Seawater Input Research Articles

Ages and geochemistry of garnet reveal multi-types of iron-copper mineralization in the Eastern Tianshan, NW China

The Aqishan-Yamansu Fe-Cu-Au metallogenic belt in the Eastern Tianshan, NW China, hosts numerous Fe and Fe-Cu deposits that may have different genetic models, such as volcanic-hosted and skarn/IOCG types. These variations in genetic models are attributed to whether the mineralization is associated with hydrothermal activity related to volcanic or intrusive rocks. This study primarily focuses on garnets formed during the early skarn alteration in the Shuanglong Fe-Cu and Shaquanzi Fe deposits within this belt. Garnets from the Shuanglong deposit can be divided into two types and exhibit general homogeneity, with SL-Grt1 being Fe-rich and subsequently replaced by the Fe-poor SL-Grt2. Garnets from the Shaquanzi deposit display complex zonation patterns, SQZ-Grt1 show core–oscillatory zoned rim and SQZ-Grt2 show core–mantle–oscillatory zoned rim. Laser-ablation inductively coupled plasma-mass spectrometry (LA-ICP-MS) dating of SL-Grt1 and SL-Grt2 produced lower intercept 206Pb/238U ages ranging from 318.0 ± 6.4 Ma to 303.7 ± 16.4 Ma, coinciding with the multi-stage granite occurrence. In contrast, SQZ-Grt1 and SQZ-Grt2 yielded ages between 328.0 ± 2.6 Ma and 320.4 ± 1.7 Ma, corresponding to the timing of the hosted rhyolite. SL-Grt1 show light rare earth element (LREE) enrichment, and low concentrations of high field strength elements (HFSE), such as V and Zr, and appears to have formed rapidly within an open system. Conversely, SL-Grt2 is characterized by heavy rare earth element (HREE) enrichment and elevated HFSE contents, which could be formed slowly in a closed system. The variable composition in the SQZ-Grt1 and SQZ-Grt2 record cyclical changes in fluid kinetics (vigorous fluid flow vs. fluid stagnation). The cyclical zones in SQZ-Grt2 with HREE and HFSE concentrations below the detection limit indicate multiple inputs of external seawater. The distinct characteristics between Shuanglong and Shaquanzi garnets may reflect the difference between the single magma intrusion and complex volcanic activity. Combining previously published chronological data, this study elucidates a transition from the Middle Carboniferous volcanic-hosted Fe deposits (335–320 Ma) to the Late Carboniferous intrusion-related skarn or IOCG type Fe-Cu deposits (310–300 Ma) in the Aqishan-Yamansu belt.

Eco-friendly atmospheric water generation: A novel desiccant-based variable pressure humidification-dehumidification system

This study introduces a zero-brine discharge approach, eliminating the necessity for continuous seawater input and brine disposal—major drawbacks in traditional desalination methods. This research’s core is a humidification-dehumidification (HDH) system operating under variable pressures, significantly boosting efficiency. The system comprises two synergistic components: a variable-pressure HDH unit and a desiccant-based moisture extractor utilizing a lithium chloride solution. After freshwater is extracted, the concentrated desiccant cycles through the moisture extractor to absorb atmospheric water vapor, diluting it for reuse and thus completing the desiccant loop. The heat and mass transfer processes were scrutinized through mathematical modeling, and parameters for maximizing the Gain Output Ratio (GOR) were optimized. The results underscore the system’s capacity for sustainable, efficient freshwater production. This methodology offers a feasible solution to challenges in desalination and significantly contributes to alleviating global water scarcity, particularly in coastal areas. Further analysis shows that systematic optimization of key parameters, such as pressure ratios and desiccant temperatures, considerably improves performance metrics. Adjusting the pressure ratio from 1.22, where the GOR peaks at 2.44, to 1.56 directly impacts system efficiency. Modulating the maximum desiccant temperature at an optimal pressure ratio of 1.25 reveals that the GOR can increase from 1.635 at 0.7 to 2.44 at an effectiveness of 0.8. Optimized manipulation of these parameters can potentially enhance the GOR by up to 50% and improve mass transfer efficiency by about 20% within the HDH process.

