Evaluate climate change and anthropogenic activities influencing geochemical variations in sediment between and within the avulsion period in the Lower Yellow River avulsion channels.

The geochemical data from sediments in avulsion channels provide historical evidence of climate change and human-induced alterations in river basin environments. The present study focused on the particle size of sediments in cores and the level of geochemical variation in avulsion channels of the Lower Yellow River Delta (YRD), China. The sediment samples were collected in a depth range of 20-400 cm in avulsion channels. The collected samples were analyzed for sediment particle size and geochemical composition using standard methods. The results demonstrated rapid increases in agriculture practices, rainfall pattern changes, and terrestrial sediment runoff reduction in river basins after the 1960s. The reduced sediment loads in the Sanmenxia Reservoir significantly changed the sediment grain size and geochemical levels in the avulsion channel from August 1960.8 to January -1961.1. In particular, TC, TN, and C/N levels decreased with increasing sediment depth. The C/N values of <12 denoted completely reduced terrestrial sources of organic matter in the channel during the August 1960-January 1961 period compared to the July 1953-August 1960 period. The two-way ANOVA p-values were (p <0.016-p<0.001) strong between the avulsion periods but had no significant variation within the avulsion periods. We emphasize that this study provides a close interplay of different historical periods of geochemical variation in avulsion channel sediments in the alluvial fan YRD, and we argue that the evolution of the middle upstream river basin was subjective by climate change and human developmental actions, which impacted the YRD. In particular, reservoir-interrupted water flow and sediment reduction impacts associated with geochemical fluctuations are documented in the YRD.

Analysis of future nitrogen and phosphorus loading in watershed and the risk of lake blooms under the influence of complex factors: Implications for management.

For the management of eutrophic lakes, watershed nitrogen and phosphorus control is oriented to future water quality. Assessing future nutrient dynamics and the risk of lake eutrophication is necessary. However, current assessments often lack integrated consideration of socioeconomic and climatic factors, which reduces the reference value of the results. In this study, a typical large shallow lake Chaohu, which is highly influenced by human activities, was selected as the study area, and the current and future total nitrogen (TN) and total phosphorus (TP) loading in the basin were analysed using the improved MARINA model, and the risk of water bloom were assessed. The results showed that socioeconomic factors alone varied future TN and TP loading by -24% to 32% and -40% to 34%, respectively, under different development patterns. After considering the effect of increased precipitation, the changes of TN and TP loading became -10% to 163% and -29% to 108%, respectively. The effect on loading reduction under the sustainable development pattern was weakened (58% and 28% for TN and TP loading, respectively) and the increase in loading under the brutal development pattern was significantly amplified (409% and 215% for TN and TP loading, respectively). The adoption of active environmental policies remained an effective way of loading control. However, the risk of water bloom in local lake areas might persist due to factors such as urbanization. Timely and comprehensive assessments can provide managers with more information to identify key factors that contribute to the risk of water blooms and to develop diverse water quality improvement measures. The insights from our study are applicable to other watersheds around the world with similar socio-economic background and climatic conditions.

Flow and turbulence in unevenly obstructed channels with rigid and flexible vegetation.

The pattern of vegetation along the cross-section of macrophyte-dominated shallow waters is generally uneven, which affects water velocity and turbulence. This study examined the velocity and turbulence in the open channel with an uneven transverse distribution of vegetation in laboratory flume experiments. Two vegetation patterns were tested: emergent vegetation which covered part of the channel, and a symmetrical combination of submerged and emergent vegetation canopies along the lateral direction of the flume. The flow was measured using a three-dimensional Acoustic Doppler Velocimeter. The velocity and turbulence characteristics were analyzed under three vegetation densities and five discharge scenarios. Results showed that the longitudinal mean velocity changed with vegetation density and flow discharge when vegetation was unevenly distributed in a lateral direction. The strong variation in shear stress at the emergent vegetation-open water intersections and submerged-emergent vegetation intersections resulted in large-scale vortices at the interfaces. The formation processes of stem-scale turbulence and shear-scale turbulence under different vegetation scenarios were discussed. A turbulent kinetic energy model within partly obstructed vegetation canopies was established, which helped to identify the development of horizontal and vertical coherent vertices.

Disentangling the effects of phosphorus loading on food web stability in a large shallow lake.

