Daily Accumulation Research Articles

Analysis of field monitoring of precipitation and pore pressure over seven years at Morro do Boi of Serra do Mar/Brazil

The stability of slopes or the occurrence of mass movements is directly related to the incidence of rainfall. In this work a qualitative analysis of the historical series was made for the period between May 2012 and February 2019, where the development of pore pressures was evaluated, analyzing the behaviors of the instruments, correlating their readings with precipitation and with variations in the water table. Pore pressure was measured using vibrating wire piezometers, and precipitation data was collected using pluviometers with tipper buckets, whose readings were obtained by a datalogger model ML1-FL. From the data collected, it was possible to estimate the duration of a rainfall event for the soil, as that time interval between the occurrence of rain and the dissipation of excess pore pressure. These intervals are between 3 and 26 days in duration. The main results were: the period between the end of June and August is the driest and the highest precipitation occurs from December to early June; Precipitation of up to 100 mm of daily accumulation is well distributed throughout the year and occurs in all seasons. The pore pressure values developed were low, with a maximum of 9.3 kPa for the deepest piezometer on elevation 92.40 m. There is a delay between the occurrence of precipitation and the recording of the peak pore pressure. The in-depth knowledge of variations in precipitation and pore pressure can support the development of more robust geotechnical engineering projects. This preventive approach, based on concrete data and correlations, offers a more reliable strategy for mitigating the risks associated with landslides, directly contributing to the safety and continuous operation of the BR-101/SC highway.

The role of lifestyle physical activity in preventing multiple sclerosis

Multiple sclerosis (MS) is a devastating neurodegenerative disorder that affects more than three million people worldwide. Among the environmental, lifestyle, dietary, comorbid, and pharmacological factors investigated as possible modifiable protective or risk factors for MS, physical activity (PA) seems to play a valuable role in its prevention. Currently, there is no comprehensive review article on the preventive effects of PA in MS. This narrative review aimed to evaluate the most recent and extensive pooled analysis and evidence and to explore the influence of lifestyle PA on primary and secondary prevention in MS. Literature articles were searched through several databases, including PubMed, Cochrane Library, Embase, and Web of Science, from 1985 to March 2024. The review focused on lifestyle PA, defined as the daily accumulation of at least 30 min of self-selected activities. This includes all leisure, occupational, or household activities that are at least moderate to vigorous in intensity and may be planned or unplanned activities that are part of everyday life. The most valuable and representative reports on primary and secondary prevention in MS have been selected. Lifestyle PA, practised at moderate and high intensity, plays a protective role in reducing the risk of developing MS and delaying the onset of disability in persons with MS. Future studies are required to identify specific types of PA that are particularly recommended for patients with MS.

A first assessment of marine litter on a beach of an uninhabited island in the Mozambique Channel

Marine litter is ubiquitous and associated with both ecological and socio-economic consequences. Beaches are major sinks of marine litter and as such its assessment and monitoring are needed. An opportunistic marine litter survey was performed for 12 consecutive days on the island of Juan de Nova in the central Mozambique Channel in February 2007. Plastic dominated the marine beach litter with daily accumulation of plastic positively related to the tide height (R2 = 0.768, p<0.01). Annual deposits could reach an average of 1 t.km-1, suggesting that regular cleaning of the coastline should be conducted to limit the impact on the local wildlife of this protected area.

Disasters in Petrópolis, Brazil: political, urban planning, and geometeorological factors that contributed to the event on February 15, 2022

In Brazil, Petrópolis, situated in the mountainous region of the Rio de Janeiro, stands out as one of the areas most severely affected by disasters. The present study aims to provide: i) an overview of disaster cases in Petrópolis (2018 to 2022); ii) the geometeorological mechanisms that supported the occurrence of the extreme precipitation event on February 15, 2022; and iii) the role of urban planning policies in disaster risk management in Petrópolis. 194 different disasters events were identified, with the majority (51%) being landslides. In February 2022, the landslides and floods resulted from the contribution of the extreme precipitation event, which led to a daily accumulation of 260 mm. A cold front over the ocean brought moisture to the southeast of Brazil, and local topography favored southward winds, supporting storm formation. It is worth noting that despite the existence of a previous risk assessment study conducted by the municipality's administration, disasters continue to occur, highlighting the need for monitoring and revision of local public policies. Beyond random misfortunes, the occurrence of disasters underscores the socio-environmental injustices produced by the omission of public administration, contributing to Petrópolis becoming a risk-prone area.

