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Background: A minority of children experience in-hospital recurrence of intestinal intussusception after treatment. This study investigated the factors associated with in-hospital recurrence of intussusception in pediatric patients in China. Methods: This retrospective study included patients aged 0–18 years-old with intestinal intussusception treated at Hainan Women and Children's Medical Center between January 2019 and December 2019. Demographic and clinical characteristics were extracted from the medical records. Factors associated with in-hospital recurrence of intussusception were identified by logistic regression analysis. Results: The analysis included 624 children (400 boys) with a median age of 1.8 years (range, 2 months and 6 days to 9 years). Seventy-three children (11.7%) had in-hospital recurrence of intussusception after successful reduction with air enema. Multivariate logistic regression analysis identified age > 1 year-old (odds ratio [OR]: 7.65; 95% confidence interval [95%CI]: 2.70–21.71; P < 0.001), secondary intestinal intussusception (OR: 14.40; 95%CI: 4.31–48.14; P < 0.001) and mesenteric lymph node enlargement (OR: 1.90; 95%CI: 1.13–3.18; P = 0.015) as factors independently associated with in-hospital recurrence of intussusception. Conclusions: Age > 1 year-old, secondary intussusception and mesenteric lymph node enlargement were independently associated with increased odds of in-hospital recurrence of intussusception after successful reduction with air enema. [ABSTRACT FROM AUTHOR]

Objective: To explore the current status and influencing factors of quality of life in patients with lung cancer after surgery in a tertiary hospital in Hainan province. Methods: To investigate the influencing factors of quality of life of lung cancer patients after surgery in a tertiary hospital in Hainan province by cross-sectional survey method. Results: The scores of insomnia, appetite loss, constipation and pain in 186 lung cancer patients after surgery in a tertiary hospital in Hainan Province were significantly higher than the reference value. Multiple linear regression analysis showed that older patients (> 60 years) had lower scores in physical function domain (β=-0.193), and female patients had more appetite loss symptoms (β=0.245). Compared with other minority ethnic groups, Han ethnic group had lower scores in role function domain (β=0.179), more severe fatigue symptoms (β=-0.162), and higher general health level (β=0.166). Patients with employee medical insurance had lower scores of emotional function (β=0.194), cognitive function (β=0.281), the lowest score in social function (β=0.188), and severe pain in other parts (β=-0.227). Smokers had less cough symptoms (β=0.175) and more arm and shoulder pain symptoms (β=-0.21) than non-smokers. Patients with secondhand smoke exposure had lower cognitive function scores (β=-0.158) and more obvious symptoms of oral ulcer (β=0.185). Patients who drank alcohol frequently (drinking frequency > 1 time/day) had more severe cough symptoms (β=0.27). Patients with small number of children (0-1) had milder cough symptoms (β=0.178). Patients who did not understand the disease had obvious symptoms of arm and shoulder pain (β=0.151). Patients with early pathological stage (stage I-II) had more severe shortness of breath (β=- 0.159) and pain (β=-0.181). The symptoms of appetite loss were more obvious in patients living in cities (β=0.192). The symptoms of peripheral neuropathy were more obvious (β=0.174). Patients who often consumed pickulated food had severe pain symptoms (β=- 0.219), and pain in other parts was obvious (β=-0.149). Male patients had obvious alopecia symptoms (β=-0.306). Conclusion: Age, ethnicity, residence, type of medical insurance, number of children, pathological stage of lung cancer, smoking, second-hand smoke exposure, alcohol consumption, and frequent consumption of pickled food were related to the quality of life of lung cancer patients in hospital after surgery. Medical staff and family members should pay attention to the emotional communication of patients during the treatment of lung cancer patients in hospital after surgery. Patients should avoid exposure to smoking, alcohol and second-hand smoke, and reduce consumption of pickled food. [ABSTRACT FROM AUTHOR]

