Flow Pollution Research Articles

The influence of meteorological factors and terrain on air pollution concentration and migration: a geostatistical case study from Krakow, Poland

Despite the very restrictive laws, Krakow is known as the city with the highest level of air pollution in Europe. It has been proven that, due to its location, air pollutants are transported to this city from neighboring municipalities. In this study, a complex geostatistical approach for spatio-temporal analysis of particulate matter (PM) concentrations was applied. For background noise reduction, data were recorded during the COVID-19 lockdown using 100 low-cost sensors and were validated based on indications from reference stations. Standardized Geographically Weighted Regression, local Moran’s I spatial autocorrelation analysis, and Getis–Ord Gi* statistic for hot-spot detection with Kernel Density Estimation maps were used. The results indicate the relation between the topography, meteorological variables, and PM concentrations. The main factors are wind speed (even if relatively low) and terrain elevation. The study of the PM2.5/PM10 ratio allowed for a detailed analysis of spatial pollution migration, including source differentiation. This research indicates that Krakow’s unfavorable location makes it prone to accumulating pollutants from its neighborhood. The main source of air pollution in the investigated period is solid fuel heating outside the city. The study shows the importance and variability of the analyzed factors’ influence on air pollution inflow and outflow from the city.

Effect of anthropogenicity on the temporal diversity and abundance of macro-invertebrates in Calabar River, Okomita, Cross River State, Nigeria

The influence of anthropogenicity on the abundance and diversity of macro-invertebrates was investigated in Calabar River, Okomita, Cross River State for a period of 24 months (August, 2014-September, 2016) in six sampling stations. Bank root macro-invertebrates were collected by kick sampling while substrata macro-invertebrate samples were collected with a van-Veen grab. Seasonal variations in the values of the macro-invertebrates abundance were determined by pooling together the values for the wet and dry seasons. The difference in values in the six stations in each season was tested for significant difference (p < 0.05) while the pooled differences in the two seasons were tested using unpaired (independent) student’s t-test. Spcies diversity was estimated using the Shannon-Wiener index (H’), species richness (d) and evenness (J) of individual distribution among species. All macro-invertebrate groups had highest percentage abundance in the dry season months. Seasonal percentage abundance of insects was significantly different (p˂0.05). Higher seasonal abundance of the total macro-invertebrates was recorded in the dry season and the seasonal variation was significant (p˂0.05). Lower number of pollution intolerant species of macro-invertebrates (Sudanonautes africanus, Orectochilus orbisonorum, Dineutus discolour, Phaon iridipennis, Pila ovata, Natica flammulata and Eulima fischeri) recorded during the rainy season was an indication that the river was more perturbed during the rainy season as a result of influx of pollutants from refuse dumps, farmlands, Okomita Market, abattoir and mechanic workshop. The results of the PCA revealed that DO, hardness, alkalinity, magnesium and cadmium were the most important parameters influencing the abundance of macro-invertebrates in Calabar River, Okomita. Intermediate values and values less than one of Shannon-Weiner diversity index were observed, indicating that Calabar River, Okomita is moving from moderately polluted state to severely polluted condition.

Mineral composition and seasonal dynamics of the content of heavy metals in bed loads of ravines and small rivers in the city of Kamyshin (Volgograd oblast, Russia)

The article presents the study of the mineral composition and content of heavy metals (Ni, Cu, Cd, Cr, Pb, Zn) in bed loads (0–1 cm layer) of ravines and small rivers in the city of Kamyshin (Volgograd oblast, Russia). We established that quartz is the most widespread rock-forming mineral found all-over the place. In areas, where proportion of quartz decreases, the content of hydromica and feldspars increases. We discovered that the content of heavy metals in the bed loads increases in 61.1% of cases in spring compared to summer due to the inflow of pollutants from the urban watersheds with snowmelt runoff. Bed loads with a high content of heavy metals should be considered as an object of accumulated environmental damage. Reclamation of the beds of small rivers and ravines is required in order to create a comfortable urban environment and reduce the negative impact on the Volgograd Reservoir.

