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To study the temporal and spatial distribution characteristics of soil organic carbon density in grassland and explore the relationship between organic carbon density and influencing factors is of great significance to the management and maintenance of grassland ecosystems in Gannan Autonomous Prefecture, which is conducive to realizing the goal of "double carbon," promoting carbon sink, and mitigating climate change. Taking Gannan Tibetan Autonomous Prefecture of Gansu Province as the research object, based on data from two CMIP6 future climate scenarios (SSP126 and SSP585), the CENTURY model was used to simulate and predict the temporal and spatial changes in soil organic carbon density in grassland of Gannan during 2023-2100. The main conclusions were as follows:① From 2023 to 2100, total organic carbon density, slow organic carbon density, and inert organic carbon density all showed a downward trend, whereas active organic carbon density fluctuated first and then increased. Meanwhile, the total organic carbon density, active organic carbon density, slow organic carbon density, and inert organic carbon density under the SSP585 scenario were higher than those under the SSP126 scenario. ② Mann-Kendall mutation analysis showed that the abrupt change in the difference of soil total organic carbon density (Δsomtc) occurred in 2030. The abrupt change in the difference of soil active carbon density (Δsom1c) occurred in 2027. ③ During the study period, the average soil organic carbon density of Gannan grassland was 7 505.69 g·m -2 under the SSP126 scenario and 7 551.87 g·m -2 under the SSP585 scenario. Gannan grassland soil organic carbon density was higher in the west and lower in the east, and the coefficient of variation was relatively stable. ④ The results of partial correlation analysis showed that precipitation was positively correlated with soil organic carbon density, whereas temperature was significantly negatively correlated with soil organic carbon density under future climate scenarios. ⑤ The results of the Theil-Sen Median trend analysis and Mann-Kendall test showed that under the two climate scenarios, the soil organic carbon density in Gannan showed an overall downward trend, in which Luqu County showed the fastest downward trend and Dibe County showed the slowest.

Under the background of carbon peak and carbon neutrality, grassland carbon sinks are a key pathway to carbon neutrality. Based on the Coupled Model Intercomparison Project Phase 6 (CMIP6) climate scenario data, the Daycent model was used to simulate the carbon budget of Gansu grasslands from 2015 to 2100, and the trend analysis was used to study the spatial and temporal changes in grassland carbon budget in the next 78 years. The results revealed that, under the future climate scenario of SSP245, the net ecosystem productivity (NEP) indicated a non-significant fluctuating downward trend with a rate of -0.20 g·(m 2 ·a) -1 (in C, the same below), and the grassland carbon sink was in a declining state. Under the future climate scenario of SSP585, the grassland NEP indicated a significant fluctuating increase trend with a growth rate of 1.36 g·(m 2 ·a) -1 , and the grassland carbon sink gradually increased under this scenario; the spatial distribution of grassland carbon budget increased from northwest to southeast. The increase in temperature and precipitation under the SSP585 climate scenario was higher than that under the SSP245 climate scenario, and the grassland carbon budget strongly correlated positively with precipitation. However, a negative correlation was observed between grassland carbon budget and temperature. We identified the carbon sink intensity in Gansu grasslands under different climate conditions, which provides a reference for and contribution to effective carbon sequestration.

The Modaomen and Hongwan waterways are the main estuaries of the Pearl River system. Affected by tides, the Fenghuangshan Reservoir, Dajingshan Reservoir, and Zhuxiandong Reservoir, which are subject to water transfer along the river line, are important drinking water sources in the central part of Zhuhai City in the Guangdong-Hong Kong-Macao Greater Bay Area. Eight heavy metals in 15 sampling points in the reservoir area were monitored in the two seasons (August and October) of 2019. The environmental quality of the surface sediments of the three water supply reservoirs was surveyed using correlation analysis, geoaccumulation index evaluation, ecological risk assessment, and traceability analysis in the present study. The results showed that the order of the average content of the eight heavy metals in the three reservoirs was as follows: Zhuxiandong Reservoir>Dajingshan Reservoir>Fenghuangshan Reservoir. The contents of Hg, Zn, and Pb in Fenghuangshan Reservoir; Hg, As, Mn, Ni, Cu, Zn, and Pb in Dajingshan Reservoir; and Zhuxiandong Reservoir exceeded the background values of soil heavy metals in Guangdong province by 1.88-2.75, 1.05-2.32, and 1.69-6.45 times. Except for As in Fenghuangshan Reservoir, As and Cu in Dajingshan Reservoir and Cr and Ni in Zhuxiandong Reservoir, the other heavy metals elements showed the content characteristics of dry season>wet season. The evaluation results of the geoaccumulation index method indicated that the pollution degree of the three reservoirs was in the order of: Zhuxiandong Reservoir>Dajingshan Reservoir>Fenghuangshan Reservoir. Among them, the Fenghuangshan Reservoir and the Dajingshan Reservoir were only slightly polluted by Hg, Zn, and Pb elements, and the Zhuxiandong Reservoir as a whole was slightly or moderately polluted. The evaluation results of the potential ecological risk index showed that the overall ecological risk of Fenghuangshan Reservoir and Dajingshan Reservoir was low, and Zhuxiandong Reservoir was at a medium ecological risk level. Hg was the main ecological risk-contributing factor of the three reservoirs, with contribution rates of 78.8%, 64.4%, and 51.0%, respectively.