Degradation processes on coral reefs are associated with changes in macroalgal assemblages. In this study, a floristic study of the macrophyte species on coral reefs along a pollution gradient at 3 transects in southern Hainan Island, China, was conducted in April 2014. A total of 73 benthic macroalgal taxa were collected, of which 58% were reds, 23% browns and 19% greens. Along with the distance away from the outlet of fish farms, macroalgal species richness increased significantly from 40 species to 71 species. However, macroalgal biomass decreased from 1.58 kg m−2to 1.1 kg m−2. Brown blooms ofChnoospora implexa,Padina australis, Sargassum polycystumandS. sanyaensechanged to green blooms ofUlva lactucaandCaulerpa racemosafrom moderately polluted sites to severely polluted sites close to the outlet. This study supports the results that severe pollution can lead not only to a significant decline of macroalgal species richness and changes in macroalgal assemblages, but also to the occurrence of green blooms. This study will hopefully provide more accurate cases to link nutrient pollution to changes in benthic organisms on coral reefs. [ABSTRACT FROM AUTHOR]

Abstract: The structure and function of coastal ecosystems is affected by land-based human activities, including changes in water, sediment and pollutant input, as well as land reclamation in coastal areas. Many coastal areas can be considered over-stressed systems as a whole, the ecosystem services of which are strongly impaired. This is particularly important in tropical regions, where the coastal zone is under the influence of a strong climate variability including monsoons and frequent extreme weather events, such as typhoons. During the past decades the continuous development of Hainan’s coastal zone and its hinterland, in combination with episodic natural events (e.g., typhoons), caused environmental changes in its coastal ecosystems. However, little is known on the consequences of environmental changes for the biogeochemistry and ecology and, hence, the natural resources of the Hainan coastal ecosystems. The Sino-German inter-disciplinary LANCET (land–sea interactions along coastal ecosystems of tropical China: Hainan) project was designed to address these issues on a local to regional scale and at the same time, to contribute to the global data base in which this type of information from tropical regions is still under-represented. The results obtained from LANCET have been delivered to the local government for an adaptive management at the ecosystem level, and the knowledge is believed to be relevant to other studies of tropical and coastal regions. [Copyright &y& Elsevier]

Mangrove-derived dissolved organic matter (DOM) has an important effect on estuarine and coastal area on a large scale. In order to improve the understanding of origin, composition, and fate of DOM in mangrove-fringed estuarine and coastal areas, dissolved humic substances (DHS) were isolated from one mangrove pore-water sample and one near-shore seawater sample downstream the mangrove pore-water site in the eastern coast of Hainan Island, South China. Fulvic acids, humic acids and XAD-4 fractions were obtained from the two water samples by using a two-column array of XAD-8 and XAD-4 resins. Chemical and spectroscopic methods were used to analyze the features of these DHS. Compared to the mangrove pore-water DHS, the near-shore seawater DHS were found rich in C with lower C/N ratios and more aliphatic compounds and carbohydrates, but less aromatic structures and carboxyl groups. As for the three fractions of the two DHS, XAD-4 fractions contain more aliphatics, carbohydrates, carboxyl groups, and enrich in C with respect to both fulvic and humic acids. Photo-oxidation transformation and contribution from marine-derived DOM were considered as the main reasons resulted in the difference in compositional features for these DHS in this study. [ABSTRACT FROM AUTHOR]

The diffuse coevolution between two moth species (Epicephala lativalvaris and E. mirivalvata) and two plant species (Breynia fruticosa and B. rostrata) is reported based on field observations and indoor experiments conducted in Hainan and Fujian, China. Study results showed that the two Epicephala species jointly pollinated the two Breynia species, which led to a unique obligate pollination mutualism of two2to2two species specificity. A single Epicephala larva exclusively fed on seeds of host plants and developed to maturity by consuming all six seeds of each fruit, whereas a fraction of intact fruits were left to ensure the reproduction of plants within the whole population. Larvae of the two Epicephala species are competitive for resources; the population of E. mirivalvata is much smaller than that of E. lativalvaris, which has resulted from the differences in the female ovipositor structures and oviposition mode. The life history of Epicephala species highly coincides with the phenology of Breynia plants, and different phenology of B. fruticosa resulted in the different life history of the two Epicephala species in Hainan and Fujian. The natural hybridization of two host plants, possibly induced by the alternate pollination of two Epicephala species, is briefly discussed. [ABSTRACT FROM AUTHOR]