The Impact of Springtime‐Transported Air Pollutants on Local Air Quality With Satellite‐Constrained NOx Emission Adjustments Over East Asia

AbstractTo quantify the impact of transported air pollutants on local air quality, this study applies an inverse modeling technique with tropospheric nitrogen dioxide column retrievals from TROPOspheric Monitoring Instrument, and the CMAQ‐ISAM model, which computes source attribution over six regions of interest in spring 2019 over East Asia. Satellite‐constrained nitrogen oxides (NOx) emissions successfully improve model performance by significantly reducing the normalized mean bias of concentrations of NOx, Ozone (O3), and PM2.5 from most regions in China and South Korea. Anticyclones over the Yellow Sea transport air pollutants and increase the contribution of emissions from adjacent regions to local air quality. Fluxes of air pollutants with posterior emissions showed notable enhancements in their magnitude by 3%–24% for NOy, O3, and PM2.5. The contributions of emissions from neighboring regions on local NOx and O3 budgets in the planetary boundary layer were 22.96%–35.24% and 24.23%–42.26%. The contribution of emissions from North Korea was notable despite its comparably lower emission rates. Regarding the impact of external influences on local air quality, the enhanced chemical loss of NOx compensated for increases by transport. Also, the increased vertical gradient of maximum daily 8‐hr average O3 amplified vertical transport and dry deposition processes in the opposite direction along with slight changes in the chemical net O3 production rate. This study shows the nonlinear response of local air quality to changes in the transport of air pollutants, which could be further investigated concerning changes in emissions and climatological factors that would modify the inflow of air pollutants.

Analysis of the Bacterial Biocenosis of Activated Sludge Treated with Leachate from Municipal Landfills.

The influx of toxic pollutants into wastewater treatment plants can negatively affect the quality of the activated sludge (AS). One source is landfill leachate. The identification of microorganisms present in AS is very important, e.g., while improving wastewater treatment technology. Therefore, the aim of the study was to investigate the effect of raw leachate and after purification of Phragmites australis and Ceratophyllum demersum on the composition of the AS bacterial biocenosis. In addition, AS status was assessed by LIVE/DEAD BacLight ™ fluorescent staining. The obtained results showed that the leachate did not significantly affect the cell membranes of AS bacteria, and even a slight improvement was noted. The research carried out using the next-generation sequencing method shows that the origin of the samples (active and closed storage) and the method of processing do not significantly affect the composition of the AS bacterial biocenosis at higher taxonomic levels. However, at the species level, the appearance of bacteria not previously present in AS was observed, namely: Flavobacterium luticocti, Candidimonas nitroreducens and Nitrobacter hamburgensis. The obtained results suggest that the leachate may be a source of microorganisms positively influencing the condition of AS bacteria.

Labile Components of the Amur River Flood Silts

The paper considers the possibility of inflow and accumulation of pollutants on the Amur River floodplain as a result of floods and deposition of the flood silts (FS). Labile components of FS – water-dispersible clays (WPC) – are a good indicator of transfer and removal of nutrients and contaminants. The study was focused on FS of the floodplain islands below the confluence of the Sungari River (near Khabarovsk, Far East, Russia). It is shown that, the content of major and trace elements in FS corresponds to the average values for sedimentary rocks independently of the flood power. However, after minor flood, there was a significant accumulation of calcium and phosphorus in WDC, which is accompanied by an abnormal accumulation of As up to 70 mg/kg. After the extreme flood, the As content in WDC fell by more than three times, which is associated with the duration of standing water in the floodplain. The latter causes the dissolution and leaching of apatite group phosphates and the arsenates contained in them as impurities. The process of As accumulation in WDC of the flood silts in low-water years (at minor floods) is not critical, but requires monitoring and further research.

