Trends in urban storm water quality in Tallinn and influences from stormflow and baseflow

Temporal trends provide a good interpretation of change in stormwater quality over time. This study aimed to analyse trends and influences due to stormflow and baseflow. Grab samples of 18-19 years from 1995 to 2014 recorded at outlets of 7 Tallinn watersheds were analysed for monotonic trend through seasonal Mann Kendall test for long-term, short-term, baseflow and stormflow. Statistically significant downward trends (P-value (p) < 0.05) were found for 6 – hydrocarbon (HC), 1 – suspended solids (SS), 3 – biological oxygen demand (BOD), 4 – total nitrogen (TN) and 2 – total phosphorus (TP) out of 7 sampling outlets over the last 10 years. Less significant decreasing trends (p > 0.05 and < 0.2) for 3 – SS, 1 – BOD, 1 – TN and 1 – TP were identified. Statistically significant long-term upward trends of pH were re-vealed in 5 basins, which reduced to 2 with 5 less significant upward trends over the 10 year period, indicating improve-ments in pH reduction. Härjapea has the highest pH without trend but it includes an upward trend of TN at p = 0.051. The highly possible causes for downward trends are street sweeping, sewer network improvement, decline in sub-urban agri-cultural areas, etc. The upward trend results of pH are related to increased alkalinisation due to acidic rain, weathering of carbonate rocks, sewage discharge and alkaline road dust. In most of the basins, stormflow has more influence on trends than baseflow.

Download Full-text

Long-term trend analysis of climatic variables and reference evapotranspiration over different urban areas in Tunisia

Brazilian Journal of Biological Sciences ◽

10.21472/bjbs.061218 ◽

2019 ◽

Vol 6 (12) ◽

pp. 189-201

Author(s):

Basma Latrech ◽

Hiba Ghazouani ◽

Lasram Asma ◽

Boutheina M. Douh ◽

Mansour Mohsen ◽

...

Keyword(s):

Trend Analysis ◽

Urban Areas ◽

Kendall Test ◽

Climatic Variables ◽

Upward Trend ◽

Slope Estimator ◽

Increasing Trends ◽

Regression Tests ◽

Long Term Trend

In this study, the trend analysis of annual climatic variables including Tmax, Tmin, Tmean, RHmean, WS and SR as well as FAO-56 PM ET0 were investigated in three locations in Tunisia during 1984-2007. The Mann-Kendall Test, the Sen's Slope Estimator and linear regression tests were used for the analysis. The obtained results showed a significant increasing trends (a < 0.001) and (a < 0.01) in annual Tmax, Tmin and Tmean at all the considered locations. However, Tmin increase faster than Tmax with a slope of magnitudes ranging between 0.057 to 0.1 oC year-1. For RHmean, a non-significant tendency of decrease was observed in Chott-Mariem station. However, significantly increasing trends were found for Kelibia and Tunis Carthage. Concerning the WS variable, a tendency of decrease is observed during the study period for all the stations. Nevertheless, the statistical analysis of decreasing tendency of wind speed varied from non-significant for Tunis Carthage to highly significant (a <= 0.001) at Chott-Mariem and Kelibia. Despite the highly significant upward trend of temperature, the temporal pattern of mean annual FAO56 PM-ET0, over the different stations, did not exhibit any significant trend except for Kelibia station.

Download Full-text

Analysis of Long-Term Variations of Drought Characteristics Using Standardized Precipitation Index over Zambia

Atmosphere ◽

10.3390/atmos11121268 ◽

2020 ◽

Vol 11 (12) ◽

pp. 1268

Author(s):

Bathsheba Musonda ◽

Yuanshu Jing ◽

Vedaste Iyakaremye ◽

Moses Ojara

Keyword(s):