Geochemistry and sources of boron and strontium of geothermal waters from the Pearl River Delta region, South China: Implications for water-rock interactions

Pearl River Delta (PRD) region of South China is abundant of geothermal water resources. However, the development and utilization level of geothermal resources in this region is relatively low, due in part to the lack of fundamental geochemical research. To access water-rock interaction processes of the PRD geothermal system, we analyzed the geochemistry of geothermal waters by combining trace elements (B, Sr, and Br) and isotopes (δ11B and 87Sr/86Sr) with conventional tracers (major elements) that had been reported. The Cl/Br ratios (from 31 to 639) confirm the multi-source salinity of marine origin, precipitation, and a minor dissolution of halite. Major ions chemistry highlights the influence of ions exchange, the dissolution of carbonate, silicate, and sulphate minerals as well as the contribution of seawater. The Cl/B ratios (61 to 22,583) suggest interactions with carbonate rock and felsic rock, input of seawater, and groundwater mixing. Boron isotopic compositions (δ11B) range between −9.22 and +39.78 ‰. Sr contents and 87Sr/86Sr ratios are more homogeneous, falling between 0.06 and 32.26 mg/L and between 0.71239 and 0.72121, respectively. The B and Sr isotopic signatures show that three processes contribute to geochemistry of geothermal waters: 1) water/rock interaction involving marine carbonate rock, evaporite, and granitoid or/and gneiss, 2) seawater intrusion, and 3) shallow groundwater mixing. Major-trace element chemistry and these isotope systematics on their own indicates essential information on the aspects of fluid origin or water-rock interaction processes, and however provide a more comprehensive understanding of the geothermal system in the PRD region, South China.

Hydrogeochemical conditions of submarine and terrestrial karst sulfur springs in the Northern Adriatic

Submarine springs near Izola, in the Northern Adriatic Sea, appear in funnel-shaped depressions and smell strongly of sulfur. Along the Mediterranean coast there are many submarine karst springs containing brackish or fresh water, but submarine sulfur springs are not particularly common. Three submarine sulfur springs and one terrestrial sulfur spring were investigated to better understand the water properties, water–rock interaction within the aquifer, and to explore the origin of the spring water. Groundwater and seawater samples were also collected for comparison. Based on the geological setting, physicochemical parameters, hydrogeochemical data, and stable isotope data (δ18O, δ2H, δ13CDIC, δ34SSO4, δ18OSO4), we can affirm that (1) the large concentration of seawater in the submarine springs samples is due to sampling challenges; (2) springs recharge from precipitation where confined karst aquifers outcrop; (3) deep water circulation is indicated; (4) redox conditions can provide a suitable environment for bacterial reduction of the marine or organic sulfate to the odorous H2S; (5) geological data suggests that the coals beneath the alveolinic-nummulitic limestones are the source of sulfur. A multi-parameter and interdisciplinary approach has proven important in assessing submarine sulfur springs affected by seawater input.

Estuaries House Earth’s oldest known non-marine eukaryotes

Some of the oldest postulated non-marine eukaryotic microfossils occur in the 1.1–1.0 Ga Poll a’Mhuillt, Loch na Dal, and Diabaig formations in NW Scotland. These sedimentary strata have traditionally been interpreted as lacustrine. Here we report new trace element, sulfur isotope and metal abundance data and sedimentological observations for the latter two units. The geochemical data imply low salinity, oxic conditions whereas sedimentological features indicate marine tide and storm processes. Interpreting their depositional settings as estuaries, rather than lakes, with seawater-freshwater mixing fronts reconciles the contrasting datasets. Thus, whist these microbial habitats likely experienced frequent seawater input, they appear to have experienced the lowest salinity conditions of all known in situ fossil assemblages in the Precambrian. The Torridonian may in fact be representative of the low-salinity habitats predicted for ancestral eukaryotes based on phylogenetic reconstructions. Estuarine settings with gradients in water chemistry over space and time may have facilitated the transition of eukaryotic life from land to sea.

Coastal lakes of Southern Far East: climatic impact and natural hazards records

The study of sediments of coastal lakes and palaeo-lakes in the southern Far East allowed us to identify several short-term paleoclimatic events in the transition “continent-ocean” zone. In the southern Kurils, palaeo-lakes that existed since the Late Glacial were found. Most of the lagoonal lakes were formed when sea level stabilized or declined slightly during the Holocene transgression. The most detailed data on hydroclimatic changes were obtained for the Middle-Late Holocene. The intensity of the summer monsoon and cyclogenesis activity associated with ocean and atmospheric anomalies in the Asia-Pacific region played a major role in the lake evolution. Sea water input to reservoirs occurred during extreme storms and tsunamis.