Excessive nutrient loads reduce ecosystem resilience, resulting in fundamental changes in ecosystem structure and function when exceeding a certain threshold. However, quantitative analysis of the processes by which nutrient loading affects ecosystem resilience requires further exploration. Food web stability is at the heart of ecosystem resilience. In this study, we simulated the dynamics of the food web under different phosphorus loads for Lake Baiyangdian using the PCLake model and calculated the food web stability. Our results showed that there was a good correspondence between the food web stability and ecosystem state response to phosphorus loads. This relationship confirmed that food web stability could be regarded as a signal for the state transition in a real lake ecosystem. Moreover, our estimates suggested that food web stability was influenced only by several functional groups and their interaction strength. Diatoms and zooplankton were the key functional groups that affected food web stability. Phosphorus loads alter the distribution of functional group biomass, which in turn affects energy delivery and, ultimately, the stability of the food web. Corresponding to functional groups, the interactions among zooplankton, diatoms and detritus had the greatest impact, and the interaction strength of the three was positively correlated with food web stability. Overall, our study explained that food-web stability was critical to characterize ecosystem resilience response to external disturbances and can be turned into a scientific tool for lake ecosystem management.

The long-term changes in food web structure and ecosystem functioning of a shallow lake: Implications for the lake management.

The food web structure (FWS) and ecosystem functioning (EF) of lakes worldwide are impacted by multiple disturbances. The historical evolution of the FWS and EF are not well understood due to the lack of sufficient long-term records of biotic variations. This study reconstructed the food web models in the 1950s, 1980s, 1990s, 2000s, and 2010s for Baiyangdian Lake (BYDL), the largest shallow lake in northern China, using the Linear Inverse Modeling (LIM) and investigated EF in different periods. Our results confirmed that the FWS and EF of BYDL have undergone significant changes. The biomass of phytoplankton continuously increased, and the primary productivity of phytoplankton began to replace the primary productivity of submerged macrophytes in the 2000s and became the largest energy flow in the food web. Changes in the energy flow of primary producers are transmitted to high-trophic functional groups, which affects the diet composition of fish. Based on the ecological network analysis indices and food web stability indicators, it was concluded that after a turning point in the 1990s, the ecosystem showed initial stability and then gradually became unstable. Water level fluctuations and nutrient enrichment may be the key driving factors for changes in ecosystem state. Therefore, to maintain a good state of the ecosystem, we recommend implementing comprehensive management measures of hydrological management, nutrient-loading reduction, and biomanipulation. Furthermore, this study extended LIM to lake ecosystems, which may provide a new method for lake ecological environment management.

The relationship between ecosystem service supply and demand in plain areas undergoing urbanization: A case study of China's Baiyangdian Basin.

Urbanization is an inevitable trend associated with social development that occurs preferentially in plain areas. Ecosystem services (ES) refer to the various benefits that human beings obtain from ecosystems. Competing priorities of economic development and ecological protection lead to conflicts in land use under conditions of urbanization, the root cause of which is an imbalance in the ES supply and demand. Whereas existing studies have mainly focused on the decline of ES supply capacities, an exploration of the extent to which the supply and demand of ES are matched and of their changing trends would be instructive and have practical implications. In this study, we examined changes in the temporal and spatial characteristics of the relationship between ES supply and demand in the Baiyangdian Basin in the North China Plain. We found that ES supply and demand were spatially distinctive. ES supply areas were concentrated in the western mountainous region, whereas ES demand areas were predominantly located in the eastern plain area. The main sources of ES surplus in the study area were woodland and grassland in mountainous areas, comprising 12% of the study region. Strict protection on these lands during the period 1980-2015 ensured a consistently high level of ES supply. In recent years, urbanization has been a major driver of increasing ES demand and decreasing ES surplus and is projected to accentuate the trend of declining ES surplus in the future. However, current policies remain focused on the protection of forests and grassland that predominate in mountainous areas, where urban expansion poses a lower threat compared with plain areas. We therefore recommend a policy emphasis on sustainable urban planning to mitigate ES degradation.

The changes in physicochemical and stable isotope compositions in the lower Yellow River of China due to artificial flooding.

