Impact of the water-sediment regulation and a rainstorm on nutrient transport in the Huanghe River

Dissolved nutrient concentration in the Huanghe （Yellow） River at Lijin was monitored during a water-sediment regulation period and a subsequent rainstorm from 14 June to 19 July, 2005. This study provides detailed information on nutrient concentrations in the Huanghe River during the water-sediment regulation and rainstorm periods, and is of significance for the downstream area of the Huanghe River and the Bohai Sea. The average concentrations of nitrate, nitrite and ammonia were 304.7 μmol/L, 0.19 μmol/L, and 1.10 μmol/L, respectively, while the average concentrations of dissolved inorganic phosphorus （DIP） and dissolved silicate （DSi） were 0.23 gmol/L and 122.9 ktmol/L, respectively. Nutrient concentrations during the water-sediment regulation period were mainly influenced by the dilution effect, floodplain effect and sediment resuspension while dilution and erosion effects were the main factors during the rainstorm. The fluxes of dissolved inorganic nitrogen （DIN）, DIP and DSi during the water-sediment regulation and rainstorm periods accounted for 20.4%, 19.5%, 16.7% and 4.97%, 6.45%, 5.47% of the annual nutrient fluxes, respectively. Discharge was the main factor influencing the fluxes of nutrients during both the water- sediment regulation and the rainstorm periods.

水土中抗生素赋存形态提取方法的优化与应用

为优化水土中抗生素赋存形态的提取方法,选取典型抗生素诺氟沙星(NOR)、土霉素(OTC)和磺胺甲噁唑(SMX)为研究对象,通过改进固相萃取参数和色谱条件,确立高效提取方法。研究结果表明:结合絮凝法絮凝12 h可高效分离水中抗生素的不同形态;当固液比为1∶10时,连续超声萃取法可高效分离土中抗生素的不同形态;研究区NOR水溶态含量分布不均,OTC各形态含量差异较大,SMX以可交换态、吸附态为主;水土中抗生素各赋存形态提取后回收率均大于80%,且回收能力大小依次为SMX>NOR>OTC。该研究结果可为其他抗生素赋存形态提取和抗生素生态风险评估提供一定理论依据。

Sedimentary facies of the subaqueous Changjiang River delta since the late Pleistocene

The sedimentary facies of the subaqueous Changjiang （Yangtze） River delta since the late Pleistocene was studied based on lithology and foraminifera analysis for two boreholes, CJK07 and CJK11, along with 14C dating. Four sedimentary facies were identified, namely fluvial, tidal flat, offshore, and prodelta facies. The fluvial sedimentary facies is comprised of fluvial channel lag deposits, fluvial point bar deposits, and floodplain deposits, showing a fining-upward sequence in general with no benthic foraminifera. A layer of stiff clay overlies the fluvial deposits in core CJK07, indicating a long-term exposure environment during the Last Glacial Maximum （LGM）. During the postglacial sea-level rise around 13-7.5 cal ka BP, the tidal flat facies was deposited in core CJK11, characterized by abundant silt-clay couplets. Euryhaline species dominate the subtidal fiat foraminiferal assemblages, while almost no foraminifera was found in the intertidal fiat. The offshore environment was the major sedimentary environment when the sea level reached its highest level around 7.5 cal ka BP, with a maximum accumulation rate of 10 mm/a found in core CJK11. Prodelta sediments have been deposited in core CJK11 since -3 cal ka BP, after the formation of the Changjiang River delta. The difference in sedimentary facies between core CJK07 and CJK11 is due to their location： core CJK07 was in an interfluve while core CJK11 was in an incised valley during the LGM. Furthermore, AMS 14C dating of core CJK07 shows poor chronological order, indicating that the sediments were reworked by strong tidal currents and that sediment deposited since -7.7 cal ka BP in core CJK07 was eroded away by modem hydrodynamic forces caused by the southward shift of the Changjiang River delta depocenter.

Effect of Water and Sediment Regulation on Lower Yellow River

According to the results of the water and sediment regulations of the Yellow River in year 2002—2007,the effect of erosion and deposition on the lower reaches,the amount and distribution of erosion and deposition in the river mouth area,the adjustment of river regime,the effect of river regulation projects and changes of flowing capacity of the channel are analyzed.It is revealed that the water and sediment regulation is efficient to reduce deposition and improve the flowing capacity and the conditions of sediment transport.