Water Quality Analysis for Vannamei Shrimp Culture in Coastal of Banyuwangi Regency

The coastal of Banyuwangi Regency is the longest coast and has a high potential for vannamei shrimp culture with the largest production in East Java Province, Indonesia. The sustainability of vannamei shrimp culture depends on seawater input, where water quality is the main thing that must always be considered. The purpose of this study was to analyze water quality for the benefit of vannamei shrimp culture. The method used is descriptive. While data collection using surveys and direct observations, with water quality parameters taken there are 14 types, namely temperature, salinity, pH, DO, alkalinity, ammonia, nitrate, nitrite, phosphate, TOM, TSS, vibrio, redox and plankton. Data analysis used factor analysis based on the Principal Component Analysis (PCA). The results from the calculation of PCA analysis, it can be seen that there are 5 components that are able to describe the overall water quality on the coast of Banyuwangi Regency for the benefit of vannamei shrimp cultivation with a total variance of 80,522%. Component 1 filled with parameters Salinity, Nitrite, Nitrate and Vibrio. Component 2 are pH, TOM and Redox. Component 3 are DO, TOM, TSS and Plankton. Component 4 are Alkalinity, Ammonia, Nitrite and Phosphate. Component 5 are Temperature, Salinity and Plankton.

Assessment of gill microbiome of two strains of Atlantic salmon reared in flowthrough and recirculation hatcheries and following seawater transfer

The gill mucosal microbiome of Atlantic salmon has a significant impact on mucosal health and physiology under homeostatic conditions, but the microbial community may itself be influenced by host genetics, the culture system and seawater transfer. In this study, the impact of two commercial strains of Atlantic salmon, reared in two parallel hatchery systems (flow-through -FT and recirculation -RAS) on the gill microbiome was investigated. Samples of gill mucosal microbiome, tank biofilm and water were collected from the fish cohorts at the hatcheries and following seawater transfer. Though the gill microbiome of fish from the two commercially equivalent FT and RAS hatcheries had similar beta and alpha diversity, the alpha diversity indicators of bacterial communities of gills significantly increased after seawater input. Ultimately, no effect of the genetic strain on the gill microbiome was detected. Our results showed that under commercially equivalent FT or RAS hatchery systems with a common water source, two strains of Atlantic salmon had comparable gill microbiomes.

Sources and melt flux of methylmercury in sea ice on the Chukchi Plateau, Arctic Ocean

To identify the major source and melt flux of Hg in sea ice, we measured total Hg (THg) and methylmercury (MeHg) concentrations from sea ice cores collected from the Chukchi Plateau, Arctic Ocean. The THg maxima were found in the surface section (0–40 cm) of the cold cores (−2.3 ± 0.19 °C) and middle section (30–75 cm) of the warm cores (−1.9 ± 0.38 °C), whereas MeHg concentrations were nearly constant by core depth in the cold and warm cores. Using the enrichment factor mixing model, we estimated seawater to be the dominant source of THg over atmospheric deposition, both in the cold (89.1–99.6 %) and warm cores (98.4–99.7 %). The preliminary input estimation for MeHg showed that in situ methylation, instead of seawater input, was the potential source of MeHg in sea ice. The sea ice melt flux of MeHg in the Arctic Ocean was estimated to be 231 ± 77 kg yr−1 in the period of 2010–2020, which is insignificant compared with other external sources, such as atmospheric deposition, river discharge, and coastal erosion. Based on the results of the present study, the ongoing decline of sea ice extent related to polar amplification is likely to enhance MeHg production in sea ice in late spring and summer as a result of the improved light availability and consequent promotion of algal and microbial activities.