Scyphiphora hydrophyllacea Gaertn. f. (Rubiaceae) is an endangered mangrove species found in China, and its only known location is in Hainan Island. Previous studies conducted on S. hydrophyllaceae have mainly focused on its location, biological characteristics, and medical effects. However, to date, there has been no published report regarding the genetics or genome of this endangered mangrove species. In this study, we developed valuable chloroplast genome-related molecular resources of S. hydrophyllaceae by comparing with it related Rubiaceae species. The chloroplast genome of S. hydrophyllaceae was found to be a circular molecule with a total size of 155,132 bp, and it is observed to have a quadripartite structure. The whole chloroplast genome contains 132 genes, of which 88 and 36 are protein-coding and transfer RNA genes, respectively; it also contains four ribosomal RNA genes with an overall GC content of 37.60%. A total of 52 microsatellites were detected in the S. hydrophyllacea chloroplast genome, and microsatellite marker detection identified A/T mononucleotides as majority simple sequence repeats in all nine Rubiaceae chloroplast genomes. Comparative analyses of these nine chloroplast genomes revealed variable regions, including matK, rps16, and atpF. All nine species shared 13 RNA-editing sites distributed across eight coding genes. Phylogenetic analyses based on the complete sequences of the chloroplast genomes revealed that the position of S. hydrophyllaceae is closer to the Coffeeae genus than to Cinchoneae, Naucleeae, Morindeae, and Rubieae in the Rubiaceae family. The genome information reported in this study could find further application in the evolution and population genetic studies, and it helps improve our understanding of the endangered mechanism and the development of conservation strategies of this endangered mangrove plant. [ABSTRACT FROM AUTHOR]

Abstract: Dissolved and particulate cadmium, copper, iron, lead, cobalt and nickel were analyzed in surface waters of the Wanquan River estuary and the Wenchang/Wenjiao River estuary in East-Hainan Island during the dry season (December 2006) and two wet seasons (August 2007 and July/August 2008). A major difference to other Chinese rivers was the very low concentration of suspended particles in these tropical Hainan estuaries. In the dissolved phase, a positive deviation from the theoretical dilution line was observed for Cd during different expeditions. Dissolved Cu and Ni essentially behaved conservatively, while Fe, Pb and partly also Co correlated in their negative deviation from simple mixing. Strong seasonal variability was observed only for dissolved Fe, Pb and Cd: sorption by the much higher loading with suspended particles during the dry season lead to a strong lowering of dissolved Fe and Pb, while the opposite was observed for dissolved Cd. In both estuaries all six metals in particulate form showed almost constant values with a tendency for slight decreases along the salinity profile. The normalization to particulate Al revealed some specific particle properties during the different expeditions. The dynamics of Fe chemistry dominated the distribution of Pb in all forms. The distribution coefficients KD showed a general decrease in the order Fe>Pb>Co>Ni>Cu≈Cd. There was no “particle concentration effect”; rather the KD’s of Fe and Pb exhibited slightly positive correlations with the suspended particle loadings. Elevated concentrations levels in the Wenchang/Wenjiao river estuary, especially during the wet season 2008, were ascribed to diffuse inputs from aquaculture ponds which girdle the upper estuary. In comparison to major Chinese rivers, the tropical Hainan estuaries (S>0) showed similar levels for Cd, Cu, Pb, Co and Ni in particles and solution, while Fe was enriched in both matrices. On a global scale, neither in the Wanquan river estuary nor in the Wenchang/Wenjiao river estuary significant trace metal contamination was observed. [Copyright &y& Elsevier]