Beach Litter Variability According to the Number of Visitors in Cádiz Beaches, SW Spain

The amount and composition of litter was evaluated during May and June 2021 at two urban beaches, i.e., La Victoria and La Cortadura, in Cádiz, SW Spain. Surveys were carried out daily in the morning and in the evening during the weekends to quantify the daily accumulation of beach litter and relate it to the number of beach users, which was assessed at around 1:00 p.m. Litter amount was also related to cleanup operations that were very mechanically and manually carried out each day very early in the morning. A total of 8108 items were collected at the two investigated sectors during the study period and beach visitors were quantified in 22 surveys. Plastic was the most common material, representing 82% in La Victoria and 68% in La Cortadura. The most common items were cigarette butts and small, hard plastic fragments. Some litter items that were hazardous to beach visitors were identified, such as broken glass. The number of visitors was positively related to the amount of litter. Significant differences were seen in the litter abundance between the morning and evening assessments since the beaches were cleaned daily and bins were available to facilitate trash disposal. Cleaning operations remove many of the litter items but always leave small quantities of small items uncollected. Efforts to prevent litter on these beaches should focus on informing visitors properly in order to avoid littering and on improving cleanup operations.

Tree foliage as a net accumulator of highly toxic methylmercury

Tree canopies are known to elevate atmospheric inputs of both mercury (Hg) and methylmercury (MeHg). While foliar uptake of gaseous Hg is well documented, little is known regarding the temporal dynamics and origins of MeHg in tree foliage, which represents typically less than 1% of total Hg in foliage. In this work, we examined the foliar total Hg and MeHg content by following the growth of five individual trees of American Beech (Fagus grandifolia) for one growing season (April–November, 2017) in North Carolina, USA. We show that similar to other studies foliar Hg content increased almost linearly over time, with daily accumulation rates ranging from 0.123 to 0.161 ng/g/day. However, not all trees showed linear increases of foliar MeHg content along the growing season; we found that 2 out of 5 trees showed elevated foliar MeHg content at the initial phase of the growing season but their MeHg content declined through early summer. However, foliar MeHg content among all 5 trees showed eventual increases through the end of the growing season, proving that foliage is a net accumulator of MeHg while foliar gain of biomass did not “dilute” MeHg content.

Towards global coverage of gridded parameterization for CLImate GENerator (CLIGEN)

ABSTRACT Stochastic weather generators create time series that reproduce key weather dynamics present in long-term observations. The dataset detailed herein is a large-scale gridded parameterization for CLImate GENerator (CLIGEN) that fills spatial gaps in the coverage of existing regional CLIGEN parameterizations, thereby obtaining near-global availability of combined coverages. This dataset primarily covers countries north of 40° latitude with 0.25° spatial resolution. Various CLIGEN parameters were estimated based on 20-year records from four popular global climate products. Precipitation parameters were statistically downscaled to estimate point-scale values, while point-scale temperature and solar radiation parameters were approximated by direct calculation from high-resolution datasets. Surrogate parameter values were used in some cases, such as with wind parameters. Cross-validation was done to assess the downscaling approach for six precipitation parameters using known point-scale values from ground-based CLIGEN parameterizations. These parameter values were derived from daily accumulation records at 7,281 stations and high temporal resolution records at 609 stations. Two sensitive parameters, monthly average storm accumulation and maximum 30-minute intensity, were shown have RMSE values of 1.48 mm and 4.67 mm hr−1, respectively. Cumulative precipitation and the annual number of days with precipitation occurrence were both within 5% of ground-based parameterizations, effectively improving climate data availability.