Increasingly, modern hydrological technologies are dynamically altering river water flow and drastically affecting river hydrogeochemical cycle regimes globally. The present study focused on the reservoir discharges of artificial floodwaters that influence spatiotemporal variations in the physicochemical and stable isotope compositions in the lower Yellow River (LYR) of China. The surface water samples were collected at the nine sites along the LYR during the pre-, inter-and post-flood periods. Then, the collected samples were analysed with the following standard method. The δD and δ18O slopes of the waterline clearly indicated that the prolonged reservoir water and different water flows impacted the hydrological cycle in the LYR regions compared to GMWL (global meteoric water line) and LMWL (local meteoric water line). The thermal stratification processes of the water in the largest reservoir slightly enriched the heavy isotopes, and physicochemical alteration was neglected. Statistical analysis of two-way ANOVA revealed that the p-values (p < 0.01, p < 0.05) were very strong for most of the variables between the periods, and the linear regression exhibited weak values (R2 = 0.253, R2 = 0.150) at the surface water temperature variations and suggested no significant influence of isotope composition. Overall, the Xiaolangdi reservoir water prolonged time rates, and artificial floodwater flow had a very small effect on the isotope composition; in particular, a large high turbidity concentration in the discharged artificial floodwaters was the only considerable ecological risk condition in the LYR. This kind of proper monitoring work is immensely important and prevents reservoirs from causing hydrological cycle impacts in the LYR and the adjacent coastal ecosystems.

Ecological risk assessment of heavy metal concentrations in sediment and fish of a shallow lake: a case study of Baiyangdian Lake, North China.

The pollution levels of lakes vary in quantity and type of contaminants accumulated in their sediment and water. The second Chinese capital city will be built around Baiyangdian Lake in the near future, and thus, it is important to monitor pollution status of Baiyangdian Lake. This study mainly focused on the accumulated heavy metal concentrations in the surface sediment and in variety of fish bodies. Sediment pollution status and ecological risk were evaluated through geo-accumulation (I-geo), contamination factor (CF), pollution load index (PLI), potential ecological risk ([Formula: see text]), and mean probable effect concentration quotient (mPEC-Q). In addition, human health risks via fish consumption were also evaluated. Based on the results, the average sediment trace As, Cd, Cr, Cu, Mn, Ni, Pb, and Zn concentrations were 9.53, 0.35, 56.37, 32.33, 617.05, 30.18, 19.17, and 84.24 mg/kg dry wt, respectively. Both I-geo and [Formula: see text] inferred low pollution levels and low ecological risks from all assessed trace metals except Cd. Cd posed moderate to high ecological risks. Based on sediment quality guidelines (SQGs), average Ni and Cr concentrations exceeded the threshold effect concentrations (TEC), but their [Formula: see text] are low as their average concentrations is below Hebei province pre-contaminations (30.8 mg/kg for Ni and 68.3 mg/kg for Cr). There is no cumulative toxicity from all the metals through mPEC-Q. Omnivorous fish accumulated statistically insignificantly higher amounts of metals than carnivorous fish, except for Hg. The intake of 12.22 g/person/day fish muscle for the entire life is safe from noncarcinogenic human health problems.

Health risk assessment of heavy metals in fish and accumulation patterns in food web in the upper Yangtze River, China.

This study aims to concern the distribution of As, Cr, Cd, Hg, Cu, Zn, Pb and Fe in surface sediment, zoobenthos and fishes, and quantify the accumulative ecological risk and human health risk of metals in river ecological system based on the field investigation in the upper Yangtze River. The results revealed high ecological risk of As, Cd, Cu, Hg, Zn and Pb in sediment. As and Cd in fish presented potential human health risk of metals by assessing integrated target hazard quotient results based on average and maximum concentrations, respectively. No detrimental health effects of heavy metals on humans were found by daily fish consumption. While, the total target hazard quotient (1.659) exceeding 1, it meant that the exposed population might experience noncarcinogenic health risks from the accumulative effect of metals. Ecological network analysis model was established to identify the transfer routes and quantify accumulative effects of metals on river ecosystem. Control analysis between compartments showed large predator fish firstly depended on the omnivorous fish. Accumulative ecological risk of metals indicated that zoobenthos had the largest metal propagation risk and compartments located at higher trophic levels were not easier affected by the external environment pollution. CAPSULE: A potential accumulative ecological risk of heavy metal in the food web was quantified, and the noncarcinogenic health risk of fish consumption was revealed for the upper reach of the Yangtze River.

Risk analysis of emergent water pollution accidents based on a Bayesian Network.

