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The review shows the relevance and advantages of application of controlled-release fertilizers and describes their production methods and practical implementations. A classification method developed by the authors is proposed, and the main properties and quality control indicators for such fertilizer products are determined.

A detailed description of alkali water springs (pH > 10) found within the ultrabasic massif of Mount Soldatskaya in the Kamchatsky Mys Peninsula in Kamchatka is presented for the first time. The chemical composition of the springs and the dependence of the ratios and concentrations of some components on pH are indicative of the fact that these waters were involved in the present-day serpentinization of ultrabasic rocks. The springs with the highest alkali levels (pH 12.3) contain dissolved hydrogen at a concentration of about 0.6 mmol/l. The isotopic composition behavior of carbonate travertines deposited from these springs (δ 13 C and δ 18 O) differs from the known trend of “meteogenic” travertines related to serpentinization of ultrabasic rocks in Oman and California. The age of travertines determined by the radiocarbon method is close to modern.

Lake Kipyashchee ~4.6 ha in area whose greatest depth is 25 m fills an explosion crater near an extrusive dome in the Golovnin caldera. The lake water is ultra acid (рН 2.2–2.5), is of the chloride–sulfate type with a salinity of 2.0–2.2 g/L. The water temperature varies between 30 and 100°С at the surface, with the mean value being 37°С. The lake emptied itself via Protoka into Lake Goryachee at a rate of 120 L/s in August 2021. The hydrothermal drainage of magmatic Cl and S (in the form SO 4 ) from Lake Kipyashchee is 10 and 5.4 t/day, respectively. The first ever estimate of the total diffusion output of carbon dioxide from the surface of Lake Kipyashchee is over 5.4 t/day. The geochemical data acquired during the 2020–2021 field surveys indicate an increase (compared with 2015) in the hydrothermal activity in the Golovnin caldera.

This paper reports a detailed geochemical study of thermal occurrences as observed in the edifice and on the flanks of Mendeleev Volcano, Kunashir Island in August and September 2015. We showed that three main types of thermal water are discharged there (neutral chloride sodium, acid chloride sulfate, and acid sulfate types); these waters exhibit a zonality that is typical of volcano-hydrothermal island arc systems. Spontaneous and solfataric gases have relatively low 3 He/ 4 He ratios, ranging between 5.4Ra and 5.6Ra, and δ 13 C-CO 2 between –4.8‰ and –3.1‰, and contain a light isotope of carbon in methane (δ 13 C ≈ –40‰). Gas and isotope geothermometers yield relatively low temperatures around 200°C. The isotope compositions in all types of water are similar to that of local meteoric water. The distribution of microcomponents varies among different types. The isotope composition of dissolved Sr varies considerably, from 0.7034 as observed in Kunashir rocks on an average to 0.7052 in coastal springs, which may have resulted from admixtures of seawater. The total hydrothermal transport rates of magmatic Cl and SO 4 , as observed for Mendeleev Volcano, are 7.8 t/d and 11.6 t/d, respectively. The natural outward transport of heat by the volcano’s hydrothermal system is estimated as 21 MW.

The data obtained during the fieldworks in July 2016 were used for the geochemical description of thermal manifestations of Ketoi and Pallas Peak volcanoes on Ketoi Island in the middle of the Kuril Island arc. It is shown that the older edifice of Ketoi Volcano hosts a high temperature hydrothermal system whose surface manifestations are concentrated in the eroded crater of the volcano. Two main types of thermal water are discharged there: the acid and low-acid waters of the Ca–SO4 composition in thermal pools that are diluted to varying degrees with meteoric water, and boron-rich neutral boiling water of the Na–Ca–SO4 composition. The isotopic composition of both water types is similar to that of the local meteoric waters. Calculation of mineral saturation indices for hydrothermal minerals, as well as the behavior of boron, suggest that the waters of the first type are formed nearer the surface, while the boiling sulfate waters are most likely derived from steam condensates formed at depth at a temperature of approximately 200°С. The thermal springs related to Pallas Peak Volcano discharge acid sulfate chloride water. The total measured hydrothermal output of Cl and SO4 from Ketoi and Pallas Peak volcanoes is 8.5 t/day and 30 t/day, respectively.

The high-temperature (865°C according to data of an IR-camera) gases and the crater lake water of Gorelyi volcano were sampled in September 2011. The gas and condensate were collected from the active crater in bocca, which was formed in June 2010. The chemical composition and the δ 18 O and δD values of the condensate and lake water were analyzed. In comparison with the isotopic data on volcanic condensates of the adjacent Mutnovskii volcano, the data points of samples from Gorelyi volcano fall to the mixing line of meteoric and magmatic water. The isotopic characteristics of the water component of the fluid mostly correspond to the high-temperature equilibrium with silicate rocks or melts; the portion of local meteoric water is ~25%. The high metal content of gases of the volcano is determined. The total removal of Cu, Zn, Pb, Mo, Cd, In, Sn, Tl, and Bi by gases of Gorelyi volcano (~30 t/year) comparable to that of the Kudryavyi volcano (20–80 t/year) indicates the high ore-bearing capacity of the volcanic gas fluids.

An Erratum to this paper has been published: https://doi.org/10.1134/S1028334X23070097

An Erratum to this paper has been published:

A detailed description of alkali water springs (pH > 10) found within the ultrabasic massif of Mount Soldatskaya in the Kamchatsky Mys Peninsula in Kamchatka is presented for the first time. The chemical composition of the springs and the dependence of the ratios and concentrations of some components on pH are indicative of the fact that these waters were involved in the present-day serpentinization of ultrabasic rocks. The springs with the highest alkali levels (pH 12.3) contain dissolved hydrogen at a concentration of about 0.6 mmol/l. The isotopic composition behavior of carbonate travertines deposited from these springs ([delta].sup.13C and [delta].sup.18O) differs from the known trend of \"meteogenic\" travertines related to serpentinization of ultrabasic rocks in Oman and California. The age of travertines determined by the radiocarbon method is close to modern.

Mass balance calculations of volatiles were performed for Mutnovsky volcano, Kamchatka, by comparing the chemical and isotopic compositions of gas emissions with the compositions of the main geochemical reservoirs in the subduction zone using a simple mixing model. The predominant deep component (up to 73% in the highest temperature fumaroles) is composed of slab fluid released during dehydration of the Pacific Plate. The mantle component does not exceed 2.1%. The fraction of gases from the continental crust varies from 0.5 to 5% depending on the composition of the crustal endmember that was used in the calculations. In terms of the gas composition, Mutnovsky volcano is a typical subduction volcano, but its fluid system has a complex structure. The observed compositional pattern in the volcanic fumaroles can be explained by degassing of two independent magma bodies.