Southeast Coast Of China Research Articles

Zircon U–Pb dating of the Shipu limestone in Zhejiang Province, coastal southeast China: Implications for the Early Cretaceous environment

The age of the Shipu limestone-bearing section in Zhejiang Province, coastal southeast China, which is commonly called the Shipu limestone, is important for understanding the depositional environment and tectonic background of the region. However, previous chronostratigraphic and chronometric studies have produced competing results from the Palaeozoic to the Cenozoic. In order to provide some constraints, 115 zircon grains from tuff interbeds within the three limestone units and of the base and the top of the section were selected for U–Pb dating. A total of 86 valid results were obtained. The results demonstrate that the base of the section is no older than 119±2Ma and the top is approximately 99±3Ma. These dates are possibly the best time constraints on the section so far. They are generally comparable to the upper part of the Lower Cretaceous Jiuliping, Guantou and the lower part of the Chaochuan formations in neighbouring areas. The zircon ages in combination with new stratigraphic correlation suggest that a transgression most likely took place widely in coastal southeast China during the Aptian–Albian. In addition, the three limestone units in the section are roughly synchronous with high stages of Pacific sea levels, according to the zircon ages (i.e., 113±3Ma, 109±2Ma and 100±2Ma). It appears, therefore, that the transgression may have been caused sea-level changes in the Pacific Ocean. These results have broad implications for regional Cretaceous geological studies in general.

Mesozoic and early Cenozoic tectonic convergence-to-rifting transition prior to opening of the South China Sea

We have investigated Mesozoic geological problems around the South China Sea (SCS) based on gravimetric, magnetic, seismic, and lithofacies data. Three-dimensional analytical signal amplitudes (ASA) of magnetic anomalies clearly define the inland tectonic boundaries and the residual Mesozoic basins offshore. The ASA suggest that the degree of magmatism and/or the average magnetic susceptibility of igneous rocks increase southeastwards and that late-stage A-type igneous rocks present along the coast of southeast China possess the highest effective susceptibility. The geophysical data define Mesozoic sedimentary and tectonic structures and reveal four major unconformities [Pz/T–J, T–J/J, J/K, and Mesozoic/Cenozoic (Pz, Palaeozic; T, Triassic; J, Jurassic; K, Cretaceous)], corresponding to regional tectonic events revealed by nine palaeogeographic time slices based on prior geological surveys and our new fieldwork. Showing both sedimentary and volcanic facies and regional faults, our palaeogeographic maps confirm an early Mesozoic northwestward-migrating orogeny that gradually obliterated the Tethyan regime, and a middle-to-late Mesozoic southeastward migration and younging in synchronized extension, faulting, and magmatism. Three major phases of marine deposition developed but were subsequently terminated by tectonic compression, uplift, erosion, faulting, rifting, and/or magmatism. The tectonic transition from the Tethyan to Pacific regimes was completed by the end of the Middle Triassic (ca. 220 Ma), reflecting widespread Mesozoic orogeny. The transition from an active to a passive continental margin occurred at the end of the Early Cretaceous (ca. 100 Ma); this was accompanied by significant changes in sedimentary environments, due likely to an eastward retreat of the palaeo-Pacific subduction zone and/or to the collision of the West Philippine block with Eurasia. The overall Mesozoic evolution of southeast China comprised almost an entire cycle of orogenic build-up, peneplanation, and later extension, all under the influence of the subducting palaeo-Pacific plate. Continental margin extension and rifting continued into the early Cenozoic, eventually triggering the Oligocene opening of the SCS.

Invasive alien plants increase CH4 emissions from a subtropical tidal estuarine wetland

Methane (CH4) is an important greenhouse gas whose emission from the largest source, wetlands is controlled by a number of environmental variables amongst which temperature, water-table, the availability of substrates and the CH4 transport properties of plants are most prominent and well characterised. Coastal wetland ecosystems are vulnerable to invasion by alien plant species which can make a significant local contribution to altering their species composition. However the effect of these changes in species composition on CH4 flux is rarely examined and so is poorly understood. Spartina alterniflora, a perennial grass native to North America, has spread rapidly along the south-east coast of China since its introduction in 1979. From 2002, this rapid invasion has extended to the tidal marshes of the Min River estuary, an area that, prior to invasion was dominated by the native plant Cyperus malaccensis. Here, we compare CH4 flux from the exotic invasive plant S. alterniflora with measurements from the aggressive native species Phragmites australis and the native species C. malaccensis following 3-years of monitoring. CH4 emissions were measured over entire tidal cycles. Soil CH4 production potentials were estimated for stands of each of above plants both in situ and in laboratory incubations. Mean annual CH4 fluxes from S. alterniflora, P. australis and C. malaccensis dominated stands over the 3 years were 95.7 (±18.7), 38.9 (±3.26) and 10.9 (±5.26) g m−2 year−1, respectively. Our results demonstrate that recent invasion of the exotic species S. alterniflora and the increasing presence of the native plant P. australis has significantly increased CH4 emission from marshes that were previously dominated by the native species C. malaccensis. We also conclude that higher above ground biomass, higher CH4 production and more effective plant CH4 transport of S. alterniflora collectively contribute to its higher CH4 emission in the Min River estuary.

