Quantifying the impact of damming on phosphorus reallocation: Finer particles offset the reduction in soluble reactive phosphorus (SRP) by decreasing suspended sediment concentration.

In this research, an innovative approach to quantify the impact of damming on phosphorus (P) reallocation between suspended sediments (SS) and water was proposed. P allocation can be described by the surface complexation model, with the impact of damming quantified by four variables: P load, suspended sediment concentration (SSC), particle size, and pH. Iron/aluminium (Fe/Al) oxide-adsorbed P (Fe/Al-P) was identified as the exchangeable P during adsorption/desorption equilibrium with a series of heterogeneous sediment samples from two large Asian rivers, the Mekong River and the Yellow River.

Particulate and water-mobilizable phosphorus from a watershed with a plain river network contributes equal amounts of algal available phosphorus to its downstream lake.

This research was designed to estimate the contributions of phosphorus (P) in different factions from an upstream plain river network to algal growth in a downstream shallow eutrophic lake, Taihu Lake, in China. During three flow regimes, the P fractions in multiple phases (particulate, colloidal and dissolved phases) and their algal availabilities were assessed via bioassays with Dolichospermum flos-aquae as the test organism. The P partitioning patterns among multiple phases were strongly affected by the concentration of total suspended solids (TSS) that changed with the river flow regime, with stronger disturbance of sediments at lower water levels (low flow) and weaker disturbance of sediments at higher water levels (high flow) in the plain river network.

Suspended particulate matter <2.5 μm (SPM) in shallow lakes: Sedimentation resistance and bioavailable phosphorus enrichment after sediment resuspension.

Resuspended particulate matter in shallow lakes contributes remarkable phosphorus (P) concentrations to the water column that potentially support algal/cyanobacterial growth. However, only fine particulate matter can be retained in the water column for a long time after sediment resuspension events. The size at which fine particulate matter has ecological implications remains undefined.

Quantifying phosphorus levels in water columns equilibrated with sediment particles in shallow lakes: From algae/cyanobacteria-available phosphorus pools to pH response.

Sediment phosphorus (P) release in shallow eutrophic lakes is a major contributor of P to algal blooms. This research proposes an innovative notion in which the P diffusive fluxes at the sediment-water interface (SWI) of shallow lakes are controlled by the P adsorption-desorption equilibria, with pH as the major regulating factor. The P equilibrium concentration (C) at SWI was conceptualized into a dependent variable responding to two factor-dependent variables, the algae/cyanobacteria-available P pools of the SWI and the pH in the water column, resulting in the empirical equation C(pH) = C/[1 + e].

Connecting sources, fractions and algal availability of sediment phosphorus in shallow lakes: An approach to the criteria for sediment phosphorus concentrations.

Although point and nonpoint sources contribute roughly equal nutrient loads to lakes, their relative role in supporting algae growth has not been clarified. In this research, we have established a quantitative relationship between algae-available phosphorus (P) and P chemical fractions in sediments; the latter indicates the relative contribution of point versus nonpoint sources. Surface sediments from three large shallow lakes in eastern China, namely, the Chaohu, Taihu and Hongzehu Lakes, were sampled to assess their algae-available P and chemically extracted P fractions.

Environmental filtering dominated the antibiotic resistome assembly in river networks.

River networks play important roles in dissemination of antibiotic resistance genes (ARGs). The occurrence, diversity, and abundance of ARGs in river networks have been widely investigated. However, the assembly processes that shaped ARGs profiles across space and time are largely unknown.

Similar geographic patterns but distinct assembly processes of abundant and rare bacterioplankton communities in river networks of the Taihu Basin.

Bacterioplankton play an important role in the biogeochemical cycling in rivers. The dynamics of hydrologic conditions in rivers were believed to affect geographic pattern and assembly process of these microorganisms, which have not been widely investigated. In this study, the geographic pattern and assembly process of bacterioplankton community in river networks of the Taihu Basin were systematically explored using amplicon sequencing of the 16S rRNA gene.

Phosphorous partitioning in sediments by particle size distribution in shallow lakes: From its mechanisms and patterns to its ecological implications.

This study revealed a general pattern of P partitioning onto sediment particles that has ecological implications for shallow lakes. Six individual sediment samples from two large shallow lakes in eastern China were sieved into five sediment particle size classes ranging from 0.5 μm to 50 μm.

