Display omitted
•River ecological health with multiple-damming was evaluated by P-IBI.•The indicators for phytoplankton in different seasons were established.•The river-type reservoirs were often ...observed worse ecological health.•Seasonal variation in flows and N/P ratios impact riverine ecological health.
North Creek of Jiulong River is characterized by large falls and a high degree of cascade-driven hydropower development. In this paper, ecological health assessments for North Creek of Jiulong River were carried out by a field survey of seasonal phytoplankton community structure dynamics and constructing an index system, the planktonic index of biotic integrity, P-IBI, to compare ecosystem health across different seasons. North Creek were relatively healthy in the summer and fall, but exhibited the worst conditions in the winter. With the exception of fall samples, the assessments for more than 50% of the sites in the dam reservoir area were lower than “moderate.” Further, the ecological health of the mainstream was lower than that of the tributaries. The P-IBI index across different seasons was correlated with some basic water physicochemical parameters (chlorophyll a, COD and DO concentrations). Importantly, these assessment results were consistent with actual water quality monitoring results, indicating that it is feasible to use P-IBI to evaluate river health status. The assessment of seasonal changes in algal community health is helpful for developing management strategies for rivers with multiple dams.
Nitrate (NO
) contamination of surface water is a global environmental problem that has serious consequences for watershed ecosystems and endangers human health. It is crucial to identify influences ...of different sources of NO
, especially the incoming water from upper reaches. A combination of hydrochemistry and multi-isotope tracers (δ
B, δ
N-NO
, and δ
O-NO
) were used to determine NO
sources and their transformation the North Jiulong River (NJLR), Southeast China. The findings revealed that NO
, which accounted for an average of 87.1% of dissolved inorganic nitrogen (DIN), was the main chemical form of nitrogen species. The integration of dual stable isotopes of NO
, δ
B, and hydrochemistry showed that NO
was primarily contributed by sewage, soil nitrogen (SN), and ammonium (NH
) via precipitation or fertilizers. The contributions from the sewage and soil nitrate source were almost equivalent and much higher than those from other sources in the NJLR watershed. The contributions from diverse sources varied seasonally and spatially. Manure and sewage (M&S) were the leading sources in the summer and autumn, accounting for 60.9 ± 8.5% and 47.3 ± 7.9%, respectively. However, NO
fertilizers were the predominant source in the spring and winter. The NO
inflow from upper reaches was proposed as an additional end-member to identify its contribution in the midstream and downstream in this study. The contributions of NO
from the upper reaches were significant sources in the midstream and downstream, accounting for 27.2 ± 17.8% and 42.9 ± 21.9%, respectively. The obvious decline in local NO
contribution shares from midstream to downstream implied structural changes in pollutant sources and regional environmental responsibility. Therefore, tracing nitrate sources and quantifying their contributions is critical for clarifying environmental responsibilities for precise local nitrogen management in watersheds.
•Annual nutrient losses of N/P values largely range from 0 to 20.•Key factors influencing N and P are latitude, precipitation and fertilizer.•Changes in N and P losses have resulted in a decline of ...N/P values.•N and P losses was generated according to SMC values for typical land use.
Studies worldwide have indicated that agricultural pollution is the main source of nitrogen and phosphorus (N and P) in surface waters. A systematic understanding of N and P sources and sinks in agricultural systems is important for selecting the appropriate remedial strategies to control nutrient losses and water pollution. Based on nationwide data and a long-term monitoring program in Southeast China, the nationwide spatial and temporal patterns of N and P losses and the relationships between such losses and N and P inputs and rainfall were analyzed. The results showed that the annual nutrient losses from agricultural systems in China strongly varied, and the N/P values ranged from 0.01 to 51.0, with a majority at approximately 0–20, and an arithmetic mean of 9.73; these values mostly overlap the suitable range of N/P (6–15) for red bloom algae.
Cancer is a common malignant disease worldwide with an increasing mortality in recent years.