Geochemical characteristics and provenance implication of rare earth elements in surface sediments from bays along Guangdong Coast, Southeast China

A systematic study of the granulometric properties and the occurrence and distribution of rare earth elements (REE) within surface sediments from ten bays situated along the coast of Southeast China has facilitated a more rigorous understanding of constraints on sediment provenance in the area. The results show that REE concentrations are similar within a single bay, but vary considerably (133.58–251.77 mg/kg) among the bays. The chondrite-normalized distribution patterns show the typical enrichment of light REEs (LREEs: La–Eu) relative to heavy REEs (HREEs: Gd–Lu), and an apparent depletion of Eu, which is diagnostic of a terrigenous sediment source. Obvious enrichments of the middle REEs (MREEs: Sm–Ho) in the PAAS-normalized (Post-Archean Australian Shale) distribution patterns of these bay sediments are similar to results reported from large rivers in China. Comparing the REE composition of the bay sediments with those of adjoining fluvial sediments and with the bedrock of the surrounding drainage basins, the latter are indicated as the dominant sediment source. The uniform REE distribution patterns, and MREE enrichments, prove that the sediments are derived from the material transported by the streams and rivers that discharge into the bays.

Current study and prospect of the Old Red Sand along the southeast coast of China

Current study and prospect of the Old Red Sand along the southeast coast of China

An Analysis of Vulnerability to Agricultural Drought in China Using the Expand Grey Relation Analysis Method

The identification of agricultural drought vulnerability is an essential step in addressing the issue of drought vulnerability in the country and can lead to mitigation-oriented drought management. In this study, it developed an approach to estimate vulnerability to agricultural drought based on the expand grey relation analysis method (GRA).The new methodology consists of (1) developing the main influence factors of vulnerability to agricultural drought and converting them into quantitative indicators, (2) constructing the evaluation standards and their relative weights based on the collected data on the values of the indicators from 31 provinces and cities in China, (3) computing the vulnerability to agricultural drought of 31 provinces and cities in China in 2009 using expand GRA method. The results indicated that the vulnerability to agricultural drought in the southeast coast of China with more precipitation and irrigation is lower than the central areas; the most vulnerable areas are the west area with less precipitation and irrigation. Some measures for mitigating the vulnerability to agricultural drought in different areas were proposed.

Effects of Aroclor 1254 on reproductive organ weight, sperm quality and testicular mitochondria oxidative stress of Boleophthalmus pectinirostris

Boleophthalmus pectinirostris is an amphibious economic fish and wildly distributed in the southeast coast of China. In this study, Aroclor 1254 was intraperitoneally injected into B. pectinirostris with 1, 2 and 4 µg/(g·d) for 28 d to assay the reproductive organ weight, the sperm quality (sperm concentration and motility), and the testicular mitochondrial testicular mitochondria oxidative stress. The results show that the sperm number and motility in seminal vesicles, the absolute weight of testes and seminal vesicles of B. pectinirostris treated with 2 and 4 µg/(g·d) Aroclor 1254 decreased significantly as compared to the controls (p <0.05), while those treated with 1 µg/(g·d) Aroclor 1254 had no significant effects on these indictors. For the relative weight of reproductive organs, significant reduction (p <0.05) was only observed in the seminal vesicles of B. pectinirostris treated with 4 µg/(g·d). SOD activities and GSH levels in all the Aroclor 1254 treatments were significantly lower than those of the controls (p <0.05). The activities of CAT, GPx, GR and the levels of Vit C also decreased significantly in comparison with the controls (p <0.05) at the higher dose of 2 and 4 µg/(g·d) Aroclor 1254 treatments. In addition, both H2O2 level and MDA content in testicular mitochondria of B. pectinirostris had a close correlation with Aroclor 1254 dosage, and were significantly higher than the controls (p <0.05). Those indicate that Aroclor 1254 can induce the oxidative stress of testicular mitochondria, and impair the reproductive function of male B. pectinirostris.

