3m Depth Research Articles

Diversity of Coral Fish At Saebus Island, East Java, Indonesia

Coral reef ecosystem is known as an important place to live various types of fish, where coral conditions will affect the diversity and abundance of the fish. In healthy coral reef ecosystems generally can be found many types of fish with high density. This research aims to investigate the diversity and abundance of coral fishes at Saebus Island, East Java. The observation conducted at 4 stations, according to cardinal point by UVS (underwater visual census) methods with belt transect with the visibility of 2,5 m horizontally, and 5 m vertically. The length of transect was 100 m parallel with coastline, with the area of observation is 500 m2. The censuses were conducted at 2 different depths (3 and 10 m). This study found 70 kinds of coral fish originated form 20 family at all stations. These fishes were from 3 different fish categories i.e. 7 target fishes, 13 indicator fishes, and 50 major fishes. Three different fishes that dominated target fish, indicator fish and major fish wereEpinephelus fasciatus, Chaetodon baronessaandAulostomus chinensis,respectively. There was similar value of fish diversity index at two different depths which were 3.635 and 3,623. While uniformity index at the depth of 3m was 0.153 and at 10m was 0.217, and domination index at the depth of 3m was 0.11 and at 10m was 0.167. These values suggest that diversity of coral fish at Saebus island can be categorized as high diversity.

A multi-species modelling approach to select appropriate submerged macrophyte species for ecological restoration in Gonghu Bay, Lake Taihu, China

In this study, we built a submerged macrophyte model (GBAEDM) that could simulate several macrophyte species simultaneously. The model was calibrated and validated using pilot-scale experimental data, with satisfactory results. The coefficient of determination (R2) and root-mean-square error (RMSE) values were 0.86 and 0.03 for TP, 0.71 and 0.38 for TN, 0.93 and 6.78 for Chl a, and 0.99 and 27.61 for submerged macrophyte biomass. The GBAEDM was then used to choose appropriate species and suitable initial plant biomass submerged macrophyte recovery in Gonghu Bay. The appropriate species at 1m depth were Vallisneria spinulosa (1150g/m2), Myriophyllum spicatum (525g/m2), and V. spinulosa–M. spicatum mixed (600g/m2; 3:1) communities. At 2m depth, the appropriate species were M. spicatum (1450g/m2) and V. spinulosa–M. spicatum mixed (1950g/m2; 12:1) communities. Only M. spicatum (1608g/m2) was recommended at 3m depth. Finally, the GBAEDM was used to determine the critical water transparency thresholds for submerged macrophytes in Gonghu Bay. A transparency value of 0.62m at 2m (the WT/H value of 0.31) was determined as the critical underwater light threshold for the recovery of submerged macrophytes in Gonghu Bay.

Contaminants Leaching from Fresh Poultry Waste: A Lysimeter Study on Sandy Soils under Tropical Conditions

A lysimeter study was conducted on sandy soil of Minna, North central Nigeria to assess the migration of nitrates, phosphates, bacteriological parameters and heavy metals contents of poultry manure through Minna soil. This is with a view to examining the environmental effect of indiscriminate land application of excessive poultry manure on shallow groundwater quality. A lysimeter and rainfall simulator assembly was installed on an undisturbed 0.9m diameter, 3m depth soil core after which 50kg of characterized poultry manure was applied at the top. Rainfall of 125mm was simulated and water samples were collected at different depths of the soil core through the lysimeter and were taken to laboratory for analysis. Results showed that nitrate and phosphate in poultry manure were able to leach to a depth of 2.5m of the soil core four months after poultry manure application while turbidity and electrical conductivity reached their maximum value at depth 2.5m after three months. Faecal coliform, total coliform and faecal streptococci were detected at depth 2.5m also two months after the application. Statistical analysis using New Duncan Multiple Range test showed significant variation (p<0.05) of all the parameters tested with depth of sample collection and months after application of poultry manure. Spearman’s correlation coefficient established both positive and negative correlation between the parameters studied in this research. Heavy metals tested, Arsenic, copper, zinc, chromium and manganese were not able to leach beyond 0.5m depth of the soil core throughout the experimental period.