, a well-known traditional Chinese medicine, has been used for the treatment of cardiovascular and ...cerebrovascular diseases for thousands of years. The liposoluble tanshinones in
are important bioactive components and mainly include tanshinone IIA, dihydrodanshinone, tanshinone I, and cryptotanshinone. Previous studies showed that these four tanshinones exhibited distinct inhibitory effects on tumor cells through different molecular mechanisms
and
. The mechanisms mainly include the inhibition of tumor cell growth, metastasis, invasion, and angiogenesis, apoptosis induction, cell autophagy, and antitumor immunity, and so on. In this review, we describe the latest progress on the antitumor functions and mechanisms of these four tanshinones to provide a deeper understanding of the efficacy. In addition, the important role of tumor immunology is also reviewed.
Graphene is a one-atom-thick sheet, possessing a high electron mobility, constructed from sp2-bonded carbon atoms. Here, we hypothesize that graphene functions as a conductive material to promote ...anaerobic ammonium oxidation coupled with Fe(III) reduction (Feammox) in mangrove sediments slurries. In this study, graphene and 9,10-anthraquinone-2-sulfonate (AQS) were both investigated using a nitrogen isotope tracing technique. Graphene and AQS addition increased the Feammox rates by 31% and 56%. Graphene also increased the Fe(III) reduction rate by 43%, but Feammox-associated Fe(III) reduction accounted for only 1.5–4.9% of the total Fe(III) reduction. Graphene may have behaved as a conductive bridge to promote electron transfer to the Fe(III) acceptor in the Feammox process; however, the mechanisms by which graphene and AQS stimulate Feammox are different.
•Feammox was detected in mangrove sediments using an isotope tracing technique.•Feammox contributed 1.5–4.9% of total Fe(III) reduction.•Graphene behaved as a conductive bridge to promote the Feammox process.
Although advanced statistical models have been proposed to fit complex data better, the advances of science and technology have generated more complex data, e.g., Big Data, in which existing ...probability theory and statistical models find their limitations. This work establishes probability foundations for studying extreme values of data generated from a mixture process with the mixture pattern depending on the sample length and data generating sources. In particular, we show that the limit distribution, termed as the accelerated max-stable distribution, of the maxima of maxima of sequences of random variables with the above mixture pattern is a product of three types of extreme value distributions. As a result, our theoretical results are more general than the classical extreme value theory and can be applicable to research problems related to Big Data. Examples are provided to give intuitions of the new distribution family. We also establish mixing conditions for a sequence of random variables to have the limit distributions. The results for the associated independent sequence and the maxima over arbitrary intervals are also developed. We use simulations to demonstrate the advantages of our newly established maxima of maxima extreme value theory.
Saltwater intrusion results in increased estuarine salinity, affecting both ecosystem nutrient dynamics and bacterial community composition in estuarine tidal marshes. However, whether soil microbial ...biomass (SMB) and bacterial community composition have different responses to low levels of salinity increase is largely unknown. We designed an experiment to investigate the stoichiometry of microbial biomass and bacterial community composition in both the rhizospheres and bulk soils along a low-level salinity gradient across two freshwater and three oligohaline marshes. Soil microbial biomass C (MBC) and microbial biomass nitrogen (MBN) significantly decreased in both rhizospheres and bulk soils as salinity increased, while microbial biomass phosphorus (MBP) increased only in the rhizospheres. Rhizospheric effects increased the concentrations of MBC and MBP but did not significantly affect the concentration of MBN relative to the bulk soils. MBC/MBN/MBP ratios fluctuated drastically, and no clear trends were observed for both the rhizospheres and bulk soils along the salinity gradient. The composition of the bacterial communities changed greatly with increases in salinity, affected by changes in the proportional frequencies of the bacterial taxa, while bacterial alpha diversity was not significantly affected by salinity. A redundancy analysis found that the overlying water salinity and sulfate and soil total organic carbon had a synergistic effect on SMB and bacterial community composition. Our findings demonstrate that increased salinity, even in the low-level salinity range, had a large effect on decreasing MBC and MBN pools, increasing MBP stocks, and affecting bacterial community composition. However, it had a small effect on bacterial diversity. Also, rhizospheres exerted a major control on increasing MBC and MBP but rarely affected bacterial community composition or diversity.