East Asian Precipitation Pattern: Competition Between Monsoon and Transient Eddies

AbstractThis paper aims at investigating climate integrated column moisture transport (MT in brief hereafter) over the troposphere for 1971~2000 and the relationship between the MT divergence and seasonal precipitation in East Asia. The result made from ERA‐40 shows that the spatial pattern of the precipitation is approximately coincided with large‐scale MT divergence. A further decomposition manifests that the monthly‐wind moisture transport (MMT) is the dominant role for seasonal divergence patterns. The MMT convergence areas approximately fit the big precipitation areas, while its divergence almost covers the arid and semi‐arid zones in Northwest China and Mongolia. The transient eddy moisture transport (EMT) is about ten times smaller than MMT's in magnitude and plays a key role in the MT northward during the non‐monsoon period. Usually, the EMT divergence is of inverse phase to MMT's, suppressing the MMT impact on precipitation in summer monsoon zones, and it is the major one that supplies water vapor to the precipitation in arid and semi‐arid zones. However, their divergences are compatible and overlapped in phase around the phase transition belt of the MT divergence. It turns out that large‐scale precipitation characteristics greatly rely on the competition of the MMT and EMT, being the physical cause that leads to a specific pattern of the large‐scale precipitation. Besides, the mechanism of regional climate formation also implies possible mechanism of regional precipitation change. A case study shows that the severe floods in both the Yangtze River basin and Songhuajiang‐Nenjiang River basin in 1998 were resulted from anomalous MMT convergence with the monsoon MT, while both the MMT and EMT divergences led to anomalous dry climate in the north and the northwest of China. In addition, it is the strong EMT divergence resulting in significant rainfall reduction in south part of North China and the southeast coast of China. One could also make a further investigation on the causes that lead to the anomalies of the MMT or the EMT, or both. This is a new way for exploring the mechanism of regional climate change.

Research on Countermeasures Used in Low-Carbon Economy to Promote the Sustainable Development in Fujian Province of China

Low-carbon economy is a new path which our country is taking to develop economy. As one of the provinces in the southeast coast of China, Fujian develop a low-carbon economy directly relating to the transformation of its economic growth, conservation of energy, improvement of productivity, innovation of technology and so on. We can say that the development of low-carbon economy directly affects the sustainable development of economy and society in Fujian province of China. Therefore, firstly, we believe that government and enterprise should optimize the allocation of resource and improve the utilization of resource. Secondly, the tax policies are supposed to adjust to stimulate the development of environmental protection industry. Thirdly, government should accelerate the construction of infrastructures. Fourthly, the legal system needs to be built and perfected so as to promote the development of low-carbon economy. At last, the investment of techniques is supposed to increase to a certain degree, and the ability of innovation and management of enterprises should be promoted to adapt the development of low-carbon economy of Fujian province.

Levoglucosan and carbonaceous species in the background aerosol of coastal southeast China: case study on transport of biomass burning smoke from the Philippines

Levoglucosan and carbonaceous species in the background aerosol of coastal southeast China were measured at Jianfengling (JFL), a background mountain site in a National Reserve Park on Hainan Island, and at Hok Tsui (HT), a rural site on the southern coast of Hong Kong from April to May of 2004 during an intensive field study. We integrated the information from field study, satellite and backward trajectory model to examine the long-range transport of biomass burning smoke from the Philippines and assess its impact on background aerosol in coastal southeast China. The average levoglucosan concentrations were 42 and 30 ng m(-3) at JFL and HT, respectively, while the organic and elemental carbon concentrations were 3.1 and 0.4 μg C m(-3) respectively at JFL, and 4.1 and 1.3 μg C m(-3) respectively at HT. Elevated levoglucosan concentrations of 85-106 ng m(-3) (250-340% extra loadings) at JFL and 57 ng m(-3) (170% extra loading) at HT were observed during transport events in which air masses originated from the Philippines. Fire hot spot counts and aerosol index derived from satellite data showed that the spread of biomass burning smoke from the Philippines resulted in large-scale dense aerosol clouds in the adjacent South China Sea and the western Pacific Ocean. The observed high ratio of two biomass-burning tracers (levoglucosan to mannosan) at JFL (7-36) and HT (27) indicated that the biomass smoke originating from the Philippines had significant contributions from open-field burning of agricultural residues, such as rice straw. The pollution plumes were transported to southeast China resulting in elevated concentrations of carbonaceous aerosol and levoglucosan in particular. Using a simplified receptor-based approach, biomass smoke aerosol was estimated to account for 16-28% of OC in the background atmosphere of Hainan and 4.9% of OC at the rural site of Hong Kong during these episode cases, indicating that biomass burning smoke generated in the Philippines could have a significant contribution to background ambient aerosol of southeast coastal China.

