Extensive surveys of the fluorescence and absorption of chromophore‐containing dissolved organic matter (CDOM), dissolved organic C (DOC) concentration, chlorophyll fluorescence, and salinity were performed during August and November 1993 and March and April 1994 along a cruise line extending from the mouth of Delaware Bay southeast to the Sargasso Sea. With shallow stratification in August, photobleaching dramatically altered the optical properties of the surface waters, with ∼70% of the CDOM absorption and fluorescence lost through photooxidation in the waters at the outer shelf. S, the slope of the log‐linearized absorption spectrum of CDOM, increased offshore and seemed to increase with photodegradation. The increase in S combined with the seasonal variation in the relationship between Chl and CDOM underscores the difficulty in developing algorithms to predict Chl concentrations in turbid coastal waters with ocean color data. Despite the photooxidation of CDOM, the seasonal variation in the CDOM fluorescence‐absorption relationship and fluorescence quantum yields was <15%. When using appropriate methods, the airborne lidar approach for remote determination of CDOM absorption coefficients seems to be a very robust technique. The photooxidation of CDOM in August also affected the relationship between CDOM and DOC concentration in the surface waters, although for the rest of the year the relationship was reasonably linear. The results of a simple model suggest ∼10% of the DOC in the mixed layer was directly converted photochemically to dissolved inorganic C (DIC).

Agriculture plays a key role in global food security. Agriculture is critical to global food security and economic development. Precision farming using machine learning (ML) and the Internet of Things (IoT) is a promising approach to increasing crop productivity and optimizing resource use. This paper presents an integrated crop and fertilizer recommendation system aimed at optimizing agricultural practices in Rwanda. The system is built on two predictive models: a machine learning model for crop recommendations and a rule-based fertilization recommendation model. The crop recommendation system is based on a neural network model trained on a dataset of major Rwandan crops and their key growth parameters such as nitrogen, phosphorus, potassium levels, and soil pH. The fertilizer recommendation system uses a rule-based approach to provide personalized fertilizer recommendations based on pre-compiled tables. The proposed prediction model achieves 97% accuracy. The study makes a significant contribution to the field of precision agriculture by providing decision support tools that combine artificial intelligence and domain knowledge.

The quantitative relationship between the absorption and fluorescence emission of chromophoric (colored) dissolved organic matter (CDOM) has been determined along five cruise tracks in the western North Atlantic Ocean, the Gulf of Mexico, and Monterey Bay, and includes Gulf Stream, Loop Current, slope, shelf, and coastal waters. We present a protocol for the determination of CDOM fluorescence that will allow both interlaboratory comparisons and the calibration of airborne fluorescence measurements. This protocol is based on the use of the water Raman signal as an internal radiometric standard and quinine sulfate as an external standard. This study demonstrates that when an appropriate and consistent procedure is used to standardize fluorescence measurements, the fluorescence per unit absorption exhibits surprisingly little variation for diverse waters. The maximum variability observed between all sites was 36% and within the western North Atlantic the variability was only 12%. Algorithms are presented for retrieval of the absorption coefficient of CDOM at 355 and 337 nm from shipboard or airborne measurements of the water‐Raman‐normalized fluorescence emission resulting from 355‐ and 337‐nm excitation.

We compared the fluorescence (λ_ex = 355 nm, λ_em = 450 nm) of chromophore‐containing dissolved organic matter (CDOM) determined in the laboratory to that determined with a shipboard fluorometer and an airborne laser fluorosensor off the U.S. mid‐Atlantic coast. Fluorescence was highly correlated with CDOM absorption at the excitation wavelength despite the presence of multiple sources of CDOM and a changing contribution of CDOM to the total dissolved organic C (DOC) pool, both in surface waters and down the water column. The mean quantum yield (0.8±0.1%) fell within the narrow range of yields previously determined for U.S. east coast and south Florida waters. These results show that CDOM absorption can be reliably determined from in situ or airborne fluorescence over wide areas of the ocean and that it may be possible to estimate DOC concentration from fluorescence or absorption measurements.