Soil and Crop Damages as a Result of Levee Breaches on Ohio and Mississippi Rivers

Whenever levees on the Ohio or Mississippi rivers are breached, there are soil damages in the flooded areas that impact agricultural management capacities and crop productivity. Floodwaters coat the entire flooded land surface with sediments which include a variety of pollutants, nutrients and contaminants. The nature of the sediments in floodwaters varies with the topographical and land use characteristics of the watershed. The soil types, hydro-geologic features, volume of flow, time of year, agricultural use of fertilizers, pesticides, and other chemicals as well as upstream point sources such as sewage treatment plants, storm sewer drainage and other urban land uses will affect the extent of the contamination and fine scale remediation needed. Preliminary characterization and measurement of soils and sediment deposit at three locations that experienced recent natural and man induced levee breaches are analyzed to identify patterns of soil and crop damage. These findings provide guidance to the restoration of craters, gullies, land scoured areas and contaminated sediment depositional sites with a goal to improve decision-making, risk analysis and remedial effectiveness. Recommendations include： （1） improve characterization and measurement of eroded soils and distribution of sediment contaminants after levee breaching; （2） assess contamination effects on soil productivity and long term agricultural production in order to understand the impacts of flooding on agricultural soils; （3） evaluate reconstruction investments needed to repair levees based on return of the land to productivity and increased landscape resilience by reducing vulnerability to future flooding and levee breaching stress.

Water Quality and Some Heavy Metals in Water and Sediments of Euphrates River, Iraq

Water samples, sediments from three stations in Euphrates River, lraq were analyzed quantitatively for some physical and chemical characters and six heavy metals （Co, Cu, Fe, Mn, Ni and Pb） using flam atomic absorption spectrophotpmeter in period Sept. 2009-Oct. 2010. The physical and chemical characters included temperature, pH, water flow, salinity, dissolved oxygen, BOD5, alkalinity total hardness, calcium and nutrients （nitrite, nitrate reactive phosphate and silicate）. The results showed variation in water flow 0.05-0.40 m/sec., according to the values of salinity 0.40%-0.60% values of the BOD5 were ranged between 0.2-4.3 mg/L. The mean concentration of the heavy metals （Pb, Ni, Mn, Co, Cu and Fe） of the dissolved phase in water were 0.13 μg/L, 0.021 μg/L, 0.31 μg/L, 4.29 μg/L, 7.78 μg/L, 6.46 μg/L and 79.04 μg/L, respectively, while their concentration in the particulate phase were 0.59 μg/g, 0.06 μg/g, 0.42 μg/g, 50.06 μg/g, 6.61 μg/g, 7.17 vg/g and 149.42 μg/g dry weight, respectively. Also the mean concentrations of heavy metals in sediment （exchangeable phase） were 0.51 vg/g,0.18 vg/g, 0.08 μg/g, 61.39 μg/g, 5.40 μg/g, 14.06 vg/g and 130.05 μg/g dry weight respectively, and 0.40 μg/g, 0.17 μg/g, 0.10 μg/g, 63.01 μg/g, 4.64 μg/g, 18.44 μg/g and 126.26 μg/g D.W. respectively in residual phase of sediment.

Anomalies of bromine in the estuarine sediments as a signal of floods associated with typhoons

X-ray fluorescence scanning with synchrotron radiation was performed to study sediment core records of floods in Amur Bay,Sea of Japan.Interlayers of 3–8 mm with abnormally low bromine content were formed by the Razdolnaya River discharge to the central part of the bay during extreme floods,accompanied by severe storms at sea.Such conditions in the region are typical for periods of deep tropical cyclones(typhoons),to which the distinguished interlayers were compared on the timescale.This approach was made possible thanks to the high rate of sedimentation in the bay(3–5 mm/a) and low bioturbation of sediments under anoxic conditions.

Acute toxicity and biodegradation of endosulfan by the polychaeta Perinereis aibuhitensis in an indoor culture

The polychaete Perinereis aibuhitensis, a key species in estuarine ecosystems, can improve the culture condition of sediment. Endosulfan is an organochlorine pesticide used globally to control insects and mites; however, it is a source of pollution in aquaculture as a result of runoff or accidental release. In this study, we evaluated the toxicity of endosulfan to polychaeta and its ability to improve polluted sediment. Specifically, the effects of a series of endosulfan concentrations （0, 1.25, 2.5, 5, 10, 15, and 20 mg/L） were investigated, and the results indicated that the 24-h median lethal concentration （24-h LCs0） was 55.57 mg/L, while the 48-h median lethal concentration （48-h LCs0） was 15.56 mg/L, and the safe concentration was about 1.556 mg/L. In a 30-d exposure experiment, the animal specimen could decompose endosulfan effectively while improving endosulfan-polluted aquatic sediment.

