric Particles over Marginal Seas of China*

AbstractIn this paper, the concentration, the size distribution, and the formation of dimethylaminium (DMA+) and trimethylaminium (TMA+) ions in atmospheric particles were studied during a cruise campaign over the Yellow Sea and the Bohai Sea of China in May 2012. The concentrations of DMA+ and TMA+ in particles smaller than 11 µm were 4.4 ± 3.7 and 7.2 ± 7.1 nmol m−3, respectively. The two ions had a good correlation (R2 = 0.86), and both had a moderately good correlation with chlorophyll a fluorescence (R2 = 0.66–0.67). The observed concentrations were from one to three orders of magnitude larger than the concentrations reported in other marine atmospheres. They were also much larger than the values observed at a coastal site neighboring the Yellow Sea in May–June 2013. The high concentrations of DMA+ and TMA+ observed in the marine atmosphere were probably associated with local biogenic activity instead of the long-range transport of these species from adjacent continents. The calculated mole ratios of...

Sources and characteristics of fine particles over the Yellow Sea and Bohai Sea using online single particle aerosol mass spectrometer

Marine aerosols over the East China Seas are heavily polluted by continental sources. During the Chinese Comprehensive Ocean Experiment in November 2012, size and mass spectra of individual atmospheric particles in the size range from 0.2 to 2.0 μm were measured on board by a single particle aerosol mass spectrometer (SPAMS). The average hourly particle number (PN) was around 4560±3240 in the South Yellow Sea (SYS), 2900±3970 in the North Yellow Sea (NYS), and 1700±2220 in the Bohai Sea (BS). PN in NYS and BS varied greatly over 3 orders of magnitude, while that in SYS varied slightly. The size distributions were fitted with two log-normal modes. Accumulation mode dominated in NYS and BS, especially during episodic periods. Coarse mode particles played an important role in SYS. Particles were classified using an adaptive resonance theory based neural network algorithm (ART-2a). Six particle types were identified with secondary-containing, aged sea-salt, soot-like, biomass burning, fresh sea-salt, and lead-containing particles accounting for 32%, 21%, 18%, 16%, 4%, and 3% of total PN, respectively. Aerosols in BS were relatively enriched in particles from anthropogenic sources compared to SYS, probably due to emissions from more developed upwind regions and indicating stronger influence of continental outflow on marine environment. Variation of source types depended mainly on origins of transported air masses. This study examined rapid changes in PN, size distribution and source types of fine particles in marine atmospheres. It also demonstrated the effectiveness of high-time-resolution source apportionment by ART-2a.