Distribution and Formation Causes of PM_(2.5) and O_(3) Double High Pollution Events in China during 2013–20

Fine particulate matter(PM_(2.5))and ozone(O_(3))double high pollution(DHP)events have occurred frequently over China in recent years,but their causes are not completely clear.In this study,the spatiotemporal distribution of DHP events in China during 2013–20 is analyzed.The synoptic types affecting DHP events are identified with the Lamb–Jenkinson circulation classification method.The meteorological and chemical causes of DHP events controlled by the main synoptic types are further investigated.Results show that DHP events(1655 in total for China during 2013–20)mainly occur over the North China Plain,Yangtze River Delta,Pearl River Delta,Sichuan Basin,and Central China.The occurrence frequency increases by 5.1%during 2013–15,and then decreases by 56.1%during 2015–20.The main circulation types of DHP events are“cyclone”and“anticyclone”,accounting for over 40%of all DHP events over five main polluted regions in China,followed by southerly or easterly flat airflow types,like“southeast”,“southwest”,and“east”.Compared with non-DHP events,DHP events are characterized by static or weak wind,high temperature(20.9℃ versus 23.1℃)and low humidity(70.0%versus 64.9%).The diurnal cycles of meteorological conditions cause PM_(2.5)(0300–1200 LST,Local Standard Time=UTC+8 hours)and O_(3)(1500–2100 LST)to exceed the national standards at different periods of the DHP day.Three pollutant conversion indices further indicate the rapid secondary conversions during DHP events,and thus the concentrations of NO_(2),SO_(2) and volatile organic compounds decrease by 13.1%,4.7%and 4.4%,respectively.The results of this study can be informative for future decisions on the management of DHP events.

Characteristics and Genesis of Acid Drainage Contamination from a Rock Tunneling Project Site

While acid mine drainage(AMD)issues have become a topic of global concern,few studies have focused on acid drainage problems of non-mining activities.We conducted field research and a series of laboratory experiments to investigate the characteristics,release processes and formation of acid drainage contamination.Spoil rock samples and adjacent surface water,groundwater,soil and sediment samples were collected at a railway tunnel construction site in central China,and various parameters,such as the p H,mineral ion concentrations,and heavy metal concentrations,were measured.Based on the measured concentrations,surface water and sediments were seriously contaminated by acids,sulfate salts and heavy metals.Contamination in surface water showed a decreasing tendency as the distance from the spoils increased,while that in sediments showed a greater influence of coprecipitation and adsorption processes of heavy metal ions.The eluviation experiments of three rock samples indicated that R2(silty fine sandstone)was the most likely major acid drainage contributor.Thiobacillus ferrooxidans was cultured and isolated from contaminated water to study the oxidation conditions during the release processes.The significant release of acid drainage when air and bacteria were both in the culture container suggested that oxygen and bacteria were necessary to produce acid drainage from spoils.

Petrogenesis, Tectonic Evolution and Geothermal Implications of Mesozoic Granites in the Huangshadong Geothermal Field, South China