Management of toxic and hazardous contents of oil sludge in Siri Island

Sirri Island is one of the most important islands in Iran where contains massive amounts of crude oil reservoirs and is a crude oil exporting and storage spot. Petroleum sludge wastes produced by the refineries are deposited in outdoor 2-ha open pits. 30 sludge samples from different depot locations were conducted in 3-time intervals and mixed with each other to form one homogenized sample. The sample was treated by solvent extraction method using methyl ethyl ketone as an efficient polar solvent in order to recover the valuable hydrocarbon and oil. About 99.8% of the oil was recovered and determined to reach almost the same quality as the exportable crude oil of Sirri Island. The sediments were also tested for size distribution range and titled as fine-grained soil. Toxicity characteristics leaching procedure test was conducted on the residuals to determine whether the waste is categorized as toxic and hazardous. The industrial waste evaluation model used in the current work suggested different leachate concentrations (10%, 30%, 50%, 70% and 90% of total leachate) based on toxicity characteristics leaching procedure for different probable leaching scenarios. The surface and subsurface regional conditions such as depth to underground water table, climate condition, subsurface pH, soil texture and material were defined to the model as well. Then, the model simulated 10000 possible runs considering the leaching procedure, contaminant concentrations, maximum contaminant limits and surface and sub-surface conditions. The final outcomes regarding heavy metals results showed that nickel, chromium and vanadium were protective under composite liner while cobalt and lead were not safe under such liner and need proper treatment before landfilling. As the final step, the size and details of landfill were designed. The landfill was selected as a square with side and depth of 55m and 3m respectively. The composite liner consisted of 1.5mm high density polyethylene layer with 50cm compacted clay liner of 10-7 cm/s hydraulic conductivity underneath.

ADAPTIVE MANAGEMENT FOR SUSTAINABLE DEVELOPMENT OF AMARA LAKE (S-E ROMANIA)

The Amara Lake is located at the south-eastern part of Romania. It is a shallow lake with an average depth of 3m and average extent of 1.32 km2, having a particular importance for the area in which is situated. This importance derives from its main functions in the ecosystem, namely: source of food, shelter and breeding place for almost 54 bird, balneary tourism attraction and jobs for the residents of Amara who live in the northern part of the lake. Under these conditions, the sustainable development of this area is required, and this can be attained by proposing and implementing practices which will protect and harmonize the area from economic, social and ecological point of view. In this study, a SWOT (Strengths, Weaknesses, Opportunities and Threats) analysis of Amara Lake ecosystem was performed in order to found the most adequate management solution, whose implementation would allow the sustainable development of area. The proposed management solution considers the forestation of southern shore of the lake with Acer campestre tree species. The effects of this solution on Amara Lake ecosystem were evaluated by monitoring three water quality indicators (total nitrogen, total phosphorus and biochemical oxygen demand (BOD5)) during of six years (2010-2015). These indicators are strictly related to the eutrophication process of lake water, and their variations during the monitoring period indicated that the forestation of southern shore of the lake can be considered a viable management solution.

A new approach to temporal modelling for landslide hazard assessment using an extreme rainfall induced-landslide index

An ever-increasing trend of extreme rainfall events in South Korea due to climate change is causing shallow landslides and shallow landslide induced debris flows in the mountains that cover 70% of the total land area of the nation. These catastrophic, gravity-driven processes cost the government several billion won in losses, and attendant fatalities, every year. The most common type of landslide observed is the shallow landslide occurring at 1–3m depth, which may mobilize into a catastrophic debris flow. A landslide early warning system encompassing different scale-based stages is used to predict potential areas for both the landslide types. Current study focusing on the first stage landslide hazard assessment at regional or medium scale requires the development of spatially evolving landslide hazard maps for both types of landslides based on the real-time rainfall. However, lack of complete landslide inventory data motivates the development of temporal and spatial models as independent components of the landslide hazard. Most of the existing temporal assessment schemes traditionally rooted in recurrence-based concepts does not consider soil factors and are not suitable to be incorporated in to the landslide early warning system since real-time rainfall cannot be considered. This motivated the development of a new probabilistic temporal model termed the extreme rainfall-induced landslide index. The probabilistic index was developed in Gangwon Province through a logistic regression using four factors; namely, continuous rainfall, 20-days antecedent rainfall, saturated hydraulic conductivity, and storage capacity. The developed model exhibited high area under the curve (AUC) values of 82% and 91% obtained for the training and validation curves, exhibiting good performance of the statistical index. Also, a high performance susceptibility model (training and validation AUC values of 96% and 94%, respectively) was developed using a logistic regression analysis, for Deokjeok-ri Creek, located in Gangwon province. Assuming the independence of the hazard components, a dynamic hazard index (DHI) was established through a joint probability of both the well validated models. The DHI was used to study the evolution of landslide hazard for the July 2006 extreme rainfall-induced landslide events in Deokjeok-ri Creek.