Modaomen Waterway is the main outlet of the Pear River system and an important water source for Zhuhai and Macao. The water quality of 13 sampling sites in Modaomen Waterway, phytoplankton, and environmental factors were investigated at 21 sampling sites in 4 drinking water source groups, which transport water from Modaomen Waterway and connect with each other, in August and October of 2021. A total of 73 genera of phytoplankton in eight phyla were identified, with a total of 150 species, most of them belonging to Cyanophyta, Chlorophyta, and Bacillariophyta . The relative abundance of Cyanophyta was higher than 90% in the DJS and YL reservoirs during flood and dry seasons; Cyanophyta, Chlorophyta, and Bacillariophyta were dominant phyla during different seasons; and their distribution was balanced in the ZXD and ZY reservoirs. The Shannon-Wiener index, Pielous uniformity index, and Margalef richness index showed that the ZY reservoir had the most abundant biodiversity, which indicated the best water quality, followed by the ZXD and YL reservoirs. Conversely, the DJS was the least diverse reservoir for phytoplankton. The PCoA analysis indicated significant differences in plankton structures in ZXD and ZY with the other two reservoirs ( P <0.05), respectively. Redundancy analysis (RDA) showed that the main environmental factors affecting the distribution of the phytoplankton community were NO 3 - , TOC, TP, Cl - , and NH 4 + -N. These results indicated that the phytoplankton community of the four reservoirs were greatly affected by the nutrient salt caused by water transport, which suggested that the water quality of Modaomen Waterway should be improved to increase reservoir water nutrition to ensure the safety of drinking water sources.

A pilot-scale study with conventional water treatment and ozone-biological activated carbon (O 3 -BAC) treatment was conducted to evaluate the impact of ammonia and hydrogen peroxide (H 2 O 2 ) addition on the bromate and disinfection by-products formation potential (DBPFP) control, with bromide containing water as raw water. It was found that bromate concentration would exceed 10.00 μg·L -1 as ozone doses were higher than 1.0 mg·L -1 under different water qualities. Ammonia and H 2 O 2 could effectively control bromate formation and bromate concentration decreased as ammonia and H 2 O 2 doses increased. Bromate concentration could be controlled below 10.00 μg·L -1 as ammonia dose was 0.10-0.30 mg·L -1 or the m (H 2 O 2 )/ m (O 3 ) was 0.2-1.0. However, as ammonia-H 2 O 2 was combined for the same purpose, bromate increased firstly and then decreased. Ammonia addition would not significantly affect the THMFP control but H 2 O 2 application would depress the efficiency of THMFP removal.

The effect of typical disinfection byproducts (DBPs) on bacterial antibiotic resistance was investigated in this study. chlorodibromomethane (CDBM), iodoacetic acid (IAA) and chloral hydrate (CH) were selected, which belong to trihalomethanes (THMs), haloacetic acids (HAAs) and aldehydes, respectively. After exposure to the selected DBPs, the resistance change of the tested strains to antibiotics was determined. As a result, all of the three DBPs induced Pseudomonas aeruginosa PAO1 to gain increased resistance to the five antibiotics tested, and the DBPs ranked as IAA > CH > CDBM according to their enhancement effects. Multidrug resistance could also be enhanced by treatment with IAA. The same result was observed in Escherichia coli K12, suggesting that the effect of DBPs on antibiotic resistance was a common phenomenon. The mechanism was probably that DBPs stimulated oxidative stress, which induced mutagenesis. And the antibiotic resistance mutation frequency could be increased along with mutagenesis. This study revealed that the acquisition of bacterial antibiotic resistance might be related to DBPs in drinking water systems. Besides the genotoxicological risks, the epidemiological risks of DBPs should not be overlooked.