Mesozoic multi-stage tectono-magmatic events produced widely distributed granitoids in the South China Block. Huangshadong(HSD) is located in south-eastern South China Block, where closely spaced hot springs accompany outcrops of Mesozoic granites. New data on whole-rock geochemistry, zircon U-Pb geochronology, and zircon Lu-Hf isotopes are presented, to study the petrogenesis and tectonic evolution of the granites, and to explore the relationship between granites and geothermal anomalies. Zircon U-Pb isotopes display three periods of granites in the HSD area: Indosinian(ca. 253 Ma, G4) muscovite-bearing monzonitic granite, early Yanshanian(ca. 175–155 Ma, G5 and G3) monzonitic granite and granodiorite, and late Yanshanian(ca. 140 Ma, G1 and G2) biotite monzonitic granite. In petrogenetic type, granites of the three periods are I-type granite. Among them, G1, G2, G3, and G4 are characterized by high fractionation, with high values of SiO2, alkalis, Ga/Al, and Rb/Sr, and depletion in Sr, Ba, Zr, Nb, Ti, REEs, with low(La/Yb)N, Nb/Ta, and Zr/Hf ratios and negative Eu anomalies. In terms of tectonic setting, 253 Ma G4 may be the product of partial melting of the ancient lower crust under post-orogenic extensional tectonics, as the closure of the Paleo-Tethys Ocean resulted in an intracontinental orogeny. At 175 Ma, the subduction of the Pacific Plate became the dominant tectonic system, and low-angle subduction of the Paleo-Pacific Plate facilitated partial melting of the subducted oceanic crust and basement to generate the hornblende-bearing I-type granodiorite. As the dip angle of the subducting plate increased, the continental arc tectonic setting was transformed to back-arc extension, inducing intense partial melting of the lower crust at ca. 158 Ma and resulting in the most frequent granitic magmatic activity in the South China hinterland. When slab foundering occurred at ca. 140 Ma, underplating of mantle-derived magmas caused melting of the continental crust, generating extensive highly fractionated granites in HSD. Combining the granitic evolution of HSD and adjacent areas and radioactive heat production rates, it is suggested that highly fractionated granites are connected to the enrichments in U and Th with magma evolution. The high radioactive heat derived from the Yanshanian granites is an important part of the crustal heat, which contributes significantly to the terrestrial heat flow. Drilling ZK8 reveals deep, ca. 140 Ma granite, which implies the heat source of the geothermal anomalies is mainly the concealed Yanshanian granites, combining the granite distribution on the surface.

Soil concentrations and soil-air exchange of organochlorine pesticides along the Aba profile, east of the Tibetan Plateau, western China

Mianzhu--Aba profile, east of the Tibetan Plateau, was selected to study the occurrence of organo- chlorine pesticides （OCPs） along an altitudinal gradient. Dichlorodiphenyltrichloroethanes （DDTs）, hexachlorocy- clohexanes （HCHs） and Aldrin, Dieldrin and Endrin （Drins） in surface soils were detected in winter （March） and summer （July）. Soil concentrations （ng.g-1, dw） in winter and summer ranged as follws： DDTs, 0.37-179.16 and 0.32-42.57; HCHs, 0.14-10.76 and 0.55-32.71; Drins, N.D-3.99 and 0.02-6.93, respectively. Main soil OCPs were p,p＇-DDT, p,p＇-DDE, fl-HCH and Drins, among which Drins were rarely reported in current literature of the Tibetan Plateau. Higher OCP concentra- tions in the profile were attributed close to the agricultural fields of the Sichuan Basin, current lindane and non- dicofol DDTs inputs, and also long-range atmospheric transport from abroad. Soil OCP concentrations underwent obvious seasonal variation, with higher DDTs in winter and higher HCHs and Drins in summer. It may be caused by climatic conditions, summer monsoon type, and physico-chemical properties of such contaminants. Though ＂rest＂ phenomenon occurred in some sampling sites, HCHs and Drins showed an increasing trend with increasing altitude, while DDTs showed an evident decrease with increasing altitude. The altitudinal distribu- tions of OCPs were all consistent with previous findings in other mountainous regions. A primary fugacity analysis on OCPs soil-air exchange indicated that the profile may be secondary sources for HCHs and Endrin. As with Aldrin,Dieldrin, and DDTs, the profile may be both secondary sources and sinks.

Fate of PM2.5-bound PAHs in Xiangyang, central China during 2018 Chinese spring festival: Influence of fireworks burning and air-mass transport

Variations of levels,possible source and air mass transmission were investigated for 16 USEPA priority-controlled PAHs in PM2.5 during 2018 Chinese Spring Festival(CSF)in Xiangyang City,central China which is the North-South pollutant airmass transport channel of China.Totally 37 samples were collected.Mass concentrations of 16 PAHs for the Pre–CSF day(Pre–CSFD),during the CSF day(CSFD)and after the CSF day(Af–CSFD)are 33.78±17.68 ng/m3,22.98±6.49 ng/m3,and 8.99±4.44 ng/m3,respectively.High resolution samples showed that 16 PAHs are higher in the morning(06:00–11:00)or afternoon(11:30–16:30),than those in the evening(17:00–22:00)and at night(22:30–05:30),whereas the result is reversed during the CSFD.Fireworks burning can obviously increase the mass concentration of PAHs.Air mass trajectory indicated that Xiangyang is a sink area of pollutants for northwest and southeast,and the sources of the northeast and southwest.The air mass only can be transmitted out through northeast and southwest.It is effective for improvement of air quality in Wuhan and Hunan to control fireworks emission in Henan and local areas.Fireworks burning was an important source for PAHs during CSFD,biomass,coal combustion,and traffic emission were the main sources of PAHs for Pre–CSFD and Af–CSFD periods.The health risk on the CSFD was higher than the acceptable levels,especially during the intensive fireworks burning,the risk value far exceed 1.0×10^-4,controlling burning fireworks is required.