Occurrence of ammonium in the acidic-circumneutral coastal groundwater of Beihai, Southern China: δ15N, δ13C, and hydrochemical constraints

High levels of ammonium (NH4+) in groundwater can threaten the health of surface ecosystems and the safety of water supplies. To ascertain the occurrence of NH4+ in the coastal acidic groundwater of Beihai, Southern China, a combined hydrochemical and isotopic (δ15N in nitrate (NO3−) and NH4+; δ13C in dissolved inorganic carbon (DIC)) study was performed. In addition to a chloride concentration-based fresh water-seawater mixing model, δ15NNO3 vs δ15NNH4, Δδ13CDIC,react (changes in δ13CDIC values caused by reaction), and ΔCSO4,react (changes in sulfate concentrations caused by reaction) were applied to interpret the genesis of NH4+. The results show groundwater NH4+ loadings range from < 0.04 to 6.2 mg/L, with typically higher loadings along the coastline than in the plains. Elevated NH4+ loadings (>0.2 mg/L) are commonly accompanied by enriched δ15NNO3 and depleted δ15NNH4 values in relation to the anthropogenic endmember, depleted or enriched Δδ13CDIC,react values, and ΔCSO4,react > 0.00 or < 0.00 mmol/L. Such isotopic fingerprints and hydrochemical features indicate dissimilatory nitrate reduction to ammonium (DNRA), glucose fermentation, methanogenesis (acetate fermentation), and sulfide oxidation or sulfate reduction. The findings suggest acidic rainwater, sulfide oxidation, and NO3− reduction by ferrous iron (Fe2+) could jointly account for the formation of acidic groundwater (pH as low as 4.0) that is of meteoric origin. Fermentative and sulfide-driven DNRA with anthropogenic NO3− is notably responsible for the enrichment of groundwater NH4+ concentrations, with a minor contribution from anthropogenic NH4+ infiltration and algae decomposition. As a result of silicate and carbonate weathering, seawater inputs, and fermentation, the addition of bicarbonate (HCO3−) results in circumneutral pH values. These results indicate DNRA plays a critical role in the enrichment of NH4+ and, hence, improve understanding of its genesis in the groundwater of Beihai and other similar areas.

16s rRNA diversity of Mirror Lake in Gilindire Cave (Turkey) shows abundant Nitrospira

We present the prokaryotic microbial diversity of Mirror Lake, located at the end of Gilindire Cave (Turkey), whose geomorphology shows development in multiple geologic periods and by multiple mechanisms. The lake comprises brackish water with both fresh and seawater inputs. In total, 5 liters of water was sampled from Mirror Lake and was filtered through a 0.22 µm membrane, and after the DNA isolation, 16S amplicon sequencing was conducted to get whole prokaryotic diversity. The bacterial community of this system is predominately composed of nitrite-oxidizing Nitrospira with a relative abundance of 28 %. We hypothesize that Nitrospira recovered in our samples mediates nitrification by reciprocal feeding with ammonia-oxidizing archaea (Nitrososphaeria). We found Nitrospira had a close association with Planctomycetes CL500-3 clade and Marinimicrobia (SAR406) in the cave habitat, with a relative abundance of 8.3 % and 5.7 %, respectively. To our knowledge, this is the first time that the presence of marine clade SAR324 has been reported from brackish cave waters.

Occurrence mode of Holocene tsunami overwash controlled by the geomorphic development along the eastern Nankai Trough, central Japan

Re-analysis of the lithological, paleontological, and geochemical data of three lagoonal sediment cores reveal the tsunami overwash history from 8000 to 6500 cal BP along the northern Suruga Bay coast, facing the eastern Nankai Trough. The coring sites are located in a transcect 0.8, 1.5, and 1.7 km inland, respectively, from the coastline at the time the overwash events occurred. The washover sand beds are distinguished from the lagoonal muds by the presence of quartz and mica, which are abundant on the outer (marine) side of the lagoon, as well as marine shell fossils. The increased C/S ratio often associated with sand beds, reflects input of open seawater to the reductive lagoon, and supports this interpretation. A maximum of eight tsunami deposits were identified between ∼7800 and 6500 cal BP, many of which can be correlated between the three cores. The magnitude of tsunami overwash implied by the thickness and grain size of tsunami deposits, and increase of C/S ratio following their deposition is relatively large at ∼7500-7200 cal BP during the post-glacial sea level rise and decreases with time during the subsequent high sea level stand. This occurrence mode (timing and scale of formation) of tsunami washover is explained by temporal changes in coastal geomorphology, rather than differences in the magnitude of individual tsunamis. Around 7500-7200 cal BP, sea level rise equilibrated with or exceeded the growth of the bay mouth barrier, and tsunamis could easily cross the small barrier and enter the lagoon, leaving behind thick and coarse-grained deposits. As the barrier becomes larger during the subsequent sea-level highstand, only the highest-amplitude waves exceeded the height of the barrier. By ∼6500 years ago, the barrier was high enough to prevent tsunamis from entering the lagoon. Similarly, the occurrence mode of tsunami deposits reported along the coast of Suruga Bay and Enshu-nada over the past 6000 years can be explained in relation to the growth of coastal barriers.