Temporal Trends ◽

Standardized Precipitation Index ◽

Kendall Test ◽

Precipitation Index ◽

Adaptation Measures ◽

Drought Characteristics ◽

Northern Areas ◽

Seasonal Time Scale ◽

The Standardized Precipitation Index

This study examines long-term spatial and temporal trends of drought characteristics based on the Standardized Precipitation Index at three different time scales (3, 6, and 12 months) over Zambia from 1981 to 2017. Drought characteristic conditions such as duration, severity, and intensity at monthly, seasonal, and annual levels were analyzed to investigate the drought patterns over Zambia. The results show a significant increase in drought events over the southwestern regions and a decrease over the northeastern regions. It is in this regard that two stations from different locations (southwest and northeast) were analyzed. The results show increasing trends of drought over Sesheke (southwest) and decreasing trends over Kasama (northeast). More drought impacts are felt over southern compared to northern areas, which poses a serious concern to both agriculture and hydrological industries over the drought-prone areas of Southern Zambia. However, the analysis further shows that droughts were more intense, persistent, and severe over the southwest, while moderate droughts were found in some few areas of Northeast Zambia. The Mann–Kendall test trend and slope indicated that both annual and seasonal drought have increased. However, drought increment at an annual level shows a low magnitude as compared to the seasonal level. This suggested the importance of evaluating drought at an interannual and seasonal time scale over Zambia. Specifically, the drought increased determinedly before 2010 and became erratic between 2010 and 2017 with considerable regional variation. Zambia experienced moderate to severe droughts during 1991–1992, 1994–1995, 2006–2005, and 2015–2016, which resulted in serious damages to the environment and society. According to the findings of this study, it is suggested that the implications of drought can be managed by creating strategies and adaptation measures.

Download Full-text

Long-term variations of water quality in a reservoir in China

Water Science & Technology ◽

10.2166/wst.2012.034 ◽

2012 ◽

Vol 65 (8) ◽

pp. 1454-1460 ◽

Cited By ~ 18

Author(s):

Y. Y. Chen ◽

C. Zhang ◽

X. P. Gao ◽

L. Y. Wang

Keyword(s):

Water Quality ◽

Dissolved Oxygen ◽

Temporal Trends ◽

Oxygen Demand ◽

Temporal Variations ◽

Quality Parameters ◽

Quality Data ◽

Water Quality Data ◽

Yuqiao Reservoir

To study the spatial and temporal trends of water quality in the Yuqiao Reservoir (Ji County, Tianjin) in China, water quality data for ten physical and chemical parameters from three monitoring stations (S1, S2 and S3) was collected from 1989 to 2007 and from an other three stations (S4, S5 and S6) during the period of 1999–2007. A one-way ANOVA was employed to evaluate the spatial variation of water quality for each station. The results showed that there were statistically significant spatial differences for most water quality parameters except temperature and dissolved oxygen in the entire reservoir, and the concentrations of most parameters were higher in the uppermost part of the reservoir. The temporal trend study was conducted using the Seasonal–Kendall's test. The results revealed improving trends of water quality from 1989 to 2007, including a reduction of total phosphorous, temperature and biochemical oxygen demand and an increase of dissolved oxygen. High N:P ratios, ranging from 52.61 to 78.75, indicated that the reservoir was a phosphorous-limited environment. This study suggests long-term spatial and temporal variations of water quality in the Yuqiao Reservoir, which could be informative for water quality managers and scientists.

Download Full-text

Nonstationary Analysis of Annual Maximum Streamflow of Canada

Journal of Climate ◽

10.1175/jcli-d-14-00538.1 ◽

2015 ◽

Vol 28 (5) ◽

pp. 1788-1805 ◽

Cited By ~ 35

Author(s):

Xuezhi Tan ◽

Thian Yew Gan

Keyword(s):

Land Use ◽

Frequency Analysis ◽

Anthropogenic Impacts ◽

Probability Distributions ◽

Temporal Trends ◽

Annual Maximum ◽

Monotonic Trend ◽

Abrupt Changes ◽

Nonstationary Frequency

Abstract Both natural climate change and anthropogenic impacts may cause nonstationarities in hydrological extremes. In this study, long-term annual maximum streamflow (AMS) records from 145 stations over Canada were used to investigate the nonstationary characteristics of AMS, which include abrupt changes and monotonic temporal trends. The nonparameteric Pettitt test was applied to detect abrupt changes, while temporal monotonic trend analysis in AMS series was conducted using the nonparameteric Mann–Kendall and Spearman tests, as well as a parametric Pearson test. Nonstationary frequency analysis of the AMS series was done using a group of nonstationary probability distributions. The nonstationary characteristics of Canadian AMS were further investigated in terms of the Hurst exponent (H), which represents the long-term persistence (LTP) of streamflow data. The results presented here indicate that for Canadian AMS data, abrupt changes are detected more frequently than monotonic trends, partly because many rivers began to be regulated in the twentieth century. Drainage basins that have experienced significant land-use changes are more likely to show temporal trends in AMS, compared to pristine basins with stable land-use conditions. The nonstationary characteristics of AMS were accounted for by fitting the data with probability distributions with time-varying parameters. Large H found in almost ⅔ of the Canadian AMS dataset indicates strong LTP, which may partly represent the presence of long-term memories in many Canadian river basins. Furthermore, H values of AMS data are positively correlated with the basin area of Canadian rivers. It seems that nonstationary frequency analysis, instead of the traditional stationary hydrologic frequency analysis, should be employed in the future.