Contrasting nutrient stocks and litter decomposition in stands of native and invasive species in a sub-tropical estuarine marsh

We compared the influence of invasion by an alien invasive species ( Spartina alterniflora, smooth cordgrass) and a native aggressive species ( Phragmites australis, common reed) as they have expanded into the native Cyperus malaccensis (shichito matgrass)-dominated wetland ecosystem in the Min River estuary of southeast China. S. alterniflora is a perennial grass native to North America, which has spread rapidly along the southeast coast of China since its introduction in 1979. Our study compared the above and belowground biomass, net primary production, litter decomposition, plant nutrient stocks and soil organic carbon storage of the grasses in three ecosystems: (1) the native ecosystem dominated by C. malaccensis; (2) ecosystems previously dominated by C. malaccensis but presently replaced by P. australis; and (3) ecosystems previously dominated by C. malaccensis but presently replaced by S. alterniflora. Our results demonstrate that the recent invasion (3 years) of the exotic invasive species S. alterniflora has already significantly increased live aboveground biomass and aboveground plant nutrient stocks. However, there was no significant difference in these variables between native aggressive species P. australis and native C. malaccensis. The majority of belowground root Carbon (C), Nitrogen (N) and phosphorus (P) stocks of the three plant species were all distributed in the upper surface layer and there was a decrease with soil depth. There was little difference in litter decomposition rates among the three grass species; they were ranked in the following order: C. malaccensis>S. alterniflora> P. australis. Litter element concentration showed similar patterns for the three species. However, important differences were found between N and P; the litter N concentrations in each of the three species were greater at the end of the 280 days decomposition than at the start, but P concentrations followed a fluctuating pattern during the decomposition period. Soil organic carbon stocks (0–50 cm) under S. alterniflora, P. australis and C. malaccensis stands were statistically indistinguishable, which may be due to the invasion of S. alterniflora having been a relatively recent phenomenon. Thus, recent invasion of the exotic species S. alterniflora has already altered the nutrient cycle of C. malaccensis in the ecosystem in the Min River estuary.

Selection on the Human Bitter Taste Gene, TAS2R16, in Eurasian Populations

Bitter taste is one of the most important senses alerting humans to noxious foods. In gatherer communities, sensitivity to bitterness is presumably advantageous because of various noxious plants. TAS2R16 is the gene coding the taste receptor molecules for some of the most common toxins in plants. A previous study of this gene indicated selection has increased the frequency of a derived allele in this gene that arose before the human expansion out of Africa. We have applied a different methodology for detecting selection, the Long Range Haplotype (LRH) analysis, to TAS2R16 in a larger sampling of populations from around the world. The haplotype with the derived alleles at both the functional polymorphism and a polymorphism in the regulatory region of TAS2R16 showed evidence for recent positive selection in most of the Eurasian populations, though the highest selection signal occurs in Mbuti Pygmies, an African hunter-gatherer group. In Eurasia, only populations of Mesopotamia and the southeast coast of China have no signals of selection. The evidence of recent selection found in most Eurasian populations differs from the geographic pattern seen in the earlier study of selection. One can speculate that the difference may result from a gathering lifestyle extending into the most recent 10,000 yrs and the need to recognize newly encountered bitter natural toxins as populations expanded into new environments and the biota changes with the ending of the most recent ice age. Alternatively, the promoter region variant may be a marker for altered function beyond what the derived amino acid allele conferred.

Selection on the Human Bitter Taste Gene, TAS2R16, in Eurasian Populations

Bitter taste is one of the most important senses alerting humans to noxious foods. In gatherer communities, sensitivity to bitterness is presumably advantageous because of various noxious plants. TAS2R16 is the gene coding the taste receptor molecules for some of the most common toxins in plants. A previous study of this gene indicated selection has increased the frequency of a derived allele in this gene that arose before the human expansion out of Africa. We have applied a different methodology for detecting selection, the Long Range Haplotype (LRH) analysis, to TAS2R16 in a larger sampling of populations from around the world. The haplotype with the derived alleles at both the functional polymorphism and a polymorphism in the regulatory region of TAS2R16 showed evidence for recent positive selection in most of the Eurasian populations, though the highest selection signal occurs in Mbuti Pygmies, an African hunter-gatherer group. In Eurasia, only populations of Mesopotamia and the southeast coast of China have no signals of selection. The evidence of recent selection found in most Eurasian populations differs from the geographic pattern seen in the earlier study of selection. One can speculate that the difference may result from a gathering lifestyle extending into the most recent 10,000 yrs and the need to recognize newly encountered bitter natural toxins as populations expanded into new environments and the biota changes with the ending of the most recent ice age. Alternatively, the promoter region variant may be a marker for altered function beyond what the derived amino acid allele conferred.