Experimental Performance of Buried Tube Heat Exchanger Validated by Simulation Performance in Heating Climate Condition

Background: Earth energy is one of the important renewable energy sources which can be used for the cooling of room in summer and for heating in winter with a less impact on the environmental condition. Buried tube Heat Exchanger (BTHE) is a beneficial feature that reduces energy consumption in case of residential buildings. Objectives: The major objective of the research is to find out the optimum dimension of BTHE at Indian climate condition for that BTHE is used to reduce conventional air conditioning load and save energy sources for reducing the heating or cooling load of residential or any buildings. However, BTHE system can improve the indoor thermal comfort and reduce greenhouse gas emission. Core objective is to determine the exact tonnage capacity of BTHE for specific load in cooling and heating mode with respect to design and materials of BTHE. Methods/Statistical Analysis: BTHE consists of one or more tubes which are lied under the ground at buried depth for cooling in summer and for heating in winter and the air is to be supply in any building. Research work shows that there is a constant temperature at the depth of 3m from ground level by experimental setup of Temperature measuring probe throughout the year. The system has been setup at the depth of 3m from ground level and experiment has been done at the place, Vallabh Vidyanagar in India located at Latitude 22°N and Longitude 72°E by using RCC pipes. Computational Fluid Dynamics (CFD) is necessary for the comparison of experimental data and simulation data with the help of Ansys software. The research in CFD simulations were performed on various performance measurements, with different length of heat exchanger. Findings: From the above analysis we could find out dimension of Buried tube heat exchanger (BTHE), we installed an experimental setup at Vallabh Vidyanagar. It can be concluded from the comparison of the simulation results and experimental result that optimum performance of the BTHE system is at 3m depth from the ground this called buried depth and horizontal 25m buried length at specific dimension i.e. 110mm outer diameter with 6mm thickness of RCC pipes. Air velocity can be a major effective parameter for the performance of BTHE. Optimum performance of horizontal buried tube heat exchanger is obtained at 3 m/s with 25m length and 0.11 outer diameter of pipe; therefore a BTHE can be used for room cooling and heating purpose and can achieve the above objectives. Applications/Improvements: Buried tube heat exchanger is used as Buried tube air conditioning system. It can be used in summer climate condition for cooling purpose and in winter for heating the building. BTHE is also useful partially or fully to handle the building thermal loads.

Sampling effort of periphytic diatoms for bioassessment research using taxonomic distinctness in marine ecosystems: A case study in coastal waters

The sampling effort for detecting taxonomic distinctness of periphytic diatom communities was studied in coastal waters of the Yellow Sea, northern China, from May to June 2014. Samples with different sizes (microscopy glass slides) were collected at two depths of 1m and 3m. To obtain the communities with dissimilarities of <10%, 2 slide replicates were sufficient for sampling at a depth of 1m, while 4 were required for the those at a depth of 3m. The values of four taxonomic distinctness indices represented a low sensitivity to sample sizes over all exposure period ages: at a coefficient of variation of <10%, 2 and 9 slide replicates were required at a depth of 1m and 3m, respectively. We suggest that the sampling strategy of the diatoms for detecting taxonomic distinctness might be better at 1m than at a deeper layer in coastal waters.