Among many ecological services provided by mangrove ecosystems, soil organic carbon (SOC) storages have recently received much attention owing to the increasing atmospheric partial pressure of ...dissolved CO2 (pCO2). Bacteria are fundamental to ecosystem functions and strongly influence the coupling of coastal carbon, nitrogen, and sulfur cycling in soils. The SOC storage and bacterial communities along a restored mangrove soil chronosequence in the Jiulong River Estuary were explored using the 16S rDNA sequencing technique. The results showed the SOC storage in the 100 cm soil profile was 103.31±5.87 kg C m−2 and 93.10±11.28 kg C m−2 for mangroves with afforestation ages of 36 and 60 years, respectively. The total nitrogen (TN) and total sulfur (TS) contents exhibited significant correlations with the SOC in the mangrove soils, but only TN and SOC showed significant correlation in tidal flat soils. Although the tidal flats and mangroves occupied the contiguous intertidal zone within several kilometers, the variations in the SOC storage along the restored mangrove soil chronosequence were notably higher. The Functional Annotation of Prokaryotic Taxa (FAPROTAX) database was used to annotate the metabolic functions of the bacteria in the soils. The annotation revealed that only four metabolic functions were enriched with a higher relative abundance of the corresponding bacteria, and these enriched functions were largely associated with sulfate reduction. In addition, the specifically critical bacterial taxa that were associated with the SOC accumulation and nutrient cycling, shaped the distinct metabolic functions, and consequently facilitated the SOC accumulation in the mangrove soils with various afforestation ages. The general homogenization of the microbial community and composition along the intertidal soil chronosequence was primarily driven by the reciprocating tidal flows and geographical contiguity.
Display omitted
Releasing environmental flows is a valuable strategy for mitigating negative impacts of small-scale hydropower projects on river and riparian ecosystems. However, maintaining environmental flows has ...faced considerable resistance from different stakeholders, and previous studies have failed to appropriately investigate solutions. Here, online questionnaires and interviews were conducted among small-scale hydropower project owners, government administrators, and the public in Fujian Province, China. The results showed that the major hindrance to implementing environmental flows was the potential economic loss resulting from reductions in electricity production, stakeholders’ skepticism, technical difficulties, and a lack of the government supervision. Diversion-type projects pose the largest losses of electricity production after the release of environmental flows, and by adopting a 10% of mean annual flow as minimum target, most small-scale hydropower projects obtain low marginal profits without compensation. Here, we proposed an appropriate payment for ecosystem services by introducing an economic compensation program for different types of small-scale hydropower projects scaled by potential losses in electricity generation. Under such a scheme, economic losses from a reduction in electricity production are covered by the government, hydropower project owners, and electricity consumers. Our study offers recommendations for policymakers, officials, and researchers for conflict mitigation when implementing environmental flows.
● The availability of PD-anammox was investigated with higher NO 3 ––N concentration. ● NO 3 ––N concentration affects NO 3 ––N accumulation during denitrification. ● COD concentration is determinant ...for N removal pathways in PD-anammox process. ● The synergy/competition mechanisms between denitrifiers and anammox was explored.
Partial denitrification-anammox (PD-anammox) is an innovative process to remove nitrate (NO 3 ––N) and ammonia (NH 4 +–N) simultaneously from wastewater. Stable operation of the PD-anammox process relies on the synergy and competition between anammox bacteria and denitrifiers. However, the mechanism of metabolic between the functional bacteria in the PD-anammox system remains unclear, especially in the treatment of high-strength wastewater. The kinetics of nitrite (NO 2 ––N) accumulation during denitrification was investigated using the Michaelis-Menten equation, and it was found that low concentrations of NO 3 ––N had a more significant effect on the accumulation of NO 2 ––N during denitrification. Organic matter was a key factor to regulate the synergy of anammox and denitrification, and altered the nitrogen removal pathways. The competition for NO 2 ––N caused by high COD concentration was a crucial factor that affecting the system stability. Illumina sequencing techniques demonstrated that excess organic matter promoted the relative abundance of the Denitratesoma genus and the nitrite reductase gene nirS, causing the denitrifying bacteria Denitratisoma to compete with Cadidatus Kuenenia for NO 2 ––N, thereby affecting the stability of the system. Synergistic carbon and nitrogen removal between partial denitrifiers and anammox bacteria can be effectively achieved by controlling the COD and COD/NO 3 ––N.
PDF