Abstract: Radionuclides (i.e., 7Be and 210Pb) can be used to trace particle and sediment dynamics and to quantify coastal oceanic processes with time scales ranging from a few days to a hundred years. Here, we study the settling dynamics of suspended particles and the implication by sedimentary heavy metals in the Wenjiao/Wenchang River and Wanquan River estuaries through the measurement of the particulate 7Be and 210Pb nuclides. Activity in the particulate phase had a range of 2.1–54.5 and 4.6–67.9 Bq kg−1 for 7Be and excess 210Pb (210Pbxs), respectively, in the Wenjiao/Wenchang River estuary. In the Wanquan River estuary, activity is in the range of 1.2–43.5 Bq kg−1 for 7Be and 6.2–194.5 Bq kg−1 for 210Pbxs. At the same time, activity in the dissolved phase had a range of 0.46–1.26 and 0.30–1.17 Bq m−3 for 7Be and 210Pb, respectively, in the Wenjiao/Wenchang River estuary; ranges of 0.10–2.31 and 0.09–1.87 Bq m−3 for 7Be and 210Pb, respectively, were observed in the Wanquan River estuary. The distribution coefficients (Kd ) for the two nuclides decreased within increased in suspended particle matters (SPM) concentration and/or salinity in Wanquan River estuary. The residence times of particulate 7Be and 210Pbxs had ranges of 0.4–1.6 and 1.65–5.15 days, respectively, in the Wenjiao/Wenchang River estuary; and ranges of 0.02–3.2 and 0.61–4.44 days, respectively in the Wanquan River estuary. All residence times for the two nuclides increased in the seaward direction. In the Wenjiao/Wenchang River estuary, we found that 11.8–21.0% of Cu, 3.0–9.0% of Zn and 43.2–69.9% for Cd is removed from the water column and deposited into the estuary, and 24.2–34.8% for Cu, 7.2–23.8% for Zn, and 70.0–82.5% for Cd in the Wanquan River estuary, respectively. [Copyright &y& Elsevier]

Surface and core sediments were collected off the eastern coast of Hainan Island (South China Sea), and a sequential extraction method (SEDEX) was used to separate and quantify five sedimentary phosphorus (P) reservoirs: exchangeable or loosely sorbed P (Ex-P), iron-bound P (Fe-P), authigenic P (Ca-P), detrital P (De-P) and organic P (OP). Total P (TP) in the surface and core sediments ranged from 7.96 to 22.34 µmol g −1 , and was dominated by inorganic P (IP). De-P and Ca-P were the main chemical species of P in surface and core sediments. The distribution of the P species in surface and core sediments was governed by various factors, including terrigenous input, biological processes, Fe oxides/hydroxides, organic matter degradation, and sediment grain size. The organic carbon (OC)/OP ratio ranged from 37 to 293 (average, 107±58) in surface sediments, suggesting that the organic matter in sediments had been subject to degradation and comprised mostly refractory compounds. The OC/P reactive ratio (37–69) was relatively low in the core sediments, suggesting an excess of sedimentary reactive P compared with OC. The Fe/P ratio ranged from 2 to 19 in surface and core sediments, which indicates that the higher proportions of the crystalline phases occurred in estuarine areas relative to the offshore areas. The potential bioavailable P accounted for 20.3–54.2% of TP in the surface and core sediments. [ABSTRACT FROM AUTHOR]

Summary Tropical river systems affected by climatic extremes (typhoon) are recognized as significant source of particulate organic matter (POM) delivered to their adjacent seas. Studies on POM composition in typhoon affected rivers of tropical Hainan Island are limited. The Nandu River-Estuary (NRE) is the largest river system on Hainan Island in the South China Sea, affected by frequent typhoons every year. We used elemental contents, stable isotope ratios of organic carbon and lignin phenols to characterize POM compositions in NRE during typhoon affected wet season (August, 2011) vs. normal wet season (October, 2012). Short term and heavy precipitation during typhoon in August, 2011 was evidenced with a significant hydrologic change as well as change in POM composition along the NRE. The multi-proxy results suggest that POM was degraded and their sources significantly changed along the NRE hydrograph. Results from an end member mixing model indicated that POM constituted nearly similar OM input from soil (35%) and freshwater plankton (32%) during August, 2011, in contrast POM dominated with OM from freshwater plankton (51%) during October 2012 in riverine regions of NRE. In the estuarine region, POM constituted dominant inputs from marine plankton during August, 2011 (44%) and October, 2012 (56%) as compared to other sources. Collectively, the nature of POM composition change in the vicinity of typhoon induced copious precipitation, with potential land-use intervention across the Hainan Island are key factors affecting the carbon cycling in NRE and adjacent South China Sea. [ABSTRACT FROM AUTHOR]