Evaluation of the Effectiveness of the SED-BIO System in Reducing the Inflow of Selected Physical, Chemical and Biological Pollutants to a Lake

The aim of this study was to assess the efficiency of the innovative SED-BIO system in limiting the inflow of pollutants to Jelonek Lake. The analyses were conducted in the Gniezno Lake District in Greater Poland (the western part of Poland). Physical and chemical analyses were conducted in the years 2016–2019. The results demonstrate that the system is highly effective in the reduction of such nutrients as nitrogen (NO3−—63%; NH4+—14.9%) and phosphorus (PO43−—19.3%). Although the presence of cyanobacteria was confirmed practically throughout the whole monitoring period of the system (2016), the specimens found in most samples were not toxigenic genotypes with a potential to produce microcystins. Microcystins (3 µg·L−1) were detected only once, immediately after the SED-BIO system had been installed in the river and pond, which demonstrates that this natural toxin was eliminated from the additional pool of contaminants that might be transported to Jelonek Lake.

Seasonal Water Quality and Algal Responses to Monsoon-Mediated Nutrient Enrichment, Flow Regime, Drought, and Flood in a Drinking Water Reservoir.

Freshwater reservoirs are a crucial source of urban drinking water worldwide; thus, long-term evaluations of critical water quality determinants are essential. We conducted this study in a large drinking water reservoir for 11 years (2010–2020). The variabilities of ambient nutrients and total suspended solids (TSS) throughout the seasonal monsoon-mediated flow regime influenced algal chlorophyll (Chl-a) levels. The study determined the role of the monsoon-mediated flow regime on reservoir water chemistry. The reservoir conditions were mesotrophic to eutrophic based on nitrogen (N) and phosphorus (P) concentrations. An occasional total coliform bacteria (TCB) count of 16,000 MPN per 100 mL was recorded in the reservoir, presenting a significant risk of waterborne diseases among children. A Mann–Kendall test identified a consistent increase in water temperature, conductivity, and chemical oxygen demand (COD) over the study period, limiting a sustainable water supply. The drought and flood regime mediated by the monsoon resulted in large heterogeneities in Chl-a, TCB, TSS, and nutrients (N, P), indicating its role as a key regulator of the ecological functioning of the reservoir. The ambient N:P ratio is a reliable predictor of sestonic Chl-a productivity, and the reservoir was P-limited. Total phosphorus (TP) had a strong negative correlation (R2 = 0.59, p < 0.05) with the outflow from the dam, while both the TSS (R2 = 0.50) and Chl-a (R2 = 0.32, p < 0.05) had a strong positive correlation with the outflow. A seasonal trophic state index revealed oligo-mesotrophic conditions, indicating a limited risk of eutrophication and a positive outcome for long-term management. In conclusion, the Asian monsoon largely controlled the flood and drought conditions and manipulated the flow regime. Exceedingly intensive crop farming in the basin may lead to oligotrophic nutrient enrichment. Although the reservoir water quality was good, we strongly recommend stringent action to alleviate sewage, nutrient, and pollutant inflows to the reservoir.

Drained agricultural landscapes under the impact of airborne industrial pollution

When assessing the ecological state of drained agricultural landscapes exposed to pollution, the average daily dust load, the chemical composition of the snow cover of the drained lands, the elemental composition of soils and the yield of perennial fodder grasses were determined. Snowfall, which is a good indicator of airborne technogenic fallouts, was classified as contaminated near the mining site, as opposed to the case of road traffic. Although the average daily dust load was very high the total level of chemical pollution near the quarry was low. Depending on the type of technogenic impact, the sequences of macro- and microelements accumulation in the snow cover were identified: quarry - Al > Mn > Mg > Ca > Fe, highway -Cr > Al > Mg > Pb > Ca > Co. Depending on the physical properties of the soils and technical features of the drainage network, Multidirectional trends in the inflow of pollutants into the upper horizons of the farmland soils with surface waters were noted. According to the results of this study, the yield of perennial fodder grasses increases with distance from the pollution sources under both types of technogenic influence.