The impact of the anthropause caused by the COVID-19 pandemic on beach debris accumulation in Maui, Hawaiʻi

The COVID-19 pandemic and subsequent travel restrictions led to a considerable reduction in tourism and human activity on Maui, presenting a unique opportunity to study debris accumulation on local beaches during changing levels of human activities. Standardized daily debris accumulation surveys were completed at two beach sites in Maui, Hawai ‘i before (2017) as well as throughout the initial year of the pandemic (2020–2021) and allowed for the assessment of pandemic-related restrictions on marine debris accumulation trends. Throughout the pandemic, reduced beach use due to higher lockdown levels had significant impacts on debris accumulation at both sites, but only one of the two sites experienced a significant decrease (~ 90% reduction) in debris accumulation rates when compared to the same months in 2017. Daily accumulation rates across two sites increased from an average of 16 items/100 m during peak lockdown levels to 43 items/100 m when restrictions eased. The observed fluctuations in debris accumulation rates, driven by changes in tourism and travel restrictions during the COVID-19 pandemic emphasize the importance of proactive measures to protect the natural environment, including source reduction and effective legislation for waste prevention. By addressing both local and remote sources of debris and focusing on reducing waste at its source, it is possible to mitigate the impacts of debris accumulation on coastal environments and marine life in Hawaiʻi.

Which adjustment methods are suitable for the wind-induced errors of Geonor T-200BM3 precipitation weighing gauges in a periglacial site?

Single Alter shielded T-200BM3 weighing precipitation gauges are widely used in the measurement of all precipitation types (rainfall, snow and mixed precipitation) in unattended boreal or alpine regions, but their original datasets must be adjusted for undercatch errors caused by wind in snowy, windy and harsh environments. Therefore, previous researchers have developed many adjustment methods for all precipitation types on different time scales. However, which adjustment method is suitable for T-200BM3 weighing gauge wind-induced error adjustment in harsh alpine regions is unclear. Therefore, precipitation measurement intercomparison experiments were conducted in the Qilian Mountains from July 2018 to July 2021, and eight adjustment methods; were evaluated for wind-induced errors for daily, individual precipitation event, hourly, and half-hourly time scales. Z2004 outperformed the other adjustment methods in regard to the daily measurements of snow and mixed precipitation. Regarding individual snowfall events, M2007 reduced the absolute value of RMSE (bias) from 1.44 to 1.32 mm (0.77–0.24 mm) and could be recommended for snowfall event adjustment. K2017-1 attained a better performance than K2017-2 in regard to half-hourly snowfall and mixed sample adjustment and was more suitable for half-hourly snowfall sample adjustment. K2017-1 reduced the absolute value of bias from 0.07 to 0.00 mm for snowfall. Finally, Z2004, M2007, and K2017-1 yielded better adjustment results for the daily accumulation precipitation amount (>2 mm d−1), individual snowfall events (>2 mm per event), and half-hourly accumulation snowfall or mixed samples (>1 mm 30 min−1), respectively. However, further intercomparison in different climate regions is needed for trace precipitation samples.

Daily accumulation rates of floating debris and attached biota on continental and oceanic island shores in the SE Pacific: testing predictions based on global models.

Long-distance rafting on anthropogenic marine debris (AMD) is thought to have a significant impact on global marine biogeography and the dispersal of non-indigenous species. Therefore, early identification of arrival sites of AMD and its epibionts is crucial for the prioritization of preventive measures. As accumulation patterns along global coastlines are largely unstudied, we tested if existing oceanographic models and knowledge about upstream sources of litter and epibionts can be used as a simple and cost-efficient approach for predicting probable arrival sites of AMD-rafting biota in coastal zones. Using the Southeast Pacific as a model system, we studied daily accumulation rates, composition, and minimum floating times of AMD with and without epibionts on seven sandy beaches, covering the oceanic environment (Rapa Nui/Easter Island) and three regions (south, centre, north) along the Chilean continental coast, over a minimum of 10 consecutive days, and we contrast our results with predictions from published models. Total AMD accumulation rates varied from 56 ± 36 (mean±standard deviation) to 388 ± 433 items km-1 d-1 and differed strongly between regions, in accordance with local geomorphology and socioeconomic conditions (presence of larger cities and rivers upstream, main economic activities, etc.). Daily accumulation of items with pelagic epibionts (indicators of a pelagic trajectory) ranged from 46 ± 29 (Rapa Nui) to 0.0 items km-1 d-1 (northern continental region). Minimum floating times of rafts, as estimated from the size of pelagic epibionts, were longest in the South Pacific Subtropical Gyre's (SPSG) centre region, followed by the high-latitude continental region under the influence of the onshore West Wind Drift, and decreased along the continental alongshore upwelling current, towards lower latitudes. Apart from pelagic rafters, a wide range of benthic epibionts, including invasive and cryptogenic species, was found on rafts at the continental beaches. Similarly, we present another record of local benthic corals Pocillopora sp., on Rapa Nui rafts. Our results agree with the predictions made by recent models based on the prevailing wind and surface current regimes, with high frequencies of long-distance rafting in the oceanic SPSG centre and very low frequencies along the continental coast. These findings confirm the suitability of such models in predicting arrival hotspots of AMD and rafting species. Moreover, storm surges as well as site-related factors seem to influence AMD arrival patterns along the Chilean continental coast and might cause the observed high variability between sampling sites and days. Our results highlight the possible importance of rafting as a vector of along-shore dispersal and range expansions along the SE Pacific continental coast and add to the discussion about its role in benthic species dispersal between South Pacific oceanic islands.