Near-shore coral reefs in northeastern Hainan Island are close to river mouths and aquaculture ponds, and also located at the center of the Qiongdong Upwelling (QDU). However, it is still unclear how terrestrial runoff and upwelling influence the community composition and spatial distribution of the benthos. During three cruises in 2010 and 2011 in Wenchang, northeastern Hainan Island, we determined a subset of environmental parameters in seawater (e.g. temperature, salinity, DO, dissolved inorganic nutrient (DIN), turbidity and transparency) and macroalgal δ 15 N and investigated the benthic communities (e.g. live coral cover, coral species richness, juvenile coral density, macroalgal cover and coverage of calcified algae) by video transect and visual census techniques at 10 stations (i.e. 1S–6D). The results showed that the QDU has influenced the reef waters in Wenchang. In 2011, the upwelling started in early May, peaked in July and disappeared in September and most upwelling events lasted for 1–2 weeks between May and July. The results also demonstrated that the reef water was nutrient enriched. Stations close to the river mouth and aquaculture ponds had higher levels of DIN and a higher percentage of ammonia in DIN, and there was consistently lower live coral cover, juvenile coral density and higher macroalgal cover. At some stations in this study, live coral cover was negatively correlated with macroalgal cover (i.e. 2S–6D). Live coral cover, species richness, and juvenile coral density all increased with the distance away from the river outlet and decreased with the rise of DIN. These results suggest that terrestrial runoff and upwelling stimulate nutrient enrichment, and that overgrowing macroalgae has an important influence on the coral communities in northeastern Hainan Island. [ABSTRACT FROM AUTHOR]

High-resolution seismic surveys were conducted off the eastern coast of Hainan Island to study the distribution and mass budget of Holocene subaqueous clinoform sediments. The Holocene subaqueous clinoform extends 45 km seaward across the shelf and more than 80 km northeastward along the shore. It covers an area of over 3,000 km2, which is almost equivalent to the expansion of large river systems. Overlying the transgressive surface, the deltaic sequence can be divided into a transgressive unit and a highstand unit separated by a downlap maximum flooding surface. The volume of sediments within the Holocene subaqueous clinoform is estimated to be 33.12×109 m3, equivalent to an annual accumulation of 3.61–3.31 Mt/yr, which is substantially higher than the global average. The high sediment yield presumably resulted from strong tropical weathering and active tectonics. The sediment flux during the transgression and sea-level highstand were 3.85–3.08 and 3.47 Mt/yr, respectively, suggesting no substantial changes in sedimentation. Compared to river systems originating from high mountain glaciers, the sedimentation variation of small tropical rivers throughout the Holocene is relatively minor. However, the sediment discharge of the Wanquan River has drastically decreased in recent decades because of increased human activity. • A largescale subaqueous delta off eastern Hainan is revealed, up to 30 m in thickness • Terrigenous sediments can be transported seaward up to 45 km • There is no substantial sediment flux difference between transgression and highstand • Recent human activities have resulted in 80% decrease in riverine sediment load [ABSTRACT FROM AUTHOR]

Abstract: Hainan''s coast provides favorable climatic, geochemical and biogeographic conditions for the development of extensive coral reefs in China. Observations in five reefs along the NE coast of Hainan showed, however, that the overall density of mobile macrofauna is low and key functional groups such as browsing, scraping or excavating herbivore fish are missing altogether. Coral diseases, partial mortality or tissue degradation are abundant and growth of macroalgal space competitors extensive. Signs of eutrophication, siltation and destructive fishing practices are evident resulting in a strongly altered environment unfavorable for coral recruitment success and survival. Acclimation to the anthropogenically altered conditions in the massive coral Porites lutea occurs at the cost of a decreased photosynthesis: respiration ratio reducing the regenerative capacity of these key framebuilding organisms. Even though, on the organismal level, corals are able to cope with these stressful conditions, a shift is imminent on the ecosystem level from a coral reef to a macroalgae-dominated community if land-based disturbance prevails unabated. [Copyright &y& Elsevier]