Importance of soil thermal regime in terrestrial ecosystem carbon dynamics in the circumpolar north

In the circumpolar north (45–90°N), permafrost plays an important role in vegetation and carbon (C) dynamics. Permafrost thawing has been accelerated by the warming climate and exerts a positive feedback to climate through increasing soil C release to the atmosphere. To evaluate the influence of permafrost on C dynamics, changes in soil temperature profiles should be considered in global C models. This study incorporates a sophisticated soil thermal model (STM) into a dynamic global vegetation model (LPJ-DGVM) to improve simulations of changes in soil temperature profiles from the ground surface to 3m depth, and its impacts on C pools and fluxes during the 20th and 21st centuries. With cooler simulated soil temperatures during the summer, LPJ-STM estimates ~0.4PgCyr−1 lower present-day heterotrophic respiration but ~0.5PgCyr−1 higher net primary production than the original LPJ model resulting in an additional 0.8 to 1.0PgCyr−1 being sequestered in circumpolar ecosystems. Under a suite of projected warming scenarios, we show that the increasing active layer thickness results in the mobilization of permafrost C, which contributes to a more rapid increase in heterotrophic respiration in LPJ-STM compared to the stand-alone LPJ model. Except under the extreme warming conditions, increases in plant production due to warming and rising CO2, overwhelm the e nhanced ecosystem respiration so that both boreal forest and arctic tundra ecosystems remain a net C sink over the 21st century. This study highlights the importance of considering changes in the soil thermal regime when quantifying the C budget in the circumpolar north.

Assessment of orchard N losses to groundwater with a vadose zone monitoring network

A 2-year study was conducted to explore the impact of current and alternative best management practices (BMPs) of irrigation and fertigation on nitrate (NO3−) leaching below the root zone. Using a fully randomized complete block design, three fertigation strategies were compared: current BMP with and without accounting for NO3−-N in irrigation-water, and a high frequency fertigation treatment with low-N concentration applications. Temporal changes in water content, pore water NO3− concentrations and soil water potential were monitored within and below the root zone to a soil depth of 3m at eight sites in an almond and a pistachio orchard. NO3− concentrations below the root zone ranged from <1mgL−1 to more than 2400mgL−1 (almond), and up to 11,000 (pistachio) mgL−1, with mean concentrations of 326 and 4631mgL−1, respectively. Within the fertigation cycle, fertilizer injection at the end of an irrigation event generally resulted in lower NO3− losses below the root zone compared with fertilizer injection midway through the irrigation. Pre-bloom and post-harvest flood irrigation in the almond orchard caused deep soil wetting and flushing of NO3− below the root zone, threatening groundwater quality. Statistical analysis using principal component analysis, Chi-squared Automatic Interaction Detector and the Artificial Neural Network showed that most of the deep soil NO3− concentration variability could not be explained by irrigation duration, fertigation timing or local variations in soil physical characteristics. However, mass balance estimates for water and N indicated the annual orchard average N loss could be estimated based on eight monitoring sites in spite of the inherent spatial variations in soil properties and the spatiotemporal variations in water and NO3− applications. The study indicated that reduction of N losses at the orchard scale would require alternative fertigation and irrigation practices, including better control of fertigation amounts and irrigation duration.

A hybrid feature selection algorithm integrating an extreme learning machine for landslide susceptibility modeling of Mt. Woomyeon, South Korea

An ever-increasing trend of extreme rainfall events in South Korea owing to climate change is causing shallow landslides and debris flows in mountains that cover 70% of the total land area of the nation. These catastrophic, gravity-driven processes cost the government several billion KRW (South Korean Won) in losses in addition to fatalities every year. The most common type of landslide observed is the shallow landslide, which occurs at 1–3m depth, and may mobilize into more catastrophic flow-type landslides. Hence, to predict potential landslide areas, susceptibility maps are developed in a geographical information system (GIS) environment utilizing available morphological, hydrological, geotechnical, and geological data. Landslide susceptibility models were developed using 163 landslide points and an equal number of nonlandslide points in Mt. Woomyeon, Seoul, and 23 landslide conditioning factors. However, because not all of the factors contribute to the determination of the spatial probability for landslide initiation, and a simple filter or wrapper-based approach is not efficient in identifying all of the relevant features, a feedback-loop-based hybrid algorithm was implemented in conjunction with a learning scheme called an extreme learning machine, which is based on a single-layer, feed-forward network. Validation of the constructed susceptibility model was conducted using a testing set of landslide inventory data through a prediction rate curve. The model selected 13 relevant conditioning factors out of the initial 23; and the resulting susceptibility map shows a success rate of 85% and a prediction rate of 89.45%, indicating a good performance, in contrast to the low success and prediction rate of 69.19% and 56.19%, respectively, as obtained using a wrapper technique.

