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The oxygen isotopic composition of phosphate (δ18OP) has been increasingly used as an effective tracer for the biogeochemical cycling of phosphorus (P) in soils and other environments. However, diverse pretreatment methods (e.g. storage, preparation and extraction) are being used for soil samples. For the uniformity of methods as well as for the comparison of results, it is important to understand if specific treatment methods can compromise original δ18OP values. Here, Ag3PO4 and KH2PO4 were used to test whether a modified Hedley sequential extraction and purification procedure can alter the δ18OP values of phosphate standards. Additionally, to test the effect of sample storage and drying conditions, two types of soils were first processed by using eight different pretreatment methods including sterilizing, storing, drying, and sieving and then the δ18OP values of each soil P pool were measured. Results indicate that the extraction and purification procedure, drying temperature (

Dispersion and aggregation behavior of nanoparticles in aquatic environment may be affected by pH, salinity, and dissolved organic matter, which would change its ecological risk. Effects of time, power and temperature on the alumina nanoparticles (nano-Al2O3) ultrasonic dispersion in water were discussed. Al2O3 had a best ultrasonic dispersion for 30 min at 105 W and 30 &deg, C. The concentration of Al2O3 could be measured by ultraviolet (UV) spectrophotometer, and the method was efficient and accurate. Furthermore, the sedimentation rate of Al2O3 was related to pH, salinity, and its concentration in the artificial seawater. When pH was 7.31, approaching the isoelectric point of Al2O3, they aggregated and settled fastest. Settlement coefficient (k) of Al2O3 increased by 3 and 2.7 times while the salinity and its concentration increased. The sedimentation rate was higher in natural seawater than that in artificial seawater. All results indicated that nano-Al2O3 would be removed in aquatic environment.

Dissolved organic matter (DOM) from freshwater, mid-salinity, and seawater endmember samples in the Jiulong River Estuary, China were fractionated using cross-flow ultrafiltration with a 10-kDa membrane. The colloidal organic matter (COM; 10 kDa–0.22 μm) retentate, low molecular weight (LMW) DOM (

Ge, H.; Chen, D.; Li, S.; Zheng, A.; Zhu, Z., and Zheng, X., 2019. Determination of Fe, Ti in seawater using a flow-injection pretreatment system with ICP-MS. In: Guido-Aldana, P.A. and Mulahasan, S. (eds.), Advances in Water Resources and Exploration. Journal of Coastal Research, Special Issue No. 93, pp. 77–82. Coconut Creek (Florida), ISSN 0749-0208.In order to solve the interference caused by low metal concentration and salts matrix of seawater samples, this paper present a handy flow- injection system with solid-phase extraction to automate pretreatment procedures for offline Fe and Ti analysis in seawater by ICP-MS. By combining 8-position, 3-way and 6-way valves in the pipeline, the flow-injection system enhance the sample treatment efficiency by simultaneously loading two reagents online for: sample loading, buffering, and preconcentration. Each sample treatment spends about 16 min and consumes 12 mL of seawater sample and 8 mL of buffer solution. The chelation of Toyopearl-AF-Chelate-650M for Fe and Ti occurs in pH5.5 at an injection rate of 1.0 mL·min-1. The eluent (0.8 mol·L-1 HNO3) is able to elute Fe and Ti in 90 s at an elution rate of 1.0 mL·min-1. Seawater sample needs 90 min of 120 W UV-oxidation to dissociate metal-organic complexes. The precision and availability of this method are tested by measuring Jiulongjiang Estuary seawater samples.

Liu, C.; Chen, D.; Zheng, X., and Zheng, A., 2019. The content and distribution of nitrogen in nature colloids from Jiulongjiang River. In: Guido-Aldana, P.A. and Mulahasan, S. (eds.), Adv...

Based on pile load test results of uplift bored piles for a deep-embedded underground transformer substation, the uplift behaviour of enlarged toe pile and shaft post-grouting bored piles have been studied. The loading transfer characteristics and uplift capacity improvement mechanism for the two different type uplift piles have been investigated. The research shows that post-grouting can significantly improve bored pile uplift bearing capacity. After pile shaft grouting, the interface condition between pile and soil is improved, the friction resistance of pile side is increased obviously, and the uplift bearing capacity is improved. For long uplift pile, the uplift resistance of shaft grouting bored pile is better than that of enlarged toe pile.