Study on Pollution Level, Distribution and Sources of Polychlorinated Naphthalene in River Sediments

Polychlorinated naphthalene （PCNs） is similar structure and toxicity of dioxin （PCDD/Fs）, it can be detected in the global environmental and biological samples. This paper introduces the main source of PCNs in the environment and environmental fate, sludge PCNs pollution level in 1.48-28.21 ng/g （dry weight）, PCN-TEQs content is in 0.11-2.45 pg/g （dry weight）, far below the content of other areas in foreign countries. The results showed that the sources of wastewater, sewage treatment plant is an important factor affecting the level of polychlorinated naphthalene pollution. Discussion on the distribution characteristics of sludge in polychlorinated naphthalene congeners, found that the distribution of PCNs congeners in all of the samples is largely the same, it is mainly two chloride and three chloro naphthalene, it showed that the pollution source has a certain resemblance. Research shows that, polychlorinated naphthalenes city sludge mainly comes from industrial pollution sources; in addition, an important source of waste incineration, burning heat treatment process is caused by polychlorinated naphthalene pollution.

Response of the distributary channel of the Huanghe River estuary to water and sediment discharge regulation in 2007

The water and sediment discharge regulation （WSDR） project, which has been performed since 2002 before flood season every year, is of great significance to the river management in China. Until 2007, six experiments have been fulfilled to evaluate the effect of the project on the natural environment. To fill the gap of investigations, a study on flood and suspended sediment transportation and channel changing along the distributary channel of the Huanghe （Yellow） River was conducted during the WSDR project period in 2007. The lower channel was scoured rapidly and the channel became unobstructed gradually several days after the flood peak water was discharged from the Xiaolangdi Reservoir. Within four days after the flood peak at 3 000 m3/s entered the distributary, the channel in the river mouth area was eroded quickly. Both the mean values of area and depth of the main channel were tripled, and the maximum flood carrying capacity increased to 5 500 m3/s or more. Then, the river channel was silted anew in a very short time after completion of the WSDR. Favored by the WSDR project, the fiver status in April 2008 became better than that of the year before. The adjustment ranges of main channel parameters were about 30%, 10%, and 10% at sections C2, Q4, and Q7, respectively. The process of rapid erosion-deposition was more active 15 km away in the channel from the fiver mouth due to the marine influence. It is reasonable for discharging sediment at concentration peak from Xiaolangdi Reservoir at the end of the flood peak. As a result, the sediment peak reached the river mouth about two days later than that of the water current. In addition, the WSDR project has improved the development of the estuarine wetland. Wetland vegetation planted along the river banks restrained the water flow as a strainer and improved the main channel stability. It is suggested to draw water at mean rate of 150 m3/s from the Huanghe River during flood periods, because at the rate the water in the wetland would be stored and replenished in balance. Moreover, we believe that cropland on the river shoal of the lower Huanghe River should be replaced by wetland. These activities should achieve the Huanghe River management strategy of ＂To concentrate flow to scour sediment, stabilize the main channel, and regulate water and sediment＂.

Sediment consolidation settlement of Chengbei Sea area in the northern Huanghe River subaqueous delta,China

One of the most important factors controlling the morphology of the modem Huanghe （Yellow） River delta is consolidation settlement, which is impacted by fast deposition, high water content, and low density of seafloor sediment. Consolidation settlement of the Huanghe River subaqueous delta was studied based on field data, laboratory experiments on 12 drill holes, and the one-dimensional consolidation theory. Results show that vertical sediment characteristics varied greatly in the rapidly forming sedimentary bodies of the modem Huanghe River subaqueous delta. Sediments in the upper parts of drill holes were coarser than those in the deeper parts, and other physical and mechanical properties changed accordingly. On the basis of the one-dimensional consolidation theory and drilling depth, the final consolidation settlement of drill holes was between 0.6 m and 2.8 m, and the mean settlement of unit depth was at 1.5-3.5 cm/m. It takes about 15-20 years for the consolidation degree to reach 90% and the average sedimentation rate within the overlying 50 m strata was at 5 cm/a to 12 cm/a. This study helps to forecast the final consolidation settlement and settlement rate of the modem Huanghe River subaqueous delta, which provides key geotechnical information for marine engineers.