Experimental Investigation of Helical Tidal Turbine Characteristics with Different Twists

The helical tidal current turbine was studied and reported its performance and characteristics for free water flow electric turbine development. The scale model of tidal turbine was built in dimension as: 0.5m and 0.6m of diameters and 1.25m in length; the turbine cross section blade was the symmetric NACA0020 with a 0.07m chord length, and there were 3 blades with the helical angle of 120o, 135o, and 150o. The model was tested in a towing tank (1.46m width, 3m depth and 45m length). The rotation and torque of the turbine was measured under various tow velocity settings, while power and power efficiencies under various tip speed ratios and helical angle velocities were presented. The characteristics obtained from this experiment provide useful information for the design and development of helical tidal current electrical turbine.

U-Th isotope constraints on gas hydrate and pockmark dynamics at the Niger delta margin

The application of uranium-thorium dating methods to authigenic carbonates provides unique constraints on the temporal evolution of methane seeps at ocean margins. In this study, we report U-Th isotope measurements for carbonate breccias collected from within a hydrate-bearing pockmark located at the Niger Delta margin. These concretions were extracted from a carbonate-rich layer in the upper two meters of a sediment core (N2-KS-44; ~1200m water depth), well above the present-day sulphate-methane transition zone (about 3m depth) and the presence of gas hydrates in the sediment. The stratigraphy of core N2-KS-44 was established by tuning its downcore Al/Ti profile to a well-dated nearby reference core, and carbonate 230Th/U ages were calculated using isochron methods.Our results indicate that a major event of aragonite precipitation occurred between about 13 and 2.5ka at the studied location. Comparison of sediment accumulation rates at both core N2-KS-44 and the nearby reference site suggests that the initial stage of carbonate precipitation, between 13 and 10ka, was associated with sediment winnowing, probably related to intense fluid seepage. In contrast, our data indicate that sedimentation rates rapidly increased within the pockmark after 7ka. In agreement with the presence of carbonate breccias exhibiting U-Th ages older than their corresponding stratigraphic age, this observation would suggest that sediment reworking took place after that time, possibly caused by erosion of the surrounding sediment within the pockmark.We hypothesize that the period of carbonate formation between 13 and 2.5ka was related to an upward migration of gas-hydrate reservoirs to the near seafloor environment. After this pulse of enhanced fluid flow, the diminution of methane fluxes at the base of the local gas-hydrate occurrence zone would have led to hydrate dissolution in sub-surface sediments and pockmark formation, thereby explaining the progressive increase in sedimentation rates, the absence of recent carbonate concretions and the deepening of the sulphate-methane transition zone at site N2-KS-44 inferred from pore water data. Overall, these results provide further constraints about the relationship between gas hydrate dynamics and the evolution of pockmarks at ocean margins through time.

Panen Air Hujan di Kampus Universitas Diponegoro

The design of rainwater harvesting is planned for alternative water source in Universitas Diponegoro area and hopefully it can reduce the use of groundwater as the main source water to fill the demand of water in Universitas Diponegoro Tembalang area. The use of groundwater to fill the water demand in Universitas Diponegoro Campus for years 2014/2015 of 2.23 lt/dt it more than the optimum discharge are allowable to take the water wells is equal to 0.2-1 lt/dt. Based on that the planning of the rainwater harvesting building is made of with a volume of 245 m 3 with a dimensions of 7m x 7m x 5m and dimensions of infiltration wells with a diameter of 1.5 and depth of 3m. Planning of the rain water harvesting in the Universitas Diponegoro Tembalang area the cost of Rp 275,465,000,- with the process of work for 29 days.