Abstract: The small tropical Wenchang and Wenjiao Rivers on the island of Hainan, tropical China, are affected by effluents from municipal sewage, aquaculture and agriculture, and by contrasting hydrological regimes related to monsoon and tropical storms. In order to obtain information on the sources, transformation and fate of organic matter (OM) we investigated the amount and composition of amino acids and hexosamines as well as the carbon isotope composition in suspended particulate matter (SPM) from the Wenchang/Wenjiao Estuary. SPM was collected along the salinity gradient starting from the river sites, along the lagoon-shaped Bamen Bay to coastal waters during four sampling campaigns between 2006 and 2009. SPM concentrations ranged between 4.7 and 58.2mgL−1. Apart from highest values after heavy rain events in spring and summer, SPM showed little seasonal variation, but increased with salinity. From SPM POC% (1.2–20.9%), C/N (4.9–16.5) and δ13Corg (−31.5 to −19.5‰), the molar composition and content of amino acids and hexosamines (8.2–156.2mgg−1 dry weight) and by comparison with sediments, mangroves, soils and plants we are able to show that soil-derived material, freshwater and marine plankton were the major sources of suspended OM. High POC and amino acid contents were related to primary production sustained by dissolved nutrients to a large extent stemming from municipal and aquaculture effluents. Factor analysis showed that the suite of biogeochemical parameters measured clearly depict the terrestrial vs. marine origin and the freshness/reactivity of OM. The four groups of samples resulting from cluster analysis were basically related to varying hydrological regimes. With respect to the sources, degradation and fate of particulate OM the major factors were: (i) the year round input of labile, amino acid rich riverine OM matter at the freshwater dominated sites, (ii) high input of degraded soil OM after heavy rains with dispersal throughout the estuary and export to the adjacent coastal area, (iii) significant production of labile marine OM especially during summer inside the bay and the (iv) dominance of refractory marine OM during winter and spring season and in the offshore region. While a major part of the fresh OM fuelled by anthropogenic nutrients appears to be stored or recycled inside the bay, periodic torrential rainfalls can lead to a pulsed export of this OM to the coastal area where it may adversely affect seagrass meadows and coral reefs. [Copyright &y& Elsevier]

Abstract: The biogeochemistry of a small tropical river and estuary (the Wanquan River (WQR)) in Hainan, China, was studied to obtain information on the sources, transformation and fate of riverine organic matter. Water and total suspended matter were sampled along a salinity gradient during four field campaigns in December 2006, August 2007, July–August 2008 and April 2009. We were able to observe the effect of heavy precipitation associated with the tropical cyclone Kammuri (2008) and a strong first-rain event (2009) on the export of organic carbon. Both dissolved organic carbon (DOC) and particulate organic carbon (POC) generally decreased with increasing salinity in the estuary, with minimal seasonal or annual variations. The POC concentrations were in the range of 18–178μM for the WQR and were significantly correlated with chlorophyll a concentrations. The highest average values of DOC (∼190μM) were observed in 2009. These values could be the result of the flushing effect of the first rain. In the high-salinity zone, in situ productivity could be an important source for DOC. The δ 13 C org values of particles (−29.5‰ to −23.2‰), combined with the ratio of organic carbon to total nitrogen (OC/TN), reflect a mixture of terrestrial organic matter and in situ production. The amplitudes of the POC and DOC variations on the occasion of the first-rain event of 2009 were larger than those observed during Kammuri. It is estimated that 29.8tday−1 of DOC and 10.4tday−1 of POC, representing 6–10% of the annual loads, were delivered to the coast during the 10-day period of the first flush event in 2009. Our results demonstrate the important role of short-term aperiodic events on small rivers and estuaries along tropical coasts. [Copyright &y& Elsevier]

