Total Water Column Analysis Shows the Importance of a Single Species in Subsurface Chlorophyll Maximum Thin Layers in Stratified Waters

Marine phytoplankton form the base of marine food webs and are the driving force of the marine carbon cycle, so understanding the dynamics of their blooms is critical. While near-surface marine productivity (<10 m water depths) is extensively documented, that of the subsurface is less well characterised. Increasing evidence of the importance of subsurface chlorophyll maxima (SCM) and climatically driven increases in stratification of surface waters that promote SCM development call for improved sampling of the subsurface. To address this, we targeted the summer stratified waters of the Western English Channel, part of the NW European shelf seas, where SCM are commonly developed. In situ holography was applied to undertake the highest ever resolution, total water column, quantitative analysis of microplankton distribution, and demonstrated the importance of a SCM, co-located with the thermocline, dominated by a single species, the dinoflagellate Ceratium fusus. This species was dominant in the SCM over a wide area of the NW European shelf in the June/July 2015 study period and comprised up to 85% of the SCM biomass. Analysis of similarity and multivariate non-metric multidimensional scaling showed the phytoplankton community of the SCM to be statistically distinct from those of the surface and deep waters. Holography also revealed a fine scale layering of taxa at different levels within the SCM, likely reflecting ecological differences. Some taxa followed the peak abundance of C. fusus, while others reached maximum abundances immediately below or above the C. fusus maximum, suggesting the possible operation of exclusion mechanisms. Additionally, the detection of abundant aggregates located only within and beneath the SCM demonstrates the potential importance of this deep production for the export of carbon to the sea floor. Some predictions of phytoplankton productivity propose a shift to smaller cells in the more stratified oceans of the future resulting in declining production and export. Results presented here, however, contribute to a growing body of evidence that suggests, on the contrary, that key species among the larger celled/colonial, SCM-adapted diatoms and dinoflagellates may instead be selected in stratified conditions, driving increased production and export.

Application of Artificial Intelligence for Predicting Erosion of Biochar Amended Soils

Recently, incentives have been provided in developed countries by the government for commercial production of biochar for soil treatment, and other construction uses with an aim to reduce a significant amount of carbon emissions by 2030. Biochar is an important material for the development of circular economy. This study aims to develop a simple Artificial Neural Network (ANN) based model to predict erosion of biochar amended soils (BAS) under varying conditions (slope length, slope gradient, rainfall rate, degree of compaction (DoC), and percentage of biochar amendments). Accordingly, a model has been developed to estimate the total erosion rate and total water flow rate as a function of the above conditions. The model was developed based on available data from flume experiments. Based on ANN modelling results, it was observed that slope length was the most important factor in determining total erosion rate, followed by slope gradient, DoC, and percentage of biochar amendment. The percentage of biochar amendment was a leading factor in the total water flow rate determination as compared to other factors. It was also found that the reduction in erosion is relatively minimal during an increase in slope length up to 1.55 m, reducing sharply beyond that. At a slope length of 2 m, erosion is found to be reduced by 33% (i.e., 2.6 to 1.75), whereas the total flow rate decreases linearly from 1250 mL/m2/min to 790 mL/m2/min. The ANN model developed shows that soil biochar composite (SBC) with 5% biochar amendment gave the best results in reducing soil erosion. This study can be a helpful tool in providing preliminary guidelines for using biochar in erosion control.

Application of AMOGWO in Multi-Objective Optimal Allocation of Water Resources in Handan, China

The reasonable allocation of water resources using different optimization technologies has received extensive attention. However, not all optimization algorithms are suitable for solving this problem because of its complexity. In this study, we applied an ameliorative multi-objective gray wolf optimizer (AMOGWO) to the problem. For AMOGWO, which is based on the multi-objective gray wolf optimizer, we improved the distance control parameter calculation method, added crowding degree for the archive, and optimized the selection mechanism for leader wolves. Subsequently, AMOGWO was used to solve the multi-objective optimal allocation of water resources in Handan, China, for 2035, with the maximum economic benefit and minimum social water shortage used as objective functions. The optimal results obtained indicate a total water demand in Handan of 2740.43 × 106 m3, total water distribution of 2442.23 × 106 m3, and water shortage of 298.20 × 106 m3, which is consistent with the principles of water resource utilization in Handan. Furthermore, comparison results indicate that AMOGWO has substantially enhanced convergence rates and precision compared to the non-dominated sorting genetic algorithm II and the multi-objective particle swarm optimization algorithm, demonstrating relatively high reliability and applicability. This study thus provides a new method for solving the multi-objective optimal allocation of water resources.