Can Winter Road De-Icing Affect Mortality of Organisms in Aquatic Ecosystems? An Experimental Approach

Road maintenance in winter using de-icing agents, which is widely used in Eastern Europe, is the cause of water salinization in neighbouring environments, which might lead to biodiversity loss in aquatic ecosystems. In this study, we investigated NaCl toxicity to test young organisms: Daphnia magna and Poecilla reticulata (standard tests organisms). The salinity of NaCl was measured by electrolytic conductivity (EC). It was statistically demonstrated that the test solutions should be prepared using natural water. For D. magna the NOEC was 7.17 mS/cm and the LC50 9.76 mS/cm. Poecilla reticulata showed resistance to salinity up to a conductivity of 25.2 mS/cm, and no lethal effects were recorded for any individual in the test population. The study showed that winter salinities recorded in inland waters (without emergencies such as sudden influx of pollutants due to industrial accidents) are unlikely to affect fish but may be hazardous to small plankton. However, the high dare of D. magna may result in a reduction of planktivorous fish.

Current hydroecological state of the Ural River in the lower reaches

Climate and hydrological changes in the Ural River basin, together with water management activities determine the current hydroecological state of the river in its lower course. In comparison with the conventional natural background, the salinity of water in high water period increased by 2.5 times, in low water period- by 5-8 %. Contamination of the lower course of the river is caused by the inflow of pollutants from the upstream sections and the confluence of the polluted tributaries. In the area with no tributaries, the water is characterized as “standard-clean”. The saprobity indices, which characterize the content of organic substances in water, are located within the boundaries of the b-mesosaprobic zone, which characterize low level of water contamination. The content of dissolved oxygen indicates insufficient aeration of the river water during most of the year. The lowest oxygen content is observed during winter period.

The Effects of Land Use on Concentrations of Nutrients and Selected Metals in Bottom Sediments and the Risk Assessment for Rivers of the Warta River Catchment, Poland

Changes in the environment, aiming at agricultural intensification, progressive urbanisation and other forms of anthropopression, may cause an increase in soil erosion and a resulting increase in the pollution inflow to surface water. At the same time, this results in increased nutrient pollution of bottom sediments. In this study, the concentrations of total nitrogen (TN), total phosphorus (TP), total organic carbon (TOC), calcium (Ca), iron (Fe) and potassium (K) were analysed using bottom sediment samples collected at 39 sites located along the entire length of the Warta River and its tributaries. Agricultural use of land adjacent to rivers was found to significantly degrade sediment quality, while anthropogenic land use (as defined by Corine Land Cover classification—CLC), unlike previous studies, reduces the pollution loads in the bottom sediments. Forest use also contributes to the reduction of the pollution load in sediments. It was found that the significance of the relationship between pollutant concentrations and land use depends on the length of the river–land interface. According to the analyses, the level of correlation between the analysed constituents depends on the use of land adjacent to rivers. The impact of agricultural land use has the strongest effect in the 1 km zone and 5 km in the case of anthropogenic land use. The results showed that the variability of total phosphorus TP concentrations is strongly correlated with the variability of iron concentrations. SPI values indicate that the risk to sediment quality is low due to TOC and Fe concentrations. In contrast, the risk of sediment pollution by TN and TP shows greater differentiation. Although the risk is negligible for 40% of the samples, at the same time, for 33% of the samples, a very high risk of pollution with both TN and TP was found.

Impact of Municipal, Road Traffic, and Natural Sources on PM10: The Hourly Variability at a Rural Site in Poland