To guarantee the security of water quality in water transfer channels, especially in open channels, analysis of potential emergent pollution sources in the water transfer process is critical. It is also indispensable for forewarnings and protection from emergent pollution accidents. Bridges above open channels with large amounts of truck traffic are the main locations where emergent accidents could occur. A Bayesian Network model, which consists of six root nodes and three middle layer nodes, was developed in this paper, and was employed to identify the possibility of potential pollution risk. Dianbei Bridge is reviewed as a typical bridge on an open channel of the Middle Route of the South to North Water Transfer Project where emergent traffic accidents could occur. Risk of water pollutions caused by leakage of pollutants into water is focused in this study. The risk for potential traffic accidents at the Dianbei Bridge implies a risk for water pollution in the canal. Based on survey data, statistical analysis, and domain specialist knowledge, a Bayesian Network model was established. The human factor of emergent accidents has been considered in this model. Additionally, this model has been employed to describe the probability of accidents and the risk level. The sensitive reasons for pollution accidents have been deduced. The case has also been simulated that sensitive factors are in a state of most likely to lead to accidents.

A bacteria-based index of biotic integrity indicates aquatic ecosystem restoration.

Intensive ecological interventions have been carried out in highly polluted shallow lakes to improve their environments and restore their ecosystems. However, certain treatments, such as dredging polluted sediment and stocking fish, can impact the aquatic communities, including benthos and fishes. These impacts can alter the composition and characteristics of aquatic communities, which makes community-based ecological assessments challenging. Here we develop a bacteria-based index of biotic integrity (IBI) that can clearly indicate the restoration of aquatic ecosystems with minimal artificial interventions. We applied this method to a restored shallow lake during 3-year intensive ecological interventions. The interventions reduced nutrients and heavy metals by 27.1% and 16.7% in the sediment, while the total organic carbon (TOC) increased by 8.0% due to the proliferation of macrophytes. Additionally, the abundance of sulfur-related metabolic pathways decreased by 10.5% as the responses to improved ecosystem. The score of bacteria-based IBI, which is calculated based on the diversity, composition, and function of benthic bacterial communities, increased from 0.62 in 2018 to 0.81 in 2021. Our study not only provides an applicable method for aquatic ecological assessment under intensive artificial interventions but also extends the application of IBI to complex application scenarios, such as ecosystems with significantly different aquatic communities and comparisons between different basins.

A bacteria-based index of biotic integrity assesses aquatic ecosystems effectively in rewetted long-term dry river channel after water replenishment.

Climate-induced droughts exert a significant influence on the connectivity of river systems. It is estimated that about 25% of the world's rivers ran dry before reaching the ocean due to climate change and human activities. Ecological water replenishment is an effective measure for restoring aquatic ecosystems damaged by drought. It is urgently needed to quantitatively assess the aquatic ecosystems in rewetted dry river channels after water replenishment. This study investigated the variations in phytoplankton, zooplankton, benthic macroinvertebrates, and benthic bacterial communities in the rewetted dry river channel of Yongding River after water replenishment. In comparison with the water column communities, the benthic macroinvertebrates were identified as limiting factors for ecological restoration in rewetted dry river channels. In the absence of a certain recovery time for benthic macroinvertebrates, the benthic bacterial-based index of biological integrity, especially calculated based on their intrinsic properties, can properly assess aquatic ecosystems in rewetted dry river channels.

Functional trait-based phytoplankton biomass and assemblage analyses in the pre-growing season for comprehensive algal bloom risk assessment.

Algal bloom (AB) risk assessment is critical for maintaining ecosystem health and human sustainability. Previous AB risk assessments have focused on the potential occurrence of ABs and related factors in the growing season, whereas their hazards, especially in the pre-growing season, have attracted less attention. Here, we performed a comprehensive AB risk assessment, including water trophic levels, phytoplankton biomass, functional trait-based assemblages, and related environmental factors, in the pre-growing season in Dongting Lake, China. Although mesotrophic water and low phytoplankton biomass suggested low AB potential, toxic taxa, which constituted 13.28% of the phytoplankton biomass, indicated non-negligible AB hazards. NH4+ and water temperature were key factors affecting phytoplankton motility and toxicity. Our study establishes a new paradigm for quantitative AB risk assessment, including both potential AB occurrence and hazards. We emphasize the importance of phytoplankton functional traits for early AB warning and NH4+ reduction for AB control in the pre-growing season.

How to balance land demand conflicts to guarantee sustainable land development.

Severe arable land loss and ecological problems raise attention to protect/develop land for food and ecology demand. Spatial conflict appears in front of multidemand for urbanization, food, and ecology. Our study took China as an example and explicitly outlined spatial preference of urbanization, food, and ecology. From the aspect of land amount, there are enough lands to support multidemand with a surplus of agriculture land of 45.5 × 106 ha. However, spatial conflict widely appears among the multidemands. We tested the impacts of different priorities on urban pattern, crop yield, and ecology and found the priority of food > ecology > urbanization gave the best outcome. Our results verified the importance of including priority of land multidemand to avoid confusion and increase efficiency in the implementation of land policies.