Mechanism Study on the Impact of China Population Structure Change on the Water Use of the Three Main Industries

As the principal part of economic and social development, the demographic factor is the fundamental factor driving the change of water resources, and achieving the harmony of human and water has been one of the most important tasks to promote high-quality development. Based on Maslow’s hierarchy of needs theory, this article applied panel data for 19 years and employed impulse response functions and threshold models to do a mechanism analysis of the impact of population structure changes on the water consumption changes of the three main industries. The study found the following: Firstly, the urban population promotes an increase of the total water consumption, industrial water consumption, and domestic water consumption, which suppresses agricultural water consumption and shows an inverted “N” trend. Secondly, the aging population has expanded the total water consumption, and agricultural and domestic water demand, and reduced industrial water consumption. Thirdly, food consumption helps to reduce the total water consumption and agricultural water consumption, but increases the industrial water consumption and the growth rate rises. Fourthly, the increase in the proportion of agricultural employment reduces the total water consumption, and agricultural and domestic water consumption, and increases industrial water consumption. Fifthly, the total water consumption and domestic water consumption both increase with the improvement of the population education level, while the agricultural water consumption declines first and then rises. The empirical results can provide a reference for analyzing the driving mechanisms of regional water consumption changes.

Water-tourism nexus: impact of the water footprint of inbound tourists to China

The water footprint is a new concept used to understand the water resources uses; however, few studies have applied it to the service industry and the impact analysis are not abundant. This study explored how water footprint of tourism influenced water resources based on inbound tourists to China from 2001 to 2018. The total water footprint of inbound tourists (ITWF) was 7273.15*106 m3, and showed an upward trend. The spatial pattern was agglomerated, being mainly concentrated in North China, East China, and South China. The standard deviation ellipse showed that the horizontal axis was first east, and then west. According to the background water footprint, the ‘contribution’ of ITWF to the background water surplus differed in each province. According to the background water stress, the impact roughly separated into large, medium, and small using overlay analysis. Based on ITWF and water stress levels, the 31 administrative regions of mainland China were separated into four types and put forward suggestions: double-high pressure type, cautious development type, double-low potential type and optimised development type. This study provided a theoretical reference for governments, and is conducive to promoting the coordinated and sustainable development of tourism and water resources.

Struktur Komunitas Vegetasi Mangrove Di Pesisir Pantai Kepulauan Karimunjawa

Mangrove merupakan tumbuhan yang berada di wilayah intertidal pesisir laut. Tujuan penelitian ini yaitu menganalisis struktur vegetasi mangrove (frekuensi, kerapatan, dominan) dan karakteristik habitatnya (kualitas lingkungan) di kawasan pesisir pantai kepulauan Karimunjawa. Penelitian dilakukan pada Desember 2019 di 3 stasiun dengan metode plot bertingkat, masing-masing stasiun dibuat 3 transek yang berukuran 10m x 10m (pohon), 5m x 5m (pancang), dan 2m x 2m (semai). Hasil penelitian ditemukan 7 jenis mangrove yaitu Rhizophora stylosa, Avicennia marina, Rhizophora apiculata, Ceriops tagal, Excoecaria agallocha, Lumnitzera racemosa, dan Ceriops decandra. Indeks nilai penting tumbuhan mangrove pada strata pohon, pancang, dan semai paling tinggi adalah Rhizopora stylosa (244,77%), (163,03%), dan (157,96%). Nilai kerapatan Rhizopora stylosa tingkat pohon, tingkat pancang dan semai yaitu (2.500-10.100 ind/ha), (10.400-48.400 ind/ha), dan (97.500-280.000 ind/ha). Kondisi lingkungan di sekitar kawasan mangrove yaitu rata-rata suhu (28,75%), pasir (10,75%), lanau (51,46%/), lempung (37,79%), salinitas (26,60%), pH (7,26), DO (3,28 mg/L), N total tanah (0,24%), P total tanah (120,49 ppm), C Organik tanah (2,10%), N total air (0,28%), P total air (0,27 mg/L), C Organik air (1,56 mg/L).ABSTRACTMangroves are a plant that are found in the intertidal area of marine coastal environments. The study aim to analyze structure of mangrove vegetation (frequency, density, and dominance) and the mangrove habitat (environmental condition) in Coastal Coast Karimunjawa Island. The research was conducted in December 2019 at the three stations using the stratified plot method, and one stations divided three observation transects sized 10m x 10m (trees), 5m x 5m (saplings), and 2m x 2m (seedlings). The result of the study found seven mangroves species were Rhizophora stylosa, Avicennia marina, Rhizophora apiculata, Ceriops tagal, Excoecaria agallocha, Lumnitzera racemosa, and Ceriops decandra. The highest value index of mangroves for trees, saplings and seedlings is the highest Rhizopora stylosa (244,77%), (163,03%), and (157,96%). Density value Rhizopora stylosa in tree level, saplings, and seedlings were (2.500-10.100 ind/ha), (10.400-48.400 ind/ha), dan (97.500-280.000 ind/ha). The environmental conditions around the mangrove area are average temperature (28,75%), sand (10,75%), silt (51,46%/), clay (37,79%), salinity (26,60%), pH (7,26), Dissolved Oxygen (3,28 mg/L), N total land (0,24%), P total land (120,49 ppm), C Organic land (2,10%), N total water (0,28%), P total water (0,27 mg/L), C Organic water (1,56 mg/L).