Agroclimatic requirements and adaptation potential to global warming of Spanish cultivars of sweet cherry (Prunus avium L.)

Traditional fruit tree cultivars are an important source of agricultural biodiversity. These genotypes are well adapted to the regions where they grow, and their fruits offer distinctive features compared to the commercial cultivars that are frequently grown. We analyzed the adaptation prospects of seven sweet cherry cultivars grown in Zaragoza (Spain) to future climate conditions. We first delineated chilling and forcing phases using Partial Least Squares (PLS) regression to correlate phenology records with daily accumulations of chill and heat during the months preceding flowering. We then calculated chill requirements using three chill models (Chilling Hours, Utah and Dynamic) and forcing requirements using one heat model (Growing Degree Hours, GDH). Results indicated that the chilling and forcing requirements ranged between 26.1 and 60.2 CP (chill portions) and from 5473 to 8030 GDH, respectively. We then assessed the cultivars’ potential to adapt to a warmer future using climate projections and comparing the chill requirements with the expected chill accumulation under two global warming scenarios, RCP4.5 (effective reduction of greenhouse gas emissions) and RCP8.5 (very high greenhouse gas emissions), by two time horizons, 2050 and 2085, with temperature projections from fifteen Global Climate Models (GCM). These projections established that chill accumulation has consistently decreased over the last 30 years, but temperate trees have shown regular breaking of dormancy, bud burst and blooming. Future chill levels are expected to continue decreasing given the sustained warming trend, so there is no guarantee that sufficient winter chill will be observed in the medium to long term if the warming trend continues. For three out of the seven cultivars we analyzed, most global climate models predict medium or low risks by 2050 and 2085 under the RCP4.5 scenario. Under the RCP8.5 scenario, particularly by the end of the 21st century (i.e. 2085), four of the cultivars with high chill needs are expected to not to meet their chill requirements very often.

Essential Mineral Elements and Potentially Toxic Elements in Orange-Fleshed Sweet Potato Cultivated in Northern Ethiopia.

This study investigated the influence of the agro-climatic environment of Northern Ethiopia on the content of essential mineral elements of selected orange-fleshed sweetpotato genotypes, the potential contribution of each genotype's essential mineral elements to the recommended dietary allowance, and the potential risk to human health from the accumulation of potentially toxic elements in the tuberous roots of the studied genotypes. The results showed consistent interspecific variations in the content of essential mineral elements among the studied orange-fleshed sweetpotato genotypes, as well as important intraspecific differences, which could depend on the variations in soil mineral and organic matter content, rainfall, temperature, as well as interactions between genotype and environment. The investigated genotypes, especially Kulfo, Ininda, Gloria, and Amelia, can provide an amount of several essential mineral elements high enough to meet 100% of the recommended dietary allowance for all age groups ≤8 years. The mean content of potentially toxic elements in tuberous roots and their daily intake values were within the recommended permissible levels; likewise, no health risk was associated with the consumption of these genotypes for Cr, As, and Pb. However, Al, Cd, Cu, Fe, Mn, and Ni is > 1, consumption imposes health risks based on daily accumulation.