Effects of brackish water inflow on methane-cycling microbial communities in a freshwater rewetted coastal fen

Abstract. Rewetted peatlands can be a significant source of methane (CH4), but in coastal ecosystems, input of sulfate-rich seawater could potentially mitigate these emissions. The presence of sulfate as an electron acceptor during organic matter decomposition is known to suppress methanogenesis by favoring the growth of sulfate reducers, which outcompete methanogens for substrate. We investigated the effects of a brackish water inflow on the microbial communities relative to CH4 production–consumption dynamics in a freshwater rewetted fen at the southern Baltic Sea coast after a storm surge in January 2019 and analyzed our data in context with the previous freshwater rewetted state (2014 serves as our baseline) and the conditions after a severe drought in 2018 (Fig. 1). We took peat cores at four previously sampled locations along a brackishness gradient to compare soil and pore water geochemistry as well as the microbial methane- and sulfate-cycling communities with the previous conditions. We used high-throughput sequencing and quantitative polymerase chain reaction (qPCR) to characterize pools of DNA and RNA targeting total and putatively active bacteria and archaea. Furthermore, we measured CH4 fluxes along the gradient and determined the concentrations and isotopic signatures of trace gases in the peat. We found that both the inflow effect of brackish water and the preceding drought increased the sulfate availability in the surface and pore water. Nevertheless, peat soil CH4 concentrations and the 13C compositions of CH4 and total dissolved inorganic carbon (DIC) indicated ongoing methanogenesis and little methane oxidation. Accordingly, we did not observe a decrease in absolute methanogenic archaea abundance or a substantial change in methanogenic community composition following the inflow but found that the methanogenic community had mainly changed during the preceding drought. In contrast, absolute abundances of aerobic methanotrophic bacteria decreased back to their pre-drought level after the inflow, while they had increased during the drought year. In line with the higher sulfate concentrations, the absolute abundances of sulfate-reducing bacteria (SRB) increased – as expected – by almost 3 orders of magnitude compared to the freshwater state and also exceeded abundances recorded during the drought by over 2 orders of magnitude. Against our expectations, methanotrophic archaea (ANME), capable of sulfate-mediated anaerobic methane oxidation, did not increase in abundance after the brackish water inflow. Altogether, we could find no microbial evidence for hampered methane production or increased methane consumption in the peat soil after the brackish water inflow. Because Koebsch et al. (2020) reported a new minimum in CH4 fluxes at this site since rewetting of the site in 2009, methane oxidation may, however, take place in the water column above the peat soil or in the loose organic litter on the ground. This highlights the importance of considering all compartments across the peat–water–atmosphere continuum to develop an in-depth understanding of inflow events in rewetted peatlands. We propose that the changes in microbial communities and greenhouse gas (GHG) fluxes relative to the previous freshwater rewetting state cannot be explained with the brackish water inflow alone but were potentially reinforced by a biogeochemical legacy effect of the preceding drought.

Sulfur Isotope and Trace Element Systematics in Arc Magmas: Seeing through the Degassing via a Melt Inclusion Study of Kyushu Island Volcanoes, Japan