The 210Pb(ex) activities and nutrient (TOC, TN and TP) contents in sediment cores of Fuxian Lake and Dianchi Lake were measured by traditional methods, as well as their vertical distribution and relationship were also comparatively analyzed in this paper. The study results indicated that the vertical distributions of 210Pb(ex) and nutrients were significantly different between Fuxian Lake and Dianchi Lake. The variation amplitude of 210Pb(ex) activities in Dianchi Lake was higher than that in Fuxian Lake. The disordered distribution characteristics of 210Pb(ex) in Dianchi Lake surface sediments were closely related to physicochemical migration of lead caused by human activities. The variation trends of nutrients in sediment cores were corresponded to local natural evolution and human activities in different historical periods. Relationship between 210Pb(ex) activities and nutrients were mainly affected by the nutrition level of lakes. The greater the lake eutrophication level was, the stronger the correlation was found. To the individual nutrient indicators, similar characteristics were shown in the two lakes, and the order was TOC > TP > TN.

Endotoxins, also known as lipopolysaccharide complexes, are anchored in the outer membrane cell wall of most Gram-negative bacteria and some cyanobacteria. They are continuously released to environment during cell decay. Being common pyrogens and highly immunogenic molecules, endotoxins are related to many human diseases. Due to the tolerances and thermo-stability of endotoxin molecules, they were hard to be removed by common methods. The health risk caused by the endotoxin contamination in drinking water and water environment by various exposure pathways have attracted more and more attention in recent years. In this paper, the physical and chemical properties, biological activities and detection assay of the endotoxin contamination were reviewed, and interfere factors of the main assay, the LAL/TAL (Limulus amebocyte lysate/Tachypleus amebocyte lysate) assay, for detecting endotoxin in water sample were investigated, and the development tendency of the endotoxin detection assay was analyzed.

The first step of biodegradation is the contact of microorganism and pollutants, in order to examine the influence of phenanthrene on Sphingomonas sp. GY2B's surface properties during its degrading process, the bacteria was cultivated at different conditions, and detected by flow cytometry combined with fluorescent dyes for its surface changes. The results indicated that, the membrane structure had been certainly damaged during the degrading process, leading to an increased membrane permeability. Moreover, the destruction of bacteria membrane integrity became more serious with a higher pollutant concentration. At the concentration of 300 mg x L(-1), the ratio of stained bacterial cells/unstained cells was 12.44 after cultured for 60 h, while at 100 mg x L(-1) and 1.2 mg x L(-1), the ratios were 1.95 and 1.11, respectively. The results of fourier transform infrared (FT-IR) absorbance spectroscopy detection, the discrimination of death, injured and intact cells, and Zeta potential detection further verified the bacterial cell surface permeability changes. Flow cytometry combined with fluorescent dye propidium iodide was used to monitor the changes of bacterial membrane integrity on single-cell level which exhibited a good potential for exploring the changes of bacterial surface properties during the degrading progress and more deeply for investigating the degradation mechanism.

Ground dry leaves of two emerged macrophytes Zinania Caduciflora and Phragmites australis from Lake Dianchi were soaked in distilled water in laboratory to track their DOM release process. The results showed that: (1) during soaking, concentration of DOM which was released to the overlying water by the two species increased at first, then decreased and increased again at last. Concentrations of DOC, DON, and DOP released by both species reached their peaks at the 8th, 8th, and 24th hour, respectively; (2) the two species showed the same DOM release trend, i.e., release rates and intensities of DOC, DON, and DOP by both species reached the peaks at the 8th hour, and for both of them, the release rates and intensities of DOC, DON, and DOP at the 8th hour followed the order of DOC > DON > DOP; (3) the SUVA254 value obtained by the UV-visible spectroscopy increased at first and then decreased; (4) Fourier transform infrared (FT-IR) spectroscopy showed that the characteristic peak -OH disappeared during the decomposition process; (5) intensity of the humic-acid fluorescence peak as showed by the 3D-EEM fluorescence intensity (F/DOC) increased along with degradation.