The paper presents data from a monthly campaign studying the elemental composition of PM10, as measured by a specific receptor in Kotórz Mały (Opole Voivodeship)—located in the vicinity of a moderately inhabited rural area—measured in one-hour samples using a Horiba PX-375 analyzer. The hourly variability of SO2, NO, NO2, CO, and O3 concentrations, as well as the variability of meteorological parameters, was also determined. On average, during the entire measurement period, the elements related to PM10 can be arranged in the following order: As &lt; V &lt; Ni &lt; Pb &lt; Cr &lt; Mn &lt; Cu &lt; Ti &lt; Zn &lt; K &lt; Fe &lt; Ca &lt; Al &lt; Si &lt; S. Trace elements, including toxic elements—such as As, V, Ni, Pb, Cr, and Mn—were present in low concentrations, not exceeding 10 ng/m3 (average daily value). These elements had fairly even concentrations, both daily and hourly. The concentrations of the main elements in the PM10, as measured by the receptor, are subject to strong hourly changes related not only to changes in the structures of the sources identified in the statistical analysis, but also to wind speed and direction changes (soil and sand particle pick-up and inflow of pollutants from coal combustion). It has been shown that the transport emissions measured by the receptor can have an intense effect on PM10 in the afternoon.

Investigation of the Factors Affecting the Treatment Performance of a Stormwater Horizontal Subsurface Flow Constructed Wetland Treating Road and Parking Lot Runoff

This study assessed the factors affecting the growth and survival of microorganisms in a small horizontal subsurface flow constructed wetland (HSSF CW) treating stormwater runoff from highly impervious road and parking lot through long-term monitoring from 2010 until present. The HSSF CW facility consisted of sedimentation or pre-treatment zone, vegetation zone, and effluent zone, and employed filter media including bio-ceramics, sand, gravel, and wood chips. Results showed that flow reduction in the wetland through filtration and sedimentation played an important part in the overall performance of the HSSF CW. In addition, vegetation growth was found to be affected by pollutant and stormwater inflow in the HSSF CW. Vegetation near the outflow port exhibited greater growth rates by about 6.5% to 64.2% compared to the vegetation near the inflow port due to the less stormwater pollutant concentrations via filtration mechanism in the plant or media zone of the HSSF CW. The pollutant inflow from road and parking lot played an important role in providing good environment for microbial growth especially for the dominant microbial phyla including Proteobacteria, Actinobacteria and Acidobacteria in the HSSF CW. The findings of this research are useful in understanding treatment mechanisms and identifying appropriate design considerations for HSSF CW.

Decade-scale change in testate amoebae community primarily driven by anthropogenic disturbance than natural change in a large subtropical reservoir

Understanding the extent of human activities leading to an influx of chemical pollutants that cause substantial environmental transformations is the focus of much ongoing research. In this study, we present a multi-proxy record based on a sediment core from a large subtropical reservoir (Xinfengjiang Reservoir) in south China with an emphasis on the changes in testate amoebae community, in combination with sedimentological (radioactivity, physicochemistry, nutrient and organochlorine pesticides) and climatological (air temperature and precipitation) data over the last three decades. Twenty-seven testate amoebae species belonging to seven genera (Arcella, Centropyxis, Cyclopyxis, Difflugia, Netzelia, Euglypha and Pseudodifflugia) were observed. Species richness, abundance and biomass of testate amoebae were in ranges of 18–26 species, 616–825 ind. ml−1 and 9.0–19.4 μg C ml−1, respectively. Two development stages of the reservoir, dated to 1978–1993 (stage 1) and 1993–2006 (stage 2), were distinguished based on testate amoebae communities. Stage 1 was characterized by elevated dry bulk density, carbon-to‑nitrogen ratio and p,p’-DDE in the sediment core and an impact of nitrogen and sulfur deficiency on testate amoebae. Stage 2 was marked by a decrease of dry bulk density, elevated concentrations of aluminum, iron and carbon, low carbon-to‑nitrogen ratio and organochlorine pesticides, fluctuations in rainfall on shorter and yearly timescales, and a stronger influence of the organochlorine pesticides on testate amoebae. Testate amoebae community change and the identified two-stage development were consistent with atmospheric deposition of organochlorine pesticides from anthropogenic sources inside and outside the reservoir watershed, nutrient influx and sediment physicochemistry. The testate amoebae community dynamics and a strong community-environment relationship in stage 2 were linked with non-random patterns in the biotic neighborhoods of species (deterministic processes). The results suggest a stronger impact of anthropogenic disturbance than natural environmental change on testate amoebae community variation of Xinfengjiang Reservoir over time.