Time of immersion of bodies found in water in Northern Patagonia Argentina

IntroductionThe estimation of the immersion time of bodies recovered from the water, through the evaluation of the cadaveric changes, allows inferring the time that they have remained in the water regardless of the cause of death. In the present study, the Daily Accumulation of Degrees (ADG) method is analyzed for the calculation of the immersion interval in bodies recovered from the water in 36 bodies with a known interval of permanence in the water. Material and methodsA total of 161 bodies were recovered from the water between 2007 and 2022, in 41 cases there was data to be analyzed by the ADG method and 36 were suitable for analysis of the method when confronted with the known intervals of immersion of the bodies. ResultsThe comparison of calculation by Daily Accumulation of Degrees versus Known Immersion Interval, of the sample of 36 cases, showed that the difference in days obtained is statistically significant (p 0.48 > 0.005). In 16 cases (44.4%) there was an underestimation by the Daily Accumulation of Degrees method with respect to the time spent in the known water that differed by an average of 40%, and in 18 cases (50%) an overestimation of 41%. Based on the observation of the cadaveric changes, the month of the year and the water temperature, a table was made to estimate the Postmortal Interval of Immersion for watercourses in Northern Patagonia. ConclusionThe method of Daily Accumulation of Degrees in bodies recovered from the water to estimate the immersion interval may give a false perception of accuracy due to the complexity of integrating all the changing factors that affect human decomposition in aquatic environments.

Data de inmersión en cuerpos recuperados del agua en el norte de la Patagonia Argentina

IntroductionThe estimation of the immersion time of bodies recovered from the water, through the evaluation of the cadaveric changes, allows inferring the time that they have remained in the water regardless of the cause of death. In the present study, the Daily Accumulation of Degrees (ADG) method is analyzed for the calculation of the immersion interval in bodies recovered from the water in 36 bodies with a known interval of permanence in the water. Material and methodsA total of 161 bodies were recovered from the water between 2007 and 2022, in 41 cases there was data to be analyzed by the ADG method and 36 were suitable for analysis of the method when confronted with the known intervals of immersion of the bodies. ResultsThe comparison of calculation by Daily Accumulation of Degrees versus Known Immersion Interval, of the sample of 36 cases, showed that the difference in days obtained is statistically significant (p= 0.48 > 0.005). In 16 cases (44.4%) there was an underestimation by the Daily Accumulation of Degrees method with respect to the time spent in the known water that differed by an average of 40%, and in 18 cases (50%) an overestimation of 41%. Based on the observation of the cadaveric changes, the month of the year and the water temperature, a table was made to estimate the Postmortal Interval of Immersion for watercourses in Northern Patagonia. ConclusionThe method of Daily Accumulation of Degrees in bodies recovered from the water to estimate the immersion interval may give a false perception of accuracy due to the complexity of integrating all the changing factors that affect human decomposition in aquatic environments.

Analysis of the effect of temperature and relative humidity on spring wheat as recorded by dataloggers installed within the crop in southern Sonora, Mexico

The objective of this work was to analyze the effect of temperature and relative humidity on spring durum wheat cultivar CIRNO C2008 as recorded by dataloggers (DL) installed within the crop in five commercial fields in southern, Sonora, Mexico, during the crop season fall-winter 2021-2022. The minimum (MINTT) (≤ 4 °C) and maximum thermal threshold (MAXTT) levels (≥ 33 °C), relative humidity (RH) (≥ 90%), and cold units (CU) (≤ 10 °C), were compared between DL and weather stations (WS) closest to the sensors. DL recorded greater number of MINTT periods from February 03 and MAXTT from March 14, and the MINTT periods were longer than those recorded by WS. With regard to the MAXTT, DL recorded 5 periods in fields located in block (B) 703 and Mocorua, two in B-2036, and one in B-2324. The main period of MINTT detected by WS was March 09 to 10. These WS did not record any continuous periods of MAXTT. The total accumulation of CU quantified in the fields with DL and with WS were: B-2036/B-1936 = 846 and 566, B-2324/B-2328 = 851 and 718, B-2814/B-2918 = 870 and 773, Mocorua/Sahuaral = 885 and 696, and B-703/B-609 = 955 and 743, respectively. DL recorded an average of 182 (21.6%) more CU than WS. DL began the recording of cold units from December 7 while WS from December 18. The daily accumulation of continuous hours with > 90% RH, had a significant difference between WS and DL. The WS in B-2918 recorded 277 more hours than the DL in B-2814, and the WS located in Sahuaral recorded 138 more hours than the DL in Morocua. However, DL in B-2036, B-703, and B-2324, recorded 539, 375, and 73 more hours with > 90% than their respective WS.