Download Full-text

Temporal and spatial variability of extreme snowfall indices over northern Xinjiang from 1959/1960 to 2008/2009

Natural Hazards and Earth System Sciences Discussions ◽

10.5194/nhessd-1-7059-2013 ◽

2013 ◽

Vol 1 (6) ◽

pp. 7059-7092 ◽

Cited By ~ 4

Author(s):

S. P. Wang ◽

F. Q. Jiang ◽

R. J. Hu ◽

Y. W. Zhang

Keyword(s):

Temporal Trends ◽

Kendall Test ◽

Winter Precipitation ◽

Kriging Interpolation ◽

Significance Level ◽

Northern Xinjiang ◽

The North ◽

Mk Test ◽

Increasing Trends

Abstract. Plentiful snowfall is an important resource in northern Xinjiang. However, extreme snowfall events can lead to destructive avalanches, traffic interruptions or even the collapse of buildings. The daily winter precipitation data from 18 stations in northern Xinjiang during 1959/1960–2008/2009 were selected for purpose of analyzing long-term variability of extreme snowfall events. Five extreme snowfall indices, Maximum 1 day snowfall amount (SX1day), Maximum 1-weather process snowfall amount (SX1process), Blizzard days (DSb), Consecutive snow days (DSc) and Blizzard weather processes (PSb), were defined and utilized to quantitatively describe the intensity and frequency of extreme snowfall events. Temporal trends of the five indices were analyzed by Mann–Kendall test and simple linear regression, and their trends were interpolated using universal kriging interpolation. Temporally, we found that most stations have upward trends in the five indices of extreme snowfall events, and over entire northern Xinjiang, they were all increasing at the 0.01 significance level (MK test), with the linear tendency rates of 0.49 mm (10 a)−1 (SX1day), 0.89 mm (10 a)−1 (SX1process), 0.024 days (10 a)−1 (DSb), 0.14 days (10 a)−1 (DSc), and 0.069 times (10 a)−1 (PSb) respectively. Meanwhile, obvious decadal fluctuations besides long-term increasing trends are identified. Trends in the intensity and frequency of extreme snowfall events show a~distinct difference spatially. In general, trends of five indices were found shifting from decreasing to increasing from the northeast to the southwest and from the north to the south of northern Xinjiang. Furthermore, the regions covered by increasing or decreasing extreme snowfall events were identified, implying the hot or cold spots for extreme snowfall events changes. These results may be helpful for northern Xinjiang on the regional and local resource and emergency planning.

Download Full-text

Isolated Liner Revision for Total Knee Arthroplasty Instability: A Road That Should Remain Less Taken

The Journal of Knee Surgery ◽

10.1055/s-0040-1721091 ◽

2020 ◽

Author(s):

Jason D. Tegethoff ◽

Rafael Walker-Santiago ◽

William M. Ralston ◽

James A. Keeney

Keyword(s):