Abstract Sulfur is a minor element in magmas but one of the major volatile elements released in volcanic systems, from the magma to the fluid phase upon ascent. Not only are sulfur gasses potentially toxic for humans and plants, they are also involved in causing drastic climate changes after major volcanic eruptions. Therefore, studies are carried out by the geoscience community to assess the magmatic sulfur flux by looking at the sulfur content and isotopes in erupted products, with the ultimate aim of improving understanding of the sulfur cycle in subduction zones. Kyushu Island in Japan hosts 25 volcanoes, among which 11 are active and represent a natural hazard for the local population. It is perhaps the most suitable site for the study of the sulfur cycle for its availability of recent volcanic deposits and its many highly monitored volcanoes. We investigated sulfur and sulfur isotope compositions of the magma source of Kyushu Island arc using olivine-hosted melt inclusions in mafic tephras and lavas, from eight volcanoes (nine Holocene samples) going from Northern Kyushu with Oninomi, Yufu, Kuju, and Aso, to Southern Kyushu volcanoes such as Kirishima-Ohachidake, Kirishima-Shinmoedake, Sumiyoshi-ike, and Kaimondake, and one back arc volcano, Fukue-Onidake. We measured major, trace and volatile elements and S isotopes (δ34S) in melt inclusions. Magma composition recorded in the inclusions ranges from basalt to andesite (SiO2 ranging from 40.3 to 60.7 wt%). For each edifice, we identified the least degassed and least differentiated compositions based on volatile and trace element systematics and selected the melt inclusions closest to their primitive melts. Comparing these primitive magmas, Sr/Y underlines a compositional dichotomy between volcanoes from northern (Sr/Y &amp;gt; 20) and southern Kyushu (Sr/Y &amp;lt; 20), separated by a non-volcanic area corresponding to the subduction of the Kyushu-Palau ridge. The δ34S in melt inclusions range from −0.32 ± 0.79‰ to +9.43 ± 0.47‰ (2σ) and trace the source of the magma from the different volcanoes, rather than degassing or crustal fractionation processes. δ34S is not fractionated by the nature of the fluid (aqueous or melt) metasomatizing the mantle wedge, therefore it is not the first-order factor controlling the sulfur isotope variations. Instead, this study illustrates the need for a heavy δ34S component, likely sulfate from seawater, contained in the agent that metasomatized the mantle beneath the arc. If such an observation is confirmed in other subduction zones, sulfur isotopes in melt inclusions may be an effective way to trace seawater input into the mantle beneath

Sequence Stratigraphy Variation and Its Implication in Shale Oil Exploration: A Case Study of the Eocene Dongying Depression, Eastern China

Organic matter (OM) and carbonate are the important organic and inorganic components, respectively, in the shales of the upper fourth member of the Eocene Shahejie Formation, Dongying Depression, Eastern China. Their enrichment affects the hydrocarbon generation capacity and reservoir development of shales. The development mechanism of sequence stratigraphy and the influence of sequence stratigraphy on OM enrichment and carbonate deposition are investigated in this study. Based on the petrological, mineralogical, and geochemical analyses, a third-order sequence is recognized, including the lowstand systems tract (LST), transgressive systems tract (TST), and highstand systems tract (HST). The total organic carbon (TOC) content is 0.11–9.05 wt% (average 2.2 wt%), and the carbonate content is 3–95 wt% (average 51 wt%). Organic matter and carbonate are enriched in TST and gradually reduced in HST and LST. The decrease in the relative lake level in LST results in the deposition of abundant siltstone, leading to both poor OM preservation and carbonate precipitation. The rapid rise in the relative lake level in TST may be triggered by marine transgression, promoting OM enrichment in terms of both production and preservation. Seawater input brought abundant Ca2+ and Mg2+, which facilitated the precipitation of carbonates. The enrichment of OM and carbonate improves the capacity of hydrocarbon generation and reservoir performance of shales in the TST. The decrease in the relative lake level in HST causes a slight increase in the terrigenous clastic content, which, on the one hand, accelerates the sedimentation rate and OM deposition and, on the other hand, reduces carbonate precipitation. This study not only explains the differential distribution of OM and carbonate but also helps to improve the accuracy of the evaluation of shale oil sweet spots.

Inputs of disinfection by-products to the marine environment from various industrial activities: Comparison to natural production

Oxidative treatment of seawater in coastal and shipboard installations is applied to control biofouling and/or minimize the input of noxious or invasive species into the marine environment. This treatment allows a safe and efficient operation of industrial installations and helps to protect human health from infectious diseases and to maintain the biodiversity in the marine environment. On the downside, the application of chemical oxidants generates undesired organic compounds, so-called disinfection by-products (DBPs), which are discharged into the marine environment. This article provides an overview on sources and quantities of DBP inputs, which could serve as basis for hazard analysis for the marine environment, human health and the atmosphere. During oxidation of marine water, mainly brominated DBPs are generated with bromoform (CHBr3) being the major DBP. CHBr3 has been used as an indicator to compare inputs from different sources. Total global annual volumes of treated seawater inputs resulting from cooling processes of coastal power stations, from desalination plants and from ballast water treatment in ships are estimated to be 470–800 × 109 m3, 46 × 109 m3 and 3.5 × 109 m3, respectively. Overall, the total estimated anthropogenic bromoform production and discharge adds up to 13.5–21.8 × 106 kg/a (kg per year) with contributions of 11.8–20.1 × 106 kg/a from cooling water treatment, 0.89 × 106 kg/a from desalination and 0.86 × 106 kg/a from ballast water treatment. This equals approximately 2–6% of the natural bromoform emissions from marine water, which is estimated to be 385–870 × 106 kg/a.