Ensemble Dressing of Meteorological Fields: Using Spatial Regression to Estimate Uncertainty in Deterministic Gridded Meteorological Datasets

Abstract Most datasets of surface meteorology are deterministic, yet many applications using these datasets require or can benefit from uncertainty estimates in meteorological fields. Motivated by this gap, we evaluated the use of a spatial regression method to estimate the uncertainty in precipitation and temperature fields of existing deterministic gridded meteorological datasets. Taking the widely used North American Land Data Assimilation System 2 (NLDAS-2) precipitation and temperature dataset as an example, we used the deterministic NLDAS-2 values to generate ensemble estimates for daily precipitation, mean temperature, and the diurnal temperature range. Our method is a form of ensemble dressing. Nine variations were tested to assess the impacts of sampling density on the estimates of the mean and uncertainty, and one strategy was selected to generate 100 ensemble members at 1/8° and daily resolution for the period 1979–2019, termed as the Ensemble Dressing of NLDAS-2 (EDN2). Compared with an independent station-based ensemble dataset, the ensemble dressing method produces reasonable uncertainty patterns for precipitation and underestimates uncertainty for temperature. For precipitation, the uncertainty increases with the increase in daily accumulation. For temperature, the uncertainty is relatively small in the warm season and large in the cold season. This ensemble dressing method is applicable to other deterministic gridded meteorological datasets. The generated spatiotemporally varying uncertainty information could support applications such as land surface and hydrologic modeling, data assimilation, and forecasting, especially where application models are tied to a specific meteorological dataset.

Atmospheric Rivers Contribute to Summer Surface Buoyancy Forcing in the Atlantic Sector of the Southern Ocean

AbstractAtmospheric rivers (ARs) dominate moisture transport globally; however, it is unknown what impact ARs have on surface ocean buoyancy. This study explores the surface buoyancy gained by ARs using high‐resolution surface observations from a Wave Glider deployed in the subpolar Southern Ocean (54°S, 0°E) between 19 December 2018 and 12 February 2019 (55 days). When ARs combine with storms, the associated precipitation is significantly enhanced (189%). In addition, the daily accumulation of AR‐induced precipitation provides a buoyancy gain to the surface ocean equivalent to warming by surface heat fluxes. Over the 55 days, ARs accounted for 47% of the total precipitation equating to 10% of the summer surface ocean buoyancy gain. This study indicates that ARs play an important role in the summer precipitation over the subpolar Southern Ocean and that they can alter the upper‐ocean buoyancy budget from synoptic to seasonal timescales.

Optional strategies for low-risk and non-risk applications of fungal pesticides to avoid solar ultraviolet damage.

Solar ultraviolet (UV) irradiation is harmful to formulated conidia as active ingredients of fungal pesticides and hence restrains their field application in sunny days of summer, a season requiring frequent pest controls. This conflict makes it necessary to explore optimal strategies for the application of fungal pesticides to suppress pest populations but avoid solar UV damage during summer. The conidia of Beauveria bassiana, a wide-spectrum fungal pesticide, were tolerable to UVB (major solar UV wavelengths) damage of ≤0.5J cm-2 . The damage of this upper limit caused a loss of conidial viability and infectivity if not photoreactivated by light exposure after irradiation. Intriguingly, the light exposure resulted in a high photoreactivation rate of UVB-inactivated conidia and an insignificant or marginal difference in insecticidal activity between normal conidia and those photoreactivated. Modeling analysis of solar UVB intensity recorded hourly over the daylight of five sunny summer days from 5:00 am to 7:00 pm at 30° 17'57''N and 120°5'7''E revealed a variation of daily accumulated UVB dose from 2.07 to 2.78 J cm-2 , which was far beyond the upper limit. A more tolerable dose of ~0.2J cm-2 appeared between 3:00 pm and 5:00 pm, and no harmful dose accumulated between 5:00 pm and 7:00 pm. Fungal UVB tolerance, fungal photoreactivation capability and the daily accumulation pattern of solar UV irradiation are based to propose an optional strategy for low-risk or non-risk application of fungal pesticides after 3:00 or 5:00 pm during summer. © 2022 Society of Chemical Industry.