Abstract: During two nominal dry seasons (December 2006, March 2009) and two wet seasons (July 2007, July/August 2008) the estuarine distribution and size speciation of arsenic was studied in the Wanquan river and the Wenchang/Wenjiao river estuaries, located in tropical East-Hainan (China). Arsenic in solution and in colloidal fractions was analyzed by anodic stripping voltammetry after oxidative UV digestion thereby including inorganic As(III) and As(V) as well as organic As forms. Particulate As was determined by high-resolution ICP-MS after a microwave assisted total decomposition protocol. Taking the two relatively similar estuaries and the two expeditions for each season together, the average concentrations of total dissolved As (<0.4μm; td-As) of the freshwater endmember were 4.4nM and 7.6nM during the dry and the wet seasons, respectively, which suggests a low – if ever – level of contamination. With one exception (uptake by phytoplankton in the lower estuary), during the dry season td-As increased essentially conservatively along the salinity gradient to 14.4nM as the mean value for salinities of about S=30. During the wet seasons, however, td-As only showed a tendency for a conservative increase; scatter in the data was attributed primarily to heavy rain and side inputs of variable As concentrations from overflowing aquaculture ponds and piles of excavated soil. The separation of colloidal fractions revealed that on average 82% of td-As remains in solution (<5kDa), followed by 13% in small colloids (5kDa to 30kDa) and 5% in large colloids (30kDa–0.4μm). Particulate As (0.24±0.06μmol/g) showed no dependence on either salinity, suspended particles, estuary or season. Relatively high distribution coefficients (logK D =4.48–4.81 in the freshwater; logK D ∼4.18 at high salinities) arose primarily from the very low td-As. Except for certain impacts from aquaculture ponds, the two estuaries might be considered uncontaminated with respect to As. [Copyright &y& Elsevier]

Abstract: Nutrient dynamics were studied in the estuary of the Wanquan River, a tropical mountainous river system of Hainan Island, China, during 2006–2009. The nutrients measured included NO3 −, NO2 −, NH4 +, PO4 3−, Si(OH)4, total dissolved nitrogen (TDN), total dissolved phosphorus (TDP), dissolved organic nitrogen (DON), and dissolved organic phosphorus (DOP). The Wanquan River showed great variation in nutrient levels, was enriched in dissolved inorganic nitrogen (DIN) and dissolved silicate, and depleted in PO4 3−. The levels of dissolved silicate were higher than average for tropical systems. As a consequence the DIN:PO4 3− and Si(OH)4:DIN ratios were higher than the Redfield ratio. DON accounted for 18% of TDN in the Wanquan River, and DOP represented approximately 61% of TDP. Nutrients in the Wanquan River estuary behave either conservatively or nonconservatively. Nutrient biogeochemistry in the estuary is affected by human activities in adjacent areas and heavy rainfall associated with typhoons. Phosphorus may be the potential limiting nutrient for phytoplankton growth. A simple steady-state box model showed that riverine input was the major source of nutrients to the estuary, which acted as a source of all nutrients except dissolved silicate, TDP, and DOP. The results indicate that substantial quantities of nitrogen and PO4 3− are transported to the coastal system, and suggest that dissolved silicate accumulates in the sediment or is transformed into other forms. [Copyright &y& Elsevier]

Abstract: The study of sediment sources and transport processes from land to ocean can help in predicting the fate of the pollutants released from land or the potential change in sediment delivery to coastal areas and/or open oceans. The activities of 7Be, excess 210Pb (210Pbxs), excess 234Th (234Thxs) and 137Cs in surface sediments collected offshore of eastern Hainan Island, China, in August of 2008 were measured by an HPGe γ-spectrometer to evaluate the sediment source and transport processes. The results showed that all the surface sediments were silt or sand, and the mean grain sizes of the northern locations were higher than those in the other regions. The ranges of activities of 7Be, 210Pbxs, 234Thxs and 137Cs in surface sediment were 0.14–12.7, 37.4–199, 2.24–176 and 0.02–1.06Bqkg−1, with averages of 3.78±4.77, 110±8.1, 66.7±8.9 and 0.52±0.22Bqkg−1, respectively. The activities of the radionuclides increased from coast to offshore in the northern section. The upwelling may cause high particle fluxes with high activities of 210Pbxs and 234Thxs. A comparison of the source and transport of the suspended sediments with river discharge along the coast shows that the coastal current and offshore upwelling are the dominant factors for the transport and sources of surface sediment in the study region. The sediment was transported from south to north by the coastal current, and sediments with a large grain size may be deposited via the north loop current. The ratios of the nuclide activities indicated that the suspended particles need approximately one year to be removed from the water column into the seabed and that the main source of the sediments off eastern Hainan Island in the study regions was terrigenous deposits. [Copyright &y& Elsevier]