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. To study the impact of the different sediment environments on the Z. japonica growth, its growth and water quality and sediment parameters were measured on the northern and southern sides of the estuary from April to October in 2019. The action of wind and tides have re-suspended and dispersed sediments over time, producing shores on the southern delta characterized by nutrient-enriched clays and shores on the northern delta characterized by coarser sands and silts with poor nutrients. During the monitoring period, the concentrations of TC, TN, and TP in the root-zone sediments at the southern site were 1.56%, 0.04%, and 0.06%, respectively, whereas they were 0.69%, 0.007%, and 0.06%, respectively, at the northern site. Sufficient nutrients supported the growth of Z. japonica at the southern site, while poor nutrition limited the continuous growth of Z. japonica at the northern site. In July, the plant height, biomass, and shoot density of Z. japonica at the southern site reached the maximum values of 23.6 cm, 0.14 g/shoot, and 3245 shoots/m2, respectively, whereas they were 16.4 cm, 0.06 g/shoot, and 2740 shoots/m2, respectively, at the northern site. The sediment grain size and their nutrients contributed to different growth patterns of Z. japonica at the southern and northern sites. Our research could provide important implication for the conservation of Z. japonica habitats in the Yellow River estuary in China.

Nitrogen and phosphorus retention budgets of a semiarid plain basin under different human activity intensity.

Excessive nitrogen (N) and phosphorus (P) runoff from human activities results in degraded water quality. It is, therefore, crucial to quantitatively assess nutrient inputs over time and their impact on riverine nutrient exports. In this study, we estimated the long-term (1995-2015) nutrient inputs at the county scale by integrating Net Anthropogenic Nitrogen Input (NANI) and Net Anthropogenic Phosphorus Input (NAPI) methods, and nutrient exports into rivers by the Export Coefficient Model (ECM) for a semiarid plain basin, the Baiyangdian (BYD) Basin, China. The results showed that N and P input intensities in the year 2015 reached 18852 kg N km2 yr-1 and 2073 kg P km-2 yr-1, showing a 35% and 11% increase in comparison with 1995, respectively. About 60% of these nutrients were derived from fertilizer application. The multi-year averaged N and P exported to rivers was 548 kg N km-2 yr-1 and 79 kg P km-2 yr-1, respectively. Hotspots for nutrient budgets were found in the southeastern counties. Hotspots covered about 12% of the total land, but contributed by 38-52% of total nutrient budgets. The nutrient export ratios showed no significantly temporal variations, and only about 2.15-2.89% of NANI and NAPI were exported into rivers. The low nutrient export ratio was due to the low water discharge that limited the nutrient transportation in the semi-arid plain basin. As most of anthropogenic nutrient inputs were retained in the basin, their impacts on the pollution of soils and aquifers need to be considered and adequately addressed in the future. This study constructs the spatial quantitative nutrient budgets, which can provide effective information for region policy formulation.

Impact of forest cover and conservation agriculture on sediment export: A case study in a montane reserve, south-western China.

Reforestation and agricultural conservation have long been recognized as important in reducing on-site soil loss and off-site sediment export. Quantitative assessment of their effectiveness is critical, and assists cost-benefit analysis and decision-making in land management and landscape planning. We applied a paired watershed approach to monitor 1-year sediment export in two watersheds with forest-dominated (reference) and mosaic (target) land use in the Naban River Watershed National Natural Reserve (NRWNNR) in Xishuangbanna, south-western China. Analysis of land-use change in the target watersheds showed decreasing total forest cover (FC) (from 57% to 47%), but increasing FC in steep areas (from 54% to 59%) from 2007 to 2012. A distributed hydrological model (Land-Use Change Impact Assessment, LUCIA) was well calibrated and validated through field data from the two watersheds. Scenarios were created representing different FCs (from 31% to 83%) and agricultural management (as-usual and conservation). Simulation results quantified the relation between FC and sediment export as a logarithmic or logit model, indicating at least one turning point of FC, beyond which further forest reduction should significantly increase sediment export. This point was identified in the range between 57% and 61% of the target watershed under as-usual management; it was shifted to 47%-53% by conservation agriculture. Compared with the reference (with 83% FC), conservation agriculture was able to almost fully compensate for increased sediment export by forest reduction to 57% in 2007. However, when forest was reduced further to 47% in 2012, sediment export increased significantly. We concluded that total FC was as important as FC in montane watershed management in steep areas; and crop type conversion, such as rubber to maize in this study, and on-site agriculture management affect more to sediment export than agricultural expansion. We recommend conservation agriculture as an efficient tool for reducing sediment export on a watershed scale.