Distribution of fatty acids in the alpine grassland soils of the Qinghai-Tibetan Plateau

As an important biomarker, fatty acids(FAs) have been extensively used to trace the origin of organic matter in sediments and soils. However, studies of the distribution and abundance of FAs in alpine grassland soils are still rare, especially on the Qinghai-Tibetan Plateau(QTP), the highest plateau in the world, which contributes sediments to many large rivers in Asia. This study investigates the composition, distribution and source of FAs with increasing soil depths from 17 typical alpine grassland sites in the QTP. The most abundant FAs included the ubiquitous C16 FA and even-numbered long-chain FAs(C20–C30), indicating mixed inputs from microbial and higher plant sources. Source apportionment showed that higher plants were the dominant contributor of FAs(approximately 40%) in QTP soils. The abundance of FAs decreased with soil depth, with the highest value(1.08±0.09 mg/g C) at a 0–10 cm depth and the lowest value(0.46±0.12 mg/g C) at a 50–70 cm depth, due to much lower plant inputs into the deeper horizons. The total concentration of FAs was negatively correlated to the mean annual temperature(MAT; P<0.05) and soil p H(P<0.01), suggesting that the preservation of FAs was favored in low-MAT and low-p H soils on the QTP. The abundance of fresh C source FAs increased significantly with the mean annual precipitation(MAP; P<0.05), indicating that high MAP facilitates the accumulation of fresh FAs in QTP soils. Other environmental parameters, such as the soil mineral content(aluminum and iron oxide), microbial community composition as well as litter quality and quantity, may also exert a strong control on the preservation of FAs in QTP soils and warrant further research to better understand the mechanisms responsible for the preservation of FAs in QTP soils.

Variations of mercury distribution in the water column during the course of a tidal cycle in the Yangtze Estuarine intertidal zone,China

Tidally induced resuspension processes play an important role in the release of mercury (Hg) into the water column, which increases the risk of Hg exposure to estuarine eco-systems. In order to further understand the geochemical activities of Hg in the intertidal area, the temporal variations of dissolved Hg (Hg D ) and particulate Hg (Hg P ) in the water column during the course of a tidal cycle and its geochemical processes were studied in the southern intertidal zone of the Yangtze Estuary, China. The concentrations of Hg D and Hg P varied between 37-612 ng/L and 51-638 ng/L respectively during the tidal cycle. The increase of Hg D was distinguished at the early flood tide and late ebb tide when the water flow rates were higher. The Hg D concentrations were negatively correlated with Hg P (r = 0.523, p < 0.05) and positively correlated with dissolved organic carbon (DOC) (r = 0.605, p < 0.05) in the bottom water, indicating that the Hg D released from the sediments into the overlying water was associated with the simultaneously released colloidal material in the bottom water. The main pathways for the translocation of Hg from the sediments to the overlying water include the processes of desorption from resuspended particles, advection or diffusion from sediments, and the oxidation of resuspended sulfide. The results of principal components analysis (PCA) and Pearson correlation analysis showed that the combined effects of the total suspended substrate (TSS), DOC, pH and dissolved oxygen (DO) influenced the geochemical activities of Hg in the water column during the course of a tidal cycle.

Effects of submerged sheet pile vanes on mobile river beds

Submerged vanes are low-height flow-training structures emerging from the riverbed with a suitable angle of attack to the incoming flow. These structures redirect the stream flow and modify erosion and depositional rates in the bottom and in the banks of a river as a result of the secondary currents generated by their installation. For this reason they have many applica- tions in river hydraulics for controlling river bed morphology. An experimental investigation is carried out to compare the effi- ciency of sheet-piling vanes versus thin plane ones in controlling sediment redistribution in the channel bed. In particular, exper- imental tests were carried out within a straight water channel, in conditions of bed load motion. The morphology of the river bed both in the area close to the structure and in the far field was examined at different angles of attack of the vane to the incoming flow and at different values of the submergence parameter, which is the ratio between the height of the water above the structure and the water level. The experimental results show that both the shape of the vanes as well as the angle of attack affect their per- formance in terms of the effects on the bed morphology, especially for greater submergence parameters. Specifically, plane and sheet-piling vanes produce comparable remodelings of the channel bed in the downstream region, but when the attack angle is increased, the thin plane vane causes deeper scour holes close to the structure. This last effect is probably due to the increased erosive capacity of the horseshoe vortex associated with the plane vane, while the uneven surface of the sheet-piling vane miti- gates the erosive strength of that vortex.