Vacuum preloading technology combined with plastic drainage board has been applied more and more widely. Because the plastic drainage board is used soft-clay in most cases, it is not recommend to study the clogging of filter fabric by gradient ratio method. Therefore, we have proposed a new experimental method, i.e. axial compression clogging. This method can be used to study the clogging of geotextile in clay. Several groups of filters fabric were carried out by this method, and their performances were compared with those obtained from on-side used plastic drainage board. The results show that soil content per unit area and vertical permeability coefficient are very close to those obtained from on-side used plastic drainage board, and the values of the former are slightly smaller than those of the latter.

Bottom slime and shaft mudcake are two principal deteriorative factors affecting the mobilization of bearing capacity of slurry bored piles. As an effective later improvement technology, post-grouting can significantly improve bored pile bearing capacity. Based on static load test results of Beijing capital international airport project, vertical bearing properties of post-grouted bored pile have been studied. The analyses reveal that: with pile-toe and pile-shaft post-grouting, the interface between pile and surrounding soil was strengthened and the relative sliding displacement in between was reduced, end resistance of pile was enhanced and could be mobilized at earlier stage with smaller sliding displacement. As a result, the performance of bored pile was improved with increased bearing capacity and reduced settlement.

The consolidation test was performed to samples of fresh soft dredger fill with heights of 2cm, 3cm and 4cm with full-automatic pneumatic consolidometer. The results show that: the soil sample deforms greatly during the consolidation with significant decrease in water content and small consolidation coefficient. The sample height has negligible effect on the deformation rate, compression modulus, compressibility coefficient, etc., while it is closely related to the consolidation coefficient with an inverse relationship.

Effects of nano-SiO2 and nano-ZnO on the concentration of chlorophyll-a in seawater were studied. Different particle size of nano-SiO2 and nano-ZnO (10~500nm) were added into seawater with different content ranging between 5~100mg/L, led to the v (growth rate) of chlorophyll-a were -11.4~-44.8% and -39.6~-74.0% respectively, and v decreased with the increasing of the concentration of nanoparticles and raised with the increasing of the nanoparticles size, and nano-ZnO had the stronger inhibitory effect than nano-SiO2. While to nano-ZnO and Zn2+(concentrations of zinc were 0.05~1.00mmol/L), chlorophyll-a growth rate decreased as the concentration of zinc increased and the average growth rates were -60.2～-68.8%, meant that nano-ZnO and Zn2+ have the same toxical mechanism. Concentrations of Zn2+ released from nano-ZnO (30nm and 90nm) with content of 5~100mg/L were 1.56~4.29mg/L, and rose with the increasing of nano-ZnO concentration, and 30nmZnO released more Zn2+ than 90nm. To nano-ZnO, percentage of the concentration of Zn2+ released by it and its v values have linear correlation, indicated that the released Zn2+ is the main reason for toxicity of nano-ZnO.

Seawater heavy metals' (Cr, Cu, As, Pb) distributions and sources were analyzed based on results of two voyages in April and August 2011 of the Northern Beibu Gulf. Average contents of Cr and As in spring and summer were less than the grade-one seawater quality standard of China, but over limit-ratios of Cu and Pb were 3% and 19% respectively relative to the grade-one standard. Contents of heavy metals which affected by runoff, drainage, atmospheric deposition, biological action and hydrodynamics were high in offshore while low in far-shore and high in central while low all around. The correlation analysis shows that Cu and Cr were strongly correlated in spring and summer, so as to Cu, Cr, Pb to nitrate ion in summer. Principle component and background value analysis show that As was related to rivers' input and background value of the studied area, while Cu, Pb and Cr were related to the sewage disposal of point source of industry.

After hydraulic reclamation of the dredger fill, as the deposition of surface sludge requires a relatively long time, the consolidation treatment cannot be immediately performed until the sludge-water separation is completed and the separated water is drained. The laboratory test makes a research on the effects of chemical agents and drainage condition on the sludge deposition process. The research shows that the early-stage deposition velocity of sludge is increased obviously and the sludge-water separation time is shortened after water hydrophobing agents and polymeric flocculants are added. However, the later-stage deposition velocity is slow and the deposition strength is low. Thus, certain drainage conditions are required to increase the later-stage deposition velocity and deposition strength of sludge.

