Using water quality data collected at 289 monitoring sites as part of the Water Pollution Control Program, we evaluated the long-term trends of pH in Japanese coastal seawater at ambient temperature from 1978 to 2009. We found that the annual maximum pH, which generally represents the pH of surface waters in winter, had decreased at 75 % of the sites, but had increased at the remaining sites. The annual maximum pH decreased at an average rate of −0.0024 yr⁻¹, with relatively large deviations.

The major microbial process producing N₂O in estuarine ecosystems remains controversial. Combining the concentrations and isotopic compositions of N₂O, distributions and transcript levels of ammonia-oxidizing bacterial and archaeal amoA and denitrifier nirS genes, and in situ incubation estimates of nitrification rates and N₂O production rates, we clarified that ammonia-oxidizing bacteria contributed the major part in N₂O production in the upper Pearl River estuary despite their low abundance.

Agropedogenesis, i.e. soil development under agricultural use, is the anthropogenic modification of soil and environmental factors for optimization of crop production. Maximization of only this function, crop production, leads to declines in all other soil functions and consequently promotes uniformity in soil properties around the globe. Here we developed a new scientific background for the theory of agropedogenesis and the identification of soil degradation stages.

Isotopic signatures of silica fossils can be used as archives of past oceanic silicon cycling, which is linked to marine carbon uptake. However, the biochemistry that lies behind such chemical fingerprints remains poorly understood. We present the first measurements of silicon isotopes in a group of protists closely related to animals, choanoflagellates. Our results highlight a taxonomic basis to silica isotope signatures, possibly via a shared transport pathway in choanoflagellates and animals.

In shade-tolerant tree species, growth is not strictly related to tree age. In this study we show that novel tree ring standardization models that incorporate tree size in the year of ring formation produce more accurate chronologies than those produced by contemporary, age-based standardization models. These findings are important for accurate and reliable long-term trend reconstruction in tree ring studies in all species but are especially so for shade-tolerant species.

We studied the upper 10 m of deep-sea sediments, including pore water, in the Peru Basin to understand small-scale variability of trace metals. Our results show high spatial variability related to topographical variations, which in turn impact organic matter contents, degradation processes, and trace metal cycling. Another interesting finding was the influence of dissolving buried nodules on the surrounding sediment and trace metal cycling.

Bidirectional interactions between vegetation and climate are unraveled over short (monthly) and long (inter-annual) temporal scales. Analyses use a novel causal inference method based on wavelet theory. The performance of climate models at representing these interactions is benchmarked against satellite data. Climate models can reproduce the overall climate controls on vegetation at all temporal scales, while their performance at representing biophysical feedbacks on climate is less adequate.

The litter decomposition model DEMENT was run under ambient temperatures and with 5 °C; of warming. We found that the loss of litter carbon to the atmosphere as CO₂ was exacerbated by warming when the microbes in the model differed in their temperature responses, compared to when all microbes responded identically to warming. Our results therefore indicate that predicted changes in litter carbon stocks are sensitive to heterogeneity in key parameters of soil decomposer physiology.