Abstract: Submarine groundwater discharge (SGD) with inputs of nutrients in certain regions may play a significant role in controlling water quality in the coastal regions. In this paper, we have determined four naturally occurring radium isotope (223Ra, 224Ra, 226Ra and 228Ra) activities and nutrient concentrations in surface water, coastal groundwater and river water in the mixing zone of Laoye Lagoon to estimate the fluxes of SGD by several models. The activities of the four radium isotopes of ground water were considerably greater than those in surface water samples. Using a 224Ra/228Ra activity ratio (AR) model, we estimated the average lagoon water age to be 3.2days, which was comparable with the flushing time of 4.0days. Based on the excess radium isotopes and the water age of the lagoon, the estimated fluxes of SGD (in 106 m3/d) ranged from 2.64 to 5.32 with an average of 4.11. Moreover, we used Si balance to evaluate the flux of SGD (4.8×106 m3/d) which was close to the result calculated by radium. The SGD-derived nutrient fluxes (in mol/d) were DIN=1.7×105, PO4 3− =5.2×102, and SiO3 =5.3×104. Furthermore, we applied the biogeochemical budget approach using SiO3 as a tracer to evaluate the impact of SGD. The differences between the results estimated by radium and SiO3 may indicate different pathways for the input of nutrients. [Copyright &y& Elsevier]

Abstract: The nutrient concentrations and stoichiometry in a coastal bay/estuary are strongly influenced by the direct riverine discharge and the submarine groundwater discharge (SGD). To estimate the fluxes of submarine groundwater discharge into the Bamen Bay (BB) and the Wanquan River Estuary (WQ) of eastern Hainan Island, China, the naturally occurring radium isotope (226Ra) was measured in water samples collected in the bay/estuary in August 2007 and 2008. Based on the distribution of 226Ra in the surface water, a 3-end-member mixing model was used to estimate the relative contributions of the sources to these systems. Flushing times of 3.9±2.7 and 12.9±9.3days were estimated for the BB and WQ, respectively, to calculate the radium fluxes for each system. Based on the radium fluxes from groundwater discharge and the Ra isotopic compositions in the groundwater samples, the estimated SGD fluxes were 3.4±5.0m3 s−1 in the BB and 0.08±0.08m3 s−1 in the WQ, or 16% and 0.06%, respectively, of the local river discharge. Using this information, the nutrient fluxes from the submarine groundwater discharge seeping into the BB and WQ regions were estimated. In comparison with the nutrient fluxes from the local rivers, the SGD-derived nutrient fluxes played a vital role in controlling the nutrient budgets and stoichiometry in the study area, especially in the BB. [Copyright &y& Elsevier]

Abstract: In order to improve the understanding of structural and reactive features of sediment organic matter from mangrove swamp as well as evaluate the relationship between such features and the impact from different sources (marine and terrestrial), humic and fulvic acids were isolated from two mangrove swamp sediments located in the Qinglan harbors on Hainan Island, China. One is a forest surface sediment site (WWM2), and the other is an estuary subaqueous sediment site (BMW). The humic and fulvic acids were characterized and compared using chemical and spectroscopic methods, including elemental analysis, thermogravimetric analysis (TGA), Fourier Transformed Infrared Spectroscopy (FTIR), 13C nuclear magnetic resonance (13C NMR) and potentiometric titrations. The results indicated that there were less aliphatic compounds but more aromatic compounds and oxygen-containing functional groups in fulvic acids. Humic acids contained more long-chain hydrocarbons and nitrogen compounds. Comparison of the C/N ratios and δ13C values for the humic substances at both sites indicated a larger marine and/or microbial contribution to the BMW site. Humic substances at the WWM2 site have more acidic functional groups than those of the BMW site. Compared to the literature, more phenolic groups existed in the samples of both sites, which may be due to the autochthonous contribution of mangrove plants. [Copyright &y& Elsevier]