Mitigation of railway-induced vibration by using subgrade stiffening

Railway-induced ground vibration is often associated with sites with soft ground. Stiffening of the subgrade beneath the railway track is one particular measure that has potential to reduce the vibration level at such sites. However, the mechanisms behind this reduction are not well understood. Here, the effects are examined in the context of two alternative approaches: (i) subgrade stiffening, where the soil directly under the track is stiffened, and (ii) stiff inclusions introduced at some depth beneath the track, sometimes known as ‘wave impeding blocks’. The efficacy of the measures is considered for different ground types in a parametric study carried out using a 2.5D coupled finite-element/boundary-element methodology. The soil is considered to consist of a soft upper layer over a stiffer substratum; corresponding homogeneous grounds are also considered. With a 6m wide, 1m thick, concrete block directly under the track, the vibration between 16 and 50Hz was found to be reduced by between 4 and 10dB for ground with a 3m deep soft upper layer. For a deeper soft layer the reductions were greater whereas, for a stiffer ground without the soft upper layer, the reductions in vibration from this block were negligible. Slightly smaller reductions in a similar frequency region were observed when the block was positioned 1m below the surface, suggesting that, as with stiffening directly under the track, the reduction in vibration was primarily due to the increase of the effective stiffness of the soil beneath the track rather than the effective creation of a new, thinner soil layer. Jet grouting is considered as an alternative to concrete and, although it is found to be less effective due to its comparatively low stiffness, it may still be considered as a practical measure for existing tracks on soft soil sites. The reduction in vibration from this form of soil improvement with a depth of 3m is similar to that for a 1m thick concrete block. Finally, results are presented for three example sites with different soil properties which show similar trends.

Profile distribution of soil–water content and its temporal stability along a 1340-m long transect on the Loess Plateau, China

Information on the profile characteristics of soil–water content (SWC) and its temporal stability is essential for an accurate understanding of hydrological processes. This study investigated changes of spatial variation and temporal stability of SWC in soil profiles and estimated mean SWC based on direct and indirect methods. SWCs were measured at 20-cm intervals in the soil profiles to a depth of 3m using neutron probes at 135 locations along a 1340-m long transect on 18 sampling dates from 2012 to 2013 on the Loess Plateau in China. The coefficient of variation over space (CVS) of SWC first decreased and then increased vertically. The coefficient of variation over time (CVT) of SWC decreased along the soil profiles. The spatial patterns of SWC strongly persisted vertically and temporally. Mean Spearman's rank correlation coefficients decreased from a depth of 10 to a depth of 20cm, fluctuated from 20 to 180cm, and then increased below 200cm. Temporal stability increased along the soil profiles based on the standard deviation of mean relative difference (SDRD) and the mean absolute bias error (MABE). The number of locations with an SDRD and/or MABE <5% increased along the soil profile, and the number of locations with a mean relative difference within ±5% and/or representative locations were variably dependent on depth. Both direct and indirect methods could accurately estimate the mean SWC for each depth based on the mean absolute relative errors and root mean square errors. The driest and wettest locations tended to remain representative for more depths than did locations with mean-moistures. The driest locations were more likely to be the most temporally stable. These findings should improve our understanding of soil–water dynamics in soil profiles.

In situ study of the shrinkage-swelling of a clay soil over several cycles of drought-rewetting

This article presents results describing the in situ behavior of clay soils (Pleistocene Brach formation) regarding shrinkage and swelling; an experimental site was established. Different types of sensors were used to continuously measure the movements of the clay bed-rock and variations in the temperature and water content of the soil. These parameters were correlated with annual climatic variations as measured at an on-site meteorological station. The results obtained thus far represent five cycles of drought-rewetting, thus enabling a medium-term study of the shrinkage-swelling of a clay soil over time. A cumulative effect of shrinkage over several cycles was observed with non-negligible variations of water content to a depth of 3m. Almost 1cm of cumulative shrinkage occurred over the first three cycles of a 2-meter-thick clay layer. The last two cycles were marked by a stabilization of the swelling. By determining the accumulated soil hydric condition over time, we discovered a correlation between this parameter and the periods of shrinkage-swelling. The accumulated hydric condition, as defined in this article, is a good indicator of the behavior of soil under shrinkage and swelling.