Application Prospect and Advantages of Power Supply System Based on 20kV Power Distribution Network and Microgrid in China

In view of high-load density, abundant in wind power and solar energy resources and well-developed areas in the southeastern coastal areas of China, A great number of power system planning problems have emerged. This paper first analyzes the limitations of electric power supply with 10kV voltage level and the advantages of using 20 kV voltage level in distribution network, and then it introduces the status and disadvantages of regenerative energy power to be incorporated into the large grid along the southeast coast of China at present. Finally it is discussed that the advantages of establishing the power supply system based on 20kV power distribution network and Microgrid according to the new resources distribution and the existing problems of medium voltage power distribution in southeast China.

Evaluation of potential hazards from teletsunami in China: Tidal observations of a teletsunami generated by the Chile 8.8 M w earthquake

At 14:34 Beijing time on February 27, 2010, an earthquake of M w 8.8 rocked the central coast of Chile. A teletsunami was triggered by the huge earthquake and then propagated across the entire Pacific in less than 24 h. The initial tsunami wave arrived at the southeast coast of China at 16:20 on February 28 and was recorded in real time by a number of tidal gauges off mainland China and Taiwan Province. The teletsunami waves have never been recorded with such a broad geographical scope in China before this event. The aim of the present work is to report the first description of sea-level oscillations generated by the Chile tsunami, and evaluate the potential hazards that teletsunami poses to the coast of China. The results reveal that the east coast of Taiwan Province, Zhejiang Province and the north coast of Fujian Province are vulnerable to transoceanic tsunami. In addition, spectral and wavelet analysis of the recorded sea-level oscillations shows that “seiches” are easily excited by the resonance resulting from the interaction between the initial tsunami waves and local geometry (such as semi-enclosed bays and ports). The superimposition of the two oscillations would amplify the wave height further.

Antifouling activity of marine sessile organisms from China against barnacle settlement

The antifouling activity of a series of hexane, ethyl acetate, ethanol and aqueous extracts from 11 species of marine sessile organisms collected from the south-east coast of China was investigated. Settlement inhibition of cyprid larvae of the barnacleBalanus albicostatuswas used to evaluate their antifouling efficacy. Screening of the 44 extracts showed antifouling activity in 90.9% of the hexane extracts followed by 90.9% of the ethyl acetate, 72.7% of the ethanol and 36.4% of the aqueous extracts. The hexane extracts ofTubularia mesembryanthemum, Notarcus leachii cirrosusandStyela canopus, the ethyl acetate extracts ofBugula neritinaandN. leachii cirrosus,and the ethanol extracts of B. neritinaandAnthopleura sp.were the most active in inhibiting the settlement ofB. albicostatus, with EC50values all below 50 μg/ml. At least one of the four extracts of each tested species exhibited antifouling activity, suggesting that all 11 marine sessile organisms contained antifouling substances and they may have evolved chemical defences against biofouling on their surfaces.

The T-TREC technique for retrieving the winds of landfalling typhoons in China

In this study, an extension of the TREC (Tracking Radar Echo by Correlations) technique, named Tropical Cyclone (TC) circulation TREC (T-TREC), is developed to retrieve the winds of landfalling typhoons in China. The T-TREC analysis is performed on a polar grid centered at the TC center, using arc-shaped correlation cells and an arc-shaped search area. The search for the best correlation match is confined along the cyclonic direction with a limited search distance in the radial direction based on the cyclonic circulation characteristics of TCs in the Northern Hemisphere. The TC center is determined objectively using reflectivity data while the Doppler radar radial velocities are incorporated to estimate the search range and create a velocity correlation matrix as auxiliary constraints. The T-TREC was applied to the landfalling Typhoon Saomai (0608) observed by Chinese next generation Weather Surveillance Radar 1998 Doppler (CINRAD WSR-98D) on the southeast coast of China. The results show that the T-TREC has the ability to estimate the typhoon circulation with an average bias of < 4 m s−1. The incorporation of radial velocity data could distinctively improve wind retrievals for intense typhoons, especially by reducing the underestimation caused by fairly uniform reflectivity patterns in the vicinity of the eyewall and the outer rainband. A quantitative evaluation of the influence of typhoon center and cell size on the wind estimation demonstrates that the quality of the T-TREC retrieved wind circulation depends on the estimation of the typhoon center. A 4-km deviation of the TC center may result in a 10% increase in the retrieved wind error. The effect of cell size depends on the typhoon scale: better wind retrieval results can be obtained for a smaller typhoon.