Transport and partitioning of metals in river networks of a plain area with sedimentary resuspension and implications for downstream lakes.

This study showed that metal transport and partitioning are primarily controlled by suspended solids with seasonal flow regimes in plain river networks with sedimentary resuspension. Eight metal species containing iron (Fe), manganese (Mn), cadmium (Cd), chrome (Cr), copper (Cu), nickel (Ni), lead (Pb), and zinc (Zn), in multiple phases of sediments, suspended solids (>0.7 μm), colloids (1 nm-0.

Transparent Exopolymer Particles in Drinking Water Treatment-A Brief Review.

Transparent exopolymer particles (TEP) have been described as a class of particulate acidic polysaccharides, which are commonly found in various surface waters. Due to their unique physicochemical characteristics, they have recently been receiving increasing attention on their effects in water treatment. Currently, TEP are commonly known as clear, gel-like polysaccharides.

Wind induced algal migration manipulates sediment denitrification N-loss patterns in shallow Taihu Lake, China.

Driven by winds, the distribution of algae is often noticeably patchy at kilometer scales in shallow lakes. The decomposition of the settled algal biomass may affect nitrogen (N) biogeochemical cycles and thereby N loss in sediments. In this study, we investigated sediment denitrification N-loss patterns along algal migration pathway in Taihu Lake, a shallow and eutrophic lake in China, and found that wind-induced algal migration in the overlying water manipulated the temporal and spatial patterns of denitrification N-loss in sediments.

Growth of Zostera japonica in different sediment habitats of the Yellow River estuary in China.

The estuarine delta of the Yellow River is a region of strong land-ocean-human interactions that undergoes a unique evolutionary process. The delta is formed by deposition of large quantities of sediments carried by the Yellow River, especially during the annual water and sediment regulation period; more than one-third of the total annual sediments is deposited to the estuary area. The seagrass Zostera japonica is located at the forefront of the Yellow River delta.

Effects of hematite on the stabilization of copper, cadmium and phosphorus in a contaminated red soil amended with hydroxyapatite.

Iron (Fe) oxides are intimately coupled with phosphorus and closely associated with the bioavailability of potential toxic elements (PTEs) in soil. Thus, Fe oxides may influence the stabilization of PTEs in contaminated soils amended by phosphorus. To evaluate the effects of hematite (HMT) on the stabilization of PTEs, 1-5% (by weight) of HMT was added into a contaminated red soil amended with hydroxyapatite (HAP) to simulate naturally occurring Fe oxides.

Hydropower reservoirs on the upper Mekong River modify nutrient bioavailability downstream.

Hydropower development is the key strategy in many developing countries for energy supply, climate-change mitigation and economic development. However, it is commonly assumed that river dams retain nutrients and therefore reduce downstream primary productivity and fishery catches, compromising food security and causing trans-boundary disputes. Contrary to expectation, here we found that a cascade of reservoirs along the upper Mekong River increased downstream bioavailability of nitrogen and phosphorus.

Nitrous oxide emissions from cascade hydropower reservoirs in the upper Mekong River.

Nitrous oxide is a powerful greenhouse gas, and its emissions from single reservoirs have been extensively studied; however, it still remains unclear about nitrous oxide emission patterns in cascade reservoirs. In this study, nitrous oxide emissions from cascade hydropower reservoirs were investigated using the thin boundary layer model in the heavily dammed upper Mekong River. Meanwhile, sediment denitrification for nitrous oxide production was analysed using the stable isotope method and the quantitative polymerase chain reaction method.

Driving factors of phytoplankton functional groups in the shallow eutrophic lakes of lowland areas of Huaihe River (China).

In this study, we want to clarify the driving factors of phytoplankton community in a set of eutrophic lakes in the lowland areas of Huaihe River, one of seven biggest rivers in China. We analyzed the phytoplankton community of five lakes located in the lowland areas of Huaihe River using Reynolds functional groups (RFG) approach, with simultaneous measurement of several environmental variables in monthly sampling campaigns during 2 years. The annual average phytoplankton biovolume of the five lakes ranged from 3.

Bioavailability and mobility of copper and cadmium in polluted soil after phytostabilization using different plants aided by limestone.