Higher water-table levels and flooding risk under grain vs. livestock production systems in the subhumid plains of the Pampas

Although the strong influence of vegetation shaping the hydrological cycle is increasingly recognized, the effects of land-use changes in very flat regions (i.e., hyperplains, regional slope <0.1%) are less understood in spite of their potentially large magnitude. In hyperplains with sub-humid climates, long-lasting flooding episodes associated to water-table raises are a distinctive ecohydrological feature and a critical environmental concern. We evaluated the hydrological impacts caused by the replacement of livestock systems, dominated by perennial alfalfa pastures, by grain production systems, dominated by annual crops, that have been taking place in the Pampas (Argentina). For this purpose, we combined remote sensing estimates of vegetation transpiration and surface water coverage with long-term (1970–2009) hydrological modeling (HYDRUS 1D), and water-table depth and soil moisture measurements. The NDVI derived from MODIS imagery was 15% higher in dairy systems than in grain production ones, suggesting higher transpiration capacity in the former (852 vs. 724mmy−1). Even higher contrasts were found among individual cover types, with perennial pastures having the highest NDVI and transpiration potential rates (0.66 and 1075mmy−1), followed by double winter/summer crops (0.55 and 778mmy−1) and single summer crop (0.45 and 679mmy−1). Significantly deeper long-term average water-table levels in dairy system compared to single and double cropping (4m, 1.5m and 2.1m, respectively) were suggested by the hydrological modeling and confirmed by field observations at nine paired sites (pasture vs. cropland, p<0.05) and two transects. At two additional paired sites, continuous water-table depth monitoring with pressure transducers, provided insights about the mechanisms behind these contrasts, which included enhanced groundwater recharge in the cropland and direct groundwater discharge by the pasture. Soil profiles, being notably drier under pastures (316 vs. 552mm stored at 0–3m depth, p<0.05), prevented the recharge episodes experienced by agricultural plots after an extraordinary rainy period. Our study highlights the key role of land-use on the hydrology of subhumid hyperplains, supporting the linkage of groundwater level raises and flood frequency and severity increases with the expansion of grain production systems in the Pampas. Given the spatial connectivity imposed by the hydrologic system and the strong association observed between the plot water balance and regional flooding, it is highly relevant to improve the quantification of the hydrological responsibility and interdependence of land use decision across plots and farms. This further step should support territorial policies that optimize the hydrological services of the region.

Geological–geotechnical characterisation of Sarapuí II clay

The paper presents the geological–geotechnical characterisation of the very soft organic plastic slightly overconsolidated Sarapuí II clay. Dissipation tests showed no artesian pressure in the deposit. The organic content is in the range 5–18%, the higher values to 3m depth. NaCl content increases almost linearly with depth, from 7g/l at 1m depth to 24–26g/l at 6m depth. Kaolinite is predominant throughout the profile, increasing almost linearly with depth. However, smectite has almost the same percentage until 3.5m depth. The plasticity index varies in the range 60–170% and may be directly related to the clay minerals. Go values decrease with depth, from 14–28MPa to 1MPa at 3m depth, then increase with depth, reaching 5MPa at the bottom of the very soft material. Vane test results indicated two regions of su versus depth, the first from 1m to 5m depth, with su in the range 8–12kPa, the second from 6m to 8m depth, with su in the range 16–18kPa. There is a trend of linear increase in sensitivity with depth, from 4.5 at 1m depth to 7–9 at 7m depth. Salt content does not seem to play a major role in the sensitivity of Sarapuí II clay.

Calcification is not the Achilles' heel of cold-water corals in an acidifying ocean.

Ocean acidification is thought to be a major threat to coral reefs: laboratory evidence and CO2 seep research has shown adverse effects on many coral species, although a few are resilient. There are concerns that cold-water corals are even more vulnerable as they live in areas where aragonite saturation (Ωara ) is lower than in the tropics and is falling rapidly due to CO2 emissions. Here, we provide laboratory evidence that net (gross calcification minus dissolution) and gross calcification rates of three common cold-water corals, Caryophyllia smithii, Dendrophyllia cornigera, and Desmophyllum dianthus, are not affected by pCO2 levels expected for 2100 (pCO2 1058μatm, Ωara 1.29), and nor are the rates of skeletal dissolution in D.dianthus. We transplanted D.dianthus to 350m depth (pHT 8.02; pCO2 448μatm, Ωara 2.58) and to a 3m depth CO2 seep in oligotrophic waters (pHT 7.35; pCO2 2879μatm, Ωara 0.76) and found that the transplants calcified at the same rates regardless of the pCO2 confirming their resilience to acidification, but at significantly lower rates than corals that were fed in aquaria. Our combination of field and laboratory evidence suggests that ocean acidification will not disrupt cold-water coral calcification although falling aragonite levels may affect other organismal physiological and/or reef community processes.