Characterization of polycyclic aromatic hydrocarbons in PM2.s and PMlo in Tanggu District, Tianjin Binhai New Area, China

Particulate matter （PMlo and PM2.5） concentrations were monitored during the November 2008 by using the filter samples collected day and night from three sites in Tanggu District at Tianjin Binhai New Area, China. The mean concentrations of PM2.5 and PMlo rank in the order of urban （150 ug/m3 for PM2.5 and 197 ug/m3 for PM10） 〉 industrial （32 ug/m3 for PM2.5 and 170 ug/m3 for PM10） 〉 suburb area （27 ug/m3 for PM2.5 and 59 ug/m3 for PM10）. Sixteen polycyclic aromatic hydrocarbons （PAHs） were analyzed in PMlo and PM2.5 samples. Concentrations of total PAHs in PM2.5 and PMlo are in the range of 8.47- 113.94ng/m3 with average of 62.88ng/m3 and 21.07- 118.23 ng/m3 with average of 73.42 ng/m3, respectively. The light ring PAils （2-4 rings） are dominant in both PM2.5 and PMlo during sampling time compares with the heavy ring （5-6 rings） PAHs. The relationship of PAHs and PM2.5 （r = 0.689, p 〈 0.05） is stronger than PAHs and PMlo （r = 0.570, p 〈 0.05）, illustrating PAHs tend to adsorb in PM2.5. In addition, principal component analysis was applied to find the source of PAHs. Three principal factors representing three types of PAHs sources in Tanggu District are extracted, which were coke production, pyrogenic sources and vehicular source.

Preliminary assessment of heavy metal contamination in surface water and sediments from Honghu Lake, East Central China

Heavy metal concentrations in surface water and sediments collected from Honghu Lake in Hubei Province, China were analyzed, and ecological risks were evaluated according to the sediment quality guidelines. The results showed that the average concentrations of heavy metals in surface water were ranked as： As 〉 Zn 〉 Cu 〉 Cr 〉 Pb 〉 Ni 〉 Cd 〉 Hg. In comparison with results reported in other rivers and the background values, The Honghu Lake was polluted by As, Cr, Pb, Cu and Ni. Most of metals might be mainly from fertilizers, industrial effluent and domestic wastewater around the lake. Heavy metals concentrations were relatively higher in the inlet area than in other areas. Negative correlations were observed between most heavy metals and pH, while a significant positive correlation was present between Zn, Cd and Pb. In the sediment core, Cu, Zn, Cr and Ni showed a decreasing trend while Cd present an increasing trend. The decrease of As, Cu, Zn, Cr and Ni in the 1990s might due to the flood event in 1998. The analysis of ecological risk assessment based on sediment quality guidelines suggested that heavy metals in most sediments from the Honghu Lake had moderate toxicity, with Cr being the highest priority pollutant.

Crustal Thermo-Structure and Geothermal Implication of the Huangshadong Geothermal Field in Guangdong Province

Dense distribution of granites and surrounding hot springs, the high anomalous heating rates of geothermal fluids and the high geothermal gradients in shallow crust in Southeast China are revealed by previous geothermal explorations. However, there have always been debates on the genesis of geothermal anomalies of Southeast China. It is imperative to look into the genesis mechanism of geothermal anomalies through selecting a typical geothermal field, and constructing fine crustal thermostructure. In this study, in-depth excavation is implemented for the previous data of geophysical exploration and deep drilling exploration in the Huangshadong area. We synthetically analyze the results of radioactive heat productions(RHPs), thermophysical properties of rocks and audio-frequency magnetotellurics(AMT) sounding. This study concludes that the coefficient of radioactive heat generation(RHG) of crustal rocks and conduction heat of concealed granites is the main formation mechanism of geothermal anomalies of South China, where occurs a Great Granite Province. There is a regional indicating implication for the genesis of geothermal anomalies, taking the Huangshadong geothermal field as a typical example. It is also an important reference to guide the exploration, evaluation, development and utilization of geothermal resources in this region.