Modeling Extreme Warm‐Air Advection in the Arctic During Summer: The Effect of Mid‐Latitude Pollution Inflow on Cloud Properties

AbstractUsually the Arctic is relatively free of anthropogenic influence in summer, which means that particles from natural sources can be the most significant nuclei for cloud droplets. However, this is not the case during anomalously warm‐air intrusions when the air origin comes from lower latitudes. In this modeling study, we investigate the effect of mid‐latitude pollution inflow (anthropogenic and biomass burning [BB]) on the aerosol‐cloud‐radiation interactions during an episode of extreme warm‐air advection. This particular episode resulted in anomalously high air temperatures over the East Siberian Sea and has accelerated sea‐ice melting. The impact of different emission sources on aerosol vertical distribution, chemical composition, cloud formation, and radiation budget is examined using the Weather Research and Forecasting model, fully coupled with chemistry. Elevated turbulent clouds that occurred at the beginning of the episode are found to be more sensitive to aerosol variations and their negative feedback on supersaturation, compared to stably stratified fog layers that were dominant during the core period. Omission of either anthropogenic or BB source results in decreased cloud liquid water and cloud droplet concentrations; however, these changes are not substantially large to significantly modify the net surface radiation budget. Significant reduction of the net surface radiation is only observed if both anthropogenic and BB transported pollution reaches the area of interest.

Spatiotemporal variation of benthic biodiversity under persistent and extreme human disturbances in the Xiamen sea area, China

This study uses benthic macroinvertebrates as indicators to analyze the variational characteristics of benthic biodiversity under persistent environmental pressures, such as rapid economic and population growth, large-scale urbanization, rapid tourism development, intensified port activities, and extreme human disturbances such as reclamation and dredging, in the Xiamen sea area during 1980–2016. From 1980 to 1990, benthic biodiversity in the area generally remained high, with a species richness of 13, individual abundance of 584 ind/m2, biomass of 79.58 g/m2, and a Shannon diversity index (H′) of 3.26. Under persistent environmental pressure, this biodiversity significantly declined from 2005 to 2007, but improved during 2013–2016 as a result of measures such as establishing reserves, prohibiting aquaculture, and controlling the inflow of pollutants. Under the extreme disturbance caused by reclamation, the average species richness, individual abundance, and H′ of the Tong'an Bay (TB) and the Dadeng sea area (DS) declined considerably. The DS closer to the open sea experienced a benthic biodiversity decrease (25.2% on average) that was significantly less than the decrease in the semi-enclosed TB with a smaller area (55.8% on average), which stopped declining after the sharp drop in the first year after reclamation. This contrasts with TB, where benthic biodiversity six years after reclamation remained considerably lower than before reclamation. However, the decrease in the local total species richness caused by reclamation can be recovered, regardless of whether it is in the open DS or the semi-enclosed TB. Under the extreme disturbance of dredging, individual abundance and biomass in the dredging areas were significantly lower than the average for the study area in 2005–2012. However, following the completion of dredging in 2012, benthic biodiversity noticeably increased in 2013–2016 to higher than the average of the area, indicating that dredging could improve the quality of benthic habitats and increase benthic biodiversity in sea areas with heavy sedimentation and pollution.

Long-Term Interannual and Seasonal Links between the Nutrient Regime, Sestonic Chlorophyll and Dominant Bluegreen Algae under the Varying Intensity of Monsoon Precipitation in a Drinking Water Reservoir.