The influences of colloids on nitrogen fixation rate of surface water were studied in the Beibu Gulf of China. The results show that the increment ratios of nitrogen fixation rates in water samples that cultured with colloids added are -96% to 1456% in spring, -9% to 64% in summer, -72% to 122% in autumn and -13% to 216% in winter. The enhancement is most significant in spring. Generally speaking, colloids can promote the nitrogen fixation rates in surface water to some extent.

Contents and distributions of heavy metals in surface sediments from the northern Beibu Gulf were analyzed using atomic absorption spectrophotometer. The results showed that the contents of Cu, Pb, Zn, Cr and Cd were 14.22～26.68, 31.85～54.59, 60.19～90.93, 29.95～67.95 and 0.030～0.130 µg•g–1, respectively, and average were 18.21, 38.88, 78.00, 48.46 and 0.09µg•g–1. The reducing environments in northern Beibu Gulf were attributed to organic matters and sulfide. The distributions of heavy metals showed the trend of higher along the coastal area and lower in the offshore area, generally controlled by terrestrial inputs, as well as hydrological conditions, depositional environments and so on.

The four species of heavy metals (Cu, Zn, Pb, Cr, Cd) were analyzed using BCR (the Bureau Communautaire de Reference) sequential extraction method. Results showed that, about the contents the four species (exchangeable and carbonate state, Fe-Mn oxides state, organic and sulfide state and residual state) in surface sediment, the average contents of Cu were 0.94 μg/g, 2.17 μg/g, 1.18 μg/g and 13.19 μg/g, respectively. the average contents of Pb were1.51 μg/g, 12.90 μg/g, 4.51 μg/g and 16.42 μg/g, respectively; the average contents of Zn were 1.82 μg/g, 13.00 μg/g, 4.20 μg/g and 48.97 μg/g, respectively; the average contents of Cd were 0.010 μg/g, 0.012 μg/g, 0.005 μg/g and 0.063 μg/g, respectively; the average contents of Cr were 0.32 μg/g, 2.98 μg/g, 4.22 μg/g and 13.19 μg/g, respectively. The predominant species of Cu, Zn, Pb, Cr, Cd is residual state. The relative abundance in residual state for these elements followed the order: Cr＞Cu＞Zn＞Cd＞Pb. The pollution degree was assessed with ratio of secondary phase to primary phase. Results showed that the sediments in the northern Beibu Gulf were uncontaminated with Cu, Zn and Cr. 12 % of the sites was slightly polluted with Cd. 47 % of the sites were polluted with Pb.

2,6-dinitrotoluene (2,6-DNT) is the preferential toxicants stipulated by OECD and EPA of USA. The present study was conducted to determine the effect of 2,6-DNT chemical on acute toxicity and subacute toxicity in common carp (Cyprinus carpio). The 24h, 48h, 72h and 96h LC50 values of common carp by 2,6-DNT were 1.137±0.023mg/L, 0.830±0.024mg/L, 0.661±0.019mg/L and 0.479±0.020mg/L, respectively. The subacute experiment shows that C. carpio are rarely affected by 0.0251mg/L 2,6-DNT, but significantly affected by 0.0398, 0.0631, 0.0794mg/L 2,6-DNT in contrast to the controlled sample (p liver > kidney.

The variation of colloidal phosphorus with salinity in estuary was studied in this paper, which was compared with those of particle and truly dissolved phosphorus with the purpose of finding out the similarities and differences between their behaviors in the estuary. Distribution patterns of phosphorus in particle, colloidal and truly dissolved phase at different salinities and their relationships with suspended particulate matter were also studied to understand the transformation and transportation of colloidal phosphorus in estuarine area. The result showed that the concentrations of total colloidal phosphorus, organic colloidal phosphorus and inorganic colloidall phosphate all descended from river-end to sea-end, illustrating their terrigenous source. Ratios of organic to total colloidal phosphorus decreased with salinity’s increment, indicating that organic phosphorus was influenced by scavenging process of colloid more significantly as compared with inorganic phosphate. Both of the phosphorus variation tendencies and the proportion between organic and inorganic phosphorus in colloidal phase was similar with that in truly dissolved phase while different from that in particle phase.