Passive air sampling of organochlorine pesticides in a northeastern state of India,Manipur

Thirty-six polyurethane foam disk passive air samplers （PUF-PAS） were deployed over a year during January to December, 2009 at three locations, i.e., Imphal （urban site）, Thoubal （rural site） and Waithou （alpine site） of Manipur, to assess the seasonal local atmospheric emission of selected organochlorine pesticides （OCPs）. The average concentration of HCHs monitored at mountain site during hot season （Mar, Apr, and May） and rainy seasons （Jun, Jul, Aug, and Sep） were 403 and 349 pg/m3, respectively. DDTs had a high concentration with 384 pg/m3 at rural site and 379 pg/m3 at urban site during hot seasons. Endosulfans and chlordane were found high in concentration during hot seasons （260 pg/m3） and low during retreating monsoon seasons （44 pg/m3） at rural site. Most of the OCPs concentrations were high during cultivation period. The OCP concentrations of rainy season were highly correlated （p 〈 0.01） with OCPs of hot seasons. Further, positive correlation （p 〈 0.05） was also obtained between cold seasons and retreating monsoon. Principal component analysis showed a significant correlation among the four seasons and distribution pattern of OCPs in air. Back trajectory analysis by using HYPSLIT model showed a long range air transport of OCPs to the present study area. Present OCP levels at Manipur is an outcome of both local emission and also movement of air mass by long range atmospheric transport.

Hydrochemical characteristics and water quality assessment for drinking and agricultural purposes in District Jacobabad,Lower Indus Plain,Pakistan

Undeniably water is of utmost importance while considering basic necessities.This investigation emphasized on the hydrochemical evaluation and drinking water quality assessment in District Jacobabad located in lower Indus plain,Pakistan.Certainly world's largest irrigation system emerged from Indus Basin,which is underlain by well transmissive aquifer resulting in higher water table.Water supply schemes with their water sources from ground water and surface water provide piped water for drinking purpose to the community.Water samples were collected from all the forty eight supply schemes of which thirty two were found nonfunctional.Analytical parameters were compared with World Health Organization(WHO)and Pakistan Water Quality Standards but adversely substantial samples were found nonpotable.Alkalinity,bicarbonate and nitrate met the standard safe limits while values for EC,TDS,hardness,cations and anions exceeded the limits in numerous samples.SPSS and ArcGIS softwares were used for statistical analysis and spatial distribution of parameters.Hydrochemical facies were developed and suitability assessment of water resources was examined for agricultural use.The ground water type was classified as Na-HCO3 type with high salinity and it required treatment prior to irrigation.The proposed research exhibited the probable drinking water contamination sources and it demanded instant actions to further protect the valuable drinking water resources in District Jacobabad.

Organochlorine pesticide residues in surface water from Sichuan Basin to Aba Prefecture profile, east of the Tibetan Plateau

Organochlorine pesticides （OCPs） found in rivers from the Sichuan Basin to Aba Prefectttre profile were analyzed to assess possible health risks to adults and children who use the river as a source of drinking water. OCP concentrations in surface water ranged between 22.29-274.28 ng·L^-1. Compared with other published data around the world, OCP levels in this study were moderate. Among all OCPs, hexachlorobenzene （HCB） and hexa- chlorocyclohexanes （HCHs） were the predominant com- pounds. Higher concentrations of OCPs were attributed close to the agricultural fields of the Sichuan Basin, current OCPs inputs, and long-range atmospheric transport from abroad. Various spatial patterns of OCPs in the profile might be affected by the usage and physicochemical properties of the pesticides, in addition to the adjacent geographical environment. The health risk assessment indicated that most OCPs had little impact on human health according to the acceptable risk level for carcino- gens （10^-6） recommended by the US EPA. However, carcinogenic effects caused by heptachlor, Aldrin, HCB, and a-HCH might occur in drinking water. The risk of negative impacts caused by OCPs is much higher for children than for adults.