Long-term variations in reservoir water chemistry could provide essential data in making sustainable water quality management decisions. Here, we analyzed the spatiotemporal variabilities of nutrients, sestonic chlorophyll-a (CHL-a), nutrient enrichment, dominant algal species, and overall chemical water health of the third-largest drinking water reservoir in South Korea during 2000–2020. Our results distinctly explained the strong influence of monsoon rainfall on spatial and annual water chemistry variations. We observed a consistent increase in the chemical oxygen demand alluding to organic matter pollutants, while a steady declining trend in the sestonic CHL-a. The long-term total phosphorus (TP) level showed a steady reduction from the riverine zone to the lacustrine area. However, a higher total coliform bacteria (TCB) was observed at the water intake tower sites. TP displayed a strong link to algal CHL-a and ambient nitrogen phosphorus ratios, suggesting a robust phosphorus-limitation state. The severe phosphorus-limitation was also corroborated by the findings of trophic state index deviation. The high and low flow dynamics exhibited the strong influence of intensive rainfall carrying many nutrients and sediments and flushing out the sestonic CHL-a. Successive eutrophic conditions prevailed along with dominating blue-green algae species (Microcystis and Anabaena). We observed a strong positive correlation (r = 0.62) between water temperature and CHL-a and between total suspended solids and TP (r = 0.65). The multi-metric water pollution index characterized the overall water quality as ‘good’ at all the study sites. In conclusion, the long-term spatiotemporal variabilities of the ecological functions based on the nutrient-CHL-a empirical models are regulated mainly by the intensive monsoon precipitation. The drinking water could become hazardous under the recurrent eutrophication events and chemical degradations due to uncontrolled and untreated inflow of sewage and wastewater treatment plant effluents. Therefore, we strongly advocate stringent criteria to mitigate phosphorus and organic pollutant influx for sustainable management of Daecheong Reservoir.

Evaluation of water quality and eutrophication status of Hawassa Lake based on different water quality indices

Lake Hawassa is one of the major Ethiopian Rift Valley Lakes having an endorheic basin system. The surrounding community makes use of the lake water for the multiple purposes of irrigation, domestic water supply, recreation and fish harvesting. The aim of the present study was to ascertain the water quality of the lake in terms of water quality indices (WQI) and its health over a period of three months covering both dry and wet seasons. Overall, the water quality of Lake was unfit and bad as per the weighted arithmetic method (120.06–228.29) and modified Bascarón water quality index (MBWQI) methods (26.81–33.89), respectively. However, the quality was indicated as marginal, as per the Canadian Council of Ministers of the Environment (CCME) water quality index method (44.2–51.1). On average, the lake was under the hypertrophic stage as per the standard based on the results of Secchi depth and nutrient concentration. The current study showed the lake being unfit for all-purposes as per WAWQI range (> 100). According to the physicochemical and biological parameters, of the lake, it requires mitigation measures to control Eutrophication and pollutants inflow.

Long-term succession of diatom community under hydro-climatic fluctuations in Taiping Reservoir, Yunnan Province, China.

Under the background of regional climate warming, frequent fluctuation of water level caused by drought events and pollutant influx due to catchment development can directly threaten the ecological safety of reservoirs. Through the analysis of physical (particle size, loss on ignition), chemical (carbon, nitrogen), biological (diatom community) and other substitute indicators of sediment, combined with monitoring data and investigation data, we reconstructed the environmental changes in Taiping Reservoir in Yunnan Province from 1937 to 2018, and analyzed the succession characteristics of diatom community and its environmental impact factors. The grain size records indicated that the hydrodynamic condition of Taiping Reservoir was increased during the impounding period (1956-1984) and was steadily reduced thereafter, corresponding well with the documented history of reservoir construction and hydrologic regulation. Changes of total nitrogen, total carbon and organic matter contents indicated the decline of water nutrient level during the construction of the reservoir and the rising process of primary productivity and endogenous organic matter after the completion of the reservoir. The dominant taxa of diatom community shifted from planktonic species to benthic species and then to planktonic ones. The main factors driving the succession of diatom community in Taiping Reservoir were climate change, hydrodynamic condition, and nutrient level. Under the background of long-term climate warming, strict controlling exogenous nutrition input, and reasonable hydrological regulation would be the important premise to maintain ecological health and environmental safety of reservoir water.