Integrated Assessment of Marine-Continental Transitional Facies Shale Gas of the Carboniferous Benxi Formation in the Eastern Ordos Basin

In the Benxi Formation of the Carboniferous system of the Upper Paleozoic in the Ordos Basin, there are many sets of coal measures dark organic-rich shale, being marine continental transitional facies, with significant unconventional natural gas potential. Previous studies are only limited to the evaluation of tight sandstone reservoir in this set of strata, with no sufficient study on gas bearing and geological characteristics of organic-rich shale, restricting the exploration and evaluation of shale gas resources. In this study, analysis has been conducted on the organic carbon content, the major elements, the trace elements, and the mineral composition of core samples from the Benxi Formation in key drilling sections. In addition, qualitative and quantitative pore observation and characterization of core samples have been conducted. The sedimentary environments and reservoir characteristics of the shale of the Benxi Formation have been analyzed. Combined with the gas content analyzing the results of the field coring samples, the shale gas resource potentials of the Benxi Formation have been studied, and the geological characteristics of the Benxi Formation shale gas in the eastern Ordos Basin have been made clear, to provide a theoretical basis for shale gas resource evaluation of the Benxi Formation in the Ordos Basin. The results show that (1) in the Hutian Member, Pangou Member, and Jinci Member of the Benxi Formation, organic-rich shale is well developed, with the characteristics of seawater input as a whole. There is a slight difference in sedimentary redox index, which shows that the reducibility increases gradually from bottom to top. (2) There is an evident difference in the mineral characteristics of shale in these three members. The Hutian Member is rich in clay minerals, while the Jinci Member is high in quartz minerals. (3) The pores are mainly inorganic mineral intergranular pores, clay interlayer fractures, and micro fractures, and organic matter pores are developed on the surface of local organic matter. (4) The mud shale in the Jinci Member has a large cumulative thickness, has relatively high gas-bearing property, and is rich in brittle minerals. The Jinci Member is a favorable section for shale gas exploration of the Benxi Formation.

Spatiotemporal Variability in Environmental Conditions Influences the Performance and Behavior of Juvenile Steelhead in a Coastal California Lagoon

In California (USA), seasonal lagoons provide important oversummer rearing habitat for juvenile steelhead trout (anadromous Oncorhynchus mykiss). However, key water quality parameters such as temperature and dissolved oxygen concentration can periodically approach or exceed the physiological tolerances of steelhead during the protracted dry season. A field study employing distributed temperature sensing technology, water quality monitoring, habitat mapping, and mark-recapture sampling was conducted to examine how shifting environmental conditions affected the performance and behavior of juvenile steelhead in the Scott Creek estuary/lagoon (Santa Cruz County). Abiotic conditions were driven by episodic inputs of seawater to the typically freshwater lagoon. During midsummer, the water column was vertically stratified which reduced suitable lagoon rearing habitat by approximately 40%. Nevertheless, steelhead abundance, growth, and condition factor were high during the summer and decreased in autumn following lagoon destratification and cooling. Unlike previous work, this study identified limited emigration from the lagoon to riverine habitat during the summer. Instead, juvenile steelhead exhibited crepuscular movement patterns within the lagoon, with peaks in upstream (to upper lagoon habitat) and downstream (to lower lagoon habitat) movement occurring at dawn and dusk, respectively. This study underscores that habitat complexity and connectivity are critical for juvenile steelhead production and persistence and provides insight into steelhead habitat use and behavior in seasonal lagoons.