Endotoxins, derived from cell walls of most Gram-negative bacteria and some cyanobacteria, are common pyrogen and highly immunogenic molecules, and related to many diseases. In this paper, a detection method for endotoxin activity in water environment using kinetic-turbid assay of Tachypleus Amebocyte Lysate (TAL) was established, the influence of pH and salts on TAL assay was investigated. Results showed that it was favorable for TAL assay in the pH range of 6.0-8.4, at low pHs, inhibition results were observed and opposite results were obtained at high pHs. The pH should be adjusted by Tris-HCl (pH = 7.4) buffer before the endotoxin detection. No significant interference was shown in the detection of water containing NaCl, Na2SO4, CaCl2, MgCl2 and KCl with a concentration of less than 50 mg x L(-1), however, the inhibition occurred at the concentration up to 1000-10,000 mg x L(-1). Only 2. 5 mg x L(-1) of FeCl, Fe2(SO4)3, AlCl3 and Al2 (SO4)3 caused significant inhibition. Endotoxin activities of ultrapure water, tap water and recreational water were detected by TAL assay, and their endotoxin activities were < 0.06 EU x mL(-1), 0.46 EU x mL(-1) and 432. 68 EU x mL(-1), respectively.

Hepatitis A virus (HAV) is single-strainded RNA virus that causes infectious hepatitis A. Detection and quantification of hepatitis A virus in Tianjin coastal seawater of Bohai Bay were carried out by conventional RT-PCR and SYBR Green real-time quantitative RT-PCR using the primers based on the conserved sequence at the VP1-VP2 genes of HAV. The nine samples were taken at Tianjin coastal seawater of Bohai Bay locating in the south of Tanggu, in summer, autumn and winter of 2007 and spring of 2008. For viral detection, seawater samples were concentrated either using a small ultrafiltration system (Millipore Pellicon Mini TFF) or a Centriprep-100 centrifugal ultrafiltration device (Millipore Centricon Plus-70). RT-PCR analysis showed that a 192 bp HAV cDNA was amplified from all nine seawater samples and the sequence identities of these cDNAs to the homologous sequence in the GenBank were between 95% and 100%. SYBR Green real-time quantitative RT-PCR analysis indicated that HAV concentration in these samples ranged from 5.35 x 10(6) to 4.51 x 10(7) virus particles/L.

A new bioaugmentation technique for petroleum contaminated soil utilizing the synergistic function between bacteria and fungi in both growth and metabolism of petroleum was proposed and investigated using E. cloacae and Cun. echinulata, both of which were isolated from Zhongyuan Oil Field, Henan, China. The maximum biomass of E. cloacae and Cun. echinulata obtained in the mixed slurry culture were 3- and 20-fold as much as their respective counterpart obtained in the pure cultures. The decrease of cell activity was considerably postponed, as compared to the pure cultures. The removal of total petroleum hydrocarbon (TPH) by the mixture was higher than the sum of the individual removal obtained in the pure culture, which could be further enhanced by repeated inoculation of fresh fungal and bacterial inocula. The optimal parameters of the in situ bioremediation of crude oil-contaminated soil sampled in Zhongyuan Oil Field were determined as follows: 25% (m/m) soil humidity, 6% (m/m) of wood scraps, 2.5 x 10(4) CFU/g of E. cloacae and 2.5 x 10(7) CFU/g dry soil of Cun. echinulata. It was demonstrated that the growth behavior of the inocula and the degradation of TPH were not inhibited by the indigenous microorganisms. The in situ remediation via inoculating the fungal-bacterial consortia removed 65% of TPH in 40 days while the control experiment with the indigenous microorganisms removed 16%.

Conversion of artificial corn stalk wastewater, which was prepared according to the main composition of the corn stalk fermentation lixivium, into bio-hydrogen gas by mixed culture was performed in a 20 L half-continuous flow fermenter. The influences of several environmental factors on the bio-hydrogen production, such as HRT, C/N ratio, Fe2+ and artificial corn stalk wastewater concentration were discussed in the tests. The experimental results showed that HRT, C/N ratio, Fe2+ and artificial corn stalk wastewater concentration significantly affected the fermentation hydrogen production. The maximum H2 yield of 11.80 mol/kg, H2 concentration of 56% and hydrogen production rate of 8.81 L/(L x d) were obtained at HRT = 10 h, C/N = 100, Fe2+ concentration of 100 mg/L and substrate concentration of 12.5 g/L by mixed culture, respectively. In the fermentation hydrogen-producing process, the conversion efficiency of the substrate was more than 90%, and 39.40% of COD was removed from the reactor. The main by-products in the liquid phase were acetic acid, butyric acid, propionic acid and a little ethanol and butanol throughout this study.