Background levels of OCPs,PCBs,and PAHs in soils from the eastern Pamirs,China,an alpine region influenced by westerly atmospheric transport

Long-range atmospheric transport(LRAT)plays a crucial role in the occurrence of persis-tent organic pollutants(POPs)in remote regions.When studying the LRAT of POPs on the Tibetan Plateau,westerly-controlled regions have received insufficient attention compared with regions influenced by the Indian monsoon or air flow from East Asia.We investigated the residual levels of POPs in soils from the eastern Pamirs and used air backward trajectory analysis to elucidate the influence of potential source regions via LRAT.Organochlorine pes-ticides(OCPs,mainly comprising DDTs,HCHs,and HCB),polychlorinated biphenyls(PCBs,mainly comprising penta-and hexa-CBs),and polycyclic aromatic hydrocarbons(PAHs,mainly comprising three-and four-ring)were detected at low concentrations of 40-1000,<MDL-88,and 2100-34,000 pg/g,respectively.We elucidated three major geographical dis-tribution patterns of POPs,which were influenced by(1)the distribution of total organic carbon and black carbon in soil,(2)historical use of pesticides in the Tarim Basin,and(3)continuous emissions.Central Asia and the Tarim Basin were major potential source regions of POPs reaching the eastern Pamirs via LRAT.Historical use of technical HCH or lindane and technical DDT in potential source regions may contribute to the accumulation of HCHs and DDTs in the eastern Pamirs,respectively.Local sources seem to play a more important role in the occurrence of PAHs in the study area.By being under the control of less contaminated westerly air flow,the eastern Pamirs are more pristine than the core of the Tibetan Plateau where the Indian and East Asia monsoons deliver contaminants from highly industrialized areas in East China and India.

Concentrations and classification of HCHs and DDTs in soil from the lower reaches of the Jiulong River, China

Soil is an important source to other environ- mental media and organisms for organochlorine pesticides （OCPs） bioaccumulation. Twenty-four representative sur- face soil samples were collected from the lower reaches of the Jiulong River, China, in 2009. The concentrations of hexachlorocyclohexane isomers （HCHs） ranged from 0.38 to 39.52 ng.g~, with a mean value of 9.51 ng.g-~. The concentrations of dichlorodiphenyltrichloroethanes （DDTs） and their metabolites were within the ranges of 0.94-700.99 ng. gl, with a mean value of 71.17 ng. g-1. The concentrations of HCHs and DDTs in the soil were lower than the first grade level （50 ng. g-a） of the Chinese Environmental Quality Standard （GB 15618-1995）. Hier- archical Cluster Analysis （HCA） and Pearson＇s bivariate Correlations Analysis （PCA） were used to analyse the distribution and contamination levels of OCPs in this region. The results showed that DDTs were the major contaminants and there were no significant correlations between various OCPs concentrations and the total organic carbon （TOC） contents. A significant positive correlation was observed between HCHs and DDTs （p 〈 0.01）, which indicates that HCHs and DDTs may have similar sources and fate in the study area.

Foreword: Toward a Quantitative Understanding of the Frontier in Geothermal Energy

Our planet, Earth, contains an enormous amount of heat just right under our feet. Harnessing this heat from 2 to 5 krn below is one of the great challenges of the 21st century, because this can solve many of the currently urgent problems in mega-cities, such as inexpensive domestic heating and airconditioning, electric power consumption and the cure of ram- pant air pollution. Around 40 TW heat are released at a steady rate by the Earth partly due to natural radioactive decay and partly due to the action inside the core. We would like to stress here that the depth of the isotherm of 200℃ （minimum tem- perature for efficient generation of electricity） varies around the globe. In general, this depth would be less than 10 km deep. Therefore these heat sources would provide ubiquitous ample, clean and sustainable electricity. In addition to this sustainable resource the potential of geothermal energy use is much greater, because it allows effective heat mining of the Earth. Geothermal energy is most commonly exploited in volcanic areas where magma is close to the surface and brings up the heat from deeper down. The largest geothermal power plant of this style is the Geysers in California, which with 1 GW power production rivals nuclear power plants.