Geochemical Characteristics and Driving Factors of NO3-Type Groundwater in the Rapidly Urbanizing Pearl River Delta

In response to rapid economic development, nitrate pollution of groundwater is becoming a serious issue in many parts of China. Urbanization and industrialization are the main drivers of NO3-type groundwater expansion. Focusing on the Pearl River Delta, the occurrence and driving factors of shallow nitrate groundwater are discussed. Overall, groundwater nitrate concentrations are generally high in this region. Of 1538 groundwater samples, 5.7% had nitrate concentrations higher than the groundwater quality standard(88.6 mg·L-1) and 18.5% were classified as NO3-type waters, which are mainly distributed in the hilly and piedmont areas. Guangzhou, Dongguan, Foshan, Zhuhai and other areas show high total dissolved solid(TDS)-concentration NO3-type waters, which are affected by urbanization and industrialization. In comparison, low-TDS NO3-type waters are distributed in the hilly and valley areas. In the Xijiang and Dongjiang plains, the TDS concentrations on groundwater increased significantly due to inputs of industrial wastewater and saline seawater. The NO3- concentration in the groundwater in this area exceeded the class III water standard but did not change the hydrochemical type classification. However, industrialization has led to the frequent appearance of SO4-type water in this area. The NO3-type water occurs in acidic or weakly acidic environments, typically characterized by low TDS and total hardness concentrations, and high Cl-, SO42-, and K+ concentrations. The formation of NO3-type water is mainly affected by domestic sewage, industrial wastewater, agricultural nitrogen fertilizer, septic tank outflows, and landfill leachate leakage. Generally, the pollution loads of high-TDS NO3-type waters are higher than low-TDS NO3-type waters. The delineation of NO3-type waters, especially the low-TDS type, is helpful for identifying groundwaters posing greater risks for human activities, and those with low nitrate concentrations but potential pollution risk, which is of great significance in the prevention and control of groundwater pollution.

Fluid inclusions, isotopes, and geochronology data constraints on the mineralization of the Carboniferous volcanogenic massive sulfide Xiaorequanzi Cu–Zn deposit in the East Tianshan, NW China

The Xiaorequanzi Cu–Zn deposit is the first and only volcanogenic massive sulfide (VMS) Cu–Zn deposit discovered in the Carboniferous volcanic-sedimentary rock series of the East Tianshan, Xinjiang. The mineralization includes stratiform, stringer/stockwork, volcanic hydrothermal-related veinlet, and subvolcanic-related vein/veinlet. The exhalative sedimentary period contributed to the majority of the Cu–Zn resource and can be subdivided into three stages: (I) stratiform (Ia) and stringer/stockwork (Ib) mineralization is represented by layered, lenticular, tabular, vein, and irregular Cu–Zn–(Au) orebodies, (II) volcanic hydrothermal-related vein mineralization is defined by pyrite–quartz ± carbonate veinlets, and (III) subvolcanic-related vein/veinlet mineralization is associated with albitophyre and dacite porphyry.Fluid inclusions study reveals that the mineralizing fluids in stage I are characterized by moderate–low temperature (peak at 160–240 °C) and low salinity (peak at 5.0–10.0 wt% NaCl eqv.). The composition of He–Ar and H–O isotopes indicate that stage I mineralizing fluids were derived from deep-circulation seawater mixed with magmatic fluids accompanied by fluid mixing. Sulfides from stage I record a range of δ34S values between 3.7 and 7.8‰, suggesting that the mineralizing sulfur was derived from seawater sulfate and volcanic rocks by thermochemical sulfate reduction. The mineralizing fluids in stage II display low temperatures (peak at 140–180 °C) and low salinities (peak at 5.0–7.0 wt% NaCl eqv.), which could indicate continuous cooling of magmatic fluids and input of seawater accelerated the precipitation of pyrite in this stage. The mineralizing fluids in stage III are characteristic of bimodal distribution temperatures (peak at 160–220 °C and 240–280 °C) and salinity (peak at 6.0–8.0 wt% NaCl eqv. and 9.0–12.0 wt% NaCl eqv.). The composition of H–O isotopes indicate that stage III mineralizing fluids were derived from magmatic fluid mixed with seawater accompanied by fluid boiling. The δ34S values range from 1.5 to 4.0‰, implying a magmatic sulfur origin.Zircon U–Pb dating of mineralization-hosting tuff and dacite porphyry yielded ages of 354.5 ± 3.9 Ma and 341.9 ± 3.1 Ma, respectively. Combining the previous Re–Os and U–Pb ages of the deposit, we conclude that the Xiaorequanzi Cu–Zn deposit is spatially and genetically associated with the volcanic exhalative sedimentation at 352–357 Ma and subvolcanic intrusion at 342–345 Ma, respectively.