Levoglucosan enhancement in ambient aerosol during springtime transport events of biomass burning smoke to Southeast China

An intensive field experiment was conducted at an urban and a rural site in Hong Kong to identify the influence of biomass burning emissions transported from distinct regions on ambient aerosol in coastal southeast China. Watersoluble ionic and carbonaceous species, specifically the biomass burning tracer levoglucosan, were analysed. Elevated levoglucosan concentrations with maxima of 91.5 and 133.7 ng m-3 and overall average concentrations of 30 and 36 ng m-3 were observed at the rural and urban sites, respectively. By combining the analysed meteorological data, backward trajectories, fire counts and Aerosol Index from the Earth Probe satellite, southwest China and the northern Philippines, together with the southeast China coast, were identified for the first time as source regions of the transported biomass burning particles at the surface level in rural Hong Kong. Occasional levoglucosan enhancements observed at urban Hong Kong were attributed to local incense and joss paper burning during the Ching-Ming festival period. The contributions of transported biomass burning emissions, especially from the northern Philippines, were estimated to account for 7.5% and 2.9% of OC and PM2.5, respectively.

Morphodynamics of a boulder beach, Putuo Island, SE China coast: The role of storms and typhoon

In this paper we examine the sedimentological properties and morphodynamic evolution of a boulder beach at Huayanpeng Cape on Putuo Island off the southeast China coast. Focus is given to the formation of the boulder beach (256–2000 mm diameter) and resulting morphology in relation to high-energy storms and seasonal typhoon. Holocene sea level rise to the present position at ca. 7000–6000 yrs BP provides a long term window for the formation of the beach. The beach is primarily characterized from east to west by: 1) the convex to concave beach morphology, 2) reduced longest axis of the skeleton boulders, 3) decreased flatness of the skeleton boulders, and 4) greater sphericity of the skeleton boulders. Infilling cobbles/pebbles in the beach demonstrate a bi-modal distribution, corresponding to dominant sizes of 100–250 mm and 50–100 mm in diameter, on the eastern beach and western beach, respectively. This reflects changed intensity of storm waves alongshore. Multiple-peaks of the distributions of infilling clasts for the western beach (supratidal) probably reflect storm and calm weather sedimentation. Statistically, both the skeleton boulders and infilling clasts follow a β-distribution, reflecting the high-energy control of beach formation and the dominance of crushing in boulder size reduction. A boulder transport model applied in the present study further reveals that boulders with an a-axis length of 500–1000 mm (the dominant component on the beach) move under a wide range of wave conditions depending on wave height and wave period with a cluster of critical wave heights in the range 2–6 m and wave periods of 5–15 s.

5-Year study of rainwater chemistry in a coastal mega-city in South China

South China is one of the major regions suffering from acid rain in the world, especially for its urban environments. However, long-term and comprehensive studies on rainwater chemistry in this region have been scarce in the literature. In order to characterize the current acid rain status in South China, a total of 208 rainfall events were collected and measured systematically at an urban site in Shenzhen, a mega-city on the southeast coast of China, from 2005 to 2009. The volume-weighted mean (VWM) pH was observed to be 4.56 during the five years, with an acid rain frequency of 84.6%. SO 4 2− was the most abundant ionic species, followed by Ca 2+, NH 4 +, H +, NO 3 −, Cl −, Na +, Mg 2+, K + and F − in sequence. Formic, acetic and oxalic acids together contributed 2.32% to the total organic carbon (TOC) content and 2.86% to the total free acidity. SO 4 2−, NO 3 −, Ca 2+, NH 4 + and TOC presented a seasonal trend of being lower in summer and higher in winter, while the other species did not show clear seasonal patterns. Based on the dataset, the sources of the species in rainwater in Shenzhen were explored using different statistical techniques, which indicated strong impact of anthropogenic pollution on the rainwater chemistry in this area.