Photosynthetic and water-related physiological characteristics of Periploca sepium in response to changing soil water conditions in a shell sand habitat

This study was performed to observe the effects of water on photosynthesis and water-related physiology in dominant shrubs in shell sand habitats. Four-year-old Periploca sepium seedlings were used as model species. A gradient of 12 water levels was established by artificially supplying the shell sand with water up to saturation and then allowing natural evapotranspiration to occur. The photosynthetic, chlorophyll fluorescence and stem sap flow parameters of P. sepium were measured under a range of water conditions. The different soil water conditions were classified according to the responses of these parameters. (1) With the increase in the relative water content (RWC) of the shell sand, the parameters of leaf photosynthesis, chlorophyll fluorescence and water-related physiology in P. sepium showed significant critical responses. The net photosynthetic rate (Pn), transpiration rate (Tr), instantaneous water use efficiency (WUE), potential water use efficiency (WUEi), maximum photochemical efficiency (Fv/Fm), actual photochemical efficiency (ΦPSII) and daily accumulation of stem sap flow all increased first and then decreased with increasing RWC, but the corresponding water conditions associated with their maximum values were not the same. An RWC of 69.40% was determined to be the optimal water condition for photosynthesis and water-related physiological activity in P. sepium. At an RWC of 36.61%, the mechanism of photosynthetic inhibition in P. sepium changed from stomatal limitation to nonstomatal limitation; this was also the minimum water requirement for maintaining normal photosynthetic processes. An RWC of 50.27% resulted in the highest WUE in P. sepium, indicating that moderate drought stress increased WUE. (2) Based on the quantitative relationship between the photosynthetic parameters of P. sepium and the shell sand water gradient, the soil water availability was classified into 6 water grades. The RWC range for maintaining strong photosynthesis and high WUE in P. sepium was 63.22–69.98%. (3) Gas exchange in P. sepium was inhibited under drought and waterlogging stresses. Under these conditions, the photosynthetic electron transport chain was blocked, and the dissipation of light energy as heat increased, which ultimately led to a decline in photosynthetic productivity; moreover, transpiration and dissipation were aggravated, and water transmission and utilization processes in P. sepium were hindered. A significant negative feedback regulation mechanism in the photosynthetic and water-related physiological processes of P. sepium was observed; this mechanism allowed P. sepium growing in shell sand to be highly adaptable to water stress.

Standing stock and daily accumulation of beach litter in KwaZulu-Natal, South Africa

Beach litter accumulation studies are an important method to investigate litter flows to the marine environment. We detail a standing stock and daily accumulation study, conducted at two locations approximately 20 km north (uMhlanga) and south (Amanzimtoti) of the Port of Durban, South Africa. The materials collected were dominated in number by plastic, which constituted more than 90% of all items found during the surveys. Accumulation ranged from 134 to 719 items 100 m−1 d−1, falling within the range of similar studies in South Africa. Accumulation weights (wet and uncleaned, WU) ranged from 0.10 to 2.49 kg per day. Between the two sites, standing stock per 100 m ranged between 921 to 1534 items, and between 1.06 to 4. 03 kg(WU). Overall, higher litter loads were observed at Amanzimtoti beach compared to uMhlanga beach. Our statistical modelling showed that litter numbers varied by beach, whether collection was above or below high tide and the amount of rainfall. At Amanzimtoti, more litter was found above the tide line throughout the study, but at uMhlanga, this was only true for the first part of the study. Analysis of the types of litter found between beaches, suggest different sources of litter that could be used to tailor waste management solutions in each local area. Greater numbers of cotton bud sticks found at uMhlanga, suggests sewage treatment outputs contribute to the litter loads in this area, while large amount of linoleum flooring fragments found at Amanzimtoti suggest construction could be the source.