Intensive land uses modify assembly process and potential metabolic function of edaphic bacterial communities in the Yellow River Delta, China.

Coastal reclamation is a global threat to natural ecosystems, disturbing biological community structure, diversity and ecological function through habitat conversion. We have limited insights into the changes brought about by coastal reclamation for different land-use types. We used the Yellow River Delta (YRD) as a model because it is a region with intensive land reclamation, and we investigated the structural and functional variations of bacterial communities and their relations to edaphic properties under different land-use types. Our results showed that the high soil organic carbon (SOC), nitrate concentrations and salinity were found in oil field, aquaculture pond and salt pan, respectively, and low values in natural wetland. Land use was found to have significant influence on bacterial community diversity. To investigate the phylogenetic conservation of specific traits, we analyzed the relationship between soil bacterial assembly processes and edaphic properties. Bacterial traits phylogenetically conserved, and differs in depth. Our findings suggest that SOC served as a deep trait due to it negative correlation with deeper branches of phylogenetic clustering, while nitrate functioned as a shallow trait due to its positive correlation with phylogenetic clustering at finer branches. Soil salinity acted as a complex trait effected on both finer and deeper branches. Further potential functional gene co-occurrence network analysis revealed that land reclamation induced shifts of metabolic function by altering the functional gene connectivity. We found that the photosynthesis pathway was enriched in hub modules related to oil field (OF), while methane metabolism was enriched in hub modules linked to sea cucumber pond (CP1). In addition, two-component systems (TCS) were enriched with nitrate, ammonia, SOC and salinity-related modules. Therefore, our study highlights the importance of integrating multi-function and multi-process identification and prediction of coastal diverse reclamation impacts on coastal ecosystems.

Generalized additive models for biomass simulation of submerged macrophytes in a shallow lake.

Submerged macrophytes are widely distributed primary producer that play important roles in maintaining healthy aquatic ecosystems. Generally, the relationships between macrophytes and environmental factors are complicated, so nonlinear nonparametric models with relatively flexible structures are optimal for macrophyte habitat simulation. In this study, generalized additive model (GAM) was used to evaluate the response of the submerged macrophytes biomass to water environmental factors in the Baiyangdian Lake. Forward stepwise method was used to implement model optimization. Likelihood ratio test was used to determine whether adding a variable enhances the model performance. Four individual variables (water depth, transparency, total nitrogen, and total phosphorus) and two interaction terms (water depth × transparency and water depth × total phosphorus) were included in the optimal GAM. The optimal model explained 70.5% of the biomass variation with a relatively low residual deviance value (22.40). There was a significant correlation between the measured and predicted data (R2 = 0.716, p = 0.0004). The response lines generated by the model indicated that macrophyte biomass had a positive correlation with transparency but negative correlations with total nitrogen and nitrite nitrogen in water. The response patterns of macrophyte biomass to water depth and total phosphorus were unimodal. The biomass reached the maximum value when the water depth was about 2.1 m and the total phosphorus concentration was 0.07 mg/L. Water depth and transparency, which affect light availability, are critical physical variables affecting the conditions associated with the submerged macrophytes, and excess nitrite and phosphorus limiting macrophyte biomass.

Biomonitoring of the environmental indicator and pathogenic microorganisms assortment in foremost pilgrimage beaches of the Bay of Bengal, Southeast coast, India.

The present study is aimed to monitoring the ecological indicator and pathogenic microorganism diversity in pilgrimage places beach sand on the Bay of Bengal coast. The samples were collected from three locations and four different sites, and were analyzed by following standard methods. The results clearly indicates, ritual activities were highly contaminated in the beach sand qualities, and exceeded with the standard permissible limit of WHO, USEPA, EU, CPCB beach sand recreational and other contacts activities including pH (11%), TBC (100%), TCB (97%), FCB (88%), TEB (75%), E. coli (75%), disease-causing possible level of Klebsiella (84%), Shigella (75%), Salmonella (63%) and Vibrio (56%). The statistical tools were applied to find the strong evidence. The current study pointed out the major effects on the diffusion of potentially pathogenic microorganisms along the shoreline provided useful information for the setup of measures for public health protection in the Bay of Bengal coast.