Phytostabilization aided by soil amendments has been advocated in areas contaminated by trace metals. In this study, the effects of indigenous weed (Setaria pumila), energy plant (Pennisetum sinese), cadmium (Cd)-hyperaccumulator (Sedum plumbizincicola), and copper (Cu)-tolerant plant (Elsholtzia splendens) on the bioavailability and mobility of Cu and Cd in polluted soil were evaluated after phytostabilization aided by limestone (0.1% wt) over four years.

[Synergy of Algal Sedimentation and Sediment Capping for Methane Emission Control in Bloom Waters].

This study tested a strategy in simulated column systems to control methane emissions from algal bloom waters using the combined technology of algae sedimentation and sediment capping. The results demonstrated that the synergy of algal sedimentation and sediment capping can effectively improve the water environment and reduce methane emissions; however, the improvement rate differed among capping materials. The use of activated carbon yielded better performance on the water environment improvement and methane emission control than soil and zeolite.

Enrichment of bioavailable phosphorus in fine particles when sediment resuspension hinders the ecological restoration of shallow eutrophic lakes.

Sediment resuspension is one of the main factors impacting the ecological restoration of shallow eutrophic lakes, but the mechanisms connecting suspended particles and algal growth have not been clarified. Our research presents an innovative approach based on P reallocation among particles with various sizes, considering the changes in redox and pH conditions from the sediments to the overlying water during resuspension. A lab-scale experiment was conducted to simulate P reallocation in particles during sediment resuspension by periodically dosing the system with P and/or organic carbon.

A method to study antibiotic emission and fate for data-scarce rural catchments.

Estimations of antibiotic emission and fate and thereby ecological risk in rural catchments still lack feasible methods due to data scarcity. This study developed a new framework to evaluate the emission and fate of typical antibiotics for data-scarce catchments with uncertainty analysis. We estimated antibiotic discharge through questionnaire surveys; predicted antibiotic fate in air, water, soil, and sediment phases using a multimedia fugacity model; and analyzed the uncertainties of predicted environmental concentrations (PECs) and ecological risks of antibiotics.

Distribution and adsorption of metals on different particle size fractions of sediments in a hydrodynamically disturbed canal.

Sediment resuspension widely occurs in environments with hydrodynamic disturbances, where particles are sieved into different grain size groups. The particles of different grain size exhibit heterogeneity of their physical, chemical or biological features. This research addressed the association of metals on size fractional particles sieved by sediment resuspension in a canal of Taihu basin, a highly urbanized and human-impacted area.

Effects of nutrient temporal variations on toxic genotype and microcystin concentration in two eutrophic lakes.

Harmful cyanobacterial blooms are a growing threat to freshwater ecosystems worldwide due to the production of microcystin (MC), which can have detrimental effects on water quality and human health. The relations between MC-producing Microcystis, MC production, and environmental variables especially nutrient conditions in eutrophic lakes, Lake Taihu and Lake Yanghe, were investigated during the bloom season of 2015. Results showed that toxigenic cells contributed to 8.

The production and release of microcystin related to phytoplankton biodiversity and water salinity in two cyanobacteria blooming lakes.

To find the connections between microcystins and the phytoplankton community, coupled with environmental factors, we investigated 2 cyanobacteria blooming lakes, Lake Taihu (at the center of the Yangtze River Delta, eastern China) and Lake Yanghe (near Qinhuangdao City, northern China). Two years of data, including water quality and the amounts of phytoplankton, microcystins, and the congeners in both algal cells and water, were collected from the 2 lakes during 2013 and 2014. The results showed that both the microcystin quota and release percentage were positively correlated with biodiversity of phytoplankton and the Chlorophyta to phytoplankton ratio, but were negatively correlated with cyanobacteria abundance and the cyanobacteria to phytoplankton ratio; both the microcystin quota and release percentage were closely related to the intensity of competition between cyanobacteria and other phytoplankton; meanwhile, microcystins played a role in the competition between cyanobacteria and other phytoplankton.

Carbon Emission from Cascade Reservoirs: Spatial Heterogeneity and Mechanisms.

Carbon emission from reservoirs is considered to tarnish the green credentials of hydropower and has been extensively studied in single reservoirs. However, it remains unclear how carbon emission differs in cascade reservoirs and the mechanism behind the differences. In this study, carbon dioxide (CO) and methane (CH) emissions from cascade hydropower reservoirs were measured in the Lancang River, the Chinese section of the Mekong River.