Total Knee Arthroplasty ◽

Femoral Component ◽

Knee Arthroplasty ◽

Primary Total Knee Arthroplasty ◽

P Value ◽

Surgical Morbidity ◽

Exact Test ◽

Total Knee ◽

Component Revision

AbstractIsolated polyethylene liner exchange (IPLE) is infrequently selected as a treatment approach for patients with primary total knee arthroplasty (TKA) prosthetic joint instability. Potential advantages of less immediate surgical morbidity, faster recovery, and lower procedural cost need to be measured against reoperation and re-revision risk. Few published studies have directly compared IPLE with combined tibial and femoral component revision to treat patients with primary TKA instability. After obtaining institutional review board (IRB) approval, we performed a retrospective comparison of 20 patients treated with IPLE and 126 patients treated with tibial and femoral component revisions at a single institution between 2011 and 2018. Patient demographic characteristics, medical comorbidities, time to initial revision TKA, and reoperation (90 days, <2 years, and >2 years) were assessed using paired Student's t-test or Fisher's exact test with a p-value <0.01 used to determine significance. Patients undergoing IPLE were more likely to undergo reoperation (60.0 vs. 17.5%, p = 0.001), component revision surgery (45.0 vs. 8.7%, p = 0.002), and component revision within 2 years (30.0 vs. 1.6%, p < 0.0001). Differences in 90-day reoperation (p = 0.14) and revision >2 years (p = 0.19) were not significant. Reoperation for instability (30.0 vs. 4.0%, p < 0.001) and infection (20.0 vs. 1.6%, p < 0.01) were both higher in the IPLE group. IPLE does not provide consistent benefits for patients undergoing TKA revision for instability. Considerations for lower immediate postoperative morbidity and cost need to be carefully measured against long-term consequences of reoperation, delayed component revision, and increased long-term costs of multiple surgical procedures. This is a level III, case–control study.

Download Full-text

Effective Chromium Adsorption From Aqueous Solutions and Tannery Wastewater Using Bimetallic Fe/Cu Nanoparticles: Response Surface Methodology and Artificial Neural Network

Air Soil and Water Research ◽

10.1177/11786221211028162 ◽

2021 ◽

Vol 14 ◽

pp. 117862212110281

Author(s):

Ahmed S. Mahmoud ◽

Nouran Y. Mohamed ◽

Mohamed K. Mostafa ◽

Mohamed S. Mahmoud

Keyword(s):

Response Surface Methodology ◽

Response Surface ◽

Industrial Effluent ◽

Oxygen Demand ◽

Operating Conditions ◽

Tannery Wastewater ◽

P Value ◽

Cu Nanoparticles ◽

Artificial Neural ◽

Cr Removal

Tannery industrial effluent is one of the most difficult wastewater types since it contains a huge concentration of organic, oil, and chrome (Cr). This study successfully prepared and applied bimetallic Fe/Cu nanoparticles (Fe/Cu NPs) for chrome removal. In the beginning, the Fe/Cu NPs was equilibrated by pure aqueous chrome solution at different operating conditions (lab scale), then the nanomaterial was applied in semi full scale. The operating conditions indicated that Fe/Cu NPs was able to adsorb 68% and 33% of Cr for initial concentrations of 1 and 9 mg/L, respectively. The removal occurred at pH 3 using 0.6 g/L Fe/Cu dose, stirring rate 200 r/min, contact time 20 min, and constant temperature 20 ± 2ºC. Adsorption isotherm proved that the Khan model is the most appropriate model for Cr removal using Fe/Cu NPs with the minimum error sum of 0.199. According to khan, the maximum uptakes was 20.5 mg/g Cr. Kinetic results proved that Pseudo Second Order mechanism with the least possible error of 0.098 indicated that the adsorption mechanism is chemisorption. Response surface methodology (RSM) equation was developed with a significant p-value = 0 to label the relations between Cr removal and different experimental parameters. Artificial neural networks (ANNs) were performed with a structure of 5-4-1 and the achieved results indicated that the effect of the dose is the most dominated variable for Cr removal. Application of Fe/Cu NPs in real tannery wastewater showed its ability to degrade and disinfect organic and biological contaminants in addition to chrome adsorption. The reduction in chemical oxygen demand (COD), biological oxygen demand (BOD), total suspended solids (TSS), total phosphorus (TP), total nitrogen (TN), Cr, hydrogen sulfide (H2S), and oil reached 61.5%, 49.5%, 44.8%, 100%, 38.9%, 96.3%, 88.7%, and 29.4%, respectively.

Download Full-text

Linking population size structure, heat stress and bleaching responses in a subtropical endemic coral

Coral Reefs ◽

10.1007/s00338-021-02081-2 ◽

2021 ◽

Author(s):

Liam Lachs ◽

Brigitte Sommer ◽

James Cant ◽

Jessica M. Hodge ◽

Hamish A. Malcolm ◽

...

Keyword(s):

Heat Stress ◽

Size Structure ◽

Temporal Trends ◽

Early Recovery ◽

Size Frequency Distribution ◽

Frequency Distributions ◽

Community Organisation ◽

Size Frequency ◽

Eastern Australia

AbstractAnthropocene coral reefs are faced with increasingly severe marine heatwaves and mass coral bleaching mortality events. The ensuing demographic changes to coral assemblages can have long-term impacts on reef community organisation. Thus, understanding the dynamics of subtropical scleractinian coral populations is essential to predict their recovery or extinction post-disturbance. Here we present a 10-yr demographic assessment of a subtropical endemic coral, Pocillopora aliciae (Schmidt-Roach et al. in Zootaxa 3626:576–582, 2013) from the Solitary Islands Marine Park, eastern Australia, paired with long-term temperature records. These coral populations are regularly affected by storms, undergo seasonal thermal variability, and are increasingly impacted by severe marine heatwaves. We examined the demographic processes governing the persistence of these populations using inference from size-frequency distributions based on log-transformed planar area measurements of 7196 coral colonies. Specifically, the size-frequency distribution mean, coefficient of variation, skewness, kurtosis, and coral density were applied to describe population dynamics. Generalised Linear Mixed Effects Models were used to determine temporal trends and test demographic responses to heat stress. Temporal variation in size-frequency distributions revealed various population processes, from recruitment pulses and cohort growth, to bleaching impacts and temperature dependencies. Sporadic recruitment pulses likely support population persistence, illustrated in 2010 by strong positively skewed size-frequency distributions and the highest density of juvenile corals measured during the study. Increasing mean colony size over the following 6 yr indicates further cohort growth of these recruits. Severe heat stress in 2016 resulted in mass bleaching mortality and a 51% decline in coral density. Moderate heat stress in the following years was associated with suppressed P. aliciae recruitment and a lack of early recovery, marked by an exponential decrease of juvenile density (i.e. recruitment) with increasing heat stress. Here, population reliance on sporadic recruitment and susceptibility to heat stress underpin the vulnerability of subtropical coral assemblages to climate change.

Download Full-text

Satellite-Derived Protein Concentration of Phytoplankton in the Southwestern East/Japan Sea

Journal of Marine Science and Engineering ◽

10.3390/jmse9020189 ◽

2021 ◽

Vol 9 (2) ◽

pp. 189

Author(s):

Hyeonji Bae ◽

Dabin Lee ◽

Jae Joong Kang ◽

Jae Hyung Lee ◽

Naeun Jo ◽

...

Keyword(s):

Protein Concentration ◽

Japan Sea ◽

Biological Properties ◽

Measured Data ◽

Trophic Levels ◽

Coefficient Of Determination ◽

P Value ◽

Chl A ◽

Major Factors

The cellular macromolecular contents and energy value of phytoplankton as primary food source determine the growth of higher trophic levels, affecting the balance and sustainability of oceanic food webs. Especially, proteins are more directly linked with basic functions of phytoplankton biosynthesis and cell division and transferred through the food chains. In recent years, the East/Japan Sea (EJS) has been changed dramatically in environmental conditions, such as physical and chemical characteristics, as well as biological properties. Therefore, developing an algorithm to estimate the protein concentration of phytoplankton and monitor their spatiotemporal variations on a broad scale would be invaluable. To derive the protein concentration of phytoplankton in EJS, the new regional algorithm was developed by using multiple linear regression analyses based on field-measured data which were obtained from 2012 to 2018 in the southwestern EJS. The major factors for the protein concentration were identified as chlorophyll-a (Chl-a) and sea surface nitrate (SSN) in the southwestern EJS. The coefficient of determination (r2) between field-measured and algorithm-derived protein concentrations was 0.55, which is rather low but reliable. The satellite-derived estimation generally follows the 1:1 line with the field-measured data, with Pearson’s correlation coefficient, which was 0.40 (p-value < 0.01, n = 135). No remarkable trend in the long-term annual protein concentration of phytoplankton was found in the study area during our observation period. However, some seasonal difference was observed in winter protein concentration between the 2003–2005 and 2017–2019 periods. The algorithm is developed for the regional East/Japan Sea (EJS) and could contribute to long-term monitoring for climate-associated ecosystem changes. For a better understanding of spatiotemporal variation in the protein concentration of phytoplankton in the EJS, this algorithm should be further improved with